Hyne Ross V, Pablo Fleur, Julli Moreno, Markich Scott J
Ecotoxicology Unit, Department of Environment and Conservation, New South Wales, c/o Centre for Ecotoxicology, PO Box 29, Lidcombe, New South Wales 1825, Australia.
Environ Toxicol Chem. 2005 Jul;24(7):1667-75. doi: 10.1897/04-497r.1.
This study determined the influence of key water chemistry parameters (pH, alkalinity, dissolved organic carbon [DOC], and hardness) on the aqueous speciation of copper and zinc and its relationship to the acute toxicity of these metals to the cladoceran Ceriodaphnia cf dubia. Immobilization tests were performed for 48-h in synthetic or natural waters buffered at various pH values from 5.5 to 8.4 (other chemical parameters held constant). The toxicity of copper to C. cf dubia decreased fivefold with increasing pH, whereas the toxicity of zinc increased fivefold with increasing pH. The effect of DOC on copper and zinc toxicity to C. cf dubia was determined using natural fulvic acid in the synthetic water. Increasing DOC was found to decrease linearly the toxicity of copper, with the mean effect concentration of copper that immobilized 50% of the cladocerans (EC50) value 45 times higher at 10 mg/L, relative to 0.1 mg/L DOC at pH 6.5. In contrast, the addition of 10 mg/L DOC only resulted in a very small (1.3-fold) reduction in the toxicity of zinc to C. cf dubia. Copper toxicity to C. cf dubia generally did not vary as a function of hardness, whereas zinc toxicity was reduced by a factor of only two, with an increase in water hardness from 44 to 374 mg CaCO3/L. Increasing bicarbonate alkalinity of synthetic waters (30-125 mg/L as CaCO3) decreased the toxicity of copper up to fivefold, which mainly could be attributed to the formation of copper-carbonate complexes, in addition to a pH effect. The toxicity of copper added to a range of natural waters with varying DOC content, pH, and hardness was consistent with the toxicity predicted using the data obtained from the synthetic waters.
本研究确定了关键水化学参数（pH值、碱度、溶解有机碳[DOC]和硬度）对铜和锌的水相形态的影响，以及这些金属对枝角类拟 dubia 角突水蚤急性毒性的关系。在pH值为5.5至8.4的不同缓冲合成水或天然水中进行了48小时的固定化试验（其他化学参数保持不变）。铜对拟 dubia 角突水蚤的毒性随pH值升高而降低了五倍，而锌的毒性随pH值升高而增加了五倍。使用合成水中的天然富里酸确定了DOC对铜和锌对拟 dubia 角突水蚤毒性的影响。发现DOC增加会使铜的毒性呈线性降低，在pH值为6.5时，使50%的枝角类固定化的铜的平均效应浓度（EC50）值在DOC为10 mg/L时比0.1 mg/L时高45倍。相比之下，添加10 mg/L DOC仅使锌对拟 dubia 角突水蚤的毒性降低了很小的幅度（1.3倍）。铜对拟 dubia 角突水蚤的毒性一般不随硬度变化，而锌的毒性仅降低了两倍，水硬度从44 mg CaCO3/L增加到374 mg CaCO3/L。合成水（30 - 125 mg/L以CaCO3计）中碳酸氢盐碱度的增加使铜的毒性降低了五倍，这主要可归因于碳酸铜络合物的形成，此外还有pH值的影响。添加到一系列DOC含量、pH值和硬度不同的天然水中的铜的毒性与使用从合成水中获得的数据预测的毒性一致。
