The Use of a Multimedia Risk Analysis Approach in Designing Waste Management Strategies

ABSTRACT

A pollution source may release residuals to any of several environmental media, depending on the process design and control strategies. These residuals then are subject to transfer, transport, and transformation within the interconnected compartments of the environmental system. The exposure and susceptibility of people and other receptors to pollutants are different in these various media, and so the risks imposed will vary according to the fate of the pollutants in the system. Because of interactions between compartments in the system, a single-medium approach to environmental management that mitigates problems in one environmental medium at a time independently of risks through other media may not minimize the aggregate risk a receptor receives from all pathways. Alternatively, a multimedia approach advocates focusing on the full environmental system providing pathways for exposure and selecting risk management strategies based on minimization of the aggregate and cumulative risk from all pathways and all compounds. This study combines multimedia risk analysis and an optimization framework to examine a methodology for selecting waste treatment/disposal and pollution control measures, applies the methodology to a sludge management decision problem, and considers the implications for continued use of single-medium analyses.     

中国土壤环境污染态势及预防、控制和修复策略

在综述中国土壤环境污染态势及成因的基础上,提出了土壤环境污染的预防、控制和修复策略.指出了当前中国土壤环境污染态势严峻,表现出土壤污染范围在扩大,污染物种类在增多,出现了复合型、混合型的高风险污染区,呈现出从污灌型向与大气沉降型并重转变、城郊向农村延伸、局部向区域蔓延的趋势;体现出土壤污染与土壤酸化的叠加、多种传统污染物与新兴污染物相互混合的态势,危及粮食生产、食物质量、生态安全、人体健康以及区域可持续发展.认为以预防为主,预防、控制和修复相结合是中国在相当长时期内的土壤环境保护策略;土壤污染预防需要法律法规、评价标准、管理政策和公众参与,土壤污染控制需要发展物化控制、生物学控制及其协同控制技术,土壤污染修复需要研发工程修复技术、材料、产品与设备,建立技术规范、评价标准和管理体系,推动市场化和产业化发展.     

Using stochastic risk assessment in setting information priorities for managing dioxin impact from a municipal waste incinerator

The objectives of this study were to assess site-specific carcinogenic risk of incinerator-emitted dioxins in a manner reflecting pollutant transfer across multimedia and multi-pathways. The study used site-specific environmental and exposure information and combined the Monte Carlo method with multimedia modeling to produce probability distributions of risk estimates. The risk estimates were further categorized by contaminated environmental media and exposure pathways that are experienced by human receptors in order to pinpoint significant sources of risk. Rank correlation coefficients were also calculated along with the Monte Carlo sampling to identify key factors that influenced estimation of risk. The results showed that ingestion accounted for more than 90% of the total risk and that risk control on ingestion of eggs, aboveground vegetables, and poultry should receive priority. It was also found that variation of parameters with variability accounted for around 35% of the total risk variance, while uncertainty contributed to the remaining 65%. Intake rates of aboveground vegetables, eggs, and poultry were the key parameters with the largest contribution to variance. In addition, sufficient sampling and analysis of dioxin contents in eggs, aboveground vegetables, poultry, soil, and fruit should be performed to improve risk estimation because the variation in concentrations in these media accounted for the largest overall risk variance. Finally, focus should be placed on reduction of uncertainty associated with the risk estimation through ingestion of aboveground vegetables, eggs, poultry, fruit, and soil because the risk estimates associated with these exposure pathways had the largest variance.     

Substance-related environmental monitoring strategies regarding soil, groundwater and surface water — an overview

Substance-related monitoring is an essential tool within environmental risk assessment processes. The soundness of policy decisions including risk management measures is often directly related to the reliability of the environmental monitoring programs. In addition, monitoring programs are required for identifying new and less-investigated pollutants of concern in different environmental media. Scientifically sound and feasible monitoring concepts strongly depend on the aim of the study. The proper definition of questions to be answered is thus of pivotal importance. Decisions on sample handling, storage and the analysis of the samples are important steps for the elaboration of problem-oriented monitoring strategies. The same applies to the selection of the sampling sites as being representative for scenarios to be investigated. These steps may become critical to handle for larger international monitoring programs and thus trigger the quality of their results. This study based on the work of an IUPAC (International Union of Pure and Applied Chemistry) task group addresses different kinds and approaches of substance-related monitoring of different compartments of soil, groundwater and surface water, and discusses their advantages and limitations. Further important aspects are the monitoring across policies and the monitoring data management using information systems.     

水环境数学模型的研究进展

在作者多年研究工作和查阅大量文献资料的基础上,本文综述了环境数学模型国内外的研究现状、发展历史及未来趋势。重点介绍了这方面研究的最新进展。该文还介绍了本领域所涉及的理论和实际应用问题,提出了今后值得进行研究的若干前沿课题,给出了60余篇关于水环境数学模型研究的主要参考文献目录。     

Model comparison for risk assessment: a case study of contaminated groundwater

Many environmental multimedia risk assessment models have been developed and widely used along with increasing sophistication of the risk assessment method. Despite of the considerable improvement, uncertainty remains a primary threat to the credibility of and users' confidence in the model-based risk assessments. In particular, it has been indicated that scenario and model uncertainty may affect significantly the assessment outcome. Furthermore, the uncertainty resulting from choosing different models has been shown more important than that caused by parameter uncertainty. Based on the relationship between exposure pathways and estimated risk results, this study develops a screening procedure to compare the relative suitability between potential multimedia models, which would facilitate the reduction of uncertainty due to model selection. MEPAS, MMSOILS, and CalTOX models, combined with Monte Carlo simulation, are applied to a realistic groundwater-contaminated site to demonstrate the process. It is also shown that the identification of important parameters and exposure pathways, and implicitly, the subsequent design of uncertainty reduction and risk management measures, would be better-formed.     

Model selection and evaluation for risk assessment of dioxin-contaminated sites

The general European population has a total intake of dioxins and dioxin-like chemicals near the limit recommended by the European Union, making additional exposure above background levels undesirable. For populations living near dioxin-contaminated sites, additional exposure may occur by intake of locally produced food, inhalation of particles, dermal contact with soils, or other exposure pathways. Risk assessment tools are required to estimate risks associated with contaminated sites and to set priorities for site remediation. Here, we review several multimedia models that can be applied as tools to support risk assessment. We then present a strategy to select, apply, evaluate, and adapt a model to address a specific situation. The case study we consider is a risk assessment of generic background dioxin exposure in Sweden, and we compare the predictions with environmental observations and exposure data from Sweden. Arguments are presented for selecting the CalTOX model for this case study. We demonstrate the application, evaluation, and adaptation of the model and discuss the requirements for extending the analysis to conduct risk assessment for subpopulations living near dioxin-contaminated sites.     

生物标志物在水源地风险评价中的作用与展望

针对肿瘤高发区饮用水污染和南水北调水质的风险评价问题,提出了可用生物标志物检测水中的“环境诱变剂量”来作为评价水体中有毒有害污染物潜在遗传危害的综合指标。简要介绍了生物标志物在国内外的研究动态及其在环境监测、环境风险评价中的应用前景。     

Using Multimedia Modeling to Expedite Site Characterization

GOAL, SCOPE AND BACKGROUND: This paper uses two case studies of U.S. Department of Energy nuclear weapons complex installations to illustrate the integration of expedited site characterization (ESC) and multimedia modeling in the remedial action decision making process. CONCEPTUAL SITE MODELS, MULTIMEDIA MODELS, AND EXPEDITED SITE CHARACTERIZATION: Conceptual site models outline assumptions about contaminates and the spatial/temporal distribution of potential receptors. Multimedia models simulate contaminant transport and fate through multiple environmental media, estimate potential human exposure via specific exposure pathways, and estimate the risk of cancer and non-cancer health outcomes. ESC relies on using monitoring data to quantify the key components of an initial conceptual site model that is modified iteratively using the multimedia model. CASE STUDIES: Two case studies are presented that used the ESC approach: Los Alamos National Laboratory (LANL) and Pantex. LANL released radionuclides, metals, and organic compounds, into canyons surrounding the facility. The Pantex Plant has past waste management operations which included burning chemical wastes in unlined pits, burying wastes in unlined landfills, and discharging plant wastewaters into on-site surface waters. CONCLUSIONS: The case studies indicate that using multimedia models with the ESC approach can inform assessors about what, where, and how much site characterization data needs to be collected to reduce the uncertainty associated with risk assessment. Lowering the degree of uncertainty reduces the time and cost associated with assessing potential risk and increases the confidence that decision makers have in the assessments performed.     

Soviet and post-Soviet environmental management: lessons from a case study on lead pollution

Through a case study on lead pollution in the former Soviet Union, the linkage of policy, environmental science, and environmental management is explored, and compared with the US experience. Soviet bans on leaded gasoline and lead-based paint appear to have been effective. Regional governments, in cooperation with the petroleum industry, are taking the initiative in phasing out leaded gasoline, to some extent in defiance of federal policy. Problems with management of lead-acid batteries have been worsened by the collapse of the political system. Lack of reliable environmental data impedes reliable environmental assessment. The types of environmental measurements reflect an emphasis on multipollutant environmental contamination, rather than on human exposure to single pollutants.     

区域污染物总量控制动态化管理技术应用研究

在对近十年江苏省扬州市社会经济环境方面几十个指标上万个数据进行科学分析的基础上,揭示出区域污染物总量控制与社会、经济、环境建设和发展相关联性,总量控制具有宏观性.区域污染物总量可纳入各级政府和相关部门行政首长政绩考核中.首次建立区域污染物总量控制考核指标体系水平等级的评定模式和动态管理的应用技术.该成果不仅为城乡可持续发展奠定了基础,也为区域实现污染物总量控制动态化、规范化管理提供技术支撑和启示.     

Resolving local-scale emissions for modeling air quality near roadways

A large body of literature published in recent years suggests increased health risk due to exposure of people to air pollution in close proximity to roadways. As a result, there is a need to more accurately represent the spatial concentration gradients near roadways to develop mitigation strategies. In this paper, we present a practical, readily adaptable methodology, using a "bottom-up" approach to develop a detailed highway vehicle emission inventory that includes emissions for individual road links. This methodology also takes advantage of geographic information system (GIS) software to improve the spatial accuracy of the activity information obtained from a Travel Demand Model. In addition, we present an air quality modeling application of this methodology in New Haven, CT. This application uses a hybrid modeling approach, in which a regional grid-based model is used to characterize average local ambient concentrations, and a Gaussian dispersion model is used to provide texture within the modeling domain because of spatial gradients associated with highway vehicle emissions and other local sources. Modeling results show substantial heterogeneity of pollutant concentrations within the modeling domain and strong spatial gradients associated with roadways, particularly for pollutants dominated by direct emissions.     

Uncertainties and data needs in risk assessment of three commercial polybrominated diphenyl ethers: probabilistic exposure analysis and comparison with European Commission results

Some environmental monitoring programs have reported increasing levels of certain polybrominated diphenyl ether (PBDE) isomers in aquatic biota and in human breast milk. The commercial PBDE products are known as penta-, octa-, and deca-brominated diphenyl ethers (PeBDE, OBDE and DBDE, respectively). Aside from the current European Commission's risk assessment initiative and efforts underway in Sweden, Canada and elsewhere to evaluate environmental levels, little is understood about sources of exposure and risks to humans. In this study, a multi-pathway human health risk assessment was performed to predict theoretical chronic daily intakes (CDIs) of PeBDE, OBDE, and DBDE by five different age groups: 0-2, 2-6, 6-12, 12-18, and 18-70 years. Sources of exposure included air, drinking water, consumption of fish, vegetables, meat and dairy products, and ingestion of breast milk by infants. In addition to a deterministic analysis, the risk assessment included a probabilistic analysis to derive the probability density functions describing the range of plausible exposures associated with eight different pathways, as well as aggregate lifetime exposures for each age group. The results were compared to CDI point estimates calculated by the European Chemicals Bureau as part of the European Commission's Existing Substances Programme. The major sources of uncertainties are discussed, including environmental sources, levels in different environmental compartments, toxicity, and human exposure. This paper also discusses the limitations in the current state-of-the-science and provides recommendations for improving the scientific relevance and accuracy of future environmental risk assessments of PBDEs.     

Air quality management in Portugal: example of needs and available tools

The Framework Directive (FWD) and the proposed Daughter Directives are the newest legislative instruments concerning a new political strategy and air quality management approach for Europe. Additionally, the member countries of the United Nations Economic Commission for Europe have included the concepts of critical load and level for planning air pollution abatement strategies and as a base of international agreements concerning limitation of the emissions of air pollutants. These concepts imply an accurate knowledge about pollutants deposition fluxes. The paper describes the main needs and the tools available to define a strategy of air quality management in Portugal. Two study cases are presented: (1) extensive monitoring plan to assess the impact of an urban incinerator plant; and (2) contribution to a methodology to estimate critical levels for a coastal region in Portugal. These different approaches allowed illustrating the complexity of the implementation of an air pollution management strategy.     

Forecasting human exposure to atmospheric pollutants in Portugal – A modelling approach

Air pollution has become one main environmental concern because of its known impact on human health. Aiming to inform the population about the air they are breathing, several air quality modelling systems have been developed and tested allowing the assessment and forecast of air pollution ambient levels in many countries. However, every day, an individual is exposed to different concentrations of atmospheric pollutants as he/she moves from and to different outdoor and indoor places (the so-called microenvironments). Therefore, a more efficient way to prevent the population from the health risks caused by air pollution should be based on exposure rather than air concentrations estimations. The objective of the present study is to develop a methodology to forecast the human exposure of the Portuguese population based on the air quality forecasting system available and validated for Portugal since 2005. Besides that, a long-term evaluation of human exposure estimates aims to be obtained using one-year of this forecasting system application. Additionally, a hypothetical 50% emission reduction scenario has been designed and studied as a contribution to study emission reduction strategies impact on human exposure.To estimate the population exposure the forecasting results of the air quality modelling system MM5-CHIMERE have been combined with the population spatial distribution over Portugal and their time-activity patterns, i.e. the fraction of the day time spent in specific indoor and outdoor places. The population characterization concerning age, work, type of occupation and related time spent was obtained from national census and available enquiries performed by the National Institute of Statistics. A daily exposure estimation module has been developed gathering all these data and considering empirical indoor/outdoor relations from literature to calculate the indoor concentrations in each one of the microenvironments considered, namely home, office/school, and other indoors (leisure activities like shopping areas, gym, theatre/cinema and restaurants). The results show how this developed modelling system can be useful to anticipate air pollution episodes and to estimate their effects on human health on a long-term basis. The two metropolitan areas of Porto and Lisbon are identified as the most critical ones in terms of air pollution effects on human health over Portugal in a long-term as well as in a short-term perspective. The coexistence of high concentration values and high population density is the key factor for these stressed areas. Regarding the 50% emission reduction scenario, the model results are significantly different for both pollutants: there is a small overall reduction in the individual exposure values of PM₁₀ (<10 μg m^?3 h), but for O₃, in contrast, there is an extended area where exposure values increase with emission reduction. This detailed knowledge is a prerequisite for the development of effective policies to reduce the foreseen adverse impact of air pollution on human health and to act on time.     

Integrated methodology for assessing the HCH groundwater pollution at the multi-source contaminated mega-site Bitterfeld/Wolfen

A large-scale groundwater contamination characterises the Pleistocene groundwater system of the former industrial and abandoned mining region Bitterfeld/Wolfen, Eastern Germany. For more than a century, local chemical production and extensive lignite mining caused a complex contaminant release from local production areas and related dump sites. Today, organic pollutants (mainly organochlorines) are present in all compartments of the environment at high concentration levels. An integrated methodology for characterising the current situation of pollution as well as the future fate development of hazardous substances is highly required to decide on further management and remediation strategies. Data analyses have been performed on regional groundwater monitoring data from about 10 years, containing approximately 3,500 samples, and up to 180 individual organic parameters from almost 250 observation wells. Run-off measurements as well as water samples were taken biweekly from local creeks during a period of 18 months. A kriging interpolation procedure was applied on groundwater analytics to generate continuous distribution patterns of the nodal contaminant samples. High-resolution geological 3-D modelling serves as a database for a regional 3-D groundwater flow model. Simulation results support the future fate assessment of contaminants. A first conceptual model of the contamination has been developed to characterise the contamination in regional surface waters and groundwater. A reliable explanation of the variant hexachlorocyclohexane (HCH) occurrence within the two local aquifer systems has been derived from the regionalised distribution patterns. Simulation results from groundwater flow modelling provide a better understanding of the future pollutant migration paths and support the overall site characterisation. The presented case study indicates that an integrated assessment of large-scale groundwater contaminations often needs more data than only from local groundwater monitoring. The developed methodology is appropriate to assess POP-contaminated mega-sites including, e.g. HCH deposits. Although HCH isomers are relevant groundwater pollutants at this site, further organochlorine pollutants are present at considerably higher levels. The study demonstrates that an effective evaluation of the current situation of contamination as well as of the related future fate development requires detailed information of the entire observed system.     

Setting the most robust effluent level under severe uncertainty: Application of information-gap decision theory to chemical management

Decisions in ecological risk management for chemical substances must be made based on incomplete information due to uncertainties. To protect the ecosystems from the adverse effect of chemicals, a precautionary approach is often taken. The precautionary approach, which is based on conservative assumptions about the risks of chemical substances, can be applied selecting management models and data. This approach can lead to an adequate margin of safety for ecosystems by reducing exposure to harmful substances, either by reducing the use of target chemicals or putting in place strict water quality criteria. However, the reduction of chemical use or effluent concentrations typically entails a financial burden. The cost effectiveness of the precautionary approach may be small. Hence, we need to develop a formulaic methodology in chemical risk management that can sufficiently protect ecosystems in a cost-effective way, even when we do not have sufficient information for chemical management. Information-gap decision theory can provide the formulaic methodology. Information-gap decision theory determines which action is the most robust to uncertainty by guaranteeing an acceptable outcome under the largest degree of uncertainty without requiring information about the extent of parameter uncertainty at the outset. In this paper, we illustrate the application of information-gap decision theory to derive a framework for setting effluent limits of pollutants for point sources under uncertainty. Our application incorporates a cost for reduction in pollutant emission and a cost to wildlife species affected by the pollutant. Our framework enables us to settle upon actions to deal with severe uncertainty in ecological risk management of chemicals.     

Fugacity superposition: a new approach to dynamic multimedia fate modeling

The fugacities, concentrations, or inventories of pollutants in environmental compartments as determined by multimedia environmental fate models of the Mackay type can be superimposed on each other. This is true for both steady-state (level III) and dynamic (level IV) models. Any problem in multimedia fate models with linear, time-invariant transfer and transformation coefficients can be solved through a superposition of a set of n independent solutions to a set of coupled, homogeneous first-order differential equations, where n is the number of compartments in the model. For initial condition problems in dynamic models, the initial inventories can be separated, e.g. by a compartment. The solution is obtained by adding the single-compartment solutions. For time-varying emissions, a convolution integral is used to superimpose solutions. The advantage of this approach is that the differential equations have to be solved only once. No numeric integration is required. Alternatively, the dynamic model can be simplified to algebraic equations using the Laplace transform. For time-varying emissions, the Laplace transform of the model equations is simply multiplied with the Laplace transform of the emission profile. It is also shown that the time-integrated inventories of the initial conditions problems are the same as the inventories in the steady-state problem. This implies that important properties of pollutants such as potential dose, persistence, and characteristic travel distance can be derived from the steady state.