PM02 Metals in the Environment: Aquatic Biological Perspectives
Exhibit Hall
8:00 AM - Monday, 10 November 2003
(PM056) The influence of nutrients on the toxicity of arsenate and arsenite.
Keteles, K1, Johnson, D2, Schroeder, M1, Walter, T1, 1 University of Central Arkansas, Conway, AR, USA2 Louisiana State University, Baton Rouge, LA, USA
ABSTRACT- Nutrient enrichment and metal/metalloid pollution often occur simultaneously due to nonpoint source runoff and sewage discharge. Therefore, it is important to understand potential interactions between nutrients and trace elements in order to assess the impact of metals and metalloids on aquatic systems. Bioassays were conducted to determine the effect of nutrients on the toxicity of arsenate and arsenite. Daphnia magna were exposed to sublethal levels of arsenate or arsenite in individual chambers with or without amended phosphate and monitored daily for reproduction over 21 days. Although both arsenate and arsenite reduced the fecundity of D. Magna, the results indicate that number of broods and total offspring were significantly reduced in daphnids exposed to arsenite. Furthermore, the addition of phosphate ameliorated the adverse effects of arsenate and arsenite on D. magna fecundity. Phosphate significantly decreased the age of first reproduction and increased total number of broods and brood size of As-exposed Daphnia. Phosphate, which is chemically similar to As, may compete with As for membrane binding sites thereby reducing toxicity. Experiments are being conducted to determine if nitrate influences the toxicity of As, and if nutrients influence the toxicity of other trace elements.
Key words: arsenic, interactions, nutrients