外源磷对湿地底泥砷形态及土壤酶活性的影响

Effects of Exogenous Phosphorus on Arsenic Form and Soil Enzyme Activity in Wetland Sediment

通过模拟湿地环境进行土培试验,设置4个砷污染处理(0、50、150、600 mg/kg),4个外源磷输入处理(0、0.2、2、20 mg/L),培养60 d后对底泥理化性质、总砷及砷形态、土壤磷酸酶、脱氢酶和脲酶进行检测,分析砷污染底泥环境下外源磷输入对底泥无机砷形态分布以土壤酶活性的影响。结果表明:外源磷对砷污染底泥pH、EC值、DO值和Eh值的影响显著;外源磷输入能显著降低底泥总砷的含量,并且底泥砷的生物有效性系数随着输入外源磷的增加而降低;砷对3种土壤酶的抑制程度为磷酸酶>脱氢酶>脲酶,外源磷对砷污染湿地底泥脱氢酶有显著的激活效应;脲酶对砷污染不敏感,600 mg/kg处理对脲酶活性有一定抑制作用,外源磷对脲酶活性有一定激活作用;磷酸酶活性与底泥砷浓度存在显著负相关关系,外源磷能提升底泥磷酸酶活性。外源磷能有效降低底泥总砷的含量,同时外源磷对底泥砷的土壤酶毒性有缓冲作用,对土壤酶活性具有保护效应。

Four arsenic pollution treatments(0,50,150,600 mg/kg)and 4 exogenous phosphorus treatments(0,0.2,2,20 mg/L)were set up to simulate arsenic pollution wetland environment.The physical and chemical properties of the sediment,T-As,arsenic form,phosphatase,urease and dehydrogenase were analyzed after 60 days cultivation.The effects of exogenous phosphorus inputs on the distribution of inorganic arsenic in sediments and soil enzyme activity in arsenic-contaminated sediments were analyzed.The results showed that soil pH,EC,DO and Eh were significantly affected by exogenous phosphorus.With the increase of exogenous phosphorus,the total arsenic was decreased and the bioavailability coefficient decreased with the increase of the exogenous phosphorus.The toxicity degree of arsenic to 3 soil enzyme was:phosphatase>dehydrogenase>urease,exogenous phosphorus can enhance dehydrogenase activity and phosphatase activity,urease is not sensitive to arsenic.The urease activity was inhibited with 600 mg/kg arsenic treatment,and urease activity was activated by exogenous phosphorus.The phosphatase activity has a significant negative correlation with the concentration of arsenic in sediment,and exogenous phosphorus could increase the phosphatase activity in sediment.Exogenous phosphorus could reduce the total arsenic content in sediment and the bioavailability of arsenic were increased by the phosphorus,soil enzyme activity were protected by phosphorus.