Influence of DOC in Dong Nai river water on nickel toxicity to Daphnia carinata and Daphnia lumholtzi

Abstract

In addition to pH and hardness, dissolved organic carbon (DOC) significantly influence on the toxicity of heavy metals to aquatic organisms. This study aims to investigate the influence of DOC on the toxicity of Nickel to Daphnia carinata, Daphnia lumholtzi in Dong Nai river water. Experiments were carried out based on OECD guidelines in 2004 for the acute toxicity testing for Daphnia. Results found that if DOC in Dong Nai river water increase from 4 to 6.1 µg/L, the LC50-Ni for D. carinata increase from 283 µg/L to 432 µg/L;if the DOC in mixed water sample increase from 1.7 to 22 µg/L, the LC50-Ni for D. carinata increase from 408 µg/L to 897 µg/L. For Daphnia lumholtzi, if DOC in Dong Nai river water increase from 4 to 15.8 µg/L, the LC50-Ni increase from 98 µg/L to 216 µg/L; if DOC in mixed water sample increase from 3.8 to 20 µg/L, the LC50-Ni increase from 122 µg/L to 311 µg/L.