Impact of beta-cypermethrin on soil microbial community associated with its bioavailability: A combined study by isothermal microcalorimetry and enzyme assay techniques

In this study, an isothermal microcalorimetric technique has been used to show that beta-cypermethrin (CYP) had no significant effect (p > 0.05) on soil microbial activity at 80 μg g−1 soil. Our soil enzyme data indicated that beta-CYP ranging 10-80 μg g−1 soil had no significant effect (p > 0.05) on soil enzyme activities such as β-glucosidase, urease, acid-phosphatase, and dehydrogenase. Therefore, our results infer that beta-CYP would not pose severe toxicity to soil microbial community, but its toxic level may vary greatly with environment that associates with its increase in bioavailability: the level in soil (at μg g−1) < the level in sediment (varying from μg g−1 to μg L−1) < the level in water (at μg L−1). The comparison of the results of solvent volatilization on soil microbial activity has shown that the acetone-treated sample had no significant difference with the control (p > 0.05). These results suggest that the heavy application of beta-CYP may not cause damage to soil microbial community which is very different from its high toxicity to the aquatic organism.