D. Bart Chadwick

Critical tissue copper residues for marine bivalve (Mytilus galloprovincialis) and echinoderm (Strongylocentrotus purpuratus) embryonic development: Conceptual, regulatory and environmental implications

Critical tissue copper (Cu) residues associated with adverse effects on embryo-larval development were determined for the Mediterranean mussel (Mytilus galloprovincialis) and purple sea urchin (Strongylocentrotus purpuratus) following laboratory exposure to Cu-spiked seawater collected from San Diego Bay, California, USA. Whole body no-observed-effect-residues (NOER) were similar, with means of 21 and 23 microg g(-1) dw, for M. galloprovincialis and S. purpuratus, respectively. Mean whole body median effect residues (ER50) were 49 and 142 microg g(-1) dw for M. galloprovincialis and S. purpuratus, respectively. The difference in ER50s between species was reduced to a factor of <2 when expressed as soft tissue residues. Coefficients of variation among whole body-ER50s were 3-fold lower than median waterborne effect concentrations (EC50) for both species exposed to samples varying in water quality characteristics. This suggests that tissue concentrations were a better predictor of toxicity than water concentrations. The CBRs described herein do not differentiate between the internal Cu concentrations that are metabolically available and those that are accumulated and then detoxified. They do appear, however, to be well enough related to the level of accumulation at the site of action of toxicity that they serve as useful surrogates for the copper concentration that affects embryonic development of the species tested. Results presented have potentially important implications for a variety of monitoring and assessment strategies. These include regulatory approaches for deriving saltwater ambient water quality criteria for Cu, contributions towards the development of a saltwater biotic ligand model, the conceptual approach of using CBRs, and ecological risk assessment.

Use of laboratory toxicity tests with bivalve and echinoderm embryos to evaluate the bioavailability of copper in San Diego Bay, California, USA

Copper concentrations in parts of San Diego Bay (CA, USA) exceed ambient water quality criteria (WQC; currently 3.1 microg/L dissolved, U.S. Environmental Protection Agency [U.S. EPA]). In order to better understand the bioavailability of copper to water-column organisms in the bay, toxicity tests were performed with copper added to surface water collected from various sites in the estuary over a three-year period. The species and endpoints used, bivalve and echinoderm embryo-larval development, are among the most sensitive in the U.S. EPAs national toxicity dataset, which is used to derive WQC. No toxicity was observed in ambient bay water samples, as indicated by high proportions of normally developed larvae in control treatments, averaging 93+/-5% across all sites and all sampling events. Median effects concentrations (EC50), obtained by copper spiking of ambient water samples, ranged from 1.7 to 3.4 times lower at sites located near the mouth compared to sites near the back of the bay. These data indicate a gradient in complexation capacity increasing from the mouth to the back of the bay, which is consistent with similar trends in dissolved organic carbon and total suspended solids. For the bay as a whole, estimates for total recoverable and dissolved water-effect ratios (WER) ranged from 2.07 to 2.27 and 1.54 to 1.67, respectively. Water-effect ratios of this magnitude suggest that adoption of a somewhat higher site-specific WQC for San Diego Bay still would achieve the level of protection that is intended by the WQC guidelines.

A sediment ecotoxicity assessment platform for in situ measures of chemistry,bioaccumulation and toxicity. Part 1: System description and proof of concept

In situ-based testing using aquatic organisms has been widely reported, but is often limited in scope and practical usefulness in making decisions on ecological risk and remediation. To provide this capability, an integrated deployment system, the Sediment Ecotoxicity Assessment (SEA) Ring was developed, which incorporates rapid in situ hydrological, chemical, bioaccumulation, and toxicological Lines-of-Evidence (LoE) for assessing sediment and overlying water contamination. The SEA Ring system allows for diver-assisted, or diverless, deployment of multiple species of ecologically relevant and indigenous organisms in three different exposures (overlying water, sediment-water interface, and bulk sediment) for periods ranging from two days to three weeks, in a range of water systems. Measured endpoints were both sublethal and lethal effects as well as bioaccumulation. In addition, integrated passive sampling devices for detecting nonpolar organics (solid phase micro-extraction fibers) and metals (diffusive gradients in thin films) provided gradient measures in overlying waters and surficial sediments.

A sediment ecotoxicity assessment platform for in situ measures of chemistry, bioaccumulation and toxicity. Part 2: Integrated application to a shallow estuary

A comprehensive, weight-of-evidence based ecological risk assessment approach integrating laboratory and in situ bioaccumulation and toxicity testing, passive sampler devices, hydrological characterization tools, continuous water quality sensing, and multi-phase chemical analyses was evaluated. The test site used to demonstrate the approach was a shallow estuarine wetland where groundwater seepage and elevated organic and inorganic contaminants were of potential concern. Although groundwater was discharging into the surficial sediments, little to no chemical contamination was associated with the infiltrating groundwater. Results from bulk chemistry analysis, toxicity testing, and bioaccumulation, however, suggested possible PAH toxicity at one station, which might have been enhanced by UV photoactivation, explaining the differences between in situ and laboratory amphipod survival. Concurrently deployed PAH bioaccumulation on solid-phase micro-extraction fibers positively correlated (r(2) ≥ 0.977) with in situ PAH bioaccumulation in amphipods, attesting to their utility as biomimetics, and contributing to the overall improved linkage between exposure and effects demonstrated by this approach.

“Flooding” versus “inundation”

As mean sea level rise (MSLR) accelerates, it will become increasingly necessary and useful to distinguish coastal “flooding” from “inundation.” The growing number of coastal MSLR vulnerability assessments makes it clear that confused usage is abundant. We propose that the term “flooding” be used when dry areas become wet temporarily—either periodically or episodically—and that “inundation” be used to denote the process of a dry area being permanently drowned or submerged. According to these proposed defnitions, flooding is always higher than inundation, but they are fundamentally different. Flooding, including tidal flooding, is and has been dominant along open coasts. However, inundation is likely to become ever more important in the coming decades and centuries and may itself eventually become a dominant physical coastal process. Differentiating between the two will clarify and emphasize the differences between these processes.

Improving power production in linear forms of microbial fuel cells

Benthic microbial fuel cells (BMFCs) are devices that generate persistent energy by coupling bioanodes and biocathodes through an external energy harvester. Advances in BMFC system design have increased feasibility for its use in ocean monitoring. Previous iterations of BMFCs designed by this same group have relied upon carpet like anodes to harvest energy from electrochemically active bacteria in the sediment at power densities of 10 - 20 mW/m-2. Although successful, these 2D anodes are difficult to deploy. In this paper, we evaluate linear cable anodes as an alternative scaling strategy. Commercially manufactured, these cable anodes are wound around insulated underwater cables and can be handled similar to linear hydrophone arrays. Used as delivered, cable anodes performed poorly and generated ~0.3 mW/m. To improve power production, we added a washing step to remove any chemical binders used in manufacturing and frayed the cable, exposing short strands of carbon yarn. Treated cable anodes generated 1-2 mW/m, which was comparable to and slightly improved over the performance of carpet like anodes.

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.