Toxicity of tri-and penta-valent arsenic alone and in combination to the Cladoceran Daphnia carinata : The influence of microbial transformation in natural waters

摘要

The acute toxicity of arsenic (III) and arsenic (V) alone and in combination to a cladoceran, Daphnia carinata, was studied in both cladoceran culture medium and natural water collected from a local suburban stream The results of this investigation sug-gests that As (III) and As (V) can interact either synergistically or additively resulting in an increase in the overall toxicity of mix-ture compared to individual As species. Furthermore, the indigenous microorganisms in natural water could play a significant role in the transformation of As, thereby influencing the toxicity of As in receiving waters. This study suggests that these two species of As when present together above 0. 1 mg · L'-1> concentration are toxic to fresh water invertebrates and, therefore, pollution with these compounds may adversely affect natural ecosystems.