Abstract: On a global scale, pathogenic contamination of drinking water poses the most significant health risk to humans, and there have been countless numbers of disease outbreaks and poisonings throughout history resulting from exposure to untreated or poorly treated drinking water. However, significant risks to human health may also result from exposure to nonpathogenic, toxic contaminants that are often globally ubiquitous in waters from which drinking water is derived. With this latter point in mind, the objective of this commission paper is to discuss the primary sources of toxic contaminants in surface waters and groundwater, the pathways through which they move in aquatic environments, factors that affect their concentration and structure along the many transport flow paths, and the relative risks that these contaminants pose to human and environmental health. In assessing the relative risk of toxic contaminants in drinking water to humans, we have organized our discussion to follow the classical risk assessment paradigm, with emphasis placed on risk characterization. In doing so, we have focused predominantly on toxic contaminants that have had a demonstrated or potential effect on human health via exposure through drinking water. In the risk assessment process, understanding the sources and pathways for contaminants in the environment is a crucial step in addressing (and reducing) uncertainty associated with estimating the likelihood of exposure to contaminants in drinking water. More importantly, understanding the sources and pathways of contaminants strengthens our ability to quantify effects through accurate measurement and testing, or to predict the likelihood of effects based on empirical models. Understanding the sources, fate, and concentrations of chemicals in water, in conjunction with assessment of effects, not only forms the basis of risk characterization, but also provides critical information required to render decisions regarding regulatory initiatives, remediation, monitoring, and management. Our discussion is divided into two primary themes. First we discuss the major sources of contaminants from anthropogenic activities to aquatic surface and groundwater and the pathways along which these contaminants move to become incorporated into drinking water supplies. Second, we assess the health significance of the contaminants reported and identify uncertainties associated with exposures and potential effects. Loading of contaminants to surface waters, groundwater, sediments, and drinking water occurs via two primary routes: (1) point-source pollution and (2) non-point-source pollution. Point-source pollution originates from discrete sources whose inputs into aquatic systems can often be defined in a spatially explicit manner. Examples of point-source pollution include industrial effluents (pulp and paper mills, steel plants, food processing plants), municipal sewage treatment plants and combined sewage-storm-water overflows, resource extraction (mining), and land disposal sites (landfill sites, industrial impoundments). Non-point-source pollution, in contrast, originates from poorly defined, diffuse sources that typically occur over broad geographical scales. Examples of non-point-source pollution include agricultural runoff (pesticides, pathogens, and fertilizers), storm-water and urban runoff, and atmospheric deposition (wet and dry deposition of persistent organic pollutants such as polychlorinated biphenyls [PCBs] and mercury). Within each source, we identify the most important contaminants that have either been demonstrated to pose significant risks to human health and/or aquatic ecosystem integrity, or which are suspected of posing such risks. Examples include nutrients, metals, pesticides, persistent organic pollutants (POPs), chlorination by-products, and pharmaceuticals. Due to the significant number of toxic contaminants in the environment, we have necessarily restricted our discussion to those chemicals that pose risks to human health via exposure through drinking water. A comprehensive and judicious consideration of the full range of contaminants that occur in surface waters, sediments, and drinking water would be a large undertaking and clearly beyond the scope of this article. However, where available, we have provided references to relevant literature to assist the reader in undertaking a detailed investigation of their own. The information collected on specific chemicals within major contaminant classes was used to determine their relative risk using the hazard quotient (HQ) approach. Hazard quotients are the most widely used method of assessing risk in which the exposure concentration of a stressor, either measured or estimated, is compared to an effect concentration (e.g., no-observed-effect concentration or NOEC). A key goal of this assessment was to develop a perspective on the relative risks associated with toxic contaminants that occur in drinking water. Data used in this assessment were collected from literature sources and from the Drinking Water Surveillance Program (DWSP) of Ontario. For many common contaminants, there was insufficient environmental exposure (concentration) information in Ontario drinking water and groundwater. Hence, our assessment was limited to specific compounds within major contaminant classes including metals, disinfection by-products, pesticides, and nitrates. For each contaminant, the HQ was estimated by expressing the maximum concentration recorded in drinking water as a function of the water quality guideline for that compound. There are limitations to using the hazard quotient approach of risk characterization. For example, HQs frequently make use of worst-case data and are thus designed to be protective of almost all possible situations that may occur. However, reduction of the probability of a type II error (false negative) through the use of very conservative application factors and assumptions can lead to the implementation of expensive measures of mitigation for stressors that may pose little threat to humans or the environment. It is important to realize that our goal was not to conduct a comprehensive, in-depth assessment of risk for each chemical; more comprehensive assessments of managing risks associated with drinking water are addressed in a separate issue paper by Krewski et al. (2001a). Rather, our goal was to provide the reader with an indication of the relative risk of major contaminant classes as a basis for understanding the risks associated with the myriad forms of toxic pollutants in aquatic systems and drinking water. For most compounds, the estimated HQs were 1 in some treated distribution waters (water distributed to households). These latter compounds were further assessed using a probabilistic approach; these assessments indicated that the maximum allowable concentrations (MAC) or interim MACs for the respective compounds were exceeded <5% of the time. In other words, the probability of finding these compounds in drinking water at levels that pose risk to humans through ingestion of drinking water is low. Our review has been carried out in accordance with the conventional principles of risk assessment. Application of the risk assessment paradigm requires rigorous data on both exposure and toxicity in order to adequately characterize potential risks of contaminants to human health and ecological integrity. Weakness rendered by poor data, or lack of data, in either the exposure or effects stages of the risk assessment process significantly reduces the confidence that can be placed in the overall risk assessment. (ABSTRACT TRUNCATED)

Abstract: Human societies have, in all ages, modified the original form of metals and metalloids in their living environment for their survival and technical development. In many cases, these anthropogenic activities have resulted in the release into the environment of contaminants that pose a threat to ecosystems and public health. Examples of local and global pollution are legion worldwide, and the reader of the environmental science literature is forever faced with ever more alarming reports on hazards due to toxic metals. For example, extensive mining and associated industrial activities have introduced large amounts of metal contaminants in nature at the local, but also global, scale since anthropogenic metals are detected in remote areas including Greenland ice (Boutron et al. 1991). Industrialized countries have countless polluted sites, and the major consequence in terms of contamination by heavy metals are areas of wasteland and sources of acid and metal-rich runoff from tailings piles and waste-rock heaps, and the subsequent pollution of coastal areas. Water supplies in many areas of many countries are also extensively polluted or threatened by high concentration of metal(loid)s, sometimes from natural sources, but most often from the activities of humans (Smedley and Kinniburgh 2002). Pollution of ground and surface waters, and hence of lands, by arsenic from alluvial aquifers in the Bengal Delta plain and in Vietnam are probably the two most catastrophic actual examples of the second type, where a modification of the chemistry of deep sediment layers by intensive well drillings and pumping of drinking water has led to vast arsenic remobilization and poisoning of ecosystems (Chatterjee et al. 1995; Nickson et al. 1998; Berg et al. 2001). Soils and sediments, being at the interface between the geosphere, the atmosphere, the biosphere and the hydrosphere, represent the major sinks for anthropogenic metals released to …

Abstract: This exposition of the principles and practice of high-temperature air combustion (HiTAC) reviews the historical background to the field, describes HiTAC combustion phenomena, and shows how to simulate and apply the technology for significant energy savings, reduced equipment size, and lower emissions of CO{sub 2} and nitric oxide. It offers design guidelines for high performance industrial furnaces, presents field trials of practical furnaces, and explores applications of HiTAC in advanced energy-to-power conversion systems. Intended for engineers and researchers, the book can also be used as a text for advanced students.

Abstract: ▪ Abstract China is rapidly developing as evidenced by enhanced urbanization and industrialization and greatly increased energy consumption. However, these have brought Chinese cities a variety of urban air pollution problems in recent decades. During the 1970s, black smoke from stacks became the characteristic of Chinese industrial cities; in the 1980s, many southern cities began to suffer serious acid rain pollution; and recently, the air quality in large cities has deteriorated due to nitrous oxides (NOx), carbon monoxide (CO), and photochemical smog, which are typical of vehicle pollution. Some cities now have a mixture of these. Urban air pollution influences both the health of citizens and the development of cities. To control air pollution and protect the atmospheric environment, the Chinese government has implemented a variety of programs. This paper first reviews the current status of air quality in Chinese cities, especially key cities, then describes the characteristics of some major urban air ...

Abstract: Prologue. Preface. Chapter One: Air Quality Impacts: A Local and Global Concern. 1. Introduction. 2. Urban Air Pollution: Historical Record. 3. Sources and Transport of Air Pollution. 4. Impacts of Air Pollution. 5. Conclusion. Chapter Two: Cleaning the Air: A Comparative Overview. 1. Introduction. 2. Cleaning the Air: The Los Angeles Experience. 3. Cleaning the Air: The Experience of the Mexico City Metropolitan Area. 4. Discussion and Conclusions. Chapter Three: Forces Driving Pollutant Emissions in the MCMA. 1. Introduction. 2. Population Growth. 3. Urban Growth. 4. Economic Growth. 5. Production and Consumption of Energy. 6. Erosion and Biogenic Emissions Sources. 7. Conclusion. Chapter Four: Health Benefits of Air Pollution Control. 1. Introduction. 2. Evidence of Air Pollution Exposures and Health Effects. 3. 'Back of the Envelope Risk Assessment. 4. Approaches to Valuing Health Effects. 5. Discussion and Conclusions. Chapter Five: Air Pollution Science in the MCMA: Understanding Source-Receptor Relationships Through Emissions Inventories, Measurements and Modeling. 1. Introduction. 2. Basic Scientific Understanding and Important Questions for Policy. 3. Measurements of Meteorology and Air Quality. 4. Emissions Inventories. 5. Air Pollution Modeling Applications. 6. Scientific Understanding, Analysis of Uncertainties, Research Methods, andRecommendations. 7. Summary of Key Recommendations. Chapter Six: The MCMA Transportation System: Mobility and air Pollution. 1. Introduction. 2. Urban Transformation. 3. Transportation Demand. 4. Transportation Supply. 5. Transport-Related Emissions. 6. Regional Architecture Framework. 7. Transportation Strategic Planning by Various Government Agencies. 8. Key Problems and Future Policy Areas. Chapter Seven: Conclusions: Key Findings and Recommendations. 1. Introduction. 2. Integrated Framework for Air Quality Management Plans. 3. Health Benefits of Pollution Control. 4. Air Pollution Science: Understanding Source-Receptor Relationships. 5. Options to Reduce Mobile Source Emissions and Improve Mobility. 6. Options to Reduce Non-Transport Emissions Sources. 7. Institutional Framework for Air Quality Management. 8. Education and Capacity Building. 9. Funding Mechanisms for Air Quality Programs. 10. Summary. Photographs. Appendix A: Mexico Metropolitan Index for Air Quality (Imeca) and the Environmental Contingency Program. Appendix B: 'No Driving Day' (Hoy No circula). Appendix C: List of Acronyms. Appendix D: Glossary. References. About the Authors. Index.

Abstract: [1] Methane (CH4) emission controls are found to be a powerful lever for reducing both global warming and air pollution via decreases in background tropospheric ozone (O3). Reducing anthropogenic CH4 emissions by 50% nearly halves the incidence of U.S. high-O3 events and lowers global radiative forcing by 0.37 W m−2 (0.30 W m−2 from CH4, 0.07 W m−2 from O3) in a 3-D model of tropospheric chemistry. A 2030 simulation based upon IPCC A1 emissions projections shows a longer and more intense U.S. O3 pollution season despite domestic emission reductions, indicating that intercontinental transport and a rising O3 background should be considered when setting air quality goals.

Abstract: Contamination of soils with heavy metals is an issue all industrial and urban regions have to deal with. Generally, chemical methods are chosen to monitor soil pollution but measurements of magnetic susceptibility proved to yield additional information at low cost and consuming less time. We measured the magnetic susceptibility of soils which had been analysed chemically during the soil surveys of three Austrian provinces. Each anomaly of susceptibility either coincided with geogenic anomalies or indicated anthropogenic input of pollutants. Regional comparisons of susceptibility with chemical analyses revealed that susceptibility can be used as an indicator for the contents of individual pollutants in soils. This calibration of susceptibility has been successfully applied to an industrial region as well as to an urban environment. Two powerful applications of susceptibility measurements of soils are shown: the identification of polluted areas, and the detailed mapping of these areas to reveal the extent of pollution.

Abstract: Preface 1 Basics and history of discovery of atmospheric chemicals 2 The Sun, the Earth, and the evolution of the Earth's atmosphere 3 Structure and composition of the present-day atmosphere 4 Urban air pollution 5 Aerosol particles in smog and the global environment 6 Effects of meteorology on air pollution 7 Effects of pollution on visibility, UV radiation, and atmosphere optics 8 International regulation of urban smog since the 1940s 9 Indoor air pollution 10 Acid deposition 11 Global stratospheric ozone reduction 12 The greenhouse effect and global warming Conversions and constants References Index

Abstract: Particulate air pollution has been shown to strongly suppress precipitation from convective clouds over land. New observations show that precipitation from similar polluted clouds over oceans is much less affected, because large sea salt nuclei override the precipitation suppression effect of the large number of small pollution nuclei. Raindrops initiated by the sea salt grow by collecting small cloud droplets that form on the pollution particles, thereby cleansing the air. Therefore, sea salt helps cleanse the atmosphere of the air pollution via cloud processes. This implies that over oceans, the climatic aerosol indirect effects are significantly smaller than current estimates.

Abstract: Pollution-free stream water and sediments are crucial to support healthy stream flora and fauna, but urban surface runoff impairs water quality and leaves a legacy of pollution in the sediments. Pollution in sediments influences the development of macroinvertebrates, the lowest members of the food chain, leading to modification of the whole ecological structure. This review focuses on the sources and impacts of zinc, nickel, copper and oil derivative polycyclic aromatic hydrocarbon (PAH) contaminants on macroinvertebrates in urban streams. Land use, and the connectivity of the runoff and sediment are seen to have an effect on the ecological integrity of the watercourse but case examples are sparse. The literature indicates that while reduced species diversity has been identified at a number of sites the dynamics are neither well understood nor well modelled. The literature evidence is compared with field evidence from a study of 62 source areas in headwater catchments with residential, urban, industrial a...

Abstract: Abstract - We consider the problem of identification of a heat source in a bounded domain Ω. Assuming that the point sources became inactive after the time T∗, we prove that they can be identified by measurements of the heat flux on Γ0× (0, T), where Γ0 is a part of the boundary of Ω, with non void interior, and T > T∗. By a standard trandformation, we derive from these results a method to identify the polluting sources on the surface of a river, a lake . . .

Abstract: Reducing pesticide loads in surface waters implies identifying the pathways responsible for the pollution. The current study documents the pesticide contamination of the river Zwester Ohm, a 4917-ha catchment in Germany with 41% of the land used for crop production. Discharges and concentrations of 19 pesticides were measured continuously at three locations for 15 mo. The load detected at the outlet of the catchment amounted to 9048 g a.i. The losses represent 0.22% of the pesticides applied by the farmers. The contamination showed a seasonal pattern following the pesticide application times. The wastewater treatment plant system (WWTPS) in the catchment (two wastewater treatment plants [WWTP], 14 combined sewer overflows (CSO), four CSO tanks) emits during dry weather periods purified sewage and during storm events sewage mixed with stormwater runoff into the river. The contribution by the WWTPS to the pesticide load was defined as point-source pollution (PSP). The load was dominated by PSP with at least 77% of the total pollution. No significant interdependencies between intrinsic properties of the pesticides, hydrometeorological factors, and the loads occurring in the stream could be found. Therefore, it is not possible to predict PSP for other catchments based on the results from this study. Whereas 65% of the total load entered the river via the WWTP, a portion of 12% was attributed to the CSO. The study points out that the influence of CSO on PSP should be taken into account in future catchment studies in areas with comparable agricultural structure.

Abstract: Environmental catalysis has continuously grown in importance over the last 2 decades not only in terms of the worldwide catalyst market, but also as a driver of advances in the whole area of catalysis. The development of innovative “environmental” catalysts is also the crucial factor towards the objective of developing a new sustainable industrial chemistry. In the last decade, considerable expansion of the traditional area of environmental catalysis (mainly NOx removal from stationary and mobile sources, and VOC conversion) has also occurred. New areas include: (i) catalytic technologies for liquid or solid waste reduction or purification; (ii) use of catalysts in energy-efficient catalytic technologies and processes; (iii) reduction of the environmental impact in the use or disposal of catalysts; (iv) new eco-compatible refinery, chemical or non-chemical catalytic processes; (v) catalysis for greenhouse gas control; (vi) use of catalysts for user-friendly technologies and reduction of indoor pollution; (vii) catalytic processes for sustainable chemistry; (viii) reduction of the environmental impact of transport. Therefore, a significant change has occurred in the last decade in the areas of interest regarding environmental catalysts and in the modality of approaching the research. This review, based on but not limited to the workshop “Environmental Catalysis: A Step Forward” (Maiori, Italy, May 2001), introduces the proceedings of this workshop reported in this issue of Catalysis Today and has the objective of providing an overview to the topic and setting the basis for a step forward in environmental catalysis research.

Abstract: Dissolved trace metals, i.e Fe, Mn, Al, Cu, Zn, Pb and Cd were determined in the Umtata River. High levels of Al, Cd, Pb, Zn and Cu were observed, which may affect the “health” of the aquatic ecosystem. The high levels of Al, Cd and Pb may also affect the health of the rural community that uses the river water directly for domestic use without treatment. Generally the sources of the metals in the river appear to be diffuse, which include rural, urban and agricultural runoff sources in the catchment, although there may be contributions from natural and point sources.

Abstract: The authors used data obtained from clinic records and environmental monitoring stations in Taiwan during 1998 to estimate the association between air pollution and daily numbers of clinic visits for lower respiratory tract illness. A small-area design and hierarchical modeling were used for the analysis. Rates of daily clinic visits were associated with current-day concentrations of nitrogen dioxide, carbon monoxide, sulfur dioxide, and particulate matter less than or equal to 10 microm in aerometric diameter. People over age 65 years were the most susceptible, and estimated pollution effects decreased as the exposure time lag increased. The analysis also suggested that several community-specific variables, such as a community's population density and yearly air pollution levels, modified the effects of air pollution. In this paper, the authors demonstrate the use of a small-area design to assess acute health effects of air pollution.

Abstract: This paper attempts to estimate the maintenance cost of water pollution abateme nt measures to the Indian industry using the methodology of distance function in the theory of production. The distance function is estimated using both programming and stochastic frontier models for a sample of water polluting industries in India. The firm specific shadow prices for pollutants, measures of efficiency and scale economies are estimated. Estimates show that on an average the cost to the Indian industry for reducing one ton of BOD and COD are respectively, Rs 0.246 and 0.077 million. Large differences in the estimates of firm specific shadow prices of pollutants reflect the use of inefficient water pollution abatement technologies. The relationships between firm specific shadow prices or marginal costs of abatement of BOD and COD and the index of compliance (ratio of effluent load to sales value) and the pollution load reductions obtained confirm the earlier empirical results of studies on the water pollution abatement in Indian industries. The earlier studies have found increasing marginal costs with respect to reductions in pollution concentrations and decreasing marginal cost with respect to the pollution loads reduced by the firms.

Abstract: I review the data on costs and benefits of the major environmental laws passed during the 1970s. The winners in terms of benefit-cost analysis include: getting lead out of gasoline; controlling particulate air pollution; reducing the concentration of lead in drinking water; and the cleanup of hazardous waste sites with the lowest cost per cancer case avoided under Superfund The losers include: mobile source air pollution control; water pollution control; and many of the regulations and cleanup decisions taken under the Federal Insecticide, Fungicide, and Rodenticide Act, the Toxic Substances Control Act, the Safe Drinking Water Act, and Superfund.