Yim Jin Hee, Kim Kyoung W, Kim Sang D
Department of Environmental Science and Engineering, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712, Republic of Korea.
J Hazard Mater. 2006 Nov 2;138(1):16-21. doi: 10.1016/j.jhazmat.2005.11.107. Epub 2006 May 20.
In this study, the effect of hardness on the combined outcome of metal mixtures was investigated using Daphnia magna. The toxic unit (TU) was calculated using modified LC(50) values based on the hardness (i.e., LC(50-soft) and LC(50-hard)). From a bioassay test, the degree of sensitivity to hardness on the toxicity changes was in the order: Cd<Cu<Zn<Pb, with 25, 66, 77 and 88% decreases in the LC(50) values, respectively, when the hard test solution was replaced with a soft test solution. In mixture toxicity tests, the difference in the test solution hardness was found to clearly cause different toxicities, as determined by the TU calculated by the LC(50-hard), using the toxicity of a standard culture medium as the reference. That is, approximately four to five times higher toxicity was observed in soft (i.e., 44+/-4 mg/L as CaCO(3)) rather than hard water (i.e., 150+/-10mg/L as CaCO(3)) test solutions. In the tests where the modified reference toxicity values (i.e., LC(50-soft) and LC(50-hard) for soft and hard test solution, respectively) obtained from the individual metal toxicity tests with different hardness were used to calculate the TU, the results showed very similar D. magna toxicities to those of the TU from the mixture of soft and hard test solutions, regardless of the hardness. According to the toxicity results of the mixture, the aquatic toxic effects of the acid mine drainage (AMD) collected from mine areas that contained metal mixtures were investigated using Daphnia magna and the modified LC(50) value of the TU hardness function calculated for varying solution hardness. The results of the biological WET test closely matched our overall prediction, with significant correlation, having a p-value of 0.513 in one way ANOVA test (n=19). Therefore, this study revealed that the predicted toxicity of the metal mixture agreed well with the biological toxicity test when the modified LC(50) value was employed as the basis of hardness in the TU calculation.
在本研究中，使用大型溞研究了硬度对金属混合物综合结果的影响。基于硬度（即LC(50-软)和LC(50-硬)），使用修正的LC(50)值计算毒性单位（TU）。从生物测定试验可知，对硬度变化的毒性敏感性程度顺序为：镉＜铜＜锌＜铅，当用软水试验溶液替代硬水试验溶液时，LC(50)值分别降低25%、66%、77%和88%。在混合毒性试验中，发现试验溶液硬度的差异明显导致不同的毒性，以标准培养基的毒性为参考，通过LC(50-硬)计算TU来确定。也就是说，在软水（即碳酸钙含量为44±4mg/L）试验溶液中观察到的毒性比硬水（即碳酸钙含量为150±10mg/L）试验溶液中大约高四到五倍。在使用从不同硬度的单个金属毒性试验中获得的修正参考毒性值（即分别针对软水和硬水试验溶液的LC(50-软)和LC(50-硬)）来计算TU的试验中，结果显示，无论硬度如何，大型溞的毒性与软水和硬水试验溶液混合物的TU毒性非常相似。根据混合物的毒性结果，使用大型溞以及针对不同溶液硬度计算的TU硬度函数的修正LC(50)值，研究了从含有金属混合物的矿区采集的酸性矿山排水（AMD）的水生毒性效应。生物WET试验结果与我们的总体预测密切匹配，具有显著相关性，在单因素方差分析试验（n = 19）中的p值为0.513。因此，本研究表明，当在TU计算中使用修正的LC(50)值作为硬度基础时，金属混合物的预测毒性与生物毒性试验结果吻合良好。
