Integrating Comparative Risk Assessment with Multi-Criteria Decision Analysis to Manage Contaminated Sediments: An Example for the New York/New Jersey Harbor

Current environmental challenges involve complex assessment and analysis of tradeoffs among differing criteria, expectations, and levels of certainty. Using multi-criteria decision analysis in combination with comparative risk assessment, a systematic and transparent framework can be created to integrate different types and sources of decision-relevant information. Although examples of decision analysis abound in the literature and academic efforts, its use within the practice of risk assessment and environmental management is still being established. This article provides an example of the use of decision analysis study that builds on a previous screening-level, comparative risk assessment of contaminated sediment from the New York/New Jersey harbor area. Using multi-criteria decision analysis, we explored the effect of different criteria weights, utility functions, and cost estimates on the ranking of seven contaminated sediment management alternatives. Values used in weighting decision criteria were surveyed from two interaction sessions with sediment management professionals.     

Environmental Risk Management Decision-Making in a Societal Context

Recent studies point to the need for improved understanding of environmental management frameworks designed to combine qualitative public and quantitative technical inputs in decision-making processes. Flux in public perception and concern about risks imply frameworks must be iterative in nature and incorporate a variety of assessment triggers in the form of decision points. A conceptual model is proposed here to explain the de facto operation of standard risk analytic frameworks within the broader sociopolitical milieu of public policy. The model is presented as a decision flow diagram that emphasizes setting environmental management goals based on societal input and the formulation of decision criteria for selecting management actions to achieve those goals. Prospective and retrospective decision control points operate to select management options that, respectively, avoid or reduce actual or predicted effects. Feedback loops that modify risk management outcomes are identified. Technical and scientific inputs (i.e., risk analysis) are assigned an essential information role within the framework and are responsible for informing the management process with the results of appropriately conducted and reviewed investigations. The proposed model is intended primarily to indicate how environmental risk management decision-making and associated technical assessments may be influenced by social pressures. It is hoped this understanding will lead to analytical transparency and better public communication of the environmental implications of policy options.     

Sensitivity Analysis in Multicriteria Spatial Decision-Making: A Review

The aim of this article is to review how sensitivity analysis has been applied to models based on Geographical Information Systems (GIS) and Multicriteria Evaluation techniques (MCE). This kind of analysis is conceived as a stage in the model evaluation that examines the extent of output variation of a model when parameters are systematically varied over a range of interest. Twenty-eight studies related to land planning processes, environmental management, and location of noxious facilities have been examined. This review reveals that sensitivity analysis is a) not a common practice, b) is more widely carried out in location of noxious facilities, and c) that the analysis most frequently used is based on the variation of the weights of the factors implied in the process to test whether it significantly modifies the results obtained.     

Toxicological Considerations of Contaminants in the Terrestrial Environment for Ecological Risk Assessment

The terrestrial environment acts as a “sink” for contaminants that have been purposely or accidentally released into the environment. Science and policy that support protective measures for terrestrial ecosystems have run behind those of aquatic toxicology and water quality concerns. As a result ecological risk assessment (ERA) involving terrestrial environments tends to be conducted at a simplistic level, relying on numeric targets (soil quality criteria) as a basis for decision-making. However, soil criteria for ecological receptors are somewhat deficient in terms of the numbers available and the data that supports these numbers. Direct toxicity assessments (DTA) for terrestrial environments, such as those used for water quality evaluations, can provide additional useful information about the toxicity and bioavailability of mixtures of contaminants present in soils. This article outlines the approaches used for assessing the toxicity of soil contaminants in terrestrial environments and critiques their advantages and pitfalls.     

Ecological Risk Assessment and Ecological Epidemiology for Contaminated Sites

After 20 years of development, ecological risk assessment is widely accepted. However, it is evolving in response to a variety of technical and societal pressures. First, pressure for greater simplicity and standardization arise from the expectation that risk assessments should require little time and resources but be defensible. Second, the advance of the environmental sciences and increasing awareness of the complexity of ecological responses generate pressure for greater realism. Third, the dominance of human health risk assessment generates a pressure to integrate ecological risk assessment with that dominant field. Fourth, the demand for cost-benefit analysis creates pressure for integration with environmental economics. Finally, the need to connect the practice of ecological epidemiology with risk-based decision-making creates a pressure of the formation of a single integrated ecological assessment practice.     

The Species Problem in a Ciliate with a High Multiple Mating Type System, Euplotes crassus

ABSTRACT. One hundred twenty non-autogamous wild-type strains of Euplotes crassus , collected over seven years, mainly from the Mediterranean coasts, were investigated for their mating interactions. The strains were mixed pair-wise and data from mating reactions were evaluated and organized by means of a specially constructed computer program. The program identified 38 strains with distinctive mating patterns which could be clustered in nine clumps, all of which were connected either directly or indirectly. Thus, all these strains appeared to be components of the same gene pool, even though direct genetic exchange between strains was not possible in every combination. Subsequently, the 38 strains were subjected to cytometric analysis and scored for zymic variations resulting from electrophoretic patterns of five enzyme systems (acid phosphatases, amylases, malic dehydrogenase, malic enzyme, and tetrazolium oxidases) of proved diagnostic value in the identification of Euplotes species. No significant discontinuities correlated with mating patterns was apparent from these analyses. It was concluded that the E. crassus strains analyzed are not properly divided in sibling species and it was consistently suggested to avoid a genetic partitioning of ciliate species endowed with high multiple mating type systems, in which the sets of wild strains brought under investigation with difficulty represent the natural dimensions of the species.     

Field Characterization of Potential Reference Sediments in the Gulf of Mexico: Chemical and Biological Quality

Baseline information on the chemical and biological quality of sediments is provided for six coastal locations in the northern Gulf of Mexico, which were considered possible candidates for regional reference areas. Chemical quality, toxicity and benthic community composition were determined for sediments collected three times from each of 12 sites during an approximate one-year period. Potential contaminants in the usually sand-dominated sediments exceeded individual threshold effects level guidelines proposed for Florida coastal areas in approximately 31% of the samples collected from 8 of 12 sites. No probable effects level guidelines were exceeded. Acute toxicity occurred in 16% or less of the sediment samples and no significant chronic toxicity was observed to the infaunal amphipod, Leptocheirus plumulosus. Approximately, 11% and 17% of the sediments were classified as poor or marginal, based on low benthic taxa abundance and diversity index values, respectively. Sediment quality at many sites was less degraded than that for nearby coastal areas receiving point and non-point source contaminants, which suggests their suitability to serve as reference sediments although further confirmation is recommended. In a broader context, the results of this survey reflect the complexity in field verification of reference conditions for near-coastal sediments. This is attributable largely to the natural variability in their physical, biological, and chemical characteristics and to the lack of biocriteria for benthic macro and meiofauna.     

Comparison of the Long-Term Risks of Removal and In Situ Management of Contaminated Sediments in the Fox River

The long-term potential risks of environmental dredging vs. in situ contaminated sediment management practices are discussed and compared for the Lower Fox River, Wisconsin. The risks are identified as being largely associated with the residual sediment contamination associated with either approach. The integral of the surface area-weighted average contaminant concentration in surface sediment is proposed as a metric to compare these risks. Capping is shown to exhibit significantly reduced exposure and risk relative to the dredging scenarios, even if potential undetected erosion of 5% of the cap is considered. Even with the improbable event of undetected failure of 25% of the cap, the exposure and risk associated with capping is approximately equal to or below all dredging scenarios. A preference for dredging due to the perception that it eliminates the long-term risk of in situ capping is not supported by this analysis. Although strictly applicable only to the Lower Fox River, the results suggest sitespecific analyses must be conducted to determine which sediment management approaches minimize the potential for long-term exposure and risk.     

A Conceptual Framework for Using Mussels as Biomonitors in Whole Effluent Toxicity

As a main source of direct and continuous input of pollutants in the aquatic ecosystem, studying the effects of effluents on receiving ecosystems has a high ecological relevance. While ecological risk assessment procedures are usually based on a chemical-based single component approach, their application for complex mixtures and effluents is less straightforward. A chemical-based approach has to rely on the knowledge of what chemicals are present in effluents, their potential toxicity, how all of these individual chemicals interact and what their individual and combined contribution to the mixture is. Whole effluent toxicity (WET) testing, however, is an integrative tool that measures the toxic effect of an effluent as a whole and accounts for uncharacterized sources of toxicity and for interactions. This paper addresses the use of transplanted bivalves, i.e., caged mussels, as a biomonitoring tool in WET testing with special reference to field situations in both freshwater and marine environments. We indicate how endpoints at different levels of biological organization within exposed mussels can give an integrative overview of effects. Finally, we will provide a framework for future research using mussels and discuss a multitude of instream responses for routine, efficient and cost-effective active biomonitoring applications.     

A Weight-of-Evidence Framework for Assessing Sediment (Or Other) Contamination: Improving Certainty in the Decision-Making Process

A basic framework is presented for the ecological weight-of-evidence (WOE) process for sediment assessment that clearly defines its essential elements and will improve the certainty of conclusions about whether or not impairment exists due to sediment contamination, and, if so, which stressors and biological species (or ecological responses) are of greatest concern. The essential “Certainty Elements” are addressed in a transparent best professional judgment (BPJ) process with multiple lines-of-evidence (LOE) ultimately quantitatively integrated (but not necessarily combined into a single value). The WOE Certainty Elements include: (1) Development of a conceptual model (showing linkages of critical receptors and ecosystem quality characteristics); (2) Explanation of linkages between measurement endpoint responses (direct and indirect with associated spatial/temporal dynamics) and conceptual model components; (3) Identification of possible natural and anthropogenic stressors with associated exposure dynamics; (4) Evaluation of appropriate and quantitatively based reference (background) comparison methods; (5) Consideration of advantages and limitations of quantification methods used to integrate LOE; (6) Consideration of advantages and limitations of each LOE used; (7) Evaluation of causality criteria used for each LOE during output verification and how they were implemented; and (8) Combining the LOE into a WOE matrix for interpretation, showing causality linkages in the conceptual model. The framework identifies several statistical approaches for integrating within LOE, the suitability of which depends on physical characteristics of the system and the scale/nature of impairment. The quantification approaches include: (1) Gradient (regression methods); (2) Paired reference/test (before/after control impact and ANOVA methods); (3) Multiple reference (ANOVA and multivariate methods); and 4) Gradient with reference (regression, ANOVA and multivariate methods). This WOE framework can be used for any environmental assessment and is most effective when incorporated into the initial and final study design stages (e.g., the Problem Formulation and Risk Characterization stages of a risk assessment) with reassessment throughout the project and decision-making process, rather than in a retrospective data analysis approach where key certainty elements cannot be adequately addressed.     

Biological guidelines for freshwater sediment based on BEnthic Assessment of SedimenT (the BEAST) using a multivariate approach for predicting biological state

Abstract This paper describes the first results for an alternative approach to the development of sediment quality criteria in the nearshore areas of the Laurentian Great Lakes. The approach is derived from methods developed in the United Kingdom for establishing predictive relationships between macroinvertebrate fauna and the physico-chemistry of riverine environments. The technique involves a multivariate statistical approach using (i) data on the structure of benthic invertebrate communities, (ii) functional responses (survival, growth and reproduction) in four sediment toxicity tests (bioassays) with benthic invertebrates; and (iii) selected environmental variables at 96 reference (‘clean’) sites in the nearshore areas of all five Great Lakes (Lakes Superior, Huron, Erie, Ontario and Michigan). Two pattern recognition techniques (using the computer software package PATN) are employed in the analysis: cluster analysis and ordination. The ordination vector scores from the original axes of the pattern analysis are correlated (using CORR in SAS) with environmental variables which are anticipated to be least affected by anthropogenic activities (e. g. alkalinity, depth, silt, sodium etc.). Multiple discriminant analysis (MDA) is used to relate the site groupings from the pattern analysis to the environmental variables and to generate a model that can be used to predict community assemblages and functional responses at new sites with unknown but potential contamination. The predicted community assemblages and functional responses are then compared with the actual benthic communities and responses at a site, and the need for remedial action is determined. The predictive capability of the discriminant model was confirmed by performing several validation runs on subsets of the data. An example of the use of the model for sediment in Collingwood Bay (an area of concern designated by the IJC in Georgian Bay, Lake Huron) is presented and the technique is shown to be more precise in determining the need for remediation than the currently used provincial sediment quality criteria based on Screening Level Concentration (SLC) and laboratory toxicity tests. The ultimate goal of the study is the development of a method to determine the need for, and the success of, remedial action and to predict what benthic communities should look like at a site if it were clean and what responses of organisms in sediment toxicity tests constitute an acceptable end-point.     

A Comparison of Three Weight-of-Evidence Approaches for Integrating Sediment Contamination Data within and Across Lines of Evidence

Multiple lines of evidence (LOE) are often considered when examining the potential impact of contaminated sediment. Three strategies are explored for combining information within and/or among different LOE. One technique uses a multivariate strategy for clustering sites into groups of similar impact. A second method employs meta-analysis to pool empirically derived P-values. The third method uses a quantitative estimation of probability derived from odds ratios. These three strategies are compared with respect to a set of data describing reference conditions and a contaminated area in the Great Lakes. Common themes in these three strategies include the critical issue of defining an appropriate set of reference/control conditions, the definition of impact as a significant departure from the normal variation observed in the reference conditions, and the use of distance from the reference distribution to define any of the effect measures. Reasons for differences in results between the three approaches are explored and strategies for improving the approaches are suggested.     

Case Study of Petroleum Contaminated Area of Novi Sad After NATO Bombing in Yugoslavia

The 1999 NATO bombing of the oil refinery in Novi Sad (Yugoslavia) has heavily contaminated the Danube River and its sediments, as well as the surrounding soil and groundwater. The destruction of the factories released 73,569 tons of crude oil of which 90% was incinerated, 560 tons reached the Danube River, and the remainder was spilled onto the soil. The contents of oil and oil derivatives in the soil were in the range of 3 to 42,000?mg/kg. The first soil layer contained an average of 67,000?mg/kg of crude oil and oil derivatives. The layers beneath it, above the groundwater table, contained 56?ml/l of free oil derivatives in the drained water. The spreading of this pollution could imperil the groundwater quality in the water supply zone because the refinery is located in the hinterland of the zone. The quality of water and sediment samples was monitored from April 1999 to November 2000 by measuring concentrations of hydrocarbons and polyaromatic hydrocarbons (PAH). The hydrocarbon content in the Danube River water in October 2000 was about 20% of the value measured at the time of the accident. Immediately after the accident the concentration of mineral oil in the surface sediment was in the range of 0.11 to 0.29?g/kg. At the same time PAH concentrations in the river sediment were up to 160?mg/kg, depending on the sampling site location. The values showed a decrease in the course of further monitoring.     

Toxicological studies of the carbamates methomyl and bendiocarb in the bulb mite Rhizoglyphus echinopus (Acari: Acaridae)

Methomyl was 15 and 31.3 times more toxic than bendiocarb to bulb mites at the LC50 and LC90 values respectively. However, methomyl (pI50 3.0) was at least 126 times less active than bendiocarb (pI50 5.1) as an inhibitor of bulb mite cholinesterase in vitro. The disparity between the high toxicity of methomyl and its extremely low activity as an inhibitor of mite cholinesterase in vitro indicated that another mechanism was likely involved in its toxic action. Pharmacokinetic studies of methomyl and bendiocarb showed that penetration and metabolism were rapid and that there were no substantial differences in the internal levels of the respective parent carbamates during the 24 h test period. However, volatile radioactive material(s), some of which was carbon dioxide, was produced in appreciably greater amounts from methomyl than from bendiocarb. We speculate that the production of volatiles, such as carbon dioxide, acetonitrile and/or methylamine, may contribute to the toxicity of methomyl to bulb mites. © Rapid Science Ltd. 1998     

Fluoranthene as a model toxicant in sediment studies with Chironomus riparius

The bioavailability of fluoranthene (as a model toxicant) in freshwater sediment tests with Chironomus riparius was investigated in relation to the partitioning of the chemical between water and sediment. Effects on survival and successful development of newly hatched larvae through to adult emergence were measured over a range of sediment concentrations. Radiolabelled fluoranthene was employed to enable sediment, aqueous and tissue concentrations to be determined. A significant effect on emergence was obtained at a measured sediment concentration of 80 mg kg^-1 (dry weight). The measured concentration in the overlying water was 88 g l^-1. Although effects at 170 mg kg^-1 (dry weight) were more severe, the measured concentration in the overlying water was similar (89 g l^-1), probably reflecting the approach towards the solubility limit. Bioaccumulation of fluoranthene, determined by analysis of emerging adults, was approximately proportional to the sediment concentration. Although the aqueous phase concentration appeared to be the principal factor controlling bioavailability, the increasing toxicity, when water concentrations had reached a plateau, suggested that other mechanisms may also be involved. Different sediment spiking procedures resulted in broadly similar partitioning of the chemical between the sediment and the overlying water. There were only minor differences in toxicity between the procedures, two of which allowed the carrier solvent used for spiking to be eliminated before addition of the test organisms. It was concluded that, for most purposes, all four procedures were equally acceptable, and by retaining a flexible approach, even for standardised regulatory tests, spiking procedures may be tailored to the physico-chemical properties of the test material.     

A Decision Making Framework for Sediment Assessment Developed for the Great Lakes

A rule-based, weight-of-evidence approach for assessing contaminated sediment on a site-by-site basis in the Laurentian Great Lakes is described. Information from four lines of evidence—surficial sediment chemistry, laboratory toxicity, invertebrate community structure and invertebrate tissue biomagnification—is integrated within each line to produce a pass (‘?’) or fail (‘+’) conclusion, then combined across lines resulting in one of 16 outcome scenarios. For each scenario, the current status of the site, interpretation, and management recommendations are given. Management recommendation(s) can range from no action to risk management required (9 of the 16 scenarios). Within each line of evidence, the strength of each response can also be ranked (e.g., score of 1 to 4), providing managers with more information to aid decision options. Other issues that influence scientific management recommendations include site stability, subsurface contamination and spatial extent of effects. The decision framework is intended to be transparent, comprehensive (incorporating exposure, effect, weight-of-evidence, and risk), and minimally uncertain.     

Assessment of Heavy Metal Contamination in the Sediments of the Shuangtaizi Estuary Using Multivariate Statistical Techniques

In order to assess heavy metal pollution of sediment samples collected from Shuangtaizi estuary, contamination factor (CF) and multivariate statistical analyses, including principal component analysis (PCA), cluster analysis (CA) and correlation analysis, are carried out in this paper. CF confirms that Pb, Cu and Hg concentrations are very low and all fall within the range of background, while Zn and Cd demonstrate moderate contamination (in A10, A13, A15, A16 and A17 sites) and very high contamination (in A10, A13, A15 and A17 sites), respectively. The PCA indicates that four significant principal components (PCs) are extracted, explaining 88.959% of total variance, which suggests that Pb, Cu and Zn are mainly associated with organic carbon (OC). The result from CA is consistent with that obtained from PCA, classifying that the heavy metals in two clusters derive from different sources. Correlation analysis supports the conclusions from PCA and CA, elucidating the relationships between heavy metals and particle sizes of the sediments.     

Uncertainty in Impact and Externality Assessments - Implications for Decision-Making (13 pp)

Goal, Scope and Background Many disciplines, amongst them LCIA, environmental impact and external cost assessments, are often faced with evaluating trade-offs between two or more alternative options in terms of a range of incommensurable indicators. Using process modeling and valuation, these indicators are quantified at mid- or endpoint levels. Recent discussion amongst LCA experts showed that because of the mutually exclusive aspects of uncertainty and relevance, the midpoint/endpoint debate is controversial and difficult to reconcile. This article is aimed at a more quantitative analysis of mid- and endpoint impacts, and the implications of uncertainty for decision-making. Methods The consequences for decision-making of uncertainties of endpoints are analysed quantitatively for the example of ExternE results, by employing statistical hypothesis testing. The Analytic Hierarchy Process (AHP) is then used to demonstrate the use of multi-criteria techniques at midpoint levels. Results and Discussion Statistical hypothesis testing at the endpoint level shows that for the ExternE example, probabilities of mistakenly favouring one alternative over another when they are in reality indistinguishable can be as high as 80%. Therefore, the best estimate of external cost is inadequate for most policy making purposes. Indicators at midpoint levels are more certain, but since they are only proxy attributes, they carry a hidden uncertainty in their relevance. Conclusion If endpoint information is too uncertain to allow a decision to be made with reasonable confidence, then the assessment can be carried out in midpoint terms. However, midpoint indicators are generally further removed from people's experience, and less relevant to the question that people actually want to solve. Nevertheless, if this ultimate question is unanswerable (within the certainty required by the decision-maker), a decision can be made on the basis of stakeholders' subjective judgments about the more certain midpoint levels. The crucial point is that these judgments are able to intuitively incorporate many aspects that impact modeling and valuation has trouble quantifying, such as perceived risk, distribution of burdens and benefits, equity, ethical, moral, religious and political beliefs and principles, immediacy and reversibility of potential impacts, voluntariness, controllability and familiarity of exposure, or perceived incompleteness of human knowledge.     

A Pooled Response Strategy for Combining Multiple Lines of Evidence to Quantitatively Estimate Impact

The impacts of sediment contaminants can be evaluated by different lines of evidence, including toxicity tests and ecological community studies. Responses from 10 different toxicity assays/tests were combined to arrive at a “site score.” We employed a relatively simple summary measure, pooled P-values where we quantify a potential decrement in response in a contaminated site relative to nominally clean reference sites. The response-specific P-values were defined relative to a “null” distribution of responses in reference sites, and were then pooled using standard meta-analytic methods. Ecological community data were also evaluated using an analogous strategy. A distribution of distances of the reference sites from thecentroid of the reference sites was obtained. The distance from each of the test sites from the centroid of the reference sites was then calculated, and the proportion of reference distances that exceed the test site difference was used to define an empirical P-value for that test site. A plot of the toxicity P-value versus the community P-value was used to identify sites based on both alteration in community structure and toxicity, that is, by weight-of-evidence. This approach provides a useful strategy for examining multiple lines of evidence that should be accessible to the broader scientific community. The use of a large collection of reference sites to empirically define P-values is appealing in that parametric distribution assumptions are avoided, although this does come at the cost of assuming the reference sites provide an appropriate comparison group for test sites.