低浓度Pb^(2+)对Cd^(2+)污染下冬小麦幼苗根微域土壤水解酶活性及与根微域土壤生化特征关系的影响

Effects of Cd and low concentration Pb/Cd on hydrolase activity and the relationship between them and biochemical characters in winter wheat seedlings rhizosphere soil

采用盆栽试验法探讨了Cd2+、低于国家"土壤环境质量标准"规定的Ⅱ类土壤环境基准值300 mg.kg-1干土时的Pb2+与Cd2+复合处理对冬小麦幼苗根微域土壤磷酸酶、转化酶和脲酶活性及与根微域土壤微生物数量和生化特征关系的影响特征。结果表明:(1)Cd2+对冬小麦幼苗根微域土壤转化酶、脲酶和磷酸酶活性表现为显著抑制效应;而低浓度Pb2+主要表现为协同Cd2+污染抑制根微域土壤水解酶活性效应;(2)Cd2+处理下,磷酸酶活性与微域土壤有机质含量呈极显著正相关;转化酶活性与细菌、真菌和放线菌数量呈显著负相关,与有机质呈显著正相关;脲酶活性与细菌、真菌和放线菌数量及微生物量碳表现为极显著正相关;(3)Pb2+/Cd2+处理下,碱性磷酸酶活性与微生物量碳表现为显著正相关;转化酶活性与全氮含量表现为显著负相关,与有机质含量呈极显著正相关;脲酶活性与全氮呈极显著正相关,与有机质为极显著负相关,总体来讲,Cd2+/Pb2+与Cd2+处理之间酶活性与生化特征的关系存在明显差异;同时Pb2+/Cd2+处理下磷酸酶、转化酶和脲酶活性与土壤微生物数量之间的相关性特点与Cd2+处理下也明显不同。

Abstract： The study explored the effects of Cd2＋ and low concentration pb^2＋（〈350.00 mg.kg^-1）/Cd^2＋on the activity of rhizosphere soil phosphatase, urease, and invertase activity from winter wheat seedlings and the relationship between them and rhizosphere soil microbial quantity and biochemical activity through pot experiment. The results indicated that： （1） the repression effect of Cd^2＋ onrhizosphere soil phosphatase, urease, and invertase activity was significant, and low concentration Pb^2＋ strengthened the influence of Cd^2＋ on them; （2） The negative correlation was significant between phosphatase activity and rhizosphere soil organic carbon with the addition of Cd^2＋. The negative correlation and was significant between invertase activity and the number of bacterial, fungi, andactinomycetes, and the positive correlation was significant between invertase activity and rhizosphere soil organic carbon with the pollution of Cd^2＋. Furthermore, the positive correlation was significant between urease activity and the number of bacterial, fungi, and actinomycetes and rhizosphere soil microbial biomass carbon under Cd. （3） With the addition of Pb/Cd, the positive correlation was significant between phosphatase activity and rhizosphere soil microbial biomass carbon. The negative correlation was significantbetween invertase activity and total nitrogen content, moreover, the positive correlation was significant between invertase activity and soil organic carbon. The correlation was significant between the urease activity and total nitrogen content and soil organic carbon. 4） Low concentration Pb^2＋ affected the relative characters between soil enzyme activity and organic carbon under the stress of Cd^2＋.