本研究以大型蚤毒性试验标准为参照进行剑水蚤的铜毒性试验,并以生物配体模型(BLM)为主要工具,实现对毒性数据的校正和毒性效应的预测.在不同水质参数下,实测铜的48 h LC50为141—566μg·L-1,相应的BLM预测值为143—1208μg·L-1,表明BLM对铜的毒性预测良好.pH升高、DOC以及钙、镁、钠离子浓度的增加均对铜毒性有不同程度减弱作用,钾离子对铜毒性影响较小,BLM对这一现象的描述较好.利用Visual MINTEQ软件对不同水参数条件下铜形态分布进行模拟,辅助解释实验现象,发现钙、镁、钠、钾离子对铜形态分布影响较小.DOC的加入则使络合态铜含量增加,而pH升高导致游离态铜浓度下降,水合态铜浓度升高.本研究表明,预测铜对剑水蚤的毒性要充分考虑水质参数的影响,BLM在铜对剑水蚤的毒性预测方面表现了非常好的应用潜力.
This study applied Daphnia magna as a representative Cyclops in copper toxicity tests,and biotic ligand model(BLM) was used as the main tool to correlate experimental toxicity data with the predicted toxic effects. Under different water quality parameters,measured 48 h LC50 of copper was in the range of 141—566 μg·L-1,and the corresponding BLM predicted values were 143—1208 μg·L-1,showing good predictability of copper toxicity using BLM. The increase of pH and concentrations of DOC or Ca,Mg,Na all inhibited copper toxicity,and the presence of K did not obviously change copper toxicity. All the observation could be described well using BLM. The visual MINTEQ software was used to calculate copper speciation distribution under the conditions of different water parameters,to better explain the experimental results. The calculation suggested that Ca,Mg,Na,K had little effect on copper speciation distribution. Addition of DOC increased the content of the complexed copper. Higher p H resulted in decreased concentration of free copper and increased concentration of hydrated Cu. This study showed that the prediction of copper toxicity for Cyclops should fully consider water quality parameters. BLM has a very good potential in the prediction of copper toxicity for Cyclops.