沉积物内源与外源重金属形态与酶活性的相关性

文章以表层沉积物为研究对象,采用改进的Tessier连续萃取法,研究了表层沉积物中重金属(内源体系:Fe、Mn、Cu、Zn和Pb;外源体系:掺杂Cu、Zn和Pb后的Fe、Mn、Cu、Zn和Pb)形态和酶(蛋白酶、脱氢酶、磷酸酶、蔗糖酶)活性在一定时间(45d)内的转化趋势,探讨了沉积物中重金属形态与酶活性的相关性。结果表明,在外源体系中,Cu、Zn和Pb的掺杂对Fe和Mn的形态转化影响较小,而Cu、Zn和Pb显著地由残渣态向相对不稳定形态转化,转化幅度均大于20%。外源重金属掺杂初期(前5d),重金属对沉积物中的酶有一定的活化作用,但经过一段时间后以抑制作用为主。相关性分析表明,当掺杂外源重金属后,沉积物中酶的活性与重金属形态的相关性减弱,与内源体系中重金属和酶的活性关系存在明显差异。

Correlation between Speciation of Native and Exogenous Heavy Metals and Enzymatic Activities in Surface Sediment

Speciation of heavy metals including Fe, Mn, Cu, Zn and Pb and activities of enzymes including protease, dyhydrogenas, sucrose and phosphatase were investigated through modified sequential extraction procedure during a period of 45 days in native system and exogenous system in the surface sediment mixed with Cu, Zn and Pb respectively, which aimed to reveal the correlation between speciation of heavy metals and enzymatic activities in surface sediment. Results showed that Cu, Zn and Pb added have slight effects on transformation of Fe and Mn speciation, but result in a dramatic transformation for Cu, Zn and Pb from residual fraction to the other forms, with variation more than 20%. During initial 5 days of the experiment, active effects were observed for heavy metals added on enzymes in sediments, but this dominant effect appeared as an inhibition after a few days. The correlation between chemical speciation of heavy metals and enzymatic activities were weakened by heavy metals added, which was distinct different with that in native system.