(PM076) Effect of Precipitation by Calcium on Toxicity of As(III) to Daphnia magna.
Yim, J1, Na, J1, Kim, S1, 1 Kwangju Institute of Science and Technology (K-JIST), Gwangju, Korea
ABSTRACT- Many literatures demonstrated that environmental impact evaluation could be clearly understood only by combining bioassays with chemical analytical studies to interpret the behavior of metal in the environment. The bioassay experiments using Daphnia magna, which are commonly used in standardized toxicity tests due to the importance of relationship in the aquatic food chain, are performed to evaluate the toxicity of As(III). The objective of this study was to investigate the effect of precipitation of calcium on the acute toxicity of As(III) to D. magna. As(III) forms its own insoluble precipitates in the presence of calcium. This is one of the key mechanisms for the removal of many arsenic species in aquatic environment. The rate of reaction of As(III) ions is a significant consideration when studying the chemistry of As(III) in natural waters. The reaction kinetics of As(III) precipitation is important to understand its toxicity in aquatic environment given a longer time to equilibrate if the reaction is so slow. Another factor that affects the bioavailability of arsenic is the pH of the water. In the present study, the kinetic of the interaction of As(III) with calcium and its influence on the toxicity of As(III) to aquatic species will be investigated by both chemical kinetic studies using an Anodic Stripping Voltametry(ASV) measuring the labile forms of As(III) and static bioassay tests with D. magna. First, arsenic titration of calcium will be performed with an ASV to determine the binding ability of the calcium ions. Then the kinetic experiments will be conducted at different pH conditions. The prediction of bioavailability of As(III) obtained from chemical analytical studies will be verified by bioassay test with D. magna.
Key words: Reaction kinetics, Arsenic, Daphnia magna, Acute toxicity