David W. Moore

Assessing and Managing Contaminated Sediments: Part I, Developing an Effective Investigation and Risk Evaluation Strategy

Abstract This is the first of a two-part review of the current state-of-the-science pertaining to the assessment and management of contaminated sediments. The goal of this review is to introduce some of the major technical and policy issues stemming from the assessment and management of contaminated sediments, highlight a number of aspects of contaminated sediment assessment and management found to be successful, and, when appropriate, address the barriers that still exist for improving contaminated sediment management. In this paper, Part I, the many key elements of an effective investigation and risk evaluation strategy are reviewed, beginning with the development of a conceptual site model (CSM) and including a discussion of some of the key factors influencing the design of sediment investigations and ecological risk assessment of sediment-bound chemicals on aquatic biota. In Part II of this paper (Apitz et al. 2005), various approaches are reviewed for evaluating sediment risk and monitoring sediment remedy effectiveness. While many of the technical and policy issues described in this review are relevant to dredged material management, the focus of this paper is on sediment assessment for environmental management.

Assessing and managing contaminated sediments: Part II, evaluating risk and monitoring sediment remedy effectiveness

Abstract This is the second of a two-part review of the current state-of-the-science pertaining to the assessment and management of contaminated sediments. The goal of this review is to introduce some of the major technical and policy issues stemming from the assessment and management of contaminated sediments, highlight a number of aspects of contaminated sediment assessment and management found to be successful, and, when appropriate, address the barriers that still exist for improving contaminated sediment management. In Part I (Apitz et al. 2005), the key elements of an effective investigation and risk evaluation strategy were reviewed, beginning with the development of a conceptual site model (CSM) and including a discussion of some of the key factors influencing the design of sediment investigations and ecological risk assessment of sediment-bound chemicals on aquatic biota. In this paper, Part II, various approaches are reviewed for evaluating sediment risk and monitoring sediment remedy effectiveness. While many of the technical and policy issues described in this review are relevant to dredged material management, the focus of this paper is on sediment assessment for environmental management.

A field test and comparison of acute and chronic sediment toxicity tests with the estuarine amphipod Leptocheirus plumulosus in Chesapeake Bay, USA

A 28-d partial life-cycle test with the estuarine amphipod Leptocheirus plumulosus was developed in response to the need for an assay to mimic chronic exposure to sediment-associated contaminants. To ensure that toxicity tests have environmental relevance, it is essential to evaluate the relationship between laboratory responses and field measures of contamination. Consequently, one objective of the study was to compare the results of the chronic sediment toxicity test with L. plumulosus to gradients of sediment contamination and the in situ benthic community in its native Chesapeake Bay. Chronic tests were conducted by two laboratories, the Army Corps of Engineers Waterways Experiment Station ([WES]; Vicksburg, MS, USA) and the University of Maryland ([UM] College Park, MD, USA) using different feeding regimes, providing the opportunity to evaluate the effect of this variable on response sensitivity. A second objective was to compare the relative sensitivity of acute and chronic tests with L. plumulosus with field-collected sediments. Overall, there was good agreement between the toxicological response of acute and chronic tests with L. plumulosus and field measures of contamination. Survival in the acute test and chronic test conducted by WES was negatively correlated with concentrations of sediment-associated contaminants. Survival in acute exposures was significantly reduced in sediments from 8 of 11 stations. Indigenous L. plumulosus were found only at two of the three stations that did not exhibit acute toxicity. An unexpected finding was the difference in responsiveness of the two chronic tests. Survival in tests conducted by UM and WES was significantly reduced in sediments from 4 and 6 of 11 stations, respectively. No additional sublethal toxicity was detected in the UM chronic test, but the WES test detected reproductive effects at two additional stations. We believe the observed differences were related to the test diet used. Partly as a result of our findings, the recommended diet for the L. plumulosus chronic test was changed in the final methods document.

A Comparative Screening-Level Ecological and Human Health Risk Assessment for Dredged Material Management Alternatives in New York/New Jersey Harbor

Managers of New York and New Jersey Harbor dredging projects are developing strategies to dispose and manage the large volumes of sediment that must be dredged to maintain passable waterways. The various management alternatives include aquatic containment facilities, upland containment, and treatment with beneficial reuse. An important consideration in the selection of an appropriate alternative is the evaluation of potential risks to ecological and human receptors. This study presents a framework for a screening-level ecological and human health risk assessment that compares risks associated with management alternatives for contaminated dredged materials. The major objectives of the work were to identify exposure routes that show the potential for risk and develop a framework that can be used to compare relative potential risks among eight management alternatives. Managers can use this framework to: • identify characteristics of the placement/treatment alternatives that contribute to potential risk, • choose one alternative over another for sediments with high concentrations of contaminants, • implement controls that mitigate risk, or • identify the need for a more comprehensive site-specific risk assessment.

Effect of growth on reproduction in the freshwater amphipod, Hyalella azteca (Saussure)

A gradient in H. azteca growth was created by reducing food ration. Tests were initiated with neonates (≤48 h old) and the effects of an altered food ration on survival and growth were examined after 10 and 49 days. Growth rates decreased significantly with reduced food ration (10 day growth rates ranged from 1.2 µg d−1 in the highest feeding regime to 0.5 µg d−1 in lowest feeding regime). Survival after 10 days was not affected by ration, ranging from 86 to 96%. A growth rate of 1.2 µg d−1 at day 10 resulted in mean dry weight (1.0 mg), survival (62%) and reproduction (9.3 neonates/female) at day 49 similar to reported values for this species. Growth rates ≤0.9 µg d−1 at day 10 corresponded to significantly reduced reproduction at day 49 (i.e., < 1 neonate per female). Time to the onset of amplexus increased with decreasing ration suggesting reduced ration may have delayed reproduction.

Long-term storage of sediments: Implications for sediment toxicity testing

Juvenile Nereis (Neanthes) arenaceodentata survival and growth were used to evaluate the effect of storage time on the toxicity of sediments with moderate PAH and metal contamination. Seven San Francisco Bay area sediments and a clean control sediment were stored (4 degrees C) and then periodically evaluated (up to two years after collection). During each test, juvenile worms (2-3 weeks post emergence) were exposed for 21 days. Test endpoints were survival and growth rate (mg dry weight/day). In general, survival was high (>75%) and long-term cold storage (740 days) did not significantly alter growth or survival. In half of the sediments a cyclical phenomenon was observed associated with the appearance of ammonia in the overlying water of bioassay beakers. The periodicity of this phenomenon was approximately one year. It was not associated with any geophysical characteristic of the test sediments (i.e. grain size, % TOC, % TKN). Significant mortality (0% survival on day 427) was associated with the largest of these peaks in overlying water ammonia concentration. Results of this study suggest that ammonia in stored sediments is an important, potentially confounding factor in sediment toxicity tests.

Application of ecosystem services in natural resource management decision making.

An ecosystem services (ES) approach to natural resource management (NRM) can provide the framework for balancing economic, ecological, and societal drivers in decision making. The efficacy of such an approach depends on the successful execution of several key activities, from early and continuous engagement with relevant stakeholders, to development and application of ecological production functions (EPFs), to explicit recognition of uncertainty in the process. Although there are obstacles to the implementation of an ES approach in NRM, including unclear regulatory and policy frameworks and the paucity of useful EPFs, many of the tools are currently available or sufficiently developed. An ES approach can and, in some cases, should involve qualitative rather than quantitative assessment when the stakes are not very high or when quantitative approaches would not be cost effective because of highly uncertain results. Integr Environ Assess Manag 2017;13:74-84.

Toxicity Reduction (and Identification) for Dredging Evaluations : Methods for Whole Sediment Elutriate Bioassays

PURPOSE: Physical, chemical, and toxicological characterization of sediment may be required to evaluate dredged material (DM) under the Clean Water Act (CWA) or Marine Protection Research and Sanctuaries Act (MPRSA). When DM evaluations indicate potential for biological effects, it is useful to identify the likely causes of those effects to better inform test interpretation and/or management decisions (USEPA/USACE, 1991). For example, when a non-persistent substance, such as ammonia, is present at elevated levels that are sufficient to alone cause a toxicological effect in laboratory bioassays, it is logical to employ methods to reduce ammonia levels prior to conducting the bioassay to allow toxicological assessment for more persistent contaminants of concern. The primary objective of this Technical Note (TN) was to disseminate methods for conducting toxicity reduction/identification evaluations (TRE/TIE) to be used in select dredging evaluations. While previous documents have discussed the utility of TRE/TIE information for dredging management decisions, this TN provides more specific guidance. In practice, TREs for ammonia in elutriate toxicity tests may be most common and applicable. TRE methods serve as supplementary testing to standard whole sediment and sediment elutriate bioassays in which significant reductions in survival (or other endpoints) are observed, but the primary cause is unknown or suspected to be ammonia, hydrogen sulfide, or other non-contaminant related factors. Through sediment and elutriate manipulations, these methods can generate lines of evidence that a certain chemical class (or specific chemical compound or element when coupled with chemistry data) is primarily responsible for observed biological effects. The drivers of the biological effects may be narrowed to typical contaminants/classes; organic compounds, metals3, ammonia, and/or sulfides (Ankley et al. 1992; Kreitinger et al. 2017). Application of the methods described herein is beneficial to align the type of data generated between different dredging projects, thus allowing greater consistency of robust, scientific data that feed management decisions.

Evaluation of PCB Availability in Sediment after the Application of an Activated Carbon Amendment at an Active U.S. Naval Shipyard

The objective of this project was to demonstrate and validate placement, stability and performance of reactive amendments for treatment of contaminated sediments in active Department of Defense (DoD) harbor settings. This project extends pilot-scale testing of the application of activated carbon (AC) to decrease the bioavailability of polychlorinated biphenyls (PCBs) in contaminated sediment to near full-scale demonstration under realistic conditions at an active DoD harbor site. The evaluation was conducted at Pier 7 of the Puget Sound Naval Shipyard and Intermediate Maintenance Facility (PSNS & IMF) in Bremerton, Washington.