Microencapsulated chlorpyrifos: degradation in soil and influence on soil microbial community structures
Chen Lie-Zhong
DOI:
Received December 27, 2013,Revised June 05, 2014, Accepted June 09, 2014, Available online 2014-08-04
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Degradation kinetics of the microencapsulated chlorpyrifos (CPF-MC) in soil and its influence on soil microbial community structures was investigated by comparing with emulsifiable concentration of chlorpyrifos (CPF-EC) in laboratory. The residual periods of CPF-MC with fortification levels of 5 and 20 mg/kg reached 120 days in soil, both of degradation curves did not fit the first-order model, and out-capsules residues of chlorpyrifos in soil were maintained at 1.76 (±0.33) and 5.92 (±1.20) mg/kg in the period between 15 and 60 days, respectively. The degradation kinetics of CPF-EC fit the first-order model, and the residual periods of 5 and 20 mg/kg treatments were 60 days. Bacterial community structures in soil treated with two concentrations of CPF-MC showed similar to those of control during the test period, as seen in the band number and relative intensities of the individual band on DGGE gels (P > 0.05). Fungal community structures were slightly affected in the 5 mg/kg treatments and returned to the control levels after 30 days, but initially differed significantly from control in the 20 mg/kg treatments (P < 0.05) and recovered to control levels until 90 days later. The CPF-EC significantly altered microbial community structures (P < 0.05) and that effects disappeared until 240 days later. Results indicate that the microcapsule technology prolong the residue periods of chlorpyrifos in soil whereas decrease its side-effects on soil microbes as compared with emulsifiable concentration formulation.
