Publications

2020
Fang, A., & Ramaswami, A. (2020). Review of Fine-Scale Air Quality Modeling for Carbon and Health Co-Benefits Assessments in Cities. In Managing Air Quality and Energy Systems . Taylor & Francis.Abstract
Global cities are simultaneously taking action to improve air quality and mitigate climate change by reducing emissions from energy and infrastructure systems. Cities are uniquely positioned to achieve improved environmental policy by managing carbon, air pollution, and health co-benefits concurrently due to the concentration of people and economic activity in cities. By accounting for the air pollution co-benefits of carbon mitigation, cities may create more political support for reducing emissions and energy use due to the large health benefits of reducing local air pollution exposure. Given the policy-relevant implications of co-benefits at the city scale, this review evaluates the existing tools/models to assess both carbon and air pollution in urban environments.
Tabory, S., & Ramaswami, A. (2020). Considering the role of urban types in coproduced policy guidance for sustainability transitions. Urban Transformations , 2 (8).Abstract
The imperative to massively and quickly scale sustainability transitions in urban areas globally stands in tension with the sustained commitments required of grounded coproduction efforts that seek to deliver locally credible, relevant, and legitimate pathways for place-specific transitions. Is it possible to develop policy guidance that meets the magnitude of the urban transitions challenge while still leveraging the benefits of coproduction? We suggest that coproducing urban transitions guidance around relevant types of cities, as compared to specific individual cities, offers a potential pathway for scaling the impact of such guidance. However, little work has been done to explicitly interrogate how concepts of credibility, relevance and legitimacy are implicated by relying on urban types in coproduction processes. In this frontiers discussion, we describe what greater emphasis on the use of types and proxies in urban transitions coproduction might entail. Elaborating the concept of ‘coproduction-by-proxy’, we articulate six key premises and draw on two real-world instances of science-policy dialogue to illustrate its operative features. This frontiers discussion aims to supply more structured language for framing debate about whether, and how best, to strategically construct and deploy urban types in coproduction processes for developing urban transitions guidance, with an emphasis on maximizing generalization and impact, while maintaining both technical and political credibility. The discussion argues that exploring the role (and limits) of urban types and proxies in coproduction processes is a key frontier for the iterative science and practice of urban transitions, with implications for advancing both overall urban systems knowledge and place-specific sustainability transitions.
Hu, Y., Cui, S., Bai, X., Zhu, Y. - G., gaobing,, Ramaswami, A., Tang, J., et al. (2020). Transboundary environmental footprints of urban food supply chain and mitigation strategies. Environmental Science & Technology.Abstract
Food supply has been the central issue of human development for millennia and has become increasingly critical in an urbanizing world. However, the environmental footprints and associated mitigation strategies of food consumption have rarely been comprehensively characterized at urban or regional scales. Here we analyze the water, carbon, reactive nitrogen and phosphorus footprints of food consumption in Chinese urban regions, and demonstrate how such information can help to formulate tailored mitigation strategies. The results show that in three of the largest urban regions of China, 44–93% of the four footprints are embodied in transboundary food supply. The size of the footprints and the effectiveness of mitigation measures in food supply chain vary across the environmental footprints and urban regions. However, targeting agriculture and food processing sectors in Hebei, Shandong and Henan Provinces can reduce these footprints by up to 47%. Our findings show that the analysis of the environmental footprints along the transboundary food supply chains could inform individualized and effective mitigation targets and strategies.
Tao, T., Wu, X., Cao, J., Y., F., Das, K., & Ramaswami, A. (2020). Exploring the Nonlinear Relationship between the Built Environment and Active Travel in the Twin Cities. Journal of Planning Education and Research.Abstract
Active travel is important to public health and the environment. Previous studies substantiate built environment influences active travel, but they seldom assess its overall contribution. Most of the studies assume that built environment characteristics have linear associations with active travel. This study uses Gradient Boosting Decision Trees to explore nonlinear relationships between the built environment and active travel in the Twin Cities. Collectively, the built environment has more predictive power for active travel than demographics, and parks, proximity to downtown, and transit access have important influences. The threshold effects of built environment variables help inform planning practice.
Lal, R. M., Ramaswami, A., & Russell, A. (2020). Assessment of the Near-road (Monitoring) Network including comparison with nearby monitors within U.S. cities. Environmental Research Letters.Abstract
Emissions from mobile sources have historically been an important anthropogenic contributor to ambient air pollution leading to high levels of air pollution near major roadways. The US EPA recently implemented the Near-Road (monitoring) Network to measure NO2 concentrations by high-traffic roadways in urban centers throughout the US, as these locations were believed to characterize worst-case human exposures to traffic-related pollutants. Many near-road sites also include PM2.5 and CO measurements, which along with the NO2 observations, were compared in a pairwise manner against non-near-road monitors located within the city-scale boundary. After controlling for primary emissions from the target highways, we found no statistical difference (α = 0.05) in PM2.5 concentrations between the near-road and non-near-road urban sites (δ = 0.42 (-0.08-0.90) µg m-3, n=35 comparisons). NO2 and CO levels, on average were significantly higher at the near-road sites compared to the non-near-road urban sites by 5.0 (3.4-6.5) ppb (n=44 comparisons) and 9.2x10-2 (0.04-0.14) ppm (n=42 comparisons), respectively. The average PM2.5 difference found here is 5%, and at 14 of the 35 (~40%) urban monitor comparisons and 28 of the 72 (~39%) overall comparisons, PM2.5 is actually higher at the non-near-road site relative to its near-road pair. Cleaner vehicle fleets, formation of secondary PM from on-road emissions occurring downwind (i.e., away from the road), decreased SOA formation rates in the near-road environment, the prevalence of other low-volume vehicular and local, non-vehicular sources of emissions at the non-near-road sites (e.g., railyards, truck yards, ports, biomass-fueled heating, backyard barbecuing, and commercial cooking, etc.) and local meteorology (e.g. wind speed and wind direction) explain this finding. The same observational data was used to assess mobile source emission estimates from the EPA National Emission Inventory, and analysis of the observations are in rough agreement with the current ratio of NOx to CO from on-road mobile sources.
Lal, R. M., Das, K., Fan, Y., Barkjohn, K., Botchwey, N., Ramaswami, A., & Russell, A. G. (2020). Connecting Air Quality with Emotional Well-Being and Neighborhood Infrastructure in a US City. Environmental Health Insights.Abstract
Cities in the United States have announced initiatives to become more sustainable, healthy, resilient, livable, and environmentally friendly. However, indicators for measuring all outcomes related to these targets and the synergies between them have not been well defined or studied. One such relationship is the linkage between air quality with emotional well-being (EWB) and neighborhood infrastructure. Here, regulatory monitoring, low-cost sensors (LCSs), and air quality modeling were combined to assess exposures to PM2.5 and traffic-related NOx in 6 Minneapolis, MN, neighborhoods of varying infrastructure parameters (median household income, urban vs suburban, and access to light rail). Residents of the study neighborhoods concurrently took real-time EWB assessments using a smart phone application, Daynamica, to gauge happiness, tiredness, stress, sadness, and pain. Both LCS PM2.5 observations and mobile-source-simulated NOx were calibrated using regulatory observations in Minneapolis. No statistically significant (α = 0.05) PM2.5 differences were found between urban poor and urban middle-income neighborhoods, but average mobile-source NOx was statistically significantly (α = 0.05) higher in the 4 urban neighborhoods than in the 2 suburban neighborhoods. Close proximity to light rail had no observable impact on average observed PM2.5 or simulated mobile-source NOx. Home-based exposure assessments found that PM2.5 was negatively correlated with positive emotions such as happiness and to net affect (the sum of positive and negative emotion scores) and positively correlated (ie, a higher PM2.5 concentration led to higher scores) for negative emotions such as tiredness, stress, sadness, and pain. Simulated mobile-source NOx, assessed from both home-based exposures and in situ exposures, had a near-zero relationship with all EWB indicators. This was attributed to low NOx levels throughout the study neighborhoods and at locations were the EWB-assessed activities took place, both owing to low on-road mobile-source NOx impacts. Although none of the air quality and EWB responses were determined to be statistically significant (α = 0.05), due in part to the relatively small sample size, the results are suggestive of linkages between air quality and a variety of EWB outcomes.
Ramaswami, A., Fang, A., & Tabory, S. (2020). A Review of Integrated Urban Planning Tools for Greenhouse Gas Mitigation: Linking Land Use, Infrastructure Transition, Technology, and Behavioral Change. Global Platform for Sustainable Cities . World Bank Group.Abstract
Achieving the Sustainable Development Goals (SDGs) over the next 30 years will critically depend upon urban land use and infrastructure development actions taken across multiple sectors (buildings, energy, transportation, water-sanitation, and waste) in global cities. Integrated urban planning addresses a multiplicity of urban sustainability objectives (e.g., economy, environment, inclusivity, and resilience) (GPSC, World Bank 2018), including cross-sectoral and cross-scale linkages (Ramaswami et al. 2016) and connection of physical planning with social, cultural, behavior, and policy dimensions. Urban land use is foundational to integrated urban planning. Grounded in urban land use, four key levers have been identified that have significant potential to result in resource-efficient, inclusive, and low-carbon cities (IRP 2018):
 
1. Compact urban development (CUD) and land use
2. Single-sector infrastructure and technology innovations
3. Cross-infrastructure interventions
4. Policy and behavior change
 
Together, these four levers shape how urban land use and infrastructure provisioning will impact the SDGs, in particular the goal of reducing greenhouse gas (GHG) emissions associated with cities—which is a key objective of the Global Platform for Sustainable Cities (GPSC).
 
Together, the four levers can have a multiplicative effect that maximizes GHG mitigation potential and thus helps achieve the targets of the Paris Agreement. For example, an inclusive compact urban form (Lever 1) can reduce travel demand, reduce material use (via high-rise construction versus single-story homes that are typical of urban sprawl), and lower the cost of physical infrastructure networks. Building upon this compact urban form, additional efficiencies and low-carbon trajectories can be achieved both within individual sectors (Lever 2, e.g., by making each building more energy efficient or supplying it with renewable energy) and across sectors (Lever 3, e.g., by having a network of buildings dense enough to reuse waste heat through district energy systems). Human behavior is critical to ensure that resourceefficient technologies and urban form are deployed in a manner that reduces energy use overall (Lever 4). The objective of this report is to review the state of knowledge (science) and the state of practice (models actually used by cities for policy) for modeling the GHG mitigation benefits achievable through integrated urban planning across the four levers, with attention to the foundational Lever 1, CUD.
Newell, J., & Ramaswami, A. (2020). Urban food–energy–water systems: past, current, and future research trajectories. Environmental Research Letters.
Tong, K., Ramaswami, A., & Feiock, R. (2020). Environmentally sustainable transitions of US district energy systems: Perspectives from infrastructure operators/designers through the Co-evolutionary lens. Journal of Cleaner Production.Abstract
Advanced district energy systems can improve local sustainability (e.g., clean production, resilience, and carbon mitigation) through reducing energy used for heating and cooling buildings. However, district energy systems (DESs) and their transitions are overlooked by US communities in their sustainable agendas. This research applied the multi-level perspective and co-evolutionary framework to investigate DESs' transition context and niche level practices from DES operators'/designers' perspectives. Document review approach was adopted to delineate DESs' transition context. Fourteen semi-structured interviews were conducted to investigate DES operators'/designers' visions and how they interact with factors related to ecosystems, technology, institutions, and users. This research found that DESs served about 10% and 12% of fully air-conditioned floor space for heating and cooling, respectively. About 93% of services provided by DESs were fueled by fossil fuels, and 79% of DESs distributed steam. Current federal and state policies did not promote DESs, while local policies can only encourage niche-level innovations. Results from interviews demonstrated that DES operators/designers foresaw that DESs would move toward the advanced ones. DES operators/designers were motivated by the users’ demand and emerging local policy preferences to take action. DES operators/designers emphasized the importance of working closely with users and policymakers, engaging potential customers, and tapping into technical expertise during the process of transition. These results indicate that DES operators took on many responsibilities with limited policy and market support. With low pressure to select DESs as a key sustainability tool at the regime level, the development of DESs may only remain at the niche level.
Zeng, L., & Ramaswami, A. (2020). Impact of locational choices and consumer behaviors on personal land footprints: An exploration across the urban-rual continuum in USA. Environmental Science & Technology.Abstract
Land is a scarce resource. We develop consumption-based land footprints (CBLF) for urban and rural US residents to evaluate new levers for reducing land-demand by combining: 1) direct land-use for human settlements including housing, 2) indirect land-use associated with personal consumptions, e.g., food and clothing. Results show that an average urban resident’s indirect land-use (199,176 ft2/capita) is ~23 times the direct land-use (8519 ft2/capita), for a total urban CBLF of 207,695 ft2/capita. Rural residents have a slightly higher (~6%) indirect land-use and ~10 times larger direct land-use compared to urban. As in both cases, indirect land-use is much larger than direct, a strategic mix of individual actions including halving food waste (-4.7%), one-day weekly plant-based diet (-3.3%), reducing clothing consumption (-2.8%), and others, can together reduce CBLF by -12.8%. Meanwhile, housing and locational choices across the urban-rural continuum evaluated for the median-density Minneapolis-St. Paul Metropolitan Statistical Area (MSP MSA) yield CBLF reductions from -1.9% (from single- to multi-family housing) to -10.6% (from rural to the urban core). The analysis demonstrates that consumer behavior changes could rival housing/locational choices in order to reduce personal CBLF. Our method of combining input-output analysis with parcel data could be applied in different regions to provide customized land conservation information.
Ambrose, G., Das, K., Fan, Y., & Ramaswami, A. (2020). Is gardening associated with greater happiness of urban residents? A multi-activity, dynamic assessment in the Twin-Cities region, USA. Landscape and Urban Planning.Abstract
As cities seek to become more livable and environment-friendly, activities like bicycling, walking, and urban gardening (household and community-gardening) are receiving much attention. However, few field studies have measured well-being of urban gardening, particularly during household gardening. Our study develops protocols to measure emotional well-being (EWB) reported during household gardening, comparing it with other leisure and day-to-day activities. We also explore how gardening EWB varies across gardener type (vegetable vs ornamental), demographics, neighborhood type, and companionship during gardening. Using a recently developed app-based Day Reconstruction Method, EWB was measured across 370 participants in the Minneapolis-St. Paul Area, USA, wherein 118 (32%) reported engaging in household gardening. Innovatively, five measures of EWB were computed for each participant for each activity type: average net affect, average happiness, average meaningfulness, the frequency of experiencing peak positive emotions (happiness and meaningfulness). Among all three average EWB measures, gardening is among the top 5 out of 15 activities assessed, and, is not statistically different from biking, walking and eating out. All four of these activities fall behind other leisure/recreation activities, which ranks first. For frequency of experiencing peak happiness, only other leisure/recreation activities were statistically higher than all the remaining (14) activities. Average net affect of gardening was significantly higher for vegetable gardeners (vs ornamental), for low-income gardeners (vs higher income) and for women. Companionship while gardening at home, race/ethnicity and urban versus suburban location showed no significant difference. Livability and equity considerations based on these EWB findings, and their impacts on urban food plans, are discussed.
Ramaswami, A. (2020). Unpacking the urban infrastructure nexus with environment, health, livability, well-being, and equity. One Earth.Abstract
Multi-objective sustainability planning in cities must address seven physical provisioning systems that are key to advancing local and planetary well-being. Recent progress in environmental and health footprinting, combined with new frontiers in unpacking infrastructure-well-being relationships, will advance urban nexus science to provide customizable information toward inclusive well-being on a finite planet, one city at a time, across the globe.
Boyer, D., & Ramaswami, A. (2020). Comparing urban food system characteristics and actions in US and Indian cities from a multi‐environmental impact perspective: Toward a streamlined approach. Journal of Industrial Ecology.Abstract
Food action plans in many global cities articulate interest in multiple objectives including reducing in‐ and trans‐boundary environmental impacts (water, land, greenhouse gas (GHG)). However, there exist few standardized analytical tools to compare food system characteristics and actions across cities and countries to assess trade‐offs between multiple objectives (i.e., health, equity) with environmental outcomes. This paper demonstrates a streamlined model applied for analysis of four cities with varying characteristics across the United States and India, to quantify system‐wide water, energy/GHG, and land impacts associated with multiple food system actions to address health, equity, and environment. Baseline diet analysis finds key differences between countries in terms of meat consumption (Delhi 4; Pondicherry 16; United States 59, kg/capita/year), and environmental impact of processing of the average diet (21%, 19%, <1%, <1% of community‐wide GHG‐emissions for New York, Minneapolis, Delhi, and Pondicherry). Analysis of supply chains finds city average distance (food‐miles) varies (Delhi 420; Pondicherry 200; United States average 1,640 km/t‐food) and the sensitivity of GHG emissions of food demand to spatial variability of energy intensity of irrigation is greater in Indian than US cities. Analysis also finds greater pre‐consumer waste in India versus larger post‐consumer accumulations in the United States. Despite these differences in food system characteristics, food waste management and diet change consistently emerge as key strategies. Among diet scenarios, all vegetarian diets are not found equal in terms of environmental benefit, with the US Government's recommended vegetarian diet resulting in less benefit than other more focused targeted diet changes.
2019
Boyer, D., Sarkar, J., & Ramaswami, A. (2019). Diets, Food Miles, and Environmental Sustainability of Urban Food Systems: Analysis of Nine Indian Cities. Earth’s Future.Abstract
With ever‐growing populations, cities are increasingly interested in ensuring a well‐functioning food system. However, knowledge of variation between individual city food systems is limited. This is particularly true in countries such as India, experiencing significant issues related to food security and sustainability. This paper advances the understanding of urban food systems, by analyzing the unique food systems of nine cities within India, through the integration of multiple city‐specific data sources including demand of residents, visitors and industries, and commodity‐specific supply chains to assess nutrition, environmental impact, and supply risk. This work finds a large degree of intercity food system variability across multiple food system characteristics. Specifically, levels of undernutrition vary, with the percentage of city populations who are underconsuming protein ranging from 0% to 70%, and for calories 0% to 90%. Environmental impacts (consumptive water loss, land use, and greenhouse gas emissions) of urban food demand also show variation, largely influenced by differing composition of residential diet. Greenhouse gas emissions are also largely influenced by location of production and spatially informed energy intensity of irrigation. Supply chain distance (“food‐miles”) also vary by city, with the range of 196 (Pondicherry) to 1,137 (Chennai) km/Mg—shorter than more industrialized nations such as the United States. Evaluating supply chain risk in terms of water scarcity in food‐producing regions that serve city demand finds production locations, on average, to be less water‐scarce than the watersheds local to the urban environments. This suggests water‐intensive agriculture may at times be best located at a distance from urban centers and competing demands.
Wu, X., Tao, T., Cao, J., Fan, Y., & Ramaswami, A. (2019). Examining threshold effects of built environment elements on travel-related carbon-dioxide emissions. Transportation Research Part D: Transport and Environment.Abstract
Understanding how built environment features are associated with travel-related carbon-dioxide (CO2) emissions is essential for planners to encourage environmentally sustainable travel through transportation and land use policies. Applying gradient boosting decision trees to the data from the Minneapolis-St. Paul metropolitan area, this study addresses two gaps in the literature by identifying critical built environment determinants of CO2 emissions, and more importantly, illustrating threshold effects of built environment elements. The results show that three neighborhood-level built environment factors have the strongest influences on CO2 emissions: distance to the nearest transit stop, job density, and land use diversity. The distance to downtowns also has a substantial impact. This study further confirms that built environment variables are effective only within a certain range. These threshold effects offer valuable implications for planners to achieve desirable environmental benefits efficiently.
Tong, K., Zhao, Z., Feiock, R., & Ramaswami, A. (2019). Patterns of urban infrastructure capital investment in Chinese cities and explanation through a political market lens. Journal of Urban Affairs.Abstract
Cities across the developing world have experienced great challenges in making sufficient capital investment in urban infrastructure (CIUI) during periods of rapid urbanization, yet this phenomenon has captured little academic attention. Focusing on Chinese cities, this study analyzed the investment patterns at the temporal, sectoral, and spatial scales and investigated the drivers through the lens of the political market framework. China’s national CIUI, relying mainly on local revenue sources, increased steadily from 2000 to 2014. The patterns of CIUI across cities indicated polarized investment attributable to the influence of public demand and governmental supply mediated by intergovernmental political institutions. These findings advance our understanding of urban infrastructure investment in the course of rapid urbanization.
Yuan, S., Stainsby, W., Li, M., Xu, K., Waite, M., Zimmerle, D., Feiock, R., et al. (2019). Future energy scenarios with distributed technology options for residential city blocks in three climate regions of the United States. Applied Energy.Abstract
To reduce greenhouse gas emissions, the electricity sector is going through two main transitions. First, the electric grid is integrating variable renewable generation, such as wind and solar. Second, demands are changing as heating systems are shifting from gas-based to high efficiency electric heat pumps. This paper provides a comparative analysis of future energy scenarios with distributed technology options including (1) wind and solar generation; (2) heat pumps for heating and cooling; and (3) battery and thermal storage in representative residential blocks in four cities, including New York City, New York; Minneapolis, Minnesota; Tallahassee, Florida; and Fort Collins, Colorado. These cities are located in three climate regions with different weather patterns which result in different demand profiles and different local renewable resources. Future energy demand scenarios with 100% penetration of air source or ground source heat pumps for heating and cooling are estimated for the four residential city blocks. Under a future scenario with all electric demand with air source heat pumps and high renewable energy penetration, this study finds that (1) the optimal wind and solar generation mix varies with location and amount of storage and (2) battery storage is more cost effective than thermal storage, ground source heat pumps, and overbuilt renewable generation.
Servadio, J., Lawal, A., Davis, T., Bates, J., Russell, A., Ramaswami, A., Convertino, A., et al. (2019). Demographic Inequities in Health Outcomes and Air Pollution Exposure in the Atlanta Area and its Relationship to Urban Infrastructure. Journal of Urban Health.Abstract
Environmental burdens such as air pollution are inequitably distributed with groups of lower socioeconomic statuses, which tend to comprise of large proportions of racial minorities, typically bearing greater exposure. Such groups have also been shown to present more severe health outcomes which can be related to adverse pollution exposure. Air pollution exposure, especially in urban areas, is usually impacted by the built environment, such as major roadways, which can be a significant source of air pollution. This study aims to examine inequities in prevalence of cardiovascular and respiratory diseases in the Atlanta metropolitan region as they relate to exposure to air pollution and characteristics of the built environment. Census tract level data were obtained from multiple sources to model health outcomes (asthma, chronic obstructive pulmonary disease, coronary heart disease, and stroke), pollution exposure (particulate matter and nitrogen oxides), demographics (ethnicity and proportion of elderly residents), and infrastructure characteristics (tree canopy cover, access to green space, and road intersection density). Conditional autoregressive models were fit to the data to account for spatial autocorrelation among census tracts. The statistical model showed areas with majority African-American populations had significantly higher exposure to both air pollutants and higher prevalence of each disease. When considering univariate associations between pollution and health outcomes, the only significant association existed between nitrogen oxides and COPD being negatively correlated. Greater percent tree canopy cover and green space access were associated with higher prevalence of COPD, CHD, and stroke. Overall, in considering health outcomes in connection with pollution exposure infrastructure and ethnic demographics, demographics remained the most significant explanatory variable.
Pant, P., Lal, R. M., Guttikunda, S. K., Russell, A. G., Nagpure, A. S., Ramaswami, A., & Peltier, R. E. (2019). Monitoring particulate matter in India: recent trends and future outlook. Air Quality, Atmosphere and Health.Abstract
Air quality remains a significant environmental health challenge in India, and large sections of the population live in areas with poor ambient air quality. This article presents a summary of the regulatory monitoring landscape in India, and includes a discussion on measurement methods and other available government data on air pollution. Coarse particulate matter (PM10) concentration data from the national regulatory monitoring network for 12 years (2004–2015) were systematically analyzed to determine broad trends. Less than 1% of all PM10 measurements (11 out of 4789) were found to meet the annual average WHO Air Quality Guideline (20 μg/m3), while 19% of the locations were in compliance with the Indian air quality standards for PM10 (60 μg/m3). Further efforts are necessary to improve measurement coverage and quality including the use of hybrid monitoring systems, harmonized approaches for sampling and data analysis, and easier data accessibility.
Chen, G., Shan, Y., Hu, Y., Tong, K., Wiedmann, T., Ramaswami, A., Guan, D., et al. (2019). Review on City-Level Carbon Accounting. Environmental Science & Technology.Abstract
Carbon accounting results for the same city can differ due to differences in protocols, methods, and data sources. A critical review of these differences and the connection among them can help to bridge our knowledge between university-based researchers and protocol practitioners in accounting and taking further mitigation actions. The purpose of this study is to provide a review of published research and protocols related to city carbon accounting, paying attention to both their science and practical actions. To begin with, the most cited articles in this field are identified and analyzed by employing a citation network analysis to illustrate the development of city-level carbon accounting from three perspectives. We also reveal the relationship between research methods and accounting protocols. Furthermore, a timeline of relevant organizations, protocols, and projects is provided to demonstrate the applications of city carbon accounting in practice. The citation networks indicate that the field is dominated by pure-geographic production-based and community infrastructure-based accounting; however, emerging models that combine economic system analysis from a consumption-based perspective are leading to new trends in the field. The emissions accounted for by various research methods consist essentially of the scope 1–3, as defined in accounting protocols. The latest accounting protocols include consumption-based accounting, but most cities still limit their accounting and reporting from pure-geographic production-based and community infrastructure-based perspectives. In conclusion, we argue that protocol practitioners require support in conducting carbon accounting, so as to explore the potential in mitigation and adaptation from a number of perspectives. This should also be a priority for future studies.
Chertow, M., Gordon, M., Hirsch, P., & Ramaswami, A. (2019). Industrial symbiosis potential and urban infrastructure capacity in Mysuru, India. Environmental Research Letters.Abstract
If the material intensive enterprises in an urban area of several million people shared physical resources that might otherwise be wasted, what environmental and public benefits would result? This study develops an algorithm based on lifecycle assessment tools for determining a city's industrial symbiosis potential—that is, the sum of the wastes and byproducts from a city's industrial enterprises that could reasonably serve as resource inputs to other local industrial processes. Rather than report, as do many previous papers, on private benefits to firms, this investigation focuses on public benefits to cities by converting the maximum quantity of resources recoverable by local enterprises into an estimate of the capacity of municipal infrastructure conserved in terms of landfill space and water demand. The results here test this novel approach for the district of Mysuru (Mysore), India. We find that the industrial symbiosis potential calculated based on analysis of the inputs and outputs of ~1000 urban enterprises, translates into 84 000 tons of industrial waste, greater than 74 000 tons of CO2e, and 22 million liters per day of wastewater. The method introduced here demonstrates how industrial symbiosis links private production and public infrastructure to improve the resource efficiency of a city by creating an opportunity to extend the capacity of public infrastructure and generate public health co-benefits.
2018
Ramaswami, A., Tabory, S., McFarlane, A., & Pelton, R. (2018). Sustainable Urban Infrastructure Transitions in the ASESAN Region: A Resource Perspective.Abstract
This regional report is based on the global findings of The Weight of Cities: Resource Requirements of Future Urbanization . However it distinguishes itself by taking into account the unique population, economic, infrastructure, socio-cultural and governance contexts of the cities in Southeast Asia (focusing on members of the ASEAN).
Swilling, M., Hajer, M., Baynes, T., Bergesen, J., Labbe, F., Musango, J. K., Ramaswami, A., et al. (2018). The Weight of Cities: Resource Requirements of Future Urbanization . United Nations Environment Programme, International Resource Panel.Abstract
With the world population expected to swell by almost two and a half billion people by 2050, new and existing cities must accommodate many of them. Depending on the choices we make, this could exacerbate existing problems like pollution, congestion, lack of infrastructure or public services, and marginalization of the poor. Or, if we rethink urban living and its governance, it could equally be an opportunity to develop the low-carbon, resource-efficient and socially just cities called for in the New Urban Agenda. This assessment report from the International Resource Panel, explores this transition through urban planning, investment in resource efficient infrastructure technologies and entrepreneurial governance. Note: Lead and contributing authors other than MS and MH are listed alphabetically.
Ramaswami, A., Bettencourt, L., Clarens, A., Das, S., Fitzgerald, G., Irwin, E., Pataki, D., et al. (2018). Sustainable Urban Systems: Articulating a Long-Term Convergence Research Agenda.Abstract

A report by the Advisory Committee for Environmental Research and Education, prepared by the Sustainable Urban Systems Subcommittee. Sponsored by the National Science Foundation.

This report articulates a vision and a compelling research agenda for developing the next generation of sustainable urban systems science.

Nixon, P., & Ramaswami, A. (2018). Assessing Current Local Capacity for Agrifood Production To Meet Household Demand: Analyzing Select Food Commodities across 377 U.S. Metropolitan Areas. Environmental Science & Technology.Abstract
Increasing food production in local urban and peri-urban areas is articulated as a potential way for local governments to achieve multiple sustainability outcomes (environmental, social, and human health). However, scientific judgements on localization are difficult to make because the degree of current food localization has not been systematically measured or defined across large numbers of cities. We develop new methods to quantify current local capacity for food production to meet total household agrifood demand, harmonizing bottom-up and top-down approaches to assess direct-plus-embodied agrifood demand of both fresh and processed foods. We find unique patterns of localization for different agrifoods, with 21% of U.S. metropolitan statistical areas (MSAs) currently capable of local self-sufficiency for eggs and milk equivalents embodied in diet, versus 12% and 16% of MSAs self-sufficient in fruits and vegetables, respectively. Focusing only on the direct fresh food demand, increased current local capacity (e.g., 45% MSAs self-sufficient in direct fluid milk), which also increases with production distances around cities. Overall, significant agricultural production is found to already occur in and around U.S. MSAs for these items. Multivariable analysis finds that state policies that promote urban agriculture may influence greater localization, which, interestingly, is independent of population density. Such spatial demand-production analysis is the first step in informing sustainable city or regional food policies and envisioning spatial food supply chains to urban areas.
Tong, K., Zhao, Z., Feiock, R., & Ramaswami, A. (2018). Patterns of urban infrastructure capital investment in Chinese cities and explanation through a political market lens. Journal of Urban Affairs.Abstract
Cities across the developing world have experienced great challenges in making sufficient capital investment in urban infrastructure (CIUI) during periods of rapid urbanization, yet this phenomenon has captured little academic attention. Focusing on Chinese cities, this study analyzed the investment patterns at the temporal, sectoral, and spatial scales and investigated the drivers through the lens of the political market framework. China’s national CIUI, relying mainly on local revenue sources, increased steadily from 2000 to 2014. The patterns of CIUI across cities indicated polarized investment attributable to the influence of public demand and governmental supply mediated by intergovernmental political institutions. These findings advance our understanding of urban infrastructure investment in the course of rapid urbanization.
Tong, K., Fang, A., Li, Y., Shi, L., Wang, Y., Wang, S., & Ramaswami, A. (2018). The collective contribution of Chinese cities to territorial and electricity-related CO2 emissions. Journal of Cleaner Production.Abstract
Many studies have quantified carbon emissions from a subset of cities in a nation, while few studies have estimated emissions from all cities in a nation to assess their collective contributions towards national total. This paper focuses on China and assesses the collective contribution of all cities to national carbon emissions, the share of carbon emissions by city types, and carbon emission per capita and per GDP. This paper describes the Chinese City Industrial-Infrastructure database including fuel/electricity use and heat supply in 644 cities, in which energy use is aligned with national data with ∼1% difference. It is found that direct carbon emissions from 644 Chinese cities collectively contribute to 62.4% of the national CO2 emissions. Further categorizing these cities based on population size, economic structure (Highly-Industrial, Highly-Commercial, and Mixed-Economy cities), and administrative level, it is found that Midsize cities (0.5–3 million) accounted for 38.1% of national CO2 emissions; Mixed-Economy cities contributed to about 40% of the national CO2 emissions; and city propers (all urban administrative districts in a city) collectively contribute to 42.9% of the national CO2 emissions. Direct emissions per capita ranged from 0.94 to 83.3 tonnes CO2 per person (8.85 tonnes/person on average). Direct emissions per GDP ranged from 0.01 to 2.60 kg CO2 per yuan-GDP (0.26 kg CO2/yuan-GDP on average). Direct plus embedded emissions in electricity were also evaluated and found to have similar patterns as direct carbon emissions. These results enhance our understanding of the share of carbon emissions from Chinese cities and suggest the importance of focusing on certain city types for mitigation efforts.
Feiock, R., Curley, C., Shen, R., Chen, L., Xu, K., Lim, T., Wassel, K., et al. (2018). The Science, Policy and Governance of Smart and Sustainable Cities: Policy Design and Voluntary Compliance in Energy Programs. Association for Public Policy Analysis and Management.Abstract
This paper is part of a larger project investigating the role of politics and policy design on suitability and energy transitions from the FSU participants in the Sustainable Healthy Cities Network. The City of Tallahassee FL is used as a test bed to examine how policy design is linked to individual behavior and outcomes. This specific piece examines voluntary compliance and explores actor motivations to comply with non-mandatory directives. We investigate the conditions and motivations shaping household-level decisions related to voluntary compliance within an energy audit (low-commitment) and a loan (high-commitment) program. We find evidence of different economic and social motivations at play, and discuss the research implications for policy design and implementation.
Nagpure, A. S., Reiner, M., & Ramaswami, A. (2018). Resource requirements of inclusive urban development in India: insights from ten cities. Environmental Research Letters.Abstract
This paper develops a methodology to assess the resource requirements of inclusive urban development in India and compares those requirements to current community-wide material and energy flows. Methods include: (a) identifying minimum service level benchmarks for the provision of infrastructure services including housing, electricity and clean cooking fuels; (b) assessing the percentage of homes that lack access to infrastructure or that consume infrastructure services below the identified benchmarks; (c) quantifying the material requirements to provide basic infrastructure services using India-specific design data; and (d) computing material and energy requirements for inclusive development and comparing it with current community-wide material and energy flows. Applying the method to ten Indian cities, we find that: 1%–6% of households do not have electricity, 14%–71% use electricity below the benchmark of 25 kWh capita-month−1; 4%–16% lack structurally sound housing; 50%–75% live in floor area less than the benchmark of 8.75 m2 floor area/capita; 10%–65% lack clean cooking fuel; and 6%–60% lack connection to a sewerage system. Across the ten cities examined, to provide basic electricity (25 kWh capita-month−1) to all will require an addition of only 1%–10% in current community-wide electricity use. To provide basic clean LPG fuel (1.2 kg capita-month−1) to all requires an increase of 5%–40% in current community-wide LPG use. Providing permanent shelter (implemented over a ten year period) to populations living in non-permanent housing in Delhi and Chandigarh would require a 6%–14% increase over current annual community-wide cement use. Conversely, to provide permanent housing to all people living in structurally unsound housing and those living in overcrowded housing (<5 m cap−2) would require 32%–115% of current community-wide cement flows. Except for the last scenario, these results suggest that social policies that seek to provide basic infrastructure provisioning for all residents would not dramatically increasing current community-wide resource flows.
2017
Bringezu, S., Ramaswami, A., Schandl, H., O'Brien, M., Pelton, R., Acquatella, J., Ayuk, E., et al. (2017). Assessing global resource use: A systems approach to resource efficiency and pollution reduction . United Nations Environment Programme, International Resource Panel.Abstract

The way in which societies use and care for natural resources fundamentally shapes the well-being of humanity, the environment and the economy. Better and more efficient use of natural resources can be one of the most cost-efficient and effective ways to reduce impacts on the environment, while also achieving the socio-economic objectives of international sustainable development and climate goals. Viable pathways exist for society to undertake such decoupling of economic growth from natural resource use and environmental impacts. But how can we get there?

Environmental and sustainability policies require a new evidence base that makes it possible to monitor the scale of the physical economy, that is – the amount of material, energy, water and land used and emissions generated in making, using and providing goods, services and infrastructure systems.

This publication provides an assessment of the state, trends and outlook of global natural resource use, with a focus on material resources as part of the evidence base for policymaking for sustainable consumption and production.

The report pinpoints seven strategies for system-wide pollution reduction and more sustainable resource use throughout the economy, including consideration of appropriate policy instruments and good practice examples from cities and countries around the world.

Ramaswami, A. (2017). Towards zero-pollution cities: Urban infrastructure transformations can produce resource-efficient, inclusive and healthy cities.
Ramaswami, A., Tong, K., Fang, A., Lal, R. M., Nagpure, A. S., Li, Y., Yu, H., et al. (2017). Urban cross-sector actions for carbon mitigation with local health co-benefits in China. Nature Climate Change.
Tong, K., Fang, A., Yu, H., Li, Y., Shi, L., Wang, Y., Wang, S., et al. (2017). Estimating the potential for industrial waste heat reutilization in urban district energy systems: Method development and implementation in two Chinese provinces. Environmental Research Letters.
Sperling, J. B., & Ramaswami, A. (2017). Cities and “budget-based” management of the energy-water-climate nexus: Case studies in transportation policy, infrastructure systems, and urban utility risk management. Environmental Progress and Sustainable Energy.
Boyer, D., & Ramaswami, A. (2017). What Is the Contribution of City-Scale Actions to the Overall Food System's Environmental Impacts?: Assessing Water, Greenhouse Gas, and Land Impacts of Future Urban Food Scenarios. Environmental Science & Technology.
Miller-Robbie, L., Ramaswami, A., & Amerasinghe, P. (2017). Wastewater treatment and reuse in urban agriculture: Exploring the food, energy, water, and health nexus in Hyderabad, India. Environmental Research Letters.
Yi, H., Suo, L., Shen, R., Zhang, J., Ramaswami, A., & Feiock, R. (2017). Regional Governance and Institutional Collective Action for Environmental Sustainability. Public Administration Review.
Ramaswami, A., Jiang, D., Tong, K., & Zhao, J. (2017). Impact of the Economic Structure of Cities on Urban Scaling Factors: Implications for Urban Material and Energy Flows in China. Journal of Industrial Ecology.
Ramaswami, A., Boyer, D., Nagpure, A. S., Fang, A., Bogra, S., Bakshi, B., Cohen, E., et al. (2017). An urban systems framework to assess the trans-boundary food-energy-water nexus: Implementation in Delhi, India. Environmental Research Letters.
2016
Ramaswami, A., Russell, A. G., Culligan, P. J., Sharma, K. H., & Kumar, E. (2016). Meta-principles for developing smart, sustainable, and healthy cities. Science.Abstract
Policy directives in several nations are focusing on the development of smart cities, linking innovations in the data sciences with the goal of advancing human well-being and sustainability on a highly urbanized planet. To achieve this goal, smart initiatives must move beyond city-level data to a higher-order understanding of cities as transboundary, multisectoral, multiscalar, social-ecological-infrastructural systems with diverse actors, priorities, and solutions. We identify five key dimensions of cities and present eight principles to focus attention on the systems-level decisions that society faces to transition toward a smart, sustainable, and healthy urban future.
Ramaswami, A., Baidwan, N. K., & Nagpure, A. J. (2016). Exploring social and infrastructural factors affecting open burning of municipal solid waste (MSW) in Indian cities: A comparative case study of three neighborhoods of Delhi. Waste Management & Research.Abstract
Open municipal solid waste (MSW)-burning is a major source of particulate matter emissions in developing world cities. Despite a legal ban, MSW-burning is observed ubiquitously in Indian cities with little being known about the factors shaping it. This study seeks to uncover social and infrastructural factors that affect MSW-burning at the neighborhood level. We couple physical assessments of the infrastructure provision and the MSW-burning incidences in three different neighborhoods of varying socio-economic status in Delhi, with an accompanying study of the social actors (interviews of waste handlers and households) to explore the extent to which, and potential reasons why, MSW-burning occurs. The observed differences in MSW-burning incidences range from 130 km−2 day−1 in low-income to 30 km−2 day−1 in the high-income areas. However, two high-income areas neighborhoods with functional infrastructure service also showed statistical differences in MSW-burning incidences. Our interviews revealed that, while the waste handlers were aware of the health risks associated with MSW-burning, it was not a high priority in the context of the other difficulties they faced. The awareness of the legal ban on MSW-burning was low among both waste handlers and households. In addition to providing infrastructure for waste pickup, informal restrictions from residents and neighborhood associations can play a significant role in restricting MSW-burning at the neighborhood scale. A more efficient management of MSW requires a combined effort that involves interplay of both social and infrastructural systems.
Lal, R. M., Nagpure, A. S., Luo, L., Tripathi, S. N., Ramaswami, A., Bergin, M. H., & Russell, A. (2016). Municipal solid waste and dung cake burning: discoloring the Taj Mahal and human health impacts in Agra. Environmental Research Letters.Abstract
The Taj Mahal—an iconic World Heritage monument built of white marble—has become discolored with time, due, in part, to high levels of particulate matter (PM) soiling its surface (Bergin et al 2015 Environ. Sci. Technol. 49 808–812). Such discoloration has required extensive and costly treatment (2015 Two Hundred Sixty Second Report on Effects of Pollution on Taj Parliament of India Rajya Sabha, New Delhi) and despite previous interventions to reduce pollution in its vicinity, the haze and darkening persists (Bergin et al 2015 Environ. Sci. Technol. 49 808–812; 2015 Two Hundred Sixty Second Report on Effects of Pollution on Taj Parliament of India Rajya Sabha, New Delhi). PM responsible for the soiling has been attributed to a variety of sources including industrial emissions, vehicular exhaust and biomass burning, but the contribution of the emissions from the burning of open municipal solid waste (MSW) may also play an important role. A recent source apportionment study of fine particulate matter (PM2.5) at the Taj Mahal showed biomass burning emissions, which would include MSW emissions, accounted for nearly 40% of organic matter (OM)—a component of PM—deposition to its surface (Bergin et al 2015 Environ. Sci. Technol. 49 808–812); dung cake burning, used extensively for cooking in the region, was the suggested culprit and banned within the city limits (2015 Two Hundred Sixty Second Report on Effects of Pollution on Taj Parliament of India Rajya Sabha, New Delhi), although the burning of MSW, a ubiquitous practice in the area (Nagpure et al 2015 Environ. Sci. Technol. 49 12904–12), may play a more important role in local air quality. Using spatially detailed emission estimates and air quality modeling, we find that open MSW burning leads to about 150 (±130) mg m−2 yr−1 of PM2.5 being deposited to the surface of the Taj Mahal compared to about 12 (±3.2) mg m−2 yr−1 from dung cake burning. Those two sources, combined, also lead to an estimated 713 (377–1050) premature mortalities in Agra each year, dominated by waste burning in socioeconomically lower status neighborhoods. An effective MSW management strategy would reduce soiling of the Taj Mahal, improve human health, and have additional aesthetic benefits.
Bringezu, S., Potočnik, J., Schandl, H., Lu, Y., Ramaswami, A., Swilling, M., & Suh, S. (2016). Multi-Scale Governance of Sustainable Natural Resource Use—Challenges and Opportunities for Monitoring and Institutional Development at the National and Global Level. Sustainability.Abstract
In a globalized economy, the use of natural resources is determined by the demand of modern production and consumption systems, and by infrastructure development. Sustainable natural resource use will require good governance and management based on sound scientific information, data and indicators. There is a rich literature on natural resource management, yet the national and global scale and macro-economic policy making has been underrepresented. We provide an overview of the scholarly literature on multi-scale governance of natural resources, focusing on the information required by relevant actors from local to global scale. Global natural resource use is largely determined by national, regional, and local policies. We observe that in recent decades, the development of public policies of natural resource use has been fostered by an “inspiration cycle” between the research, policy and statistics community, fostering social learning. Effective natural resource policies require adequate monitoring tools, in particular indicators for the use of materials, energy, land, and water as well as waste and GHG emissions of national economies. We summarize the state-of-the-art of the application of accounting methods and data sources for national material flow accounts and indicators, including territorial and product-life-cycle based approaches. We show how accounts on natural resource use can inform the Sustainable Development Goals (SDGs) and argue that information on natural resource use, and in particular footprint indicators, will be indispensable for a consistent implementation of the SDGs. We recognize that improving the knowledge base for global natural resource use will require further institutional development including at national and international levels, for which we outline options.
Zhang, C., Cao, X., & Ramaswami, A. (2016). A novel analysis of consumption-based carbon footprints in China: Unpacking the effects of urban settlement and rural-to-urban migration. Global Environmental Change.
Tong, K., Fang, A., Boyer, D., Hu, Y., Cui, S., Shi, L., Kalmykova, Y., et al. (2016). Greenhouse gas (GHG) emissions from key infrastructure sectors in large and smaller Chinese cities: method development and benchmarking. Carbon Management.
Reiner, M. B., & Ramaswami, A. (2016). What Is Remedial Secondary Infrastructure? Implications for Infrastructure Design, Policy for Sustainability, and Resilience. Journal of Infrastructure Systems.
2015
Nagpure, A. S., Ramaswami, A., & Russell, A. (2015). Characterizing the Spatial and Temporal Patterns of Open-burning of Municipal Solid Waste (MSW) in Indian Cities. Environmental Science & Technology.Abstract
Open-burning of municipal solid waste (MSW) is a major source of PM emissions in developing world cities, but few studies have characterized this phenomenon at the city and intracity (neighborhood) scale relevant to human health impacts. This paper develops a consistent field method for measuring the spatial frequency of the incidence of MSW-burning and presents results in three neighborhoods of varying socioeconomic status (SES) in Delhi, India, observed in winter and summer over 2 years. Daily MSW-burning incidents ranged from 24 to 130/km2-day during winter and 5–87/km2-day during summer, with the highest intensity in low SES neighborhoods. Distinct seasonal and diurnal patterns are observed. The daily mass of MSW-burned was also estimated at 90–1170 kg/km2-day and 13–1100 kg/km2-day in highest to low SES neighborhoods, in winter and summer, respectively. The scaled-up estimate of total MSW-burned for Delhi city ranged from 190 to 246 tons/day, about 2%–3% of total generated MSW; morning-burning contributed >65% of the total. MSW composition varied systematically across neighborhoods and season. Agra had much higher MSW-burning (39–202 incidents/km2-day; 672–3485 kg/km2-day) in the summer. The field method thus captures differences in MSW-burning across cities, neighborhoods, diurnally and seasonally, important for more fine grained air pollution modeling, and for tracking/monitoring policy effectiveness on-ground.
Lin, J., Hu, Y., Cui, S., Kang, J., & Ramaswami, A. (2015). Tracking urban carbon footprints from production and consumption perspectives. Environmental Research Letters.Abstract
Cities are hotspots of socio-economic activities and greenhouse gas emissions. The aim of this study was to extend the research range of the urban carbon footprint (CF) to cover emissions embodied in products traded among regions and intra-city sectors. Using Xiamen City as a study case, the total urban-related emissions were evaluated, and the carbon flows among regions and intra-city sectors were tracked. Then five urban CF accountings were evaluated, including purely geographic accounting (PGA), community-wide infrastructure footprint (CIF), and consumption-based footprint (CBF) methods, as well as the newly defined production-based footprint (PBF) and purely production footprint (PPF). Research results show that the total urban-related emissions of Xiamen City in 2010 were 55.2 Mt CO2e/y, of which total carbon flow among regions or intra-city sectors accounted for 53.7 Mt CO2e/y. Within the total carbon flow, import and export respectively accounted for 59 and 65%, highlighting the importance of emissions embodied in trade. By regional trade balance, North America and Europe were the largest net carbon exported-to regions, and Mainland China and Taiwan the largest net carbon imported-from regions. Among intra-sector carbon flows, manufacturing was the largest emission-consuming sector of the total urban carbon flow, accounting for 77.4, and 98% of carbon export was through industrial products trade. By the PBF, PPF, CIF, PGA and CBF methods, the urban CFs were respectively 53.7 Mt CO2e/y, 44.8 Mt CO2e/y, 28.4 Mt CO2e/y, 23.7 Mt CO2e/y, and 19.0 Mt CO2e/y, so all of the other four CFs were higher than the CBF. All of these results indicate that urban carbon mitigation must consider the supply chain management of imported goods, the production efficiency within the city, the consumption patterns of urban consumers, and the responsibility of the ultimate consumers outside the city.
Jiang, D., & Ramaswami, A. (2015). The ‘thirsty’ water-electricity nexus: field data on the scale and seasonality of thermoelectric power generation’s water intensity in China. Environmental Research Letters.Abstract
There is a lack of field data on the water withdrawal and consumption intensity of thermoelectric power plants in China. With China's ambitious electricity capacity expansion and ever-growing water deficit, the overlooked water dimension of thermoelectric power generation could soon have significant water sustainability implications, and field data on water intensity of thermoelectric power plants will be essential to further our understanding of China's water-electricity nexus. To address this knowledge gap, this paper presents field data on the water withdrawal intensity and water balance of 19 coal-fired power plants in Shandong, China, categorized by different generator capacities (<100 MW ~ >600 MW) and boiler technologies (subcritical, supercritical and ultra supercritical). This paper suggests that the annual average water withdrawal intensity of coal-fired power plants in Shandong (1.50–3.75 L kWh−1) is within the range of values reported for other countries, and that the distinction between water withdrawal and water consumption effectively vanishes since very little water is returned from withdrawal. This paper also suggests that there is quite significant seasonality in power plants' water intensity whereby the water intensity in July can be approximately 15–28% higher than the annual average. The seasonality is on a similar scale across all generator capacities, except for a small co-generation plant (<100 MW), which had substantially lower water intensity in January when a heat exchanger was used to provide heating.
2014
Seto, K. C., Dhakal, S., Bigio, A., Blanco, H., Delgado, G. C., Dewar, D., Huang, L., et al. (2014). Human Settlements, Infrastructure and Spatial Planning. In AR5 Climate Change 2014: Mitigation of Climate Change (pp. 923-1000) . Intergovernmental Panel on Climate Change.Abstract
The shift from rural to more urban societies is a global trend with significant consequences for greenhouse gas (GHG) emissions and climate change mitigation. Across multiple dimensions, the scale and speed of urbanization is unprecedented: more than half of the world population live in urban areas and each week the global urban pop-ulation increases by 1.3 million. Today there are nearly 1000 urban agglomerations with populations of 500,000 or greater; by 2050, the global urban population is expected to increase by between 2.5 to 3 billion, corresponding to 64 % to 69 % of the world population (robust evidence, high agreement). Expansion of urban areas is on average twice as fast as urban population growth, and the expected increase in urban land cover during the first three decades of the 21st century will be greater than the cumulative urban expansion in all of human history (medium evidence, high agreement). Urban areas generate around 80% of global Gross Domestic Product (GDP) (medium evi-dence, medium agreement). Urbanization is associated with increases in income, and higher urban incomes are correlated with higher con-sumption of energy use and GHG emissions (medium evidence, high agreement).
Ramaswami, A., Russell, A., Chertow, M., Hollander, R., Tripathi, S., Lei, S., & Nagpure, A. S. (2014). International, Interdisciplinary Education on Sustainable Infrastructure and Sustainable Cities: Key Concepts and Skills. The Bridge.Abstract

This paper presents the development, delivery, and assessment of an interdisciplinary education program on Sustainable Infrastructure and Sustainable Cities offered to cohorts of graduate students from the United States, India, and China. Developed by an interdisciplinary team of university instructors from the three countries, the curriculum explores how the interaction of engineered infrastructures with social and natural systems shapes urban sustainability outcomes pertaining to resource management, environmental pollution, climate change, and public health. Five key concepts and skills form the foundation of the curriculum: (1) sustainable urban systems concepts; (2) interdisciplinary systems thinking and teamwork skills; (3) intercultural skills; (4) fieldwork, including community-based interactions; and (5) knowledge of ethics in interdisciplinary and intercultural settings

The curriculum is designed for students from six disciplines: engineering, industrial ecology, environmental sciences and climatology, urban planning, public health, and public affairs. An innovative, hybrid lecture-plus-fieldwork format is delivered in several cities in each country, exposing the students to multiple cultures and diverse learning experiences.

Cohen, E., & Ramaswami, A. (2014). Water Footprint of Energy Supply to Cities: Conceptual Development and Case Study of Denver, CO. Journal of Industrial Ecology.Abstract
Water footprints traditionally estimate water lost as a result of evapotranspiration (or otherwise unavailable for downstream uses) associated with producing a certain good, and the same embodied in trade across regions is used to estimate regional and national water footprints. These footprints, however, do not address risk posed to city energy supplies characterized by insufficient streamflow to support energy production, such as cooling water intake (e.g., withdrawals) at thermoelectric power plants. Water withdrawal intensity factors for producing goods and services are being developed at the national scale, but lack sufficient spatial resolution to address these types of water-energy challenges facing cities. To address this need, this article presents a water withdrawal footprint for energy supply (WWFES) to cities and places it in the context of other water footprints defined in the literature. Analysis of electricity use versus electricity generation in 43 U.S. cities highlights the need for developing WWFES to estimate risks to transboundary city energy supplies resulting from water constraints. The magnitude of the WWFES is computed for Denver, Colorado, and compared to the city's direct use of water to offer perspective. The baseline WWFES for Denver is found to be 66% as large as all direct water uses in the city combined (mean estimate). Minimum, mean, and maximum estimates are computed to demonstrate sensitivity of the WWFES to selection of water withdrawal intensity factors. Finally, scenario analysis explores the effect of energy technology and energy policy choices in shaping the future water footprint of cities.
2013
Ramaswami, A. (2013). Understanding Infrastructure Impacts on Urban Greenhouse Gas Emissions and Key Mitigation Strategies. In Infrastructure and Land Polices . Land Policy Conference, Lincoln Institute of Land Policy.Abstract
Ramaswami, A., & Chavez, A. (2013). What metrics best reflect the energy and carbon intensity of cities? Insights from theory and modeling of 20 US cities. Environmental Research Letters.Abstract
Three broad approaches have emerged for energy and greenhouse gas (GHG) accounting for individual cities: (a) purely in-boundary source-based accounting (IB); (b) community-wide infrastructure GHG emissions footprinting (CIF) incorporating life cycle GHGs (in-boundary plus trans-boundary) of key infrastructures providing water, energy, food, shelter, mobility–connectivity, waste management/sanitation and public amenities to support community-wide activities in cities—all resident, visitor, commercial and industrial activities; and (c) consumption-based GHG emissions footprints (CBF) incorporating life cycle GHGs associated with activities of a sub-set of the community—its final consumption sector dominated by resident households. The latter two activity-based accounts are recommended in recent GHG reporting standards, to provide production-dominated and consumption perspectives of cities, respectively. Little is known, however, on how to normalize and report the different GHG numbers that arise for the same city. We propose that CIF and IB, since they incorporate production, are best reported per unit GDP, while CBF is best reported per capita. Analysis of input–output models of 20 US cities shows that GHGCIF/GDP is well suited to represent differences in urban energy intensity features across cities, while GHGCBF/capita best represents variation in expenditures across cities. These results advance our understanding of the methods and metrics used to represent the energy and GHG performance of cities.
Miller, L., Ramaswami, A., & Kumar, P. (2013). Life Cycle Energy Use and Greenhouse Gas Emission Analysis for a Water Resource Recovery Facility in India. Water Environment Research.Abstract
This paper quantifies life cycle energy use and greenhouse gas (GHG) emissions associated with water resource recovery facilities (WRRFs) in India versus water quality improvements achieved from infrastructure investments. A first such analysis is conducted using operating data for a WRRF, which employs upflow anaerobic sludge blanket (UASB) reactors and oxidation. On-site operations energy use, process GHG emissions, and embodied energy in infrastructure were quantified. The analysis showed energy use and GHG emissions of 0.2 watt-hours (Wh) and 0.3 gram carbon dioxide (CO2) equivalents per liter (gCO2e/L) wastewater treated, and 1.3 Wh and 2.1 gCO 2e/gBOD removed, achieving 81% biochemical oxygen demand (BOD) and 99% fecal coliform removal annually. Process emissions of WRRFs contributed 44% of life cycle GHG emissions, similar in magnitude to those from electricity (46%), whereas infrastructure contributed 10%. Average WRRF-associated GHG emissions (0.9gCO2e/L) were lower than those expected if untreated wastewater was released to the river. Investments made by WRRFs in developing world cities improve water quality and may mitigate overall GHG emissions.
Chavez, A., & Ramaswami, A. (2013). Articulating An Infrastructure Supply-Chain Greenhouse Gas (GHG) Emissions Footprint for Cities: Mathematical Relationships and Policy Relevance. Energy Policy.Abstract
This paper compares the policy relevance and derives mathematical relationships between three approaches for GHG emissions accounting for cities. The three approaches are: (a) Purely-Geographic Inventory, (b) Trans-boundary Community-Wide Infrastructure Footprint (CIF), and (c) Consumption-Based Footprint (CBF). Mathematical derivations coupled with case study of three US communities (Denver Colorado, Routt Colorado, and Sarasota Florida), shows that no one method provides a larger or more holistic estimate of GHG emissions associated with communities. A net-producing community (Routt) demonstrates higher CIF GHG emissions relative to the CBF, while a net-consuming community (Sarasota) yields the opposite. Trade-balanced communities (Denver) demonstrate similar numerical estimates of CIF and CBF, as predicted by the mathematical equations. Knowledge of community typology is important in understanding trans-boundary GHG emission contributions.
Ramaswami, A. (2013). Social Actors and Key Policy Levers for Mitigating the Greenhouse Gas Footprint of US Cities. Cityscape: A Journal of Policy Development And Research.Abstract
This article links policy outputs in city climate action plans with environmental outcomes. This task is challenging because different human activities in cities vary in terms of their contributions to greenhouse gas (GHG) emissions and because the engineered infrastructures that support these activities extend well beyond the city scale. I present a generalizable quantitative approach that uses the transboundary infrastructure supply chain GHG emission footprints of cities to identify key actors and policy levers most effective in reducing the global GHG impact of cities. This infrastructure supply chain GHG emission footprint represents the life-cycle energy associated with provisioning key infrastructure services—water, energy, food, shelter, sanitation, mobility, connectivity, and public spaces—to support the activities of households, businesses, and industnes in cities.
Miller, L. A., Ramaswami, A., & Ranjan, R. (2013). Contribution of Water and Wastewater Infrastructures to Urban Energy Metabolism and Greenhouse Gas Emissions in Cities in India. Environmental Engineering.Abstract
This is a first analysis of end-use energy intensity (EUEI) and greenhouse gas (GHG) emissions in water and wastewater (W/WW) sectors in India, and it examines their contribution to community-wide energy use and GHG emissions in cities in India. EUEI and related GHG emissions for W/WW infrastructures in Indian cities were analyzed and compared with data for cities in the United States. Data gathered by ICLEI-South Asia, Government of India, and the University of Colorado Denver were used to conduct this analysis. W/WW infrastructures were found to contribute 3–16% of community-wide electricity use and GHG emissions for 16 cities in India; for another 23 cities, the proportion was less than 3%. EUEI for drinking water supply and wastewater treatment averaged 0.3&#xB1;0.2&#x2009;&#x2009;W&#xB7;h/L(n=7)" id="MathJax-Element-1-Frame" role="presentation" style="position:relative;" tabindex="0">0.3±0.2Wh/L(n=7) and 0.1&#xB1;0.05&#x2009;&#x2009;W&#xB7;h/L(n=5)" id="MathJax-Element-2-Frame" role="presentation" style="position:relative;" tabindex="0">0.1±0.05Wh/L(n=5), respectively. EUEI for drinking water provision was more than double that for wastewater treatment, the reverse of typical cities in Colorado, likely a result of poorer source water quality in India. In general, although the sample size of Indian W/WW plants is small, EUEI in India appears to be much smaller than in the United States for both water and wastewater sectors based on this first review of quantitative data.
2012
Zborel, T., Holland, B., Thomas, G., Baker, L., Calhoun, K., & Ramaswami, A. (2012). Translating Research to Policy for Sustainable Cities: What Works and What Doesn’t? Journal of Industrial Ecology.
Ramaswami, A., Chavez, A., & Chertow, M. (2012). Carbon Footprinting of Cities and Implications for Analysis of Urban Material and Energy Flows. Journal of Industrial Ecology.Abstract
As we struggle to get our collective arms around the concept of urban sustainability, various ways of understanding material and energy flows associated with cities have emerged in the literature.
Chavez, A., Ramaswami, A., Dwarakanath, N., Ranjan, R., & Kumar, E. (2012). Implementing Trans-Boundary Infrastructure-Based Greenhouse Gas Accounting for Delhi, India: Data Availability and Methods. Journal of Industrial Ecology.Abstract
Community-wide greenhouse gas (GHG) emissions accounting is confounded by the relatively small spatial size of cities compared to nations—due to which, energy use in essential infrastructures serving cities, such as commuter and airline transport, energy supply, water supply, wastewater infrastructures, and others, often occurs outside the boundaries of the cities using them. The trans-boundary infrastructure supply chain footprint (TBIF) GHG emissions accounting method, tested in eight U.S. cities, incorporates supply chain aspects of these trans-boundary infrastructures serving cities, and is akin to an expanded geographic GHG emissions inventory. This article shows the results from applying the TBIF method in the rapidly developing city of Delhi, India.
Ramaswami, A., Weible, C., Main, D. S., Heikkila, T., Siddiki, S., Duvall, A., Pattison, A., et al. (2012). A Social-Ecological Infrastructural Systems (SEIS) Framework for Inter-Disciplinary Study of Sustainable City-Systems: An Integrative Curriculum across Seven Major Disciplines. Journal of Industrial Ecology.Abstract
Cities are embedded within larger‐scale engineered infrastructures (e.g., electric power, water supply, and transportation networks) that convey natural resources over large distances for use by people in cities. The sustainability of city systems therefore depends upon complex, cross‐scale interactions between the natural system, the transboundary engineered infrastructures, and the multiple social actors and institutions that govern these infrastructures. These elements, we argue, are best studied in an integrated manner using a novel social‐ecological‐infrastructural systems (SEIS) framework. In the biophysical subsystem, the SEIS framework integrates urban metabolism with life cycle assessment to articulate transboundary infrastructure supply chain water, energy, and greenhouse gas (GHG) emission footprints of cities. These infrastructure footprints make visible multiple resources (water, energy, materials) used directly or indirectly (embodied) to support human activities in cities. They inform cross‐scale and cross‐infrastructure sector strategies for mitigating environmental pollution, public health risks and supply chain risks posed to cities. In the social subsystem, multiple theories drawn from the social sciences explore interactions between three actor categories - individual resource users, infrastructure designers and operators, and policy actors - who interact with each other and with infrastructures to shape cities toward sustainability outcomes. Linking of the two subsystems occurs by integrating concepts, theories, laws, and models across environmental sciences/climatology, infrastructure engineering, industrial ecology, architecture, urban planning, behavioral sciences, public health, and public affairs. Such integration identifies high‐impact leverage points in the urban SEIS. An interdisciplinary SEIS‐based curriculum on sustainable cities is described and evaluated for its efficacy in promoting systems thinking and interdisciplinary vocabulary development, both of which are measures of effective frameworks.
Liu, R., Durham, S. A., Rens, K. L., & Ramaswami, A. (2012). Optimization of cementitious material content for sustainable concrete mixtures. ASCE Journal of Materials in Civil Engineering.Abstract
Utilization of fly ash in concrete reduces the use of virgin materials and offers benefits of reduced landfill materials and CO2 emissions avoidance—fly ash therefore contributes to industrial sustainability. This paper presents a method to optimize the cement and fly ash contents in concrete on the basis of the hardened concrete properties testing and environmental effects. Such fly ash concrete would develop an adequate 1-day and 28-day compressive strength and would be as durable as the ordinary portland cement concrete. Nine concrete mixtures with fly ash contents ranging from 15–60% and cementitious material contents from 338–391 kg/m3 (570−705 lbs/cu yd) were investigated. Environmental life cycle assessments (LCA) were completed by using a model developed for Denver, Colorado. The optimized fly ash concrete was selected to yield a similar 28-day compressive strength and durability to that of Colorado Department of Transportation (CDOT) Class D structural concrete. The durability aspects investigated included the resistance to rapid chloride-ion penetration and the resistance to the rapid cycles of freezing and thawing. The results show that the mixtures with cementitious material content lower than 365 kg/m3 (615 lbs/cu yd) and fly ash content higher than 40% meet the CDOT Class D structural concrete strength and durability requirements. On the basis of the structural performances of the concrete mixtures and environmental effects, the optimized cementitious material content and the maximum possible cement replacement percentage with the fly ash was selected to be 338 kg/m3 (570 lbs/cu yd) and 50%, respectively. The optimized concrete mixture exhibited excellent characteristics in compressive strength (32.0 MPa, 4,635 psi at 28 days), resistance to chloride-ion penetration (moderate at 28 days of age) and freeze-thaw (96, average durability factor after 300 cycles). The mixture with optimum fly ash and cementitious content had the minimum embodied energy and greenhouse gas (GHG) emission among the nine mixtures. The embodied energy and GHG emission of the optimized concrete mixture (per cubic meter) were 2,643 MJ and 361 kgCO2E, respectively, which are 32.8 and 35.2% less than the mixture with the most embodied energy and GHG emission.
Solis, A., Durham, S. A., & Ramaswami, A. (2012). Providing Storm water Management Solutions in Rajkot, India: A Pervious Concrete System Demonstration. International Journal of the Constructed Environment.
Ramaswami, A., Bernard, M., Chavez, A., Hillman, T., Whitaker, M., Thomas, G., & Marshall, M. (2012). Quantifying Carbon Mitigation Wedges in US Cities: Near-Term Strategy Analysis and Critical Review. Environmental Science & Technology.Abstract
A case study of Denver, Colorado explores the roles of three social actors—individual users, infrastructure designer-operators, and policy actors—in near-term greenhouse gas (GHG) mitigation in U.S. cities. Energy efficiency, renewable energy, urban design, price- and behavioral-feedback strategies are evaluated across buildings–facilities, transportation, and materials/waste sectors in cities, comparing voluntary versus regulatory action configurations. GHG mitigation impact depends upon strategy effectiveness per unit, as well as societal participation rates in various action-configurations. Greatest impact occurs with regulations addressing the vast existing buildings stock in cities, followed by voluntary behavior change in electricity use/purchases, technology shifts (e.g., to teleconferencing), and green-energy purchases among individual users. A portfolio mix of voluntary and regulatory actions can yield a best-case maximum of ∼1% GHG mitigation annually in buildings and transportation sectors, combined. Relying solely on voluntary actions reduces mitigation rates more than five-fold. A portfolio analysis of climate action plans in 55 U.S. cities reveals predominance of voluntary outreach programs that have low societal participation rates and hence low GHG impact, while innovative higher-impact behavioral, technological, and policy/regulatory strategies are under-utilized. Less than half the cities capitalize on cross-scale linkages with higher-impact state-scale policies. Interdisciplinary field research can help address the mis-match in plans, actions, and outcomes.
Sperling, J., & Ramaswami, A. (2012). Exploring Health Outcomes as a Motivator for Low-Carbon City Development: Implications for Infrastructure Interventions in Asian Cities. Habitat International.Abstract
Sustainable urban infrastructure interventions can help achieve both public health and low-carbon goals in cities. This paper explores the extent to which civil infrastructure (i.e., water, sanitation, energy, transport and building infrastructures) and environmental factors (e.g. air and water quality) associated with these infrastructures shape current urban health outcomes in cities in Asia using Delhi, India as a case study. Current mortality data for Delhi are used as context to estimate the extent to which urban health outcomes are shaped by infrastructure and infrastructure-related environmental factors, some of which could directly or indirectly reduce mortality through low-carbon interventions. Mortality data along with a preliminary survey of expert opinion indicate up to 19 percent of all recorded deaths in Delhi may be infrastructure-related. More detailed epidemiology studies and infrastructure models are needed to confirm these initial findings. The findings suggest public health outcomes may be a large factor in motivating low-carbon development in Asian cities.
2011
Ramaswami, A., Schauer, J., Li, X., & Chan, E. (2011). Conference Report: US–China Workshop on Pathways Toward Low Carbon Cities: quantifying baselines and interventions. Carbon Management.
Amekudzi, A., Ramaswami, A., Chan, E., Lam, K., Meng, W. H., & Zhu, D. (2011). Contextualizing carbon reduction initiatives: how should carbon mitigation be addressed by various cities worldwide? Carbon Management.
Ramaswami, A., & Dhakal, S. (2011). Low-carbon policies in the USA and China: Why Cities Play a Critical Role. Carbon Management.
Chavez, A., & Ramaswami, A. (2011). Progress toward Low Carbon Cities: Approaches for Trans-boundary GHG Emissions’ Footprinting. Carbon Management.Abstract
Cities are home to a large proportion of the world’s population and as a result, are being recognized as major contributors to global GHG emissions. There is a need to establish baseline GHG emission accounting protocols that provide consistent, reproducible, comparable and holistic GHG accounts that incorporate in-boundary and transboundary GHG impacts of urban activities and support policy intervention. This article provides a synthesis of previously published GHG accounts for cities by organizing them according to their in-boundary and transboundary considerations, and reviewing three broad approaches that are emerging for city-scale GHG emissions accounting: geographic accounting, transboundary infrastructure supply chain (TBIS) footprinting, and consumption-based footprinting. The TBIS and consumption-based footprints are two different approaches that result in different estimates of a community’s GHG emissions, and inform policies differently, as illustrated with a case study of Denver, CO, USA. The conceptual discussions around TBIS and consumption-based footprints indicate that one single metric (e.g., GHG/person) will probably not be suitable to represent GHG emissions associated with cities, and it will take a combination of variables for defining a low-carbon city.
Ramaswami, A., Chavez, A., Ewing-Thiel, J., & Reeve, K. E. (2011). Two Approaches to Greenhouse Gas Emissions Accounting at the City-scale. Environmental Science & Technology.Abstract
Community-wide greenhouse gas (GHG) accounting is confounded by the relatively small spatial size of cities compared to nations, due to which

Essential infrastructures—commuter and airline transport, energy supply, water supply, wastewater infrastructures, etc.—cross city boundaries, hence energy use to provide these services often occurs outside the boundary of the cities using them.

Significant trade of other goods and services also occurs across cities, with associated embodied GHGs.

Consequently, human activity in cities—occurring in residential, commercial, and industrial sectors—stimulates in-boundary GHG emissions occurring within the geopolitical boundary of the community, as well as trans-boundary emissions (occurring outside). Allocating in-boundary and trans-boundary GHG emissions to communities can be achieved using different approaches described below.
Ramaswami, A., Main, D., Bernard, M., Chavez, A., Davis, A., Thomas, G., & Schnoor, K. (2011). Planning for low-carbon communities in US cities: a participatory process model between academic institutions, local governments and communities in Colorado. Carbon Management.Abstract
Participatory process models combine the use of technical data with community participation to develop a sustainability plan relevant to each city. In this article, two case study applications in Denver, CO, USA and Broomfield, CO, USA use a participatory process, which combines teams from academia, local governments and community members to create city climate action plans. The participatory process is developed from concepts in community-based participatory research, analytic deliberation, and post-normal science. The refined process model developed in these two case studies goes through seven steps which include creating the deliberative body, co-developing data sets for sustainability analysis, defining sustainability goals, using scenario modeling for potential sustainability actions, prioritizing actions through deliberation, demonstrating consensus or diversity in final action plan, and conducting an outcomes assessment.
Kennedy, C., Ramaswami, A., Carney, S., & Dhakal, S. (2011). Greenhouse Gas Emission Baselines for Global Cities and Metropolitan Regions. In Cities and Climate Change: Responding to an Urgent Agenda (pp. 15-49) . Washington D.C. The World Bank.
Ramaswami, A., & Sperling, J. (2011). Epilogue: Knowledge and Field Measurements on Cities and Climate Change. In Cities and Climate Change: Responding to an Urgent Agenda (pp. 255-259) . Washington D.C. The World Bank.
Kocman, S., Guo, J. Y. C., & Ramaswami, A. (2011). Waste Incorporated Sub-base for Porous Landscape Detention Basin Design. ASCE Journal of Environmental Engineering.Abstract
Porous landscape detention basins (PLDBs) capture and filter storm water while taking advantage of the intrinsic quality of plants to act as water treatment systems. A two-layered subbase filtering medium is recommended for building PLDBs. The current design method creates the opportunity for incorporating waste symbiosis. In this study, the beneficial reuse of mixing urban waste stream materials into the subbase filtering media is identified. Based on the waste screening tests conducted in this study, three mixes were selected and examined for their leaching and clogging potentials over the years of service. They are (1) peat-sand mix, (2) compost-paper-sand mix, and (3) compost-paper-sand-tire mix. Laboratory tests showed no significant differences among these three mixes in infiltration capacity and leaching contents of nutrients, pathogens, and total metals. Subbase clogging tests were also conducted for these three mixes using sample storm water. The decay of clogged infiltration rate was measured as the sediment load was accumulated on and through the filtering layer using the selected mix. Three empirical formulas were derived to predict the clogging effect for these three waste-incorporated mixes. Using the recommended threshold infiltration rate of 2.5&#x2009;&#x2009;cm/h" id="MathJax-Element-1-Frame" role="presentation" style="position:relative;" tabindex="0">2.5cm/h, the life spans of these three mixes were assessed for an example PLDB built in the field. Based on a bench-scale test of dynamic infiltration rates, the waste-incorporated mix is predicted to reduce the clogging potential of PLDB by approximately 20% compared with the currently recommended mix using peat and sand. However, shredded tires were also found to float in water and can be washed out of the basin during overflow events. Based on environmental benefits, construction cost, material availability, and life-span potential, the subbase mix using compost, paper, and sand is recommended for PLDB designs.
Hillman, T., Janson, B., & Ramaswami, A. (2011). Spatial Allocation of Transportation Greenhouse Gas Emissions at the City Scale. ASCE Journal of Transportation Engineering.Abstract
Greenhouse gas (GHG) accounting for individual cities in large metropolitan areas is confounded by spatial scale and boundary effects that impact the allocation of transportation fuels used for surface transport and airline travel. This paper expands on a demand-based methodology to spatially allocate transportation fuel use (surface and airline) among colocated cities in the United States that are part of a larger metropolitan area commutershed on the basis of demand for surface vehicle miles traveled (VMT) exerted by individual cities. By using travel demand models for metropolitan planning organizations, the demand method was first applied as part of the city of Denver’s GHG inventory in 2005 to develop a material flow analysis (MFA) of gasoline, diesel, and jet fuel consumption at the city scale. This paper reports on the application of the same method to six major metropolitan regions across the United States and a detailed analysis of all 27 cities within the larger Denver metro region. The analysis of six metropolitan areas in the United States demonstrated (1) the demand method produces VMT estimates allocated to cities across the commutershed that are similar (within 6%) to the boundary-limited polygon approach (linear correlation coefficient R2=0.82; slope m=0.98); (2) airline travel allocation by vehicular trip count ratios to the regional airport from colocated cities produces results similar to regional airline travel allocation by population ratios (linear correlation coefficient R2=0.96; slope m=0.99); and (3) the method is replicable with necessary data available from all cities in this study through their corresponding metropolitan planning organizations. In addition, the demand-VMT allocation method is found to be more responsive to future simulated mass transit growth. Further, the method is sensitive to local travel demand features of the individual cities, of which employment intensity was found to have the largest impact on per capita VMT allocated to a city. Within the Denver commutershed, daily VMT per capita estimates ranged from 13–129 km/capita/day (8–80 mi/capita/day) among the 27 communities, with a strong positive correlation with employment intensity (employment/capita; R2=0.97) and employment density (employment/kilometer; R2=0.59).
2010
Hillman, T., & Ramaswami, A. (2010). Greenhouse Gas Emission Footprints and Energy Use Metrics for Eight US Cities. Environmental Science & Technology.Abstract
A hybrid life cycle-based trans-boundary greenhouse gas (GHG) emissions footprint is elucidated at the city-scale and evaluated for 8 US cities. The method incorporates end-uses of energy within city boundaries, plus cross-boundary demand for airline/freight transport and embodied energy of four key urban materials [food, water, energy (fuels), and shelter (cement)], essential for life in all cities. These cross-boundary activities contributed 47% on average more than the in-boundary GHG contributions traditionally reported for cities, indicating significant truncation at city boundaries of GHG emissions associated with urban activities. Incorporating cross-boundary contributions created convergence in per capita GHG emissions from the city-scale (average 23.7 mt-CO2e/capita) to the national-scale (24.5 mt-CO2e/capita), suggesting that six key cross-boundary activities may suffice to yield a holistic GHG emission footprint for cities, with important policy ramifications. Average GHG contributions from various human activity sectors include buildings/facilities energy use (47.1%), regional surface transport (20.8%), food production (14.7%), transport fuel production (6.4%), airline transport (4.8%), long-distance freight trucking (2.8%), cement production (2.2%), and water/wastewater/waste processing (1.3%). Energy-, travel-, and key materials-consumption efficiency metrics are elucidated in these sectors; these consumption metrics are observed to be largely similar across the eight U.S. cities and consistent with national/regional averages.
Ramaswami, A. (2010). Finding and Educating Self and Others Across Multiple Domains: Crossing Cultures, Disciplines and Research Modalities. In What is Global Engineering Education For? The Making of International Educators (pp. 150-174) . Williston, Morgan Claypool Publishers.Abstract

Global engineering offers the seductive image of engineers figuring out how to optimize work through collaboration and mobility. Its biggest challenge to engineers, however, is more fundamental and difficult: to better understand what they know and value qua engineers and why. This volume reports an experimental effort to help sixteen engineering educators produce "personal geographies" describing what led them to make risky career commitments to international and global engineering education. The contents of their diverse trajectories stand out in extending far beyond the narrower image of producing globally-competent engineers. Their personal geographies repeatedly highlight experiences of incongruence beyond home countries that provoked them to see themselves and understand their knowledge differently. The experiences were sufficiently profound to motivate them to design educational experiences that could challenge engineering students in similar ways.

For nine engineers, gaining new international knowledge challenged assumptions that engineering work and life are limited to purely technical practices, compelling explicit attention to broader value commitments. For five non-engineers and two hybrids, gaining new international knowledge fueled ambitions to help engineering students better recognize and critically examine the broader value commitments in their work.

Siddiki, S. N., Martell, C., & Ramaswami, A. (2010). Defining and Measuring Sustainability in Public Private Water Infrastructure Partnerships in Developing Countries. In Public Private Partnerships (pp. 266-281) . New York, Taylor and Francis.
2009
Guo, J. Y. C., Kocman, S., & Ramaswami, A. (2009). Design of Two-Layered Porous Landscaping Detention Basins. ASCE Journal of Environmental Engineering.Abstract
Under the mandate of the Federal Clean Water Act, porous landscaping detention (PLD) has been widely used to increase on-site infiltration. A PLD system consists of a surface storage basin and subsurface filtering layers. The major design parameters for a PLD system are the infiltration rate on the land surface and the seepage rate through the subsurface medium. A low infiltration rate leads to a sizable storage basin while a high infiltration rate results in standing water if the subsurface seepage does not sustain the surface loading. In this study, the design procedure of a PLD basin is revised to take both detention flow hydrology and seepage flow hydraulics into consideration. The design procedure begins with the basin sizing according to the on-site water quality control volume. The ratio of design infiltration rate to sand-mix hydraulic conductivity is the key factor to select the thickness of sand-mix layer underneath a porous bed. The total filtering thickness for both sand-mix and gravel layers is found to be related to the drain time and infiltration rate. The recommended sand-mix and granite gravel layers underneath a PLD basin are reproduced in the laboratory for infiltration tests. The empirical decay curve for sand-mix infiltration rate was derived from the laboratory data and then used to maximize the hydraulic efficiency through the subsurface filtering layers. In this study, it is recommended that a PLD system be designed with the optimal performance to consume the hydraulic head available and then evaluated using the prolonged drain time for potential standing water problems under various clogging conditions.
Kennedy, C., Gasson, B., Hansen, Y., Hillman, T., Havranek, M., Phdungslip, A., Ramaswami, A., et al. (2009). Greenhouse Gas Emissions from Global Cities. Environmental Science & Technology.Abstract
The world’s population is now over 50% urban, and cities make an important contribution to national greenhouse gas (GHG) emissions. Many cities are developing strategies to reduce their emissions. Here we ask how and why emissions differ between cities. Our study of ten global cities shows how a balance of geophysical factors (climate, access to resources, and gateway status) and technical factors (power generation, urban design, and waste processing) determine the GHGs attributable to cities. Within the overall trends, however, there are differences between cities with more or less public transit; while personal income also impacts heating and industrial fuel use. By including upstream emissions from fuels, GHG emissions attributable to cities exceed those from direct end use by up to 25%. Our findings should help foster intercity learning on reducing GHG emissions.
Kennedy, C., Gasson, B., Hansen, Y., Hillman, T., Havranek, M., Phdungslip, A., Ramaswami, A., et al. (2009). Methodology for Inventorying Greenhouse Gas Emissions From Global Cities. Energy Policy.Abstract
This paper describes the methodology and data used to determine greenhouse gas (GHG) emissions attributable to ten cities or city-regions: Los Angeles County, Denver City and County, Greater Toronto, New York City, Greater London, Geneva Canton, Greater Prague, Barcelona, Cape Town and Bangkok. Equations for determining emissions are developed for contributions from: electricity; heating and industrial fuels; ground transportation fuels; air and marine fuels; industrial processes; and waste. Gasoline consumption is estimated using three approaches: from local fuel sales; by scaling from regional fuel sales; and from counts of vehicle kilometres travelled. A simplified version of an intergovernmental panel on climate change (IPCC) method for estimating the GHG emissions from landfill waste is applied. Three measures of overall emissions are suggested: (i) actual emissions within the boundary of the city; (ii) single process emissions (from a life-cycle perspective) associated with the city's metabolism; and (iii) life-cycle emissions associated with the city's metabolism. The results and analysis of the study will be published in a second paper.
2008
Ramaswami, A., Hillman, T., Janson, B., Reiner, M., & Thomas, G. (2008). A Demand-Centered Hybrid Life Cycle Methodology for City-Scale Greenhouse Gas Inventories. Environmental Science & Technology.
2007
Rubin, E., & Ramaswami, A. (2007). Evidence for Phytodegradation of MTBE from Coupled Bench-scale and Intermediate-Scale Tests. ASCE Journal of Environmental Engineering.Abstract
This paper presents methodologies and demonstrates the need to couple bench-scale and intermediate tree-scale experiments, to fully understand the transport and fate of organic contaminants, specifically methyl tert butyl ether (MTBE), in mature trees. Bench-scale experiments showed MTBE to be optimally taken up by small poplar saplings with a transpiration stream concentration factor of approximately 1, little or no degradation in soils and, nearly 100±20% recovery in the coupled water-plant-air system, indicating no measurable phytodegradation at the bench-scale. A large 14ft tree chamber was designed to evaluate MTBE transport and fate through intermediate-scale (12ft tall) poplar trees. Abiotic MTBE volatilization tests conducted in the tree chamber showed 100±20% MTBE mass recovery, thereby demonstrating the integrity of the large chamber and its air monitoring technique. In contrast, replicate intermediate-scale experiments conducted with large (12ft) trees irrigated with a known mass of MTBE showed a deficit of MTBE mass recovery (65±20%) in replicate soil-tree-air systems monitored over a 2-week period. More significantly, tert butyl alcohol (TBA), a degradation product of MTBE, was detected in increasing concentrations in leaf biomass while MTBE concentrations in leaf biomass decreased as the experiment progressed. The MTBE mass recovery deficit, coupled with the detection of increasing TBA in leaf biomass, provides preliminary evidence of MTBE degradation in mature trees.
Ramaswami, A., Zimmerman, J. B., & Mihelcic, J. R. (2007). Integrating Developing World Knowledge into Global Discussions and Strategies for Sustainability, Part 2: Economics and Governance. Environmental Science & Technology.Abstract
Knowledge transfer from the developing to the developed world is described in the domain of economics and governance for sustainable development. Three system areas are explored:  the structure of commons governance institutions, the process of community-based participatory action research, and the role of microfinance and microenterprise for the development, adoption, and diffusion of sustainable technologies. Case studies from both the developed and developing world demonstrate the effectiveness of social networks and community cooperative strategies in a wide range of sectors. Developing world experiences are shown to be particularly rich in the application of local knowledge and social capital toward sustainable development.
Mihelcic, J. R., Zimmerman, J. B., & Ramaswami, A. (2007). Integrating Developing World Knowledge into Global Discussions and Strategies for Sustainability, Part 1: Science & Technology. Environmental Science & Technology.Abstract
Sustainable development in both the developed and developing world has the common fundamental themes of advancing economic and social prosperity while protecting and restoring natural systems. While many recent efforts have been undertaken to transfer knowledge from the developed to the developing world to achieve a more sustainable future, indigenous knowledge that often originates in developing nations also can contribute significantly to this global dialogue. Selected case studies are presented to describe important knowledge, methodologies, techniques, principles, and practices for sustainable development emerging from developing countries in two critical challenge areas to sustainability:  water and energy. These, with additional analysis and quantification, can be adapted and expanded for transfer throughout the developed and developing world in advancing sustainability. A common theme in all of the case studies presented is the integration of natural processes and material flows into the anthropogenic system. Some of these techniques, originating in rural settings, have recently been adapted for use in cities, which is especially important as the global trend of urban population growth accelerates. Innovations in science and technology, specifically applied to two critical issues of today, water and energy, are expected to fundamentally shift the type and efficiency of energy and materials utilized to advance prosperity while protecting and restoring natural systems.
Reiner, M. B., Rens, K. L., & Ramaswami, A. (2007). Sustainability of the Urban Built Environment: A Bulk Material Flow Analysis, One Material at a Time. Journal of Engineering for Sustainable Development for Energy, Environment and Health.
2006
Reiner, M. B., Rens, K. L., & Ramaswami, A. (2006). The Role of HVFA Concrete in the Sustainability of the Urban Built Environment. Journal of Green Building.Abstract
Although fly-ash as a partial replacement for cement has been utilized for many years, its use has been almost exclusively used in low volume percentages such as 10% or 20% cement replacement. This paper looks at high volume percentage replacements from 40% to 70%. A mini-mix study revealed that 50% and 60% cement replacement percentages were the best candidates for full scale testing. The environmental benefits included a 25% reduction in smog, human health, and fossil fuel reduction compared to the same element built with 100% Portland cement mix. The economic benefits included a 15% capital cost reduction and a 20% life-cycle cost reduction when compared with a 100% Portland cement mix. Full scale testing included a complete mix design in addition to the construction of four concrete infrastructure products. The products built included an alley panel and curb and gutter sections in the City and county of Denver, a precast manhole and lid, and a twin tee prestressed girder. Although cement products are just one of many materials used in the construction of the built environment, its production has a large impact on the environment. Lowering the embodied energy of multiple types of construction materials will have a significant effect on sustainable urban development. Symbiotic recycling of waste material, such as fly ash in concrete, back into the built environment can help reduce materials on the input side and pollution on the output side of the bulk material flow of an urban city.
Ramaswami, A. (2006). Engineering Sustainable Urban Infrastructure. In Sustainability Science and Engineering: Defining Principles (pp. 419-434) . Elsevier.Abstract
This chapter describes engineering processes and urban planning strategies that can be applied to improve the sustainability of urban infrastructure, where urban infrastructure refers to the engineered structures that provide energy, water, sanitation, housing, and transport (of materials, humans and information) within an urban area. It is suggested that urban systems studies must integrate the energy, water, sewage, construction, industrial production, information, and health care sectors within a city, as well as address impacts on the whole environment, including water, air, land, and bio resources. Sustainable infrastructure engineering requires addressing technical feasibility of new and innovative technologies in the context of environmental, ecosystem and socioeconomic metrics for sustainability. Engineering evaluations, along with economic analysis and suitable public policy implementation have been shown to lead to success in developing sustainable urban infrastructure in a few cities, worldwide. The challenge lies in understanding these linkages, learning from past experiences and developing a consistent framework for future sustainable urban infrastructure engineering.
2005
Ramaswami, A., Milford, J. B., & Small, M. J. (2005). Integrated Environmental Modeling: Pollutant Transport Fate and Risk in the Environment (pp. 688) . John Wiley Inc.Abstract
Integrated Environmental Modeling is a graduate-level textbook that teaches model development, model implementation, and model testing skills in a unified manner, crosscutting the three "media" comprising environmental systems--air, water, and soil--by focusing on parallels and similarities between them, and introducing a new generation of multimedia models. No other single volume offers comprehensive coverage of chemical transport and fate in all three environmental media, including the resulting impacts on the biosphere and human health, with a focus on the fundamental processes underlying environmental modeling.
Skaates, S., Ramaswami, A., & Anderson, L. (2005). Transport and fate of dieldrin in poplar and willow trees analyzed by SPME. Chemosphere.Abstract
Dieldrin is a hydrophobic organochlorine insecticide that is persistent in the environment. The fate and transport of dieldrin in trees is important both in the context of potential remediation, as well as food chain impacts through dieldrin transport to shoots and leaves. Experiments were conducted to measure the degree of dieldrin partitioning to plant tissue and the potential for biodegradation of dieldrin in the microbe rich tree rhizosphere. Dieldrin was analyzed in water and plant tissue using headspace solid-phase microextraction (SPME) coupled with gas chromatography. Poplar and willow saplings planted in soil and watered with 10 μg l−1 dieldrin for up to 9 months showed no adverse effects due to dieldrin exposure and no dieldrin was observed in plant shoots with a method detection limit (MDL) of 7 ng g−1. One-week hydroponic tests of poplar saplings exposed to aqueous dieldrin also showed no detection of dieldrin in shoots, with an average of 66% of the dieldrin partitioned to the plant roots and an overall mass balance recovery of 76% in the plant–water system. The root concentration factor (RCF) was found to be 30 ± 3 ml water g−1 root. Biodegradation of dieldrin was not observed in an aqueous batch bioreactor containing 8 μg l−1 dieldrin, nutrients and bacteria from the root zone of a poplar sapling that had been exposed to dieldrin for 9 months. These results show that planting trees is likely to be safe and potentially useful at sites containing low-levels of dieldrin in groundwater.
2004
Ramaswami, A., Milford, J. B., & Small, M. (2004). Integrated Environmental Assessment, Part II: Modeling Fate and Transport. Journal of Industrial Ecology.
2002
Ramaswami, A., Rubin, E., & Bonola, S. (2002). Non-significance of Rhizosphere Degradation during Phytoremediation of MTBE. International Journal of Phytoremediation.Abstract
Methyl tertiary butyl ether (MTBE) is a gasoline additive associated with groundwater pollution at gas station sites. Previous research on poplar trees in hydroponic systems suggests that phytovolatilization is an effective mechanism for phytoremediation of MTBE (Rubin and Ramaswami, 2001), but the potential for microbial degradation of MTBE in the rhizosphere of trees had not been assessed. MTBE had largely been considered recalcitrant to microbial processes, but recent fieldwork suggests rapid biodegradation may occur in certain cases. This paper investigates the potential for rhizosphere degradation of MTBE at time frames relevant for phytoremediation. Three experiments were conducted at different levels of aggregation to examine possible degradation of MTBE by rhizosphere microorganisms that had been acclimated to low levels of MTBE for 6 weeks. MTBE soil die-away studies, conducted with both poplar trees and fescue grass, found no significant differences between MTBE concentration in vegetated and unvegetated soils over a two-week attenuation period. Closed chamber tests comparing hydroponic and rhizospheric poplar tree systems also showed essentially complete recovery of MTBE mass in both systems, suggesting an absence of degradation. Finally, rhizosphere microbes tested in aerated bioreactors were found to be thriving and metabolizing root materials, but did not show measurable degradation of MTBE. In all tests, the MTBE degradation product, Tert Butyl Alcohol (TBA), was not detected. The insignificance of MTBE degradation by rhizosphere microorganisms suggests that plant processes be the primary focus of further research on MTBE phytoremediation.
2001
Rubin, E., & Ramaswami, A. (2001). The potential for phytoremediation of MTBE. Water Research.Abstract
This paper examines the potential for phytoremediation of MTBE, a gasoline additive that has become a prevalent and persistent groundwater pollutant, due to its’ non-sorbing and non-reactive nature in water. A novel experimental design is developed to measure plant uptake and transpiration of MTBE from hydroponic systems, separating these processes from passive volatilization of the chemical. Plant uptake experiments indicate 30% reduction in MTBE mass in water over a 1-week period by small poplar saplings, at both high (1600 ppb) and low (300 ppb) MTBE concentrations. Active plant uptake of MTBE was approximately double that achieved by passive volatilization through a balsa wood control. MTBE was detected in biomass at the 100-ppb level, confirming passage of MTBE through the plant. A mass balance indicated that MTBE was largely untransformed during transport through the small poplar saplings to air. The high degree of MTBE removal achieved by small plants over a short period of time indicates great potential for successful phytoremediation of subsurface MTBE plumes using poplar trees. The fraction of MTBE removed from the hydroponic systems correlated well with volume of water transpired by the plants; the correlation enabled computation of the MTBE transpiration stream concentration factor of approximately 1, an important parameter for the design of engineered MTBE phytoremediation systems.
Ramaswami, A., & Rubin, E. (2001). Measuring Phytoremediation Parameters for Volatile Organic Compounds: Focus on MTBE. ASCE Practice Periodical of Hazardous and Radioactive Waste: Special Issue on Phytoremediation.Abstract
Experimental techniques are described for conducting greenhouse tests to examine the pathways for phytoremediation of volatile organic compounds (VOCs), distinguishing between uptake of the VOC along with water transpired by living plants and the passive, physical process of volatilization. The experimental techniques were applied to assess the potential for phytoremediation of methyl-tertiary-butyl-ether (MTBE). Experimental data indicate that MTBE was readily taken up from water by hybrid poplar saplings, yielding 25% reduction in aqueous MTBE concentration and 30% reduction in MTBE mass over a 1-week period. These reductions in plant systems were significantly greater than in controls, indicating great potential for MTBE phytoremediation in the field. Engineering parameters for phytoremediation were determined from the experiments, yielding an MTBE transpiration stream concentration factor of 1 and a root concentration factor of 0.7–1.4. Mass balance studies showed good closure on MTBE mass balance, indicating no significant degradation of MTBE in the young poplar saplings used in this study. These results suggest that phytovolatilization may be the primary pathway for MTBE phytoremediation.
Ramaswami, A., Johansen, P., Isleyen, M., Bielefeldt, A., & Illangasekare, T. (2001). Assessing multicomponent DNAPL biostabilization. I: Coal tar. ASCE Journal of Environmental Engineering.Abstract
Subsurface spills of high-molecular weight, multicomponent, dense nonaqueous-phase liquids (DNAPLs) are intractable for remediation by conventional techniques. This paper introduces the concept of biostabilization of the DNAPL source region as a means of achieving risk reduction at DNAPL-contaminated sites. Successful biostabilization depends upon the interplay among dissolution, degradability, and toxicity of various DNAPL constituents, difficult to predict a priori for the mixture. Bench-scale screening tests are proposed for identifying those DNAPLs that are amenable to biostabilization. The screening protocols compare four criteria: (1) microbial activity; (2) composition of the DNAPL residue; (3) aqueous phase contaminant concentrations; and (4) aggregate aqueous phase toxicity—across unbiotreated controls and in mixed versus unmixed biometers. The unmixed system represents slow dissolution from DNAPL pools in the quiescent subsurface. The protocols are developed and evaluated with DNAPL coal tar in the first paper of this set (Part I). Unmixed coal tar biometers, characterized by slow mass transfer and low-level microbial activity, exhibited reduced, aqueous-phase contaminant concentrations and aggregate toxicity, as well as stable DNAPL composition, consistently indicating favorable potential for in situ biostabilization.
Bielefeldt, A., Riffel, M., Ramaswami, A., & Illangasekare, T. (2001). Assessing Multicomponent DNAPL Biostabilization Potential. II: Aroclor 1242. ASCE Journal of Environmental Engineering.Abstract
Aroclors are dense nonaqueous-phase liquids (DNAPLs) composed of polychlorinated biphenyls, which are common subsurface contaminants. Because complete remediation of Aroclor is very difficult, biostabilization may offer an alternative where risk reduction can be achieved without destruction of the DNAPL mass. The potential for aerobic in situ biostabilization of Aroclor 1242 was evaluated using laboratory protocols similar to those described in the companion paper. Total microbial concentrations increased and stabilized in both mixed and unmixed systems, while the respiring cells did not stabilize in either system. After 100 days, the DNAPL in mixed biometers was depleted in dichlorobiphenyls; the DNAPL composition in unmixed biometers did not change significantly. The total aqueous polychlorinated biphenyl concentration was lower in the unmixed than mixed biometers; both were below the predicted equilibrium concentration. After 100 days, the chronic toxicity of the aqueous phase to Cerodaphnia was greater in the biotreated systems than in the unbiotreated systems. The results indicate that aerobic microbiological activity may be insufficient to fully stabilize Aroclor in the subsurface, in contrast to the clear biostabilization potential of coal tar.
Ramaswami, A., Carr, P., & Burkhardt, M. (2001). Plant-Uptake of Uranium: Hydroponic and Soil System Studies. International Journal of Phytoremediation.Abstract

Limited information is available on screening and selection of terrestrial plants for uptake and translocation of uranium from soil. This article evaluates the removal of uranium from water and soil by selected plants, comparing plant performance in hydroponic systems with that in two soil systems (a sandy-loam soil and an organic-rich soil). Plants selected for this study were Sunflower (Helianthus giganteus), Spring Vetch (Vicia sativa), Hairy Vetch (Vicia villosa), Juniper (Juniperus monosperma), Indian Mustard (Brassica juncea), and Bush Bean (Phaseolus nanus).

Plant performance was evaluated both in terms of the percent uranium extracted from the three systems, as well as the biological absorption coefficient (BAC) that normalized uranium uptake to plant biomass. Study results indicate that uranium extraction efficiency decreased sharply across hydroponic, sandy and organic soil systems, indicating that soil organic matter sequestered uranium, rendering it largely unavailable for plant uptake. These results indicate that site-specific soils must be used to screen plants for uranium extraction capability; plant behavior in hydroponic systems does not correlate well with that in soil systems. One plant species, Juniper, exhibited consistent uranium extraction efficiencies and BACs in both sandy and organic soils, suggesting unique uranium extraction capabilities.

Ramaswami, A., Tawachsupa, S., & Isleyen, M. (2001). Batch-Mixed Iron Treatment of High Arsenic Waters. Water Research.Abstract
This paper develops batch-mixed treatment with zero-valent iron as a point-of-use technology, appropriate for arsenic removal from water stored within rural homes in Bangladesh and West Bengal, India, where arsenic poisoning has affected an estimated 20 million people. Batch tests with iron yielded the following results: (1) High arsenic removal (>93%) was achieved from highly arsenated waters (2000 μg/L) over short contact times (0.5–3 h) with iron filings added at doses ranging from 2500 to 625 mg/L; (2) Most rapid arsenic removal was observed in head-space free systems with sulphates present in solution, while phosphate buffers were observed to inhibit arsenic removal by iron; (3) The arsenic removed from water was found to be strongly bound to the elemental iron filings, such that the treated water could be decanted and iron could be reused at least 100 times; (4) Some iron dissolved into water over the contact period, at concentrations ranging from 100 to 300 μg/L, which are within safe drinking water limits. These results indicate that, with appropriate assessment of water chemistry in the affected region, treatment with metallic iron followed by simple decantation can be used as a practical, in-home, point-of-use technique for reducing human exposure to arsenic in drinking water.
2000
Ramaswami, A., & Luthy, R. G. (2000). Measuring and Modeling Physico-Chemical Limitations to Bioavailability and Biodegradation. In Manual of Environmental Microbiology (pp. 712-729) . ASM Press.

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