不同水化学特征下铜对小球藻的急性毒性研究

The Effect of Hydro-chemical Characteristics on the Toxicity of Copper to Chlorella vulgaris

配制不同单因子Ca、Mg、Na、K、pH、DOC浓度,进行铜对小球藻的48h急性毒性试验,旨在全面考察每个水质指标对其毒性值的影响权重。结果显示,金属(Ca、Mg、Na、K)在铜对小球藻的毒性中影响不显著,并没有在铜对小球藻的毒性效应中起到竞争作用;pH在5.5~8.0变化导致IC_(50)(半抑制浓度)值有所变化,其存在关系式:IC_(50)=-3.41*pH+27.18(R^2=0.66);DOC(溶解有机碳)浓度变化(0~3.65mg/L)对IC_(50)值的影响最为显著,IC_(50)值增大62倍,其关系式为:IC_(50)=30.52*DOC+1.10(R^2=0.95),铜与DOC的络合大大降低了铜的生物有效性。

A series of 48 - h copper acute toxicity experiments with Chlorella vulgaris were conducted under differ-ent concentrations of Ca, Mg, Na, K , H, and DOC in order to comprehensively study the effect of the water quali-ty parameters on IC50 （ half - inhibitory concentration） values. The results showed that no significant change in the 48h - IC50 （expressed as dissolved concentrations） was found when the concentrations of Ca, Mg, Na, and K were varied. But an increase of pH from 5. 5 to 8. 0 caused the observable changes of dissolved copper toxicity, and it was found that IC50 = -3. 41 ＊ pH ＋27. 18 （ R2 =0. 66）. More importantly, an increase of the DOC concentration from 0 to 3. 65 mg/L obviously raised dissolved copper toxicity with a factor of 62, and their regression relationship is IC50 =30. 52 ＊ DOC ＋1. 10 （/？2 =0. 95） . The metal ions did not play a competitive role in the toxicity of copper to Chlorella vulgaris, and complexation of DOC with copper greatly reduced the bioavailability of copper. This study would provide the theoretical support to the calibration of toxicity values or the establishment of ecological water quality criteria on the surface water.