不同价态砷的土壤碱性磷酸酶效应研究

Effects of arsenic valences on soil alkaline phosphatase activity

【目的】砷是土壤污染的主要元素之一,研究As5+、As3+单一和复合污染对土壤碱性磷酸酶活性的影响,揭示其对土壤碱性磷酸酶的作用机理,为砷污染监测提供理论依据。【方法】采集江西鹰潭红壤、陕西榆林风沙土、陕西杨凌土娄土各2个肥力水平的土样为供试土壤,采用室内模拟法,研究不同含量As5+、As3+以及二者复合污染下供试土壤碱性磷酸酶活性的变化。【结果】As5+和As5++As3+均能抑制土壤碱性磷酸酶活性,随As5+和As5++As3+含量的增加,相对碱性磷酸酶活性持续减小;采用模型E=A/(1+B×C)可较好表征相对碱性磷酸酶活性(E)与砷含量(C)间的关系(A、B为参数),揭示出土壤碱性磷酸酶活性可作为表征土壤As5+和As5++As3+污染程度的监测指标,且As5+和As5++As3+对碱性磷酸酶活性的作用机理为完全抑制作用(包括竞争性抑制和非竞争性抑制)。As3+对土壤相对碱性磷酸酶活性影响较小。As5+与As3+之间存在一定的交互作用,除了低肥力水平红壤及土娄土中As5+和As3+含量均小于50mg/kg时二者表现为协同作用外,在其他供试土壤中均为拮抗作用。不同供试土壤As5+的生态剂量ED10和ED50差异较大,砷对土壤造成轻度污染的含量为25mg/kg。【结论】土壤碱性磷酸酶可作为土壤As5+及As5+与As3+复合污染程度的监测指标。

【Objective】Arsenic is one of the main soil pollution elements.We studied the effects of As5＋,As3＋ alone and As5＋＋ As3＋ on soil alkaline phosphatase activity,to reveal the reaction mechanism of arsenic on soil alkaline phosphatase activity.【Method】Soil samples were red soil （sampled from Yingtan Jiangxi）,sand soil （sampled from Yulin,Shaanxi）,and lou soil （sampled from Yangling,Shaanxi）.Indoor simulation method was adopted to study the variation of soil alkaline phosphatase activity affected by different contents of As5＋, As3＋ and As5＋＋As3＋.【Result】As5＋ and As5＋＋As3＋ combined pollution significantly inhibited soil alkaline phosphatase activity.The relative alkaline phosphatase activity decreased as the increase of contents of As5＋ and As5＋＋As3＋.The model E=A/（1＋B×C） regressed the relationship of soil relative alkaline phosphatase activity （E） and arsenic content （C） （A and B are two parameters）,revealed that soil alkaline phosphatase activity could be as an index to monitor soil As5＋ and As5＋＋As3＋ pollution.The reaction mechanism of As5＋ and As5＋＋As5＋ on soil alkaline phosphatase activity was completely inhibition,including competitive and noncompetitive inhibition.As3＋ had less effect on soil relative alkaline phosphatase activity.As5＋ and As3＋ had interactions on soil alkaline phosphatase activity.It was synergy effect in red soil and lou soil when As5＋ and As3＋ contents were less than 50 mg/kg and antagonism effect in other soil samples.Ecological dose ED10 and ED50 of As5＋ differed a lot among soil samples.The critical content of arsenic slight pollution to soil was 25 mg/kg.【Conclusion】Soil alkaline phosphatase activity was an index to monitor soil pollution by As5＋ and As5＋＋As3＋.