[Influence of Cu2+, Cd2+ and cypermethrin on microbial functional diversity in different fertilization soils]

Determination the bioavailability of contaminants in different fertilizer management soils can be of great theoretical significance for predicting and decreasing the effect of pollutants on eco-environment. In this study, three different fertilization soils were employed in a 16-year field experiment: no fertilization (CK), composted wheat straw and oil cakes (OM) and NPK fertilizer (NPK). The influences of Cu2+ (100 mg/kg), Cd2+ (5 mg/kg) and cypermethrin (l0 mg/kg) and their combinations on microbial functional diversity were observed in different fertilization soils. The results showed that the highest microbial functional diversity was observed in the NPK treatment, followed by CK, and the lowest in the OM soil. At 72 h incubation, AWCD (average well color development) of the NPK soil was 1.19 times than that of the CK soil and 1.62 times than that of the OM soil. After addition of contaminants into soils, microbial functional diversity decreased to a different extent. The greatest decrease extent was recorded in the NPK soil, followed by CK and the least in OM. Combination of Cd and cypermethrin had the biggest influence on the microbial functional diversity. AWCD was decreased by 48%, six substrate groups and microbial diversity indices inhibited significantly in this treatment of the NPK soil. Although cypermethrin had little effect on soil microbial utilization of carbon source,utilization potential decreased greatly in combination pollution treatments, especially in combination with Cd2+. The effect of Cu2+, Cd2+ and cypermethrin and their combinations on soil microbes not only affected by the soil organic matter content, likely also by the constitution of organic matter and microbial community.