Affiliations: Department of Plant Protection, Zhejiang University,
Hangzhou 310029, China | Department of Horticulture, College of Agriculture and
Biotechnology, Zhejiang University, Hangzhou 310029, China
Abstract: The dissipation of chlorpyrifos in pakchoi-vegetated soil was
investigated in the summer and autumn in a greenhouse and field, respectively.
The dissipation of chlorpyrifos in pakchoi-grown soil was comparatively
described by fitting the residue data to seven models (1st-order, 1.5th-order,
2nd-order, RF 1st-order, RF 1.5th-order, RF 2nd-order, and bi-exponential or
two-compartment models). Statistical analysis was performed using the SPSS 11.5
statistical package. The bi-exponential model was selected as the optimal model
according to the coefficient of determination r^2. The
dissipation half-lives (DT_{50}) of chlorpyrifos in
pakchoi-vegetated soil at the recommended dose in the summer and autumn,
calculated by the bi-exponential model, were 0.6 and 1.2 d in a greenhouse, 0.4
and 1.0 d in a field, respectively; the corresponding values at double dose
were 1.2 and 2.1 d in a greenhouse, 0.5 and 1.3 d in a field, respectively. The
kinetic data indicate the dissipation of chlorpyrifos in pakchoi-grown soil in
a greenhouse is slower than that in a field, and dissipates slower in the
autumn than in the summer.
