G. Allen Burton

Sediment toxicity assessment

(Section Headings): Assessing Sediment Quality. Sediment Variability. Sediment Collection and Processing: Factors Affecting Realism. Ecosystem Assessment Using Estuarine and Marine Benthic Community Structure. Evaluation of Sediment Contaminant Toxicity: The Use of Freshwater Community Structure. The Emergence of Functional Attributes as EndPoints in Ecotoxicology. The Significance of In-Place Contaminated Marine Sediments on the Water Column: Processes and Effects. Plankton, macrophyte, Fish, and Amphibian Toxicity Testing of Freshwater Sediments. Assessment of Sediment Toxicity to Marine Benthos. Freshwater Benthic Toxicity Tests. Biomarkers in Hazard Assessments of Contaminated Sediments. Models, Muddles and Mud: Predicting Bioaccumulation of Sediment-Associated Pollutants. Sediment Bioaccumulation Testing with Fish. Integrative Assessments in Aquatic Ecosystems. Management Framework for Contaminated Sediments. Puget Sound Case Study. The Effects of Contaminated Sediments in the Elizabeth River. Index.

Stormwater Effects Handbook : A Toolbox for Watershed Managers, Scientists, and Engineers

Introduction Overview: The Problem of Storm Water Runoff Sources of Pollution Regulatory Program Stormwater Effects in Receiving Waters Heterogeneity Stressor Categories and Their Effects Assessment Strategies Rationale for an Integrated Approach Study Design Overview Study Design and Implementation Beginning the Assessment Sampling Ecosystem Component Characterization Hydrology Habitat Biology Fish Toxicity and Bioaccumulation Appendices Habitat Characterization Benthos Community Assessment Fish Community Assessment Toxicity Testing Glossary References

Weight-of-Evidence Approaches for Assessing Ecosystem Impairment

It is challenging determining whether an ecosystem is impaired. The complexity of direct and indirect interactions between physical, biological and chemical components with their varying temporal and spatial scales generally renders use of multiple assessment approaches mandatory, with a consequent need to integrate different lines-of-evidence. Integration generally involves some form of weight-ofevidence (WOE). WOE approaches reported in the literature vary broadly from subjective and qualitative to quantitative. No standard approach exists and no accepted guidelines exist describing how a WOE process should be conducted. This review summarizes the advantages, limitations, and uncertainties of different WOE approaches, critical issues involved in selecting and executing different lines-ofevidence, and the process for subsequent characterization of the likelihood of impairment.

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.

Assessing contaminated sediments in the context of multiple stressors

Sediments have a major role in ecosystem functioning but can also act as physical or chemical stressors. Anthropogenic activities may change the chemical constituency of sediments and the rate, frequency, and extent of sediment transport, deposition, and resuspension. The importance of sediments as stressors will depend on site ecosystem attributes and the magnitude and preponderance of co-occurring stressors. Contaminants are usually of greater ecological consequence in human-modified, depositional environments, where other anthropogenic stressors often co-occur. Risk assessments and restoration strategies should better consider the role of chemical contamination in the context of multiple stressors. There have been numerous advances in the temporal and spatial characterization of stressor exposures and quantification of biological responses. Contaminated sediments causing biological impairment tend to be patchy, whereas more pervasive anthropogenic stressors, such as alterations to habitat and flow, physical disturbance, and nutrient addition, may drive large-scale ecosystem responses. A systematic assessment of relevant ecosystem attributes and reference conditions can assist in understanding the importance of sediments in the context of other stressors. Experimental manipulations then allow for the controlled study of dominant stressors and the establishment of causal links. This approach will result in more effective management of watersheds and waterways.

Review of aquatic in situ approaches for stressor and effect diagnosis

Abstract Field-based (in situ) approaches are used increasingly for measuring biological effects and for stressor diagnoses in aquatic systems because these assessment tools provide realistic exposure environments that are rarely replicated in laboratory toxicity tests. Providing realistic exposure scenarios is important because environmental conditions can alter toxicity through complex exposure dynamics (e.g., multiple stressor interactions). In this critical review, we explore the information provided by aquatic in situ exposure and monitoring methods when compared with more traditional approaches and discuss the associated strengths and limitations of these techniques. In situ approaches can, under some circumstances, provide more valuable information to a decision maker than information from surveys of resident biota, laboratory toxicity tests, or chemical analyses alone. A decision tree is provided to assist decision makers in determining when in situ approaches can add value.

Assessing Contamination in Great Lakes Sediments Using Benthic Invertebrate Communities and the Sediment Quality Triad Approach

Abstract Sediments in many Great Lakes harbors and tributary rivers are contaminated. As part of the USEPAs Assessment and Remediation of Contaminated Sediment (ARCS) program, a number of studies were conducted to determine the nature and extent of sediment contamination in Great Lakes Areas of Concern (AOC). This paper describes the composition of benthic invertebrate communities in contaminated sediments and is one in a series of papers describing studies conducted to evaluate sediment toxicity from three AOCs (Buffalo River, NY; Indiana Harbor, IN; Saginaw River, MI), as part of the ARCS Program. Oligochaeta (worms) and Chironomidae (midge) comprised over 90% of the benthic invertebrate numbers in samples collected from depositional areas. Worms and midge consisted of taxa identified as primarily contaminant tolerant organisms. Structural deformities of mouthparts in midge larvae were pronounced in many of the samples. Good concurrence was evident between measures of laboratory toxicity, sediment contaminant concentration, and benthic invertebrate community composition in extremely contaminated samples. However, in moderately contaminated samples, less concordance was observed between the benthos community composition and either laboratory toxicity test results or sediment contaminant concentration. Laboratory sediment toxicity tests may better identify chemical contamination in sediments than many commonly used measures of benthic invertebrate community composition. Benthic measures may also reflect other factors such as habitat alteration. Evaluation of non-contaminant factors are needed to better interpret the response of benthic invertebrates to sediment contamination.

The Role of Traditional and Novel Toxicity Test Methods in Assessing Stormwater and Sediment Contamination

Traditional effluent and ambient water column toxicity tests have been used widely for evaluating the contamination of stormwaters and sediments. These assays consist of a routine bioassay exposure design of 1 to 9 days using freshwater and marine/estuarine species known to be sensitive to a wide range of toxicants. While effluent toxicity may be indicative of sediment or stormwater toxicity in the receiving system, the exposure is different, and therefore toxicity cannot be readily predicted. Traditional, standardized, whole effluent toxicity (WET) test methods have been used effectively and also misused in evaluations of whole sediments, pore (interstitial) water, elutriates (extracts), and stormwaters. Results show these methods to be very sensitive to sediment and stormwater toxicity. These traditional toxicity tests are predictive of instream sediment or stormwater effects where significant contamination exists or where exposure concentrations are similar. Modifications of these standardized test methods to include sediments or pore waters have been shown to be as sensitive as short-term, whole sediment toxicity tests using benthic species. However, the added complexity of sediments and stormwaters (e.g., partitioning, high Kow compound bioavailability, suspended solids, sporadic exposures, multiple exposure pathways) dictates that traditional toxicity test applications be integrated into a more comprehensive assessment of ecologically significant stressors. The limitations of the WET testing approach and optimized sample collection and exposure alternatives are frequently ignored when implemented. Exposure to sporadic pulses of contaminants (such as in stormwaters) often produce greater toxicity than exposure to constant concentrations. Lethality from short-term pulse exposures may not occur for weeks after the high flow event due to uptake dynamics. Pore water and elutriate exposures remove sediment ingestion routes of exposure and alter natural sorption/desorption dynamics. Traditional toxicity tests may not produce reliable conclusions when used to detect the adverse effects of: fluctuating stressor exposures, nutrients, suspended solids, temperature, UV light, flow, mutagenicity, carcinogenicity, teratogenicity, endocrine disruption, or other important subcellular responses. This reality and the fact that ecologically significant levels of high Kow compounds may not produce short-term responses in exposures dictates that additional and novel assessment tools be utilized in order to protect aquatic ecosystems. This inablilty to predict effects is largely a result of the complex biological response patterns that result from various combinations of stressor magnitudes, duration, and frequency between exposures and also the interactions of stressor mixtures, such as syngergistic effects of certain pesticides, metals, and temperature. In watersheds receiving multiple sources of stressors, accurate assessments should define spatial-temporal profiles of exposure and effects using a range of laboratory (such as WET tests) and novel in situ toxicity and bioaccumulation assays, with simultaneous characterizations of physicochemical conditions and indigenous communities.

Field validation of sediment zinc toxicity

A field study was conducted to validate concentrations of zinc in freshwater sediments that are tolerated by benthic macroinvertebrate communities and to determine whether a relationship exists with the acid volatile sulfide (AVS)-simultaneously extracted metal (SEM) model. In both the lake and riverine systems, one sediment type was high in AVS and one low in AVS, which resulted in zinc-spiked sediments that ranged from low to high SEM to AVS ratios. The colonization trays were sampled seasonally, ranging from 6 to 37 weeks of exposure, and were evaluated using several appropriate benthic indices. Results of the field evaluations at the four test sites confirmed the validity of the AVS-SEM model, predicting benthic macroinvertebrate effects correctly 92% of the time. In sediments where the SEM to AVS ratio or the AVS and organic (OC)-normalized fractions exceeded 8 and 583 micromol/g of OC, toxicity was observed from the zinc-spiked sediments. Conversely, when the SEM to AVS ratio or OC-normalized AVS fractions were less than 2 or 100 micromol/g of OC, no toxicity was observed. In the range of 148 to 154 micromol/g of OC, toxicity varied in two treatments. Total zinc concentrations in sediments showed no relationship to benthic effects. The most impaired benthic community occurred in the high-gradient stream sediments, which had low OC and AVS concentrations and SEM to AVS ratios of 33 and 44 in the spiked sediments. Five to six benthic metrics were depressed at SEM to AVS ratios of 8.32 and 9.73. The no-observed-effect level appeared to be near a SEM to AVS ratio of 2, with slight to no effects between ratios of 2.34 and 2.94. No sites with ratios of less than 2 showed any adverse effects.

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.