生物质炭对Cd污染土壤团聚体酶活性的影响

为探究生物质炭对Cd污染土壤团聚体酶活性的影响,采用盆栽试验,向模拟Cd污染土壤中添加生物质炭并测定水稻根际土壤团聚体碳循环酶与氧化还原酶活性.结果表明:Cd污染土壤团聚体酶活性对添加量为2.5%的生物质炭响应明显,氧化还原酶活性指数值介于0.522~0.792之间.在2.5mg/kg的外源Cd条件下,2.5%的生物质炭比未添加生物质炭处理显著提高蛋白酶与过氧化氢酶活性至121%与653%.在Cd污染土壤中添加生物质炭,碳循环酶与氧化还原酶及综合酶活性均在0.5~1mm中等粒径土壤团聚体中产生富集效应,其酶活性随土壤团聚体粒径的增大呈先升后降最终趋于稳定的趋势.研究显示,在2.5mg/kg的外源Cd条件下,添加2.5%的生物质炭对水稻根际土壤团聚体酶活性影响显著,土壤酶活性受酶种类、生物质炭量与团聚体粒径的综合影响;在Cd污染土壤中添加生物质炭后,土壤酶活性随团聚体粒径的增大呈“∧”形变动规律.

Effects of biochar(BC) on the enzymes activities within soil aggregate fractions of cadmium(Cd) contaminated rice rhizosphere soil

A pot experiment was conducted to investigate the effects of addition wheat straw biochar (BC) in simulated cadmium (Cd) contaminated soil on enzymes activities within soil aggregate fractions. The activities of carbon cycling enzyme and oxidoreductase were detected in rice rhizosphere soil aggregate fractions under the condition of BC and Cd treatments. The results showed that the enzymes activities of aggregate fractions in Cd contaminated soil significantly responded to the 2.5% BC treatment, value index of oxidoreductase activities ranged from 0.522 to 0.792. Under the condition of 2.5% mg/kg exogenous Cd, the activities of protease and catalase of soil aggregate were significantly increased by 121% and 653% respectively, which was compared with the treatment without BC. The activities of carbon cycling enzyme, oxidoreductase and comprehensive enzymes could result in soil aggregating effects in the rice rhizosphere soil with the medium sizes of 0.5 to 1mm. The change curve of enzymatic activities went up firstly, then went down, and became stable finally with the increase of the particle sizes of soil aggregate fractions. Studies have shown that the addition of 2.5% BC had a significant effect on the enzyme activities within rice rhizosphere soil aggregate fractions under the condition of 2.5mg/kg exogenous Cd, the activities of soil enzymes was comprehensively affected by the enzymes type, BC content and particle size of aggregate fractions. After adding BC to the Cd contaminated soil, the change curve of soil enzymes activities presented a "∧" pattern with increasing particle size of soil aggregate fractions.