A weight-of-evidence (WOE) framework was developed to evaluate potential effects on the aquatic ecosystem of Wabamun Lake (Alberta, Canada) associated with the release of Bunker “C” oil after a train derailment. The wide variety of stakeholders and interested regulatory agencies made it necessary to develop a consistent and transparent approach to assessing ecological effects on multiple ecosystem components within the lake with the use of a large number of lines of evidence (LOEs). Consequently, a scalable WOE framework was necessary to integrate the findings of 38 different LOEs. A priori and a posteriori weighting factors were applied to each individual LOE, and a combination of numeric and nonnumeric rating systems was used to integrate LOEs into an overall WOE conclusion for 5 different ecosystem components. We provide guidance regarding the development of a WOE framework and emphasize techniques that enhance the application of best professional judgement during the WOE process.

Measurements of polychlorinated biphenyl (PCB) congener concentrations and profiles from produce grown near New Bedford Harbor, Massachusetts, USA, before, during, and after remediation of PCB-contaminated sediment are presented. Samples of tomatoes collected from locations upwind and downwind relative to harbor contamination are compared with the use of measurements of 47 individual PCB congeners. The PCB concentration in the locally grown tomatoes, as expressed by the sum of congeners, is highest during the period of harbor dredging and drops to its lowest point after remediation, which included dredging and excavation. The downwind location is characterized by higher concentrations of PCBs than the upwind location in every time period. Principal component analysis is used to distinguish both the effect of remediation over time and the effect of cultivation location on the congener profiles. Evidence of the PCB congener profile representing the contaminated harbor sediments is strongest during the dredging period and in the downwind location. These results have important implications for understanding human exposure via the food chain and highlight the importance of considering exposure pathways related to atmospheric transport during remediation of contaminated sediments.

The bioavailability of sediment-associated contaminants is poorly understood. Often, a triad of chemical concentration measurements, laboratory sediment toxicity tests, and benthic infaunal community condition is used to assess whether contaminants are present at levels of ecological concern. Integration of these 3 lines of evidence is typically based on best professional judgment by experts; however, the level of consistency among expert approach and interpretation has not been determined. In this study, we compared the assessments of 6 experts who were independently provided data from 25 California embayment sites and asked to rank the relative condition of each site from best to worst. The experts were also asked to place each site into 1 of 6 predetermined categories of absolute condition. We provided no guidance regarding assessment approach or interpretation of supplied data. The relative ranking of the sites was highly correlated among the experts, with an average correlation coefficient of 0.92. Although the experts' relative rankings were highly correlated, the categorical assessments were much less consistent, with only 1 site out of 25 assigned to the same absolute condition category by all 6 experts. Most of the observed categorical differences were small in magnitude and involved the weighting of different lines of evidence in individual assessment approaches, rather than interpretation of signals within a line of evidence. We attribute categorical differences to the experts' use of individual best professional judgment and consider these differences to be indicative of potential uncertainty in the evaluation of sediment quality. The results of our study suggest that specifying key aspects of the assessment approach a priori and aligning the approach to the study objectives can reduce this uncertainty.

Modeling the effects of pesticide exposure on avian populations requires knowledge of how the pesticide changes survival and fecundity rates for the population. Although avian reproduction tests are the primary source of information on reproductive effects in the pesticide risk assessment process, current tests cannot provide a direct estimate of the effects of a pesticide on fecundity rates. We present a mathematical model that integrates information on specific types of effects from reproduction tests with information on avian life history parameters, the timing of pesticide applications, and the temporal pattern of pesticide exposure levels to estimate pesticide effects on annual reproductive success. The model demonstration follows nesting success of females in no-pesticide or pesticide-exposed populations through a breeding season to estimate the mean number of successful broods per female. We demonstrate the model by simulating populations of a songbird exposed to 1 of 2 hypothetical pesticides during a breeding season. Finally, we discuss several issues for improving the quantitative estimation of annual reproductive success.

KORea ECOlogical Risk assessment (KORECORisk) was developed to support decision making for the ecological risk-based management of chemicals in industrial complexes in South Korea. The system is based on a geographical information system and consists of a release rate estimation module, an exposure estimation module, and an ecological risk assessment module. For release rate and exposure estimation, the chemical use data from the national chemical inventory database and a dynamic multimedia fate model, respectively, were used. The ecological risk was assessed by calculating the risk quotient. A case study was presented to demonstrate an application of KORECORisk to setting a risk-based priority among the 6 major industrial complexes or among the chemicals used in the individual industrial complexes. Furthermore, a more detailed assessment was performed to demonstrate and evaluate a potential use of KORECORisk for the management of individual complexes. With 3 phthalates (1,2-benzenedicarboxylic acid dibutyl ester; 1,2-benzenedicarboxylic acid dimethyl ester; and 1,2-dibenzenedicarboxylic acid dioctyl ester) as model chemicals, KORECORisk provided prediction in time and space that are of sufficient resolution required for the aquatic risk assessment but with varying uncertainty. The uncertainty associated with the use of KORECORisk appeared to vary widely (from <10 to 10³) with the chemical. Within the range of the chemicals tested, the release rate estimation appeared to introduce larger uncertainty than the exposure estimation. A more accurate chemical use inventory would improve the accuracy of not only the chemical release estimation but the exposure estimation module by reducing the influence of the unidentified sources. The release estimation module should be modified to provide temporal variation with a time resolution relevant to the exposure duration for which toxic effects could occur.

The biotic ligand model (BLM) was used to assess copper (Cu) bioavailability, toxicity, water-effect ratios (WER), and Cu site-specific water-quality criteria (SSWQC) in the Matanza River and Pilcomayo River, Argentina, where anthropogenic inputs and natural phenomena have led to high concentrations of chemical species capable of reducing metal toxicity: Sodium, total hardness, alkalinity, dissolved organic carbon, and suspended particulate matter (SPM), as well as other metals. The purpose of this study was to evaluate the feasibility of developing Cu-SSWQC from a modified scenario of the BLM–Monte-Carlo method model. The response of the BLM model in these rivers, with water quality near its application boundary conditions, was evaluated during the 2003 to 2004 hydrological cycle. Cu toxicity tests were conducted with Daphnia magna as the test organism. The BLM (Version ap08) toxicity estimates for D. magna were within a factor of 2 of the line of perfect agreement with toxicity test results, although highly variable relevant water-quality parameters showed that mean estimates were more than 2 times the mean 50% effective concentration (EC50) derived from the corresponding toxicity tests. Suspended particulate matter was an important sink for Cu added to unfiltered water of the Pilcomayo River, but it also exerted some toxic effect. Minimums WER, estimated with a modified scenario of the BLM-MONTE, ranged from 1.5 (Pilcomayo River, at Misión La Paz) up to 11 (Matanza River, at Route 3). The corresponding Cu-SSWQC values were 30 and 105 μg/L, respectively.

Sediments are an essential component of aquatic ecosystems that must be assessed and managed properly. The use of quantitative environmental quality standards derived from consideration of sediment quality guidelines (SQGs) can be effective as part of a tiered risk assessment approach. In Part I of this 2-part paper addressing sediment quality assessment and dredged material management in Spain, different SQG methods are used to evaluate sediment quality in the Bay of Santander, located in the Cantabric Sea along the northern coast of Spain, and to guide development of empirically derived SQGs for marine sediments. The results of the study indicate a great heterogeneity of SQGs, both with regard to the numeric values for a particular chemical and the number of substances for which SQGs have been derived. The analysis highlights the scarce development of empirical SQGs for priority substances identified in current European Union water policy. Nonetheless, the application of SQGs makes it possible to classify different zones of sediment quality in the Bay of Santander. Part II of this 2-part paper considers the environmental impacts of dredged material disposal. Legislation and criteria used to regulate dredged material disposal at sea in different European countries are reviewed, and action levels derived by different countries were used to evaluate management of dredged sediments from Cádiz Bay, located on the South Atlantic coast of Spain.

When sediments are removed from aquatic bottoms, they turn into dredged material that must be managed, taking into account its environmental impact. In Part II of this 2-part paper addressing sediment quality assessment and dredged material management in Spain, legislation and criteria used to regulate dredged material disposal at sea in different European countries are reviewed, as are action levels (ALs) derived by different countries used to evaluate management of dredged sediments from Cádiz Bay located on the South Atlantic coast of Spain. Comparison of ALs established for dredged material disposal by different countries reveals orders of magnitude differences in the values established for the same chemical. In Part I of this 2-part paper, review of different sediment quality guideline (SQG) methods used to support sediment quality assessments indicated a great heterogeneity of SQGs, both with regard to the numeric values for a particular chemical and the number of substances for which SQGs have been derived. The analysis highlighted the absence of SQGs for priority substances identified in current European Union water policy. Here, in Part II, the ALs are applied to dredged sediments from Cádiz Bay (South Atlantic coast of Spain), evidencing that the heterogeneity of ALs implemented in the reviewed countries could determine different management strategies. The application of other measurements such as bioassays might offer information useful in identifying a cost-effective management option in a decision-making framework, especially for dredged material with intermediate chemical concentrations.

The US Environmental Protection Agency is developing a national water quality criterion for selenium that is based on concentrations of the element in fish tissue. Although this approach offers advantages over the current water-based regulations, it also presents new challenges with respect to implementation. A comprehensive protocol that answers the “what, where, and when” is essential with the new tissue-based approach in order to ensure proper acquisition of data that apply to the criterion. Dischargers will need to understand selenium transport, cycling, and bioaccumulation in order to effectively monitor for the criterion and, if necessary, develop site-specific standards. This paper discusses 11 key issues that affect the implementation of a tissue-based criterion, ranging from the selection of fish species to the importance of hydrological units in the sampling design. It also outlines a strategy that incorporates both water column and tissue-based approaches. A national generic safety-net water criterion could be combined with a fish tissue–based criterion for site-specific implementation. For the majority of waters nationwide, National Pollution Discharge Elimination System permitting and other activities associated with the Clean Water Act could continue without the increased expense of sampling and interpreting biological materials. Dischargers would do biotic sampling intermittently (not a routine monitoring burden) on fish tissue relative to the fish tissue criterion. Only when the fish tissue criterion is exceeded would a full site-specific analysis including development of intermedia translation factors be necessary.