The acute toxicity study of pentachlorophenol to Daphnia magna in different aquatic quality conditions

Water quality criteria and standard are derived mainly from acute toxicity data of chemicals, and acute toxicity data of chemicals are generally obtained from laboratory experiment. The nature water and experiment dilution water are different. The suspended articulate, humic acid and other factors in nature waters can change the concentrations of chemicals. In this paper, acute toxicity differences of pentachlorophenol (PCP) to Daphnia magna were studied in four aquatic quality conditions. Meanwhile, the influences of suspended particulate and humic acid were analyzed. The results showed that the 24 h LC50s of PCP to Daphnia magna were 1861 μg/L, 1369 μg/L, 565.2 μg/L and 495.3 μg/L in four aquatic conditions including the nature water, the filtered nature water, experiment dilution water with 10mgC/L of humic acid and experiment dilution water, respectively. It indicated that the humic acid and suspended particulates in water could decrease the toxicity of PCP to Daphnia magna. Water effect ratio of PCP was 3.8 calculated from the equation.