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ENVIRONMENTAL SCIENCES IN THE 21ST CENTURY: PARADIGMS, OPPORTUNITIES, AND CHALLENGES
Citation:
Block, D. S., M. Slattery, W H. Benson, AND J. C. Allgood. ENVIRONMENTAL SCIENCES IN THE 21ST CENTURY: PARADIGMS, OPPORTUNITIES, AND CHALLENGES. Presented at SETAC 21st Annual Meeting, Nashville, TN, Nov.12-16 , 2000.
Description:
In: Environmental Sciences in the 21st Century: Paradigms, Opportunities, and Challenges: Abstract Book: SETAC 21st Annual Meeting, 12-16 November 2000, Nashville, TN.. Society of Environmental Toxicology and Chemistry, Pensacola, FL. Pp. p. 180.
Bioavailability and rates of chemical partitioning can be dependent on chemical interactions of mixtures in sediment. In these experiments, influence of chemical mixtures on partitioning of chlorpyrifos was evaluated utilizing sterilized or non-sterilized sediments amended with 50 ?g/L of dieldrin and methyl mercury (MeHg). Concentrations of chlorpyrifos alone (CPF), dieldrin, and MeHg were determined utilizing gas chromatography and cold vapor atomic adsorption spectroscopy. Water, sediment and pore water samples were collected at 0, 12, 24, 48, 96, 168, and 240 hours following direct addition of chlorpyrifos (2.0 mg/L) to overlying water. The half-life of chlorpyrifos in overlying water was 74.4, 21.7, and 151.7 hours for CPF, CPF-dieldrin, and CPF-MeHg, respectively. Additionally, CPF and CPF-MeHg treatments showed no differences in the rate of chlorpyrifos partitioning into sediment when measured by the ratio of chlorpyrifos concentrations in sediment to overlying water. However, the CPF-MeHg mixture accumulated higher concentrations of chlorpyrifos in pore water (132.2 ?g/L ? 14.6 SE) than CPF-dieldrin (72.5 ?g/L ? 4.3 SE) and CPF (32.7 ?g/L ? 16.9 SE). Conversely, the CPF-dieldrin mixture showed a significantly increased rate of partitioning into sediment resulting in a 2-fold higher concentration of chlorpyrifos in sediment after 240 hours. No significant deviation in chlorpyrifos partitioning was observed in microbial free treatments. These data indicate the CPF-dieldrin mixture increases loss of chlorpyrifos from overlying water as well as uptake into sediment when compared to CPF. Additionally, the CPF-MeHg mixture increases the half-life of compound in overlying water. Increased pore water concentrations of chlorpyrifos, when in the presence of MeHg, may potentially increase the toxicological effects to benthic organisms by increasing concentrations of toxicant in the bioavailable fraction.