不同磷营养水平对重金属Cu、Zn、Cd生物毒性效应的影响

ASSESSING THE JOINT-BIOTOXICITY OF THE DIFFERENT LEVELS OF PHOSPORUS ON HEAVY METALS IN WATER BY THE PHOTOTACTIC BEHAVIOR OF DAPHNIA

运用水溞趋光行为的抑制试验,研究了水体中不同磷营养水平和重金属(Cu、Zn、Cd)共同存在时的联合生物毒性效应.结果表明,在较低浓度下,水体中无机磷的生物毒性很小;当浓度较高时,不同形态的无机磷对水溞生物毒性存在显著差异,大小顺序为:PO43->H2PO4-≈HPO42-.在富营养化的水体中,重金属的生物毒性与水体中磷的营养水平有关,磷的存在可一定程度地减轻重金属污染的生物毒害作用.研究结果可为进一步了解富营养化状态下的重金属毒性变化以及富营养化和重金属污染的相互关系及生态毒性效应提供理论依据,为淡水资源的保护及水生生态系统的健康质量评价和恢复提供理论依据和手段.

The study on the effects of the different levels of phosphorus on heavy metal （ Cu^2＋, Zn^2 ＋ and Cd^2 ＋ ） joint - biotoxicity by the phototactic behavior of Daphnia carinata. The results showed that the biotoxicities of phosphates were very low in eutrophication waters. The different forms of phosphorus had different inhibition on Daphnia g phototaxis in the sequence when their concentration was high： PO4^3-〉H2PO4-≈HPO4^2-. The toxicity of heavy metals was influenced significantly by the levels of phosphorus coexisted. The phosphates would decrease the biotoxicities of Cu, Zn and Cd in waters, and thus somewhat decrease the harm of heavy metals to aquatic organisms. It indicated that heavy metal biotoxieity was correlated not only with themselves but also with the levels of phosphorus in eutrophication waters. So, the toxicity of heavy metal was higher with lower phosphate concentration, vice versa. It is thus necessary to point out that phosphorous and heavy metals should be decreased simultaneously in tackling water pollution. Otherwise, more serious environment disaster could be produced in water tackling by reducing the discharge of phosphorus in the case of heavy metal presence, even though the concentrations of heavy metals were lower in dystrophication waters. Suitable amount of phosphorus could be beneficial to decrease the biotoxicity of heavy metals.