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2003 Progress Report: Development of Arsenic Sediment Quality Criteria using Equilibrium Partitioning

EPA Grant Number: R830844
Title: Development of Arsenic Sediment Quality Criteria using Equilibrium Partitioning
Investigators: Visviki, Ioanna , Carbonaro, Richard F. , Farley, Kevin J. , Judge, Michael L. , Mahony, John D.
Current Investigators: Visviki, Ioanna , Carbonaro, Richard F. , Judge, Michael L. , Mahony, John D.
Institution: College of Mount Saint Vincent , Manhattan College
Current Institution: College of Mount Saint Vincent
EPA Project Officer: Savage, Nora
Project Period: June 27, 2003 through June 26, 2005 (Extended to June 26, 2006)
Project Period Covered by this Report: June 27, 2003 through June 26, 2004
Project Amount: $389,391
RFA: Superfund Minority Institutions Program: Hazardous Substance Research (2002)
Research Category: Hazardous Waste/Remediation

Description:

Objective:

The objective of this research project is to test the applicability of the equilibrium partitioning (EqP) method for developing quality criteria for arsenic in sediments. Arsenic in aquatic sediments is currently a significant problem at Superfund sites. Reliable methods for determining the sediment concentrations at which arsenic poses an environmental risk are lacking. The EqP method relates the observed toxicity of a chemical in the sediment to the concentration of that chemical in the pore water of the sediment. The equilibrium-partitioning model is tested using three approaches: (1) Microtox screening assays to establish potential chemical interactions of arsenic with sulfide compounds; (2) 96-hour water-only exposures to determine the LC50 concentrations of As (III) and As (V) with amphipods; and (3) 10-day amphipod tests with As (III) or As (III)/sulfide-spiked sediments.

Progress Summary:

96-Hour Toxicity Tests With Amphipods

The water-only LC50 for As (III) has been calculated at 700 µg/L. The LC50 for As (V) is more than three times higher at 2,400 µg/L.

Cannibalism in Leptocheirus Juveniles

Several water-only experiments with arsenic or cadmium (reference toxicant) showed increased amphipod survivorship at very low toxicant concentrations. We attributed this phenomenon to cannibalism among Leptocheirus juveniles. To test this hypothesis, we added sacrificed amphipods to containers with live organisms and observed their removal within 24 hours, thus establishing that cannibalism was taking place. Subsequently, we examined food limitation and density effects and their relationship to cannibalism. Neither the presence of food in the form of Tetramin or dead conspecifics, nor the volume of the container affected survivorship, indicating that survivorship was not food or space-dependent. Survivorship decreased, however, as the number of individuals per container increased, indicating a density-dependent relationship facilitated by contact rates between individuals. This conclusion was supported by sediment experiments where cannibalism was absent. Examination of the relevant literature showed that this is a novel aspect of Leptocheirus behavior, although commonly observed in decapod crustaceans.

10-Day Spiked Sediment Tests With Amphipods

Initial experiments with natural sediments proved problematic. Natural sediments had a high sulfuric content rendering them difficult to use given the experimental goal of correlating pore water As (III) toxicity with available sulfide. We have developed an artificial sediment and tested its suitability with amphipods. We also have experimented with different feeding regimes to maximize Leptocheirus survivorship. We determined that the artificial sediment with one feeding every third day minimized amphipod mortality within acceptable levels.

Future Activities:

In Year 2 of the project, we will conduct extensive Microtox work. Our objectives are to: (1) establish the EC50 concentrations for As (III) and As (V) and to compare it with the amphipod data; and (2) investigate the effects of sulfide concentrations on arsenic toxicity. Based on Microtox screening assays, we will carry out 10-day amphipod tests in artificial sediment spiked with either As (III) or combinations of As (III) and sulfides. The results of these experiments will allow us to test the applicability of EqP for arsenic.

Journal Articles:

No journal articles submitted with this report: View all 17 publications for this project

Supplemental Keywords:

arsenic (III), arsenic (V), sulfides, Leptocheirus plumulosus, amphipods, equilibrium partitioning, EqP, aquatic ecosystem, ecotoxicology, heavy metals, aquatic sediments, sediment concentrations, EqP model, cadmium, cannibalism, survivorship, toxicity, , POLLUTANTS/TOXICS, Water, Scientific Discipline, Waste, Health, RFA, Arsenic, Risk Assessments, Water Pollutants, Environmental Chemistry, Contaminated Sediments, Geochemistry, arsenic mobility, water quality, superfund site, arsenic exposure, risk management, reservoir sediments, bioaccumulation, ecology assessment models, Superfund sites, sediment quality survey, contaminated sediment, EqP, contaminant transport, equilibrium partitioning, sediment transport, biogeochemistry, water treatment

Progress and Final Reports:
Original Abstract
2004 Progress Report
Final Report

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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