不同价态铬的土壤碱性磷酸酶效应模拟研究

铬是环境中四大污染元素之一,其不同价态间对生物的生态毒性差异较大。采用模拟方法对Cr3＋和Cr6＋的土壤碱性磷酸酶效应进行了研究。结果表明,铬显著抑制了土壤碱性磷酸酶活性,其中Cr3＋的抑制作用远强于Cr6＋,土壤轻度Cr3＋和Cr6＋污染时的临界浓度分别为151和1132mg·kg-1,二者相差6.5倍;碱性磷酸酶活性及动力学特征参数Vmax、k等与Cr浓度间达显著或极显著负相关,揭示土壤磷酸酶活性及Vmax、k可作为土壤Cr污染的监测指标之一;模型U=β0（/β1×C＋1）揭示酶与铬间的机理为完全抑制,动力学则进一步细化为非竞争性抑制;计算获得的抑制常数Ki为Cr3＋

Effect of Different Valences Chromium on Soil Alk-phosphatase Characteritics

Chromium is was one of four heavy metals to pollute environment. However, its ecological toxicity to organism varies considerably for different species of chromium. In this paper, by simulative, soil alkaline phosphatase parameters are applied to study the effect of different valences chromium. Results showed that the Soil alkaline phosphatase activity was remarkably inhibited by chromium. Cr3＋ was more seriously inhibited than Cr＋, the critical concentrations were 151 mg. kg-1 and 1 132 mg. kg-1 for Cr3＋ and Cr6＋ respectively when soil is slightly polluted, 6.5 times difference between Cr3＋ and Cr＋. Alkaline phosphatase activity, Vmax and k could be indexes to monitor soils polluted by chromium, because there were significant or remarkably significant correlation between soil alkaline phosphatase parameters and chromium concentrations. Their reaction mechanism was fully inhibited by model U=β0/（β1×C＋1 ）, and non-competitive inhibition by soil enzyme kinetic further. The inhibition constant Ki was Cr3＋〈Cr6＋, Cr3＋ had stronger affinity than Cr6＋ with active sites of alkaline phoshatase.