EFFECTS OF DISSOLVED HUMIC MATERIALS ON ACUTE TOXICITY OF SOME ORGANIC-CHEMICALS TO AQUATIC ORGANISMS

The influence of dissolved humic materials (DHM) on the acute toxicity of diazinon, tetrabromobisphenol-A (TBP), 4-chloroanilin (4-CA) and pentachlorophenol (PCP) was evaluated using the zebrafish (Brachydanio rerio Hamilton Buchanan) and waterflea (Daphnia magna Straus). The 96-h LC50 (zebrafish) and 48-h EC50 values for four chemicals were determined in the presence of 0, 0.5, 5.0 and 50 TOC mg/l. The effects of DHM on the toxicity of four test chemicals to B. rerio were not observed in all of the DHM treatments. In the daphnid toxicity test, DHM significantly reduced the toxicity of diazinon and 4-CA, while no reduction of the toxicity of TBP and PCP was observed. These results indicate that the interaction between DHM and chemicals can alter the toxicity of some chemicals to D. magna.