不同价态铬对土壤碱性磷酸酶活性的影响

Effects of different valence chromium on soil alkaline phosphatase activity

【目的】研究不同价态铬对土壤碱性磷酸酶活性的影响,为环境保护以及重金属铬的监测提供理论依据。【方法】以采自陕西杨凌、榆林、黄龙的土娄土、风沙土、褐土为供试土样,采用室内模拟方法,研究了Cr3+(0,250,500,750,1500,2500,5000 mg/kg)、Cr6+(0,500,1000,1500,2000,2500,5000 mg/kg)单一和复合污染条件下,土壤碱性磷酸酶活性的变化规律。【结果】土壤碱性磷酸酶活性(U)随铬含量(C)的增加而降低,采用U=A/(1+B×C)模型(其中A、B为复合参数)可较好地表征土壤碱性磷酸酶与铬含量之间的关系,且拟合方程均达极显著相关;土壤受铬轻度污染的Cr3++Cr6+、Cr3+、Cr6+临界含量分别为17.8,37.9,548.7 mg/kg。【结论】铬明显抑制土壤碱性磷酸酶活性,其中Cr3+的抑制作用明显强于Cr6+,土壤碱性磷酸酶可表征土壤铬污染的程度,铬对土壤碱性磷酸酶的作用机理均为完全抑制作用。

【Objective】 The effects of different valence chromium on soil alkaline phosphatase activity were studied to prouide theoretical basis to environmentd protection and chromium monitoring.【Method】 Soil samples were lou soil from Yangling,sandy soil from Yulin,and cinnamon soil from Honglong.By simulative method,soil alkaline phosphatase activity was studied under single and complex Cr3＋（0,250,500,750,1 500,2 500,5 000 mg/kg）,Cr6＋（0,500,1 000,1 500,2 000,2 500,5 000 mg/kg） pollution.【Result】 Soil alkaline phosphatase activity（U） decreased with the increase of chromium content（C）.The model U=A/（1＋B×C）（in which A,B were composite parameters）could describe the relationship better between soil enzyme activity and chromium concentration,correlation reaching remarkable significant level.The critical concentrations（ED10） of Cr3＋＋Cr6＋,Cr3＋and Cr6＋in soils were 17.8,37.9,548.7 mg/kg respectively.【Conclusion】 Soil alkaline phosphatase activity was clearly inhibited by chromium,and Cr3＋ had evidently more serious inhibition than Cr6＋,soil alkaline phosphatase activity could be an index of soil pollution from chromium,the reaction mechanism was complete inhibition.