Although urbanization often has negative effects on the environment, it can have benefits, such as low per capita resource use and increased efficiencies for the capture and treatment of emissions.
MIRI A M L . DI A MOND ERIN HODGE UNIV ERSIT Y OF TORONTO
URBAN CONTAMINANT DYNAMICS: From Source to Effect
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lobally, populations are becoming more urbanized: virtually all of the population growth expected to occur worldwide from now until 2030 is expected to occur in urban areas (1). Rates of urbanization are between 73% and 77% in Europe, North America, Latin America, and the Caribbean and are expected to increase rapidly in Africa and Asia over the next 30 years (1). Urban areas are major concentrators, repositories, and emitters of a myriad of chemicals because of the wide range and intensity of human activities and the characteristics of the built environment (Figure 1). These emissions have various negative impacts on the environment. However, some urban forms can facilitate low per capita resource use and contaminant emissions as well as increased efficiencies for the capture and treatment of emissions. Because nearly twothirds of the world’s population and three-quarters of the populations of Europe, North America, and Central America live in urban areas, a better understanding of the fate of contaminant emissions in urban settings, as well as of the potential impacts and benefits of urbanization, is needed.
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In this article, we review the array of contaminants produced, retained, and/or released in urban areas in industrialized countries and their fate in relation to the urban environment. Our focus is mainly on persistent organic pollutants (POPs), particulate matter, pharmaceuticals, and trace metals arising from nonindustrial urban processes and activities. We discuss the environmental degradation associated with urban contaminant burdens in order to demonstrate that human activities of widely varying description and scale all have environmental impacts. This discussion should be used to focus research and policies aimed at taking advantage of efficiencies associated with dense urban development in order to improve environmental quality in urban and surrounding areas, and not to condemn dense settlements because of their tendency to create significant waste and contaminant streams.
Urban contaminant stocks and emissions The concentration of people, material, and energy use in cities means that cities are nodes of chemical stocks and emissions. Urban metabolism studies have demonstrated the tremendous drawing power © 2007 American Chemical Society
photodisc
of cities—the importation of large amounts of materials and energy from a global range—and the subsequent production, incorporation, and localized release of contaminants and other wastes within and near the city (2, 3). Whereas most materials remain within the city, the fraction of contaminant stocks that is released and eventually exported from the city depends on usage patterns (2) as well as the physical–chemical properties of the contaminant. Contaminant stocks and emissions are influenced by several interrelated factors, including the size of a population and its affluence, consumption patterns, and urban form (4). In this discussion, a distinction exists between contaminant burden (stocks or emissions) per unit area and contaminant burden per capita. Per capita contaminant burdens can differ substantially among cities of similar affluence and/ or size, depending on such factors as use of public transit and residential and commercial density (4, 5). Per capita burdens can be lower in dense settlements that can support “economies of scale” of centralized utilities and infrastructure (4). Of course, possible or theoretical advantages to density are frequently overwhelmed by the insufficient capacity of current
technological measures for treatment or containment (e.g., wastewater); lack of access to, or underdeveloped, centralized treatment systems (5); lack of societal wealth; and/or lack of political will. Contaminants are emitted by or from urban industry, transportation, power generation, infrastructure (e.g., PCBs degassing from building sealants), consumption of goods (e.g., pharmaceuticals emitted as a result of the use of medicines), heating and cooling systems, and other activities. Many urban contaminants are emitted as nonpoint-source releases, which are poorly quantified and regulated. As a result of intentional or unintentional releases, urban–rural gradients of up to several orders of magnitude exist for numerous contaminants in virtually all media. These gradients cause the “urban halo” effect, in which contaminants emitted in urban areas are transported to nonurban areas where they contaminate air, water, and soils. Chemical mobility is promoted by the highly disturbed physical environment in cities, typified by impervious surfaces coated with surface film, distorted hydrologic regimes, and simplified biotic communities. Elevated contaminant concentrations in cities can lead to inJUNE 1, 2007 / Environmental Science & Technology n 3797
FIGURE 1
illustr ation by Neil Ste wart
Movement of contaminants through an urban area
Solid-waste disposal
Importation of food and goods from international hinterlands
Film volatilization
Atmospheric deposition Building ventilation to outdoor environment
Film washoff
Warehouse Electrical and communication infrastructure
Building materials and treatments Personal care products Cooking Pharmaceuticals Product constituents Lawn with ornamental (nonindigenous) species in simplified ecosystem
Transportation emissions
Wastewater treatment
Stormwater
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creased exposures and adverse health effects, but fully understanding these effects requires the assessment of multiple social and economic factors. A wide range of contaminants are emitted intentionally (e.g., combustion sources) and unintentionally (e.g., evaporative losses) in urban areas. Some contaminant emissions are large and originate from point sources, such as power plants or industrial facilities, whereas others are concentrated along pathways of transit, such as motor vehicle emissions. Other emissions, however, occur at trace levels from a remarkable range of human activities that appear mundane and benign compared with large effluent pipes or smokestacks but, in the aggregate, constitute a measurable quantity of contaminants released into a relatively restricted geographic area.
Virtually all of the population growth expected to occur worldwide from now until 2030 is expected to occur in urban areas. In many high-income countries, the expansion of the service sector and the loss of heavy industry and manufacturing in numerous cities (e.g., steel and textile production), combined with urban growth, particularly at low densities, have shifted the nature of emissions. Although environmental regulatory regimes directed at point-source emitters, such as smoke-stack industries and power plants, are relatively well established in many industrialized countries, regulatory measures to address emissions from diffuse, nonpoint-source releases are less comprehensive (6). Moreover, many nonpoint sources, such as evaporative losses, are less well characterized and more difficult to control than point sources. No master list of urban contaminant emissions exists, but to demonstrate the breadth of contaminants emitted, we note that most human activities, especially in high-income societies, are associated with the release of chemicals, a fraction of which are persistent, bioaccumulative, and toxic (PBT) (see Table 1). In addition to industrial activities (which often are or were concentrated in urban areas), motor vehicle use, and electrical power generation, emissions also originate from the domestic consumption of various products, including cleaning agents, electronics, and pharmaceuticals. Sewage treatment plants (STPs), which are classified as point sources, play a central role in the distribution of urban emissions because they pool and discharge many of the chemicals that result from diverse trace emissions. In fact, even though STPs are not large repositories of PCBs, STP discharges into aquatic systems are important sources of PCBs and other persistent compounds originating from urban areas
(7, 8). Sewage collection and discharge also funnel into surface waters less persistent but potentially highly biologically active contaminants, such as human steroid hormones (9, 10). STPs also contribute to emissions to soil, when sludge from STPs is used for soil amendments in urban areas (11). This sludge is contaminated with an array of chemicals, including halogenated organics, organotins, nitrosamines, pesticides, synthetic fragrance fixatives, surfactants, PAHs, and PCBs. Urban areas also contain stocks of chemical contaminants no longer allowed for new uses but which remain in use or as persistent residuals—the socalled legacy contaminants. This includes lead originating from past vehicle emissions and old paints; PCBs and polychlorinated naphthalenes (PCNs) in building materials and electrical transformers installed before the 1970s; asbestos and chlorofluorocarbons (CFCs) in building materials; and a variety of now-banned pesticides, such as chlordane and DDT. These stocks are slowly but steadily released from the urban fabric. Examples include PCBs in building sealants (12, 13) and CFCs, the largest mass of which are present in structural foams used in buildings constructed post-World War II. Rates of emission of these CFCs will increase as these buildings deteriorate and are renovated or demolished but will then decrease as the stock diminishes and different materials are used in construction (2). Population size and the intensity of material and energy consumption affect the degree of contamination. This phenomenon has been best demonstrated in the case of soil lead and PAH contamination but likely also holds true for other contaminants such as PCBs and polybrominated diphenyl ethers (PBDEs). Soil-lead concentrations are a function of city size; larger cities have higher traffic densities, leading to greater inputs of vehicle-related emissions to a proportionally smaller area (14, 15). This pattern is then transferred to human receptors, because blood-lead contents of children correlate with city size in the same manner as soil-lead concentrations (16).
Degradation of environmental quality Urban-to-rural gradients of up to several orders of magnitude exist for numerous chemicals in virtually all media (17–19). The array of chemicals emitted in urban areas results in highly complex mixtures that impact all urban media. In virtually every city in the world, higher concentrations of numerous contaminants have been measured in urban versus rural air, including combustion-related fine particles, reactive gases, PCBs, PBDEs, PCNs (20, 21), PAHs, oxy- and nitro-PAHs, and metals (22). Degradation of urban surface waters and sediments due to urban emissions also has been well documented (23, 24). These elevated contaminant concentrations cause various toxic impacts on aquatic species (25, 26), in addition to negative economic impacts on commercial fisheries (27). Degradation of urban soils comes as a result of diffuse inputs, such as atmospheric deposition (19, 28); runoff from building surfaces, such as roofs and walls (29, 30); and leaching from buried waste or JUNE 1, 2007 / Environmental Science & Technology n 3799
TA B L E 1
Chemicals emitted from common human activities Activity
Media into which released
Range of chemicals emitted
Cooking
Air, sewage
PAHs, fatty acids, and fine particles released during cooking (80, 81) PFCs released during use of nonstick cookware (82, 83 )
Cleaning
Air, sewage, groundwater
Diverse VOCs and SVOCs, including terpenes, ketones (e.g., acetone, butanone), dioxane, phthalates, 2-propanol, and other alcohols, glycols and glycol ethers, toluene, and ammonia released from cleaning products (84, 85 ) PCE released at dry-cleaning operations and then from garments that have been dry-cleaned and brought into the home (86 )
Personal grooming
Air, surface waters via sewage
Synthetic musks (e.g., musk ketone and musk xylene) released from lotions and other fragranced products (87, 88 ) Polysiloxanes in many personal care products (89 )
Office work
Air
Ozone, formaldehyde, black carbon (soot) aerosols, and VOCs such as toluene, m /p /o-xylene, ethylbenzene, and dichloromethane emitted from office equipment like photocopiers and printers (90, 91); can contribute as much to outdoor ambient air concentrations of VOCs as motor vehicle operation in a large city (92 )
Operation of motor vehicles
Air, surfaces, surface waters via runoff and atmospheric deposition
VOCs, NOx , SOx Combustion products, PAHs, PCDD/Fs, and soot Metals such as zinc, copper, and, in jurisdictions where catalytic converters are used, platinum and rhodium (93, 94 ) Fuel additives, depending on jurisdiction, such as lead, MTBE, and manganese sulfates and phosphates from MMT (95, 96 )
Medical care, including use of chemotherapeutic agents and other medicines, dentistry, X-rays, and other diagnostic methods
Water via sewage
Wide variety of biologically active compounds released to surface waters through sanitary discharges, to groundwater through leaking water mains, and to soils through application of sewage sludge to land (9 –11) Includes antimicrobials, antipyretics, anti-inflammatories, nonspecific alkylating agents used in chemotherapy, chemicals associated with the use of contrast media for X-rays, and metals such as mercury used in dentistry (41, 97, 98 )
structural materials (31). Although soil contaminant profiles are typically heterogeneous within an urban area, certain trends are evident. Concentrations of contaminants such as PBDEs tend to be highest toward the city center, metals and PAHs tend to increase with proximity to roadways, and concentrations of contaminants such as lead and PCBs tend to increase with the length of time the area has been in urban use (14, 15, 32). Elevated contaminant concentrations in urban soils can induce toxic or sublethal effects on soil decomposers and primary producers, which, in turn, can cause changes in soil metabolism (33, 34). The increased contaminant burdens pose risks to residents and can necessitate costly remediation before redevelopment. Not surprisingly, because of a combination of atmospheric deposition and uptake from soil, urban crops have been found to contain elevated concentrations of metals (35) and, in some cases, to pose potentially unacceptable risks to human consumers (36, 37). Urban water is frequently contaminated by 3800 n Environmental Science & Technology / JUNE 1, 2007
organic solvents and other chemicals, including chloroform, toluene, trichloroethene, and perchloroethene (38–40). Contaminants (e.g., chloroform, pharmaceuticals, X-ray contrast media) enter urban groundwater, particularly where the overburden is porous, as a result of leaking water infrastructure, septic systems, deliberate recharge associated with stormwater management practices, irrigation of green space, and natural recharge by waters contaminated with the numerous contaminants present in urban areas (41, 42).
Urban halo One aspect of the basic material–energy balance of urban systems is the export of contaminants to surrounding areas, either deliberately through discharges and solid-waste management or inadvertently through advection of polluted air masses or untreated runoff. This phenomenon has been termed the urban halo and results in elevated concentrations of contaminants in air, soil, vegetation,
Activity
Media into which released
Range of chemicals emitted
Construction, renovation, and aging of built structures
Water, air
Roofing tiles or wood treated with pesticides release metals and organic pesticides to soils and stormwater runoff (29, 30 ) Building siding (including brick, painted or unpainted wood, and vinyl siding) and roofs of varying construction release lead, copper, and zinc to soils and stormwater runoff (99 ) Wall coverings release a wide variety of VOCs Lead released during renovation of buildings that were painted with lead-containing paint
Sanitary discharges
Water
Steroid hormones, such as thyroxin and estradiol, and other “natural” chemicals released via sanitary discharges (100 )
Gardening
Soil, water, air
Rates of urban pesticide application can exceed application rates in agricultural areas (101, 102 ) Fertilizers
Use of consumer goods
Air
Aging of toys, furniture, carpets, containers, and other goods releases phthalates and other plasticizers, additive brominated flame retardants (103 ), and PFCs in surface coatings
Structural fires
Air, soil
Metals, PAHs, and halogenated organics formed or released during incomplete combustion, e.g., PCDD/Fs and PBDD/Fs (104 ) Perfluorinated surfactants released to soil and to surface waters and groundwaters via runoff after use of firefighting foams at hydrocarbon-fuel fires (105 )
Death rituals
Soil, air, water
Depending on local custom or personal choice, associated with emissions of formaldehyde, metals used in wood preserving or caskets (105 ), mercury, arsenic, lead, PCDD/Fs, PAHs, and PCBs from crematoria (106, 107 )
Waste disposal
Soil, water, air
Releases a wide range of metals and organic contaminants associated with the material disposed of and/or the use of incineration (e.g., metals such as lead, copper, and zinc; VOCs such as BTEX; and SVOCs such as PCBs, PAHs, PCNs, siloxanes, synthetic musks, and halogenated dioxins and furans).
BTEX, benzene–toluene–ethylene–xylene; MMT, methylcyclopentadienyl manganese tricarbonyl; MTBE, methyl-tert-butyl ether; NOx, nitrogen oxides; PBDD/Fs, polybrominated dibenzodioxins and furans; PBDEs, polybrominated diphenyl ethers; PCDD/Fs, polychlorinated dibenzodioxins and furans; PCE, perchloroethylene; PCNs, polychlorinated naphthalenes; PFCs, perfluorinated compounds; SOx, sulfur oxides; SVOCs, semivolatile organic compounds; VOCs, volatile organic compounds.
water, and sediments in areas downwind or downstream of urban centers. The urban halo has been amply demonstrated in estuarine, riverine, and marine systems (42, 43), including the Great Lakes basin of North America (44, 45), the northeastern seaboard of the U.S. (46, 47), and the Seine River basin in France (48, 49). One ironic aspect of urban halos is illustrated by Toronto, where the outward movement of polluted air masses from the urban core has contributed to smog episodes occurring in downwind locations that have been used by city dwellers as natural sanctuaries during holidays. Increased air concentrations and subsequent atmospheric deposition are a significant source of contaminant loads to surface waters. Van Metre et al. (24) showed a striking relationship between PAH concentrations in the sediments of 10 lakes and reservoirs in or nearby cities in the U.S. and temporal increases in vehicle miles traveled. Elevated atmospheric concentrations due to emissions from Chicago have been shown to influence concentrations
of PCBs in Lake Michigan for 15–20 km offshore and result in enhanced wet deposition of PCBs to southern Lake Michigan of 50–400% compared with background precipitation (45, 50). Similar findings have been made for contributions to the Chesapeake Bay from the Baltimore–Washington conurbation (51, 52) and to the New York–New Jersey Harbor from the surrounding New York City area (46, 47). The urban halo in terrestrial vegetation and soils has been documented for POPs (19, 32, 49, 53) and metals (54, 55). Elevated concentrations of PAHs (56) and metals (57) have also been documented in grains and vegetables cultivated downwind of urban centers.
Contaminant fate and effects in urban areas The biophysical environment of urban areas is highly altered relative to undisturbed systems, and these alterations can lead to greater contaminant mobility, such as multimedia transfer and export. The replacement of soils and vegetative cover with JUNE 1, 2007 / Environmental Science & Technology n 3801
impervious surfaces leads to disrupted hydrologic flows with higher proportions of surface runoff and lower rates of evapotranspiration. Urban air and water are more closely coupled than in forested or agricultural systems because of increased volumes of surface runoff and shorter concentration times (the time taken for runoff to reach the mouth of a watershed from its perimeter) (58). Also, perhaps counterintuitively, urban development increases rates of groundwater infiltration because of, for example, leaky subsurface infrastructure, septic systems, and lawn watering (59). The microclimatic phenomenon of urban warming results in increased local temperatures compared with surrounding hinterlands (60); these can increase evaporative emission rates of volatile and semivolatile organic compounds.
Nearly two-thirds of the world’s population and three-quarters of the populations of Europe, North America, and Central America live in urban areas. Unlike the soils that they replace, impervious surfaces, which make up typically 33–56% of urban areas (61), do not function as long-term contaminant sinks. Rather, contaminant fate is mediated by surface films that accumulate on the wide array of building materials that compose urban impervious surfaces (58, 62). Surface films change the functionality of impervious surfaces and, for example, enhance accumulation of contaminants, including compounds that do not necessarily originate from the city (17, 62). Most of the organic portion of the film is composed of biogenic compounds, some of which may be bacteria and fungal spores that have higher concentrations in urban than rural areas (63, 64). Thus, films are thicker and chemical concentrations (on an aerial basis) are higher in urban than rural areas, even of biogenic compounds (17, 65). Once deposited, organic compounds with higher vapor pressure will tend to volatilize. Less volatile and involatile contaminants in the film are subject to removal by washoff, a process that occurs independently of solubility (58). This independence can be attributed to mechanical forces involved in washoff as well as the abundance in surface films of polar organic and inorganic compounds that can function as surfactants (65, 66). As such, the film, together with the urban hydrologic regime that is designed to rapidly convey stormwater away from the city, effectively concentrates and transfers atmospherically and directly deposited contaminants to surface waters. In addition to being transient sinks, films can also be important reactive sinks by virtue of their 3802 n Environmental Science & Technology / JUNE 1, 2007
large surface areas, which can exceed that of particulate matter in the air above (67, 68). Urbanization may have opposing influences on the capacity of soils to act as a contaminant sink. Urban soils could be a less effective sink because they are often compacted, which reduces their capacity for infiltration, and they can have reduced microbial biomass available to degrade organic contaminants because of toxic, sublethal, or stress effects induced by contaminants (33, 34). Alternatively, urban soils could have an increased capacity to retain contaminants because of higher concentrations of organic carbon and black carbon (69). These higher organic carbon stores may be due to the deposition of recalcitrant carbon such as soot, poor leaf-litter quality in forested land cover, and possible increases in below-ground productivity and the longer growing seasons of lawns versus forests (69). Alterations in the biophysical environment attendant with urban development affect contaminant fate processes and distribution over local and regional scales. Diamond et al. (70) developed the fugacity-based multimedia urban model (MUMFate) that considers the fate and distribution of a contaminant emitted into an environment consisting of air, surface water, surficial sediment, soil and overlying vegetation, and surface film. Applying MUM-Fate to the downtown area of Toronto (total population 2.5 million), Priemer and Diamond (71) found that for a heptachlorobiphenyl homologue group, urban development—or, more specifically, the presence of films on impervious surfaces—could increase contaminant concentrations in receiving waters and sediment by ∼10× because of the efficient washoff of atmospherically deposited chemicals to surface films. They also estimated that contaminant concentrations in soil could be reduced in a city by ∼10× relative to a forested area. The mechanisms responsible for this reduction include the simplified vegetative structure of lawns, which accumulate less atmospherically deposited chemicals than a forest canopy. In addition, urban leaf litter, lawn cuttings, and so on tend to be removed as solid waste, rather than being incorporated into soils. In this comparison, air concentrations increase by ∼10% relative to those with a forest canopy, because of volatilization from surface films. Whereas the magnitude of these differences between contaminant concentrations in the urban versus forested area is a function of the physical–chemical properties of the chemical, in all cases contaminants are rendered more mobile by urban development. This increased mobility in soil and water helps to explain the formation of the urban halo. An example of this enhanced mobility comes from the use of MUM-Fate to estimate that ~90% of total PBDEs (excluding BDE–209) that enter the city via air advection and/or local emissions are advected out of the city; only ~10% remain in the soils and sediments of the city (72).
Implications Understanding and quantifying the ultimate impacts of urban contaminant stocks and flows on
human and ecosystem health require a complex analysis of issues and metrics including not only contaminant-related exposure but also socioeconomic, psychosocial, demographic, and sociological factors that differ among urban systems in different countries (72). Urban air pollution clearly causes and promotes a very wide range of adverse outcomes, ranging from immediate (e.g., asthma) to delayed (e.g., lung cancer) and transgenerational effects (e.g., lower-birth-weight babies and neurodevelopmental effects) (73–75). However, even for air pollution, multiple factors must be considered—for example, morbidity rates related to air pollution (using traffic as a proxy) can be mediated by socioeconomic status (76, 77). The case of prolonged lead emissions from vehicles has taught us that the widespread use of a toxic element within cities increases exposure and the probability of adverse health effects, particularly among children; again, socioeconomic factors are essential to consider (14–16). To fully appreciate the implications of urban contaminant stocks and flows on human health, we need to look beyond exposures within the city. Harrad and Diamond (78) and Jones-Otazo et al. (79) speculated that as the use and release of a persistent contaminant increases in the city, initial exposure will be dominated by local pathways, such as indoor air and dust. Over time, these localized emissions will be exported from the city; some of the contaminants may enter terrestrial and aquatic food webs and then our food supply. We subsequently import the persistent contaminants back into the city via our foods, at which point control measures are difficult to implement. In closing, although elevated rates and large stocks of chemical emissions in cities offer an environmental challenge, cities also offer opportunities for improved ecosystem and human health via more efficient use of resources (e.g., land), which can lead to reduced per capita emissions of contaminants (4, 5). For example, cities well-served by public transit, which is facilitated by compact urban forms, can reduce rates of vehicle use and hence air emissions. Similarly, the removal efficiencies and costs of centralized solid- and liquid-waste treatment systems can be superior in more densely populated areas such as cities. Ultimately, aiming for reduced per capita emissions will translate into a reduced global inventory of PBT contaminants. Conceptualizing the problem of chemical emissions as being a per capita problem, in addition to being a problem of large point sources, will potentially widen the scope and sophistication of future research into more sustainable cities, as will fostering interdisciplinary research that benefits from the combined expertise of demographers, engineers, chemists, epidemiologists, and geographers. Our challenge is to reduce both point- and nonpointsource emissions and to improve resource use through urban planning so that we can better avail ourselves of the opportunities that cities offer. Miriam L. Diamond is a professor in the departments of geography and chemical engineering and applied
chemistry at the University of Toronto. Erin Hodge is now with the Ministry of the Environment, Ontario. Address correspondence about this article to Diamond at
[email protected].
Acknowledgments Funding was provided by the Premier’s Research Excellence Award; Environment Canada; CRESTech (No. AT01TRS42); the Canadian Chlorine Coordinating Committee; Natural Sciences and Engineering Research Council (NSERC) Discovery grants to Diamond; an NSERC Strategic grant to Diamond, T. Harner, and B. Branfireun; and a Canadian Foundation for Climate and Atmospheric Sciences grant to J. Donaldson, Diamond, and P. Makar. We thank E. Tam, University of Windsor; C. O’Neill and J. P. Clarke of Environment Canada; and R. Pouyat of the U.S. Department of Agriculture Forest Service for discussions, comments, and encouragement.
References (1) United Nations. World Urbanization Prospects, the 2001 Revision: Data Tables and Highlights; Population Division, Department of Economic and Social Affairs, UN Directorate: New York, 2002; www.un.org/esa/ population/publications/wup2001/wup2001dh.pdf. (2) Brunner, P. H.; Rechberger, H. Anthropogenic Metabolism and Environmental Legacies. In Causes and Consequences of Global Environmental Change; Douglas, I., Ed.; Encyclopedia of Global Environmental Change, Vol. 3; Wiley & Sons: Chichester, U.K., 2001; pp 54–72. (3) Newman, P. W. G. Sustainability and Cities: Extending the Metabolism Model. Landscape Urban Plan. 1999, 44, 219–226. (4) United Nations. Population, Environment and Development, the Concise Report; Population Division, UN Department of Economic and Social Affairs: New York, 2001; pp 21–44; www.un.org/esa/population/ publications/concise2001/C2001English.pdf. (5) Warren-Rhodes, K.; Koenig, A. Escalating Trends in the Urban Metabolism of Hong Kong: 1971–1997. Ambio 2001, 30, 429–438. (6) Salzman, J. Beyond the Smokestack: Environmental Protection in the Service Economy. UCLA Law Rev. 1999, 47, 411–489. (7) Durell, G. S.; Lizotte, R. D., Jr. PCB Levels at 26 New York City and New Jersey WPCPs That Discharge to the New York/New Jersey Harbor Estuary. Environ. Sci. Technol. 1998, 32, 1022–1031. (8) Eganhouse, R. P.; Sherblom, P. M. Anthropogenic Organic Contaminants in the Effluent of a Combined Sewer Overflow: Impact on Boston Harbor. Mar. Environ. Res. 2001, 51, 51–74. (9) Carballa, M.; et al. Behavior of Pharmaceuticals, Cosmetics, and Hormones in Sewage Treatment Plants. Water Res. 2004, 38, 2918–2926. (10) Heberer, T. Tracking Persistent Pharmaceutical Residues from Municipal Sewage to Drinking Water. J. Hydrol. 2002, 266, 175–189. (11) Harrison, E.; et al. Organic Chemicals in Sewage Sludg es. Sci. Total Environ. 2006, 367, 481–497. (12) Herrick, R. F.; et al. An Unrecognized Source of PCB Contamination in Schools and Other Buildings. Environ. Health Perspect. 2004, 112, 1051–1053. (13) Kohler, M.; et al. Joint Sealants: An Overlooked Diffuse Source of Polychlorinated Biphenyls in Buildings. Environ. Sci. Technol. 2005, 39, 1967–1973. (14) Mielke, H. W.; et al. Soil-Dust Lead and Childhood Lead Exposure as a Function of City Size and Community Traffic Flow: The Case for Lead Abatement in Minnesota. Davies, B. E., Wixson, B. G., Eds. Environ. Geochem. Health 1989, 9 (Suppl.), 253–271. (15) Mielke, H. W. Lead Dust Contaminated U.S.A. Communities: Comparison of Louisiana and Minnesota. Appl. Geochem. 1993, 8, 257–261. (16) Mielke, H. W.; Reagan, P. L. Soil Is an Important Pathway of Human Lead Exposure. Environ. Health Perspect. 1998, 106 (Suppl. 1), 217–229. (17) Gingrich, S. E.; et al. Atmospherically Derived Organic JUNE 1, 2007 / Environmental Science & Technology n 3803
Surface Films along an Urban–Rural Gradient. Environ. Sci. Technol. 2001, 35, 4031–4037. (18) Motelay-Massei, A.; et al. Using Passive Air Samplers To Assess Urban–Rural Trends for Persistent Organic Pollutants and Polycyclic Aromatic Hydrocarbons. 2. Seasonal Trends for PAHs, PCBs, and Organochlorine Pesticides. Environ. Sci. Technol. 2005, 39, 5763–5773. (19) Wong, F.; et al. Using Experimental and Forest Soils To Investigate the Uptake of Polycyclic Aromatic Hydrocarbons (PAHs) along an Urban–Rural Gradient. Environ. Pollut. 2004, 129, 387–398. (20) Cotham, W. E.; Bidleman, T. F. Polycyclic Aromatic Hydrocarbons and Polychlorinated Biphenyls in Air at an Urban and a Rural Site near Lake Michigan. Environ. Sci. Technol. 1995, 29, 2782–2789. (21) Helm, P. A.; Bidleman, T. F. Current Combustion-Related Sources Contribute to Polychlorinated Naphthalene and Dioxin-Like Polychlorinated Biphenyl Levels and Profiles in Air in Toronto, Canada. Environ. Sci. Technol. 2003, 37, 1075–1082. (22) Bolte, S.; et al. Human Exposure to Respirable Mn in Outdoor and Indoor Air in Urban and Rural Areas. J. Toxicol. Environ. Health A 2004, 67, 459–469. (23) Callender, E.; Rice, K. C. The Urban Environmental Gradient: Anthropogenic Influences on the Spatial and Temporal Distributions of Lead and Zinc in Sediments. Environ. Sci. Technol. 2000, 34, 232–238. (24) Van Metre, P. C.; Mahler, B. J.; Furlong, E. T. Urban Sprawl Leaves Its PAH Signature. Environ. Sci. Technol. 2000, 34, 4064–4070. (25) Matthiessen, P.; Law, R. J. Contaminants and Their Effects on Estuarine and Coastal Organisms in the United Kingdom in the Late Twentieth Century. Environ. Pollut. 2002, 120, 739–757. (26) Mikaelian, I.; et al. Prevalence of Lip Neoplasms of White Sucker (Catostomus commersoni) in the St. Lawrence River Basin. Can. J. Fish Aquat. Sci. 2000, 57, 174–181. (27) Kahn, J. R.; Buerger, R. B. Valuation and the Consequences of Multiple Sources of Environmental Deterioration— The Case of the New York Striped Bass Fishery. J. Environ. Manage. 1994, 40, 257–273. (28) Krauss, M.; Wilcke, W. Polychlorinated Naphthalenes in Urban Soils: Analysis, Concentrations, and Relation to Other Persistent Organic Pollutants. Environ. Pollut. 2003, 122, 75–89. (29) Bucheli, T. D.; et al. Occurrence and Behavior of Pesticides in Rainwater, Roof Runoff, and Artificial Stormwater Infiltration. Environ. Sci. Technol. 1998, 32, 3457–3464. (30) Zobrist, J.; et al. Quality of Roof Runoff for Groundwater Infiltration. Water Res. 2000, 34, 1455–1462. (31) Chirenje, T.; et al. Cu, Cr, and As Distribution in Soils Adjacent to Pressure-Treated Decks, Fences and Poles. Environ. Pollut. 2003, 124, 407–417. (32) Harrad, S.; Hunter, S. Concentrations of Polybrominated Diphenyl Ethers in Air and Soil on a Rural–Urban Transect across a Major U.K. Conurbation. Environ. Sci. Technol. 2006, 40, 4548–4553. (33) Carreiro, M. M.; et al. Variation in Quality and Decomposability of Red Oak Leaf Litter along an Urban–Rural Gradient. Biol. Fertil. Soils 1999, 29, 258–268. (34) Groffman, P. M.; et al. Carbon Pools and Trace Gas Fluxes in Urban Forest Soils. In Soil Management and Greenhouse Effect; Lal, R., et al., Eds.; CRC Press: Boca Raton, FL, 1995; pp 147–157. (35) Sanchez-Camazano, M.; Sanchez-Martin, M. J.; Lorenzo, L. F. Lead and Cadmium in Soils and Vegetables from Urban Gardens of Salamanca (Spain). Sci. Total Environ. 1994, 146–147, 163–168. (36) Hough, R. L.; et al. Assessing Potential Risk of Heavy Metal Exposure from Consumption of Home-Produced Vegetables by Urban Populations. Environ. Health Perspect. 2004, 112, 215–221. (37) Sterrett, S. B.; et al. Influence of Fertilizer and Sewage Sludge Compost on Yield and Heavy Metal Accumulation by Lettuce Grown in Urban Soils. Environ. Geochem. Health 1996, 18, 135–142. (38) Squillace, P. J.; Moran, M. J.; Price, C. V. VOCs in Shallow Groundwater in New Residential/Commercial Areas of the United States. Environ. Sci. Technol. 2004, 38, 5327–5338. 3804 n Environmental Science & Technology / JUNE 1, 2007
(39) Lopes, T. J.; Bender, D. A. Nonpoint Sources of Volatile Organic Compounds in Urban Areas—Relative Importance of Land Surfaces and Air. Environ. Pollut. 1998, 101, 221–230. (40) Rivett, M. O.; et al. Organic Contamination of the Birmingham Aquifer. J. Hydrol. 1990, 113, 307–323. (41) Ternes, T. E.; Hirsch, R. Occurrence and Behavior of X-ray Contrast Media in Sewage Facilities and the Aquatic Environment. Environ. Sci. Technol. 2000, 34, 2741–2748. (42) Estebe, A.; Mouchel, J.-M.; Thevenot, D. R. Urban Runoff Impacts on Particulate Metal Concentrations in River Seine. Water, Air, Soil Pollut. 1998, 108, 83–105. (43) Von Gunten, H. R.; Sturm, M.; Moser, R. N. 200-Year Record of Metals in Lake Sediments and National Background Concentrations. Environ. Sci. Technol. 1997, 31, 2193–2197. (44) Hafner, W. D.; Hites, R. A. Potential Sources of Pesticides, PCBs, and PAHs to the Atmosphere of the Great Lakes. Environ. Sci. Technol. 2003, 37, 3764–3773. (45) Simcik, M. F.; et al. Urban Contamination of the Chicago Coastal Lake Michigan Atmosphere by PCBs and PAHs during AEOLOS. Environ. Sci. Technol. 1997, 31, 2141–2147. (46) Gigliotti, C. L.; et al. Polycyclic Aromatic Hydrocarbons in the New Jersey Coastal Atmosphere. Environ. Sci. Technol. 2000, 34, 3547–3554. (47) Van Ry, D. A.; et al. Wet Deposition of Polychlorinated Biphenyls in Urban and Background Areas of the Mid-Atlantic States. Environ. Sci. Technol. 2002, 36, 3201–3209. (48) Garnaud, S.; et al. Heavy Metal Concentrations in Dry and Wet Atmospheric Deposits in a Paris District: Comparison with Urban Runoff. Sci. Total Environ. 1999, 235, 235–245. (49) Motelay-Massei, A.; et al. Distribution and Spatial Trends of PAHs and PCBs in Soils in the Seine River Basin, France. Chemosphere 2004, 55, 555–565. (50) Offenberg, J. H.; Baker, J. E. Polychlorinated Biphenyls in Chicago Precipitation: Enhanced Wet Deposition to Near-Shore Lake Michigan. Environ. Sci. Technol. 1997, 31, 1534–1538. (51) Brunciak, P. A.; et al. Atmospheric Polychlorinated Biphenyl Concentrations and Apparent Degradation in Coastal New Jersey. Atmos. Environ. 2001, 35, 3325–3339. (52) Nelson, E. D.; McConnell, L. L.; Baker, J. E. Diffusive Exchange of Gaseous Polycyclic Aromatic Hydrocarbons and Polychlorinated Biphenyls across the Air–Water Interface of the Chesapeake Bay. Environ. Sci. Technol. 1998, 32, 912–919. (53) Wagrowski, D. M.; Hites, R. A. Polycyclic Aromatic Hydrocarbon Accumulation in Urban, Suburban, and Rural Vegetation. Environ. Sci. Technol. 1997, 31, 279–282. (54) Pouyat, R. V.; McDonnell, M. J. Heavy Metal Accumulations in Forest Soils along an Urban–Rural Gradient in Southeastern New York, USA. Water, Air, Soil Pollut. 1991, 57/58, 797–807. (55) Romic, M.; Romic, D. Heavy Metals Distribution in Agricultural Topsoils in Urban Area. Environ. Geol. 2003, 43, 795–805. (56) Jones, K. C.; et al. Increases in the Polynuclear Aromatic Hydrocarbon Content of an Agricultural Soil over the Last Century. Environ. Sci. Technol. 1989, 23, 95–101. (57) Voutsa, D.; Grimanis, A.; Samara, C. Trace Elements in Vegetables Grown in an Industrial Area in Relation to Soil and Air Particulate Matter. Environ. Pollut. 1996, 94, 325–335. (58) Labencki, T.; et al. Variability in and Mechanisms of PAH Washoff from Urban Impervious Surfaces. Chemosphere 2007, in press. (59) Lerner, D. N. Identifying and Quantifying Urban Recharge: A Review. Hydrogeol. J. 2002, 10, 143–152. (60) Stone, B.; Rodgers, M. O. Urban Form and Thermal Efficiency—How the Design of Cities Influences the Urban Heat Island Effect. J. Am. Plann. Assoc. 2001, 67, 186–198. (61) Boyd, M. J.; Bufill, M. C.; Knee, R. M. Pervious and Impervious Runoff in Urban Catchments. Hydrolog. Sci. J. 1993, 38, 463–478. (62) Diamond, M. L.; et al. Evidence for Organic Film on an Impervious Urban Surface: Characterization and Potential Teratogenic Effects. Environ. Sci. Technol. 2000, 34,
2900–2908. (63) Graham, B.; et al. Local and Regional Contributions to the Atmospheric Aerosol over Tel Aviv, Israel: A Case Study Using Elemental, Ionic, and Organic Tracers. Atmos. Environ. 2004, 38, 1593–1604. (64) Shaffer, B. T.; Lighthart, B. Survey of Culturable Airborne Bacteria at Four Diverse Locations in Oregon: Urban, Rural, Forest and Coastal. Microb. Ecol. 1997, 34, 167–177. (65) Liu, Q.-T.; et al. Characterization of Polar Organic Compounds in the Organic Film on Indoor and Outdoor Glass Windows. Environ. Sci. Technol. 2003, 37, 2340–2349. (66) Lam, B.; et al. Chemical Composition of Surface Films and Implications for Atmospheric Chemistry. Atmos. Environ. 2005, 39, 6578–6586. (67) Kahan, T. F.; Kwamena, N.-O. A.; Donaldson, D. J. Heterogeneous Ozonation Kinetics of Polycyclic Aromatic Hydrocarbons on Organic Films. Atmos. Environ. 2006, 40, 3448–3459. (68) Kwamena, N.-O.; et al. Assessing the Importance of Heterogeneous Reactions of Polycyclic Aromatic Hydrocarbons in the Urban Atmosphere Using the Multimedia Urban Model. Atmos. Environ. 2006, 41, 37–50. (69) Pouyat, R.; et al. Soil Carbon Pools and Fluxes in Urban Ecosystems. Environ. Pollut. 2002, 116, S107–S108. (70) Diamond, M. L.; Priemer, D. A.; Law, N. L. Developing a Multimedia Model of Chemical Dynamics in an Urban Area. Chemosphere 2001, 44, 1655–1667. (71) Priemer, D. A.; Diamond, M. L. Application of the Multimedia Urban Model To Compare the Fate of SOCs in an Urban and Forested Watershed. Environ. Sci. Technol. 2002, 36, 1004–1013. (72) Raphael, D., Ed.; Social Determinants of Health, Canadian Perspectives; Canadian Scholars’ Press Inc.: Toronto, 2004. (73) Brook, R. D.; Brook, J. R.; Rajagopalan, S. Air Pollution: The “Heart” of the Problem. Curr. Hypertens. Rep. 2003, 5, 32–39. (74) Pope, C. A., III; et al. Lung Cancer, Cardio-Pulmonary Mortality, and Long-Term Exposure to Fine Particulate Air Pollution. J. Am. Med. Assoc. 2002, 287, 1132–1141. (75) Perera, F. P.; et al. Effect of Prenatal Exposure to Airborne Polycyclic Aromatic Hydrocarbons on Neurodevelopment in the First 3 Years of Life among Inner-City Children. Environ. Health Perspect. 2006, 114, 1287–1292. (76) Smargiassi, A.; et al. Traffic Intensity, Dwelling Value, and Hospital Admissions for Respiratory Disease among the Elderly in Montreal (Canada): A Case-Control Analysis. J. Epidemiol. Community Health 2006, 60, 507–512. (77) Jerrett, M.; et al. Do Socioeconomic Characteristics Modify the Short Term Association between Air Pollution and Mortality? Evidence from a Zonal Time Series in Hamilton, Canada. J. Epidemiol. Community Health 2004, 58, 31–40. (78) Harrad, S.; Diamond, M. L. Exposure to Polybrominated Diphenyl Ethers (PBDEs) and Polychlorinated Biphenyls (PCBs): Current and Future Scenarios. Atmos. Environ. 2006, 40, 1187–1188. (79) Jones-Otazo, H. A.; et al. Is House Dust the Missing Exposure Pathway for PBDEs? An Analysis of Urban Fate and Human Exposure to PBDEs. Environ. Sci. Technol. 2005, 39, 5121–5130. (80) Dennekamp, M.; et al. Ultrafine Particles and Nitrogen Oxides Generated by Gas and Electric Cooking. Occup. Environ. Med. 2001, 58, 511–516. (81) Levy, J. I.; Dumyahn, T.; Spengler, J. D. Particulate Matter and Polycyclic Aromatic Hydrocarbon Concentrations in Indoor and Outdoor Microenvironments in Boston, MA. J. Expo. Anal. Environ. Epidemiol. 2002, 12, 104–114. (82) Ellis, D. A.; et al. Thermolysis of Fluoropolymers as a Potential Source of Halogenated Organic Acids in the Environment. Nature 2001, 412, 321–324. (83) Ellis, D. A.; et al. The Use of F-19 NMR and Mass Spectrometry for the Elucidation of Novel Fluorinated Acids and Atmospheric Fluoroacid Precursors Evolved in the Thermolysis of Fluoropolymers. Analyst 2003, 128, 756–764. (84) Nazaroff, W. W.; Weschler, C. J. Cleaning Products and Air Fresheners: Exposure to Primary and Secondary Air Pollutants. Atmos. Environ. 2004, 38, 2841–2865. (85) Wolkoff, P.; et al. Risk in Cleaning: Chemical and Physi-
cal Exposure. Sci. Total Environ. 1998, 215, 135–156. (86) Chao, C. Y. H.; et al. Indoor Perchloroethylene Accumulation from Dry Cleaned Clothing on Residential Premises. Build. Environ. 1999, 34, 319–328. (87) Gatermann, R.; et al. Synthetic Musks in the Environment. Part I: Species-Dependent Bioaccumulation of Polycyclic and Nitro Musk Fragrances in Freshwater Fish and Mussels. Arch. Environ. Contam. Toxicol. 2002, 42, 437–446. (88) Lee, H. B.; Peart, T. E.; Sarafin, K. Occurrence of Polycyclic and Nitro Musk Compounds in Canadian Sludge and Wastewater Samples. Water Qual. Res. J. Can. 2003, 38, 683–702. (89) Parker, W. J.; et al. Pilot Plant Study To Assess the Fate of Two Volatile Methyl Siloxane Compounds during Municipal Wastewater Treatment. Environ. Toxicol. Chem. 1999, 18, 172–181. (90) Lee, S. C.; Lam, S.; Fai, H. K. Characterization of VOCs, Ozone and PM10 Emissions from Office Equipment in an Environmental Chamber. Build. Environ. 2001, 36, 837–842. (91) Wolkoff, P. Photocopiers and Indoor Air Pollution. Atmos. Environ. 1999, 33, 2129–2130. (92) Na, K.; Kim, Y. P.; Moon, K. C. Diurnal Characteristics of Volatile Organic Compounds in the Seoul Atmosphere. Atmos. Environ. 2003, 37, 733–742. (93) Cinti, D.; et al. Platinum Levels in Natural and Urban Soils from Rome and Latium (Italy): Significance for Pollution by Automobile Catalytic Converter. Sci. Total Environ. 2002, 293, 47–57. (94) Ely, J. C.; et al. Implications of Platinum-Group Element Accumulation along U.S. Roads from Catalytic-Converter Attrition. Environ. Sci. Technol. 2001, 35, 3816–3822. (95) Kawamoto, K.; Arey, J.; Gschwend, P. M. Emission and Fate Assessment of Methyl Tertiary Butyl Ether in the Boston Area Airshed Using a Simple Multimedia Box Model: Comparison with Urban Air Measurements. J. Air Waste Manage. Assoc. 2003, 53, 1426–1435. (96) Zayed, J.; Hong, B.; L’Esperance, G. Characterization of Manganese-Containing Particles Collected from the Exhaust Emissions of Automobiles Running with MMT Additive. Environ. Sci. Technol. 1999, 33, 3341–3346. (97) Daughton, C. G.; Ternes, T. A. Pharmaceuticals and Personal Care Products in the Environment: Agents of Subtle Change? Environ. Health Perspect. 1999, 107 (Suppl. 6), 907–937. (98) Miao, X.-S.; et al. Occurrence of Antimicrobials in the Final Effluents of Wastewater Treatment Plants in Canada. Environ. Sci. Technol. 2004, 38, 3533–3541. (99) Davis, A. P.; Shokouhian, M.; Shubei, N. Loading Estimates of Lead, Copper, Cadmium, and Zinc in Urban Runoff from Specific Sources. Chemosphere 2001, 44, 997–1009. (100) Jobling, S.; et al. Widespread Sexual Disruption in Wild Fish. Environ. Sci. Technol. 1998, 32, 2498–2506. (101) Struger, J.; et al. Environmental Concentrations of Urban Pesticides. In Current Practices in Modelling the Management of Stormwater Impacts; James, W., Ed.; CRC Press: Boca Raton, FL, 1994; pp 85–98. (102) Templeton, S. R.; Zilberman, D.; Yoo, S. J. An Economic Perspective on Outdoor Residential Pesticide Use. Environ. Sci. Technol. 1998, 32, 416A–423A. (103) Kemmlein, S.; Hahn, O.; Jann, O. Emissions of Organophosphate and Brominated Flame Retardants from Selected Consumer Products and Building Materials. Atmos. Environ. 2003, 37, 5485–5493. (104) Lutes, C. C.; Ryan, J. V. Characterization of Air Emissions from the Simulated Open Combustion of Fiberglass Materials; Report EPA/600/SR-93/239. U.S. EPA Air and Energy Engineering Lab: Research Triangle Park, NC, 1994. (105) Moody, C. A.; Field, J. A. Perfluorinated Surfactants and the Environmental Implications of Their Use in Fire-Fighting Foams. Environ. Sci. Technol. 2000, 34, 3864–3870. (106) Spongberg, A. L.; Becks, P. M. Inorganic Soil Contamination from Cemetery Leachate. Water, Air, Soil Pollut. 2000, 117, 313–327. (107) Mills, A. Mercury and Crematoria Chimneys. Nature 1990, 346, 615. JUNE 1, 2007 / Environmental Science & Technology n 3805
