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| Chlorpyrifos dissipation in a red soil-developed paddy soil's soil-overlying water system：A laboratory incubation experiment |
| Received:December 17, 2020 |
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| KeyWord:chlorpyrifos;overlying water;paddy soil;dissipation;microbial degradation |
| Author Name | Affiliation | E-mail | | YAO Ying-lei | School of Ecological Engineering, Shanghai Institute of Technology, Shanghai 201418, China
Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China | | | TANG Xiang-yu | Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China | | | GENG Chun-nü | School of Ecological Engineering, Shanghai Institute of Technology, Shanghai 201418, China | gengchunnv@hotmail.com | | GUAN Zhuo | Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China | | | REN Mei | School of Ecological Engineering, Shanghai Institute of Technology, Shanghai 201418, China | |
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| Abstract: |
| A 60-day laboratory microcosm experiment was conducted with paddy soil collected from the hilly, red soil area of southern China. The dissipation and transformation of chlorpyrifos in the paddy soil’ s overlying water system were studied. After application, chlorpyrifos in the overlying water at 15, 25℃, and 40 ℃ dissipated rapidly during the early stage, gradually decreasing in the later stage. The dynamics of chlorpyrifos in the overlying water conformed to first-order kinetics. The half-life（0.70~1.01 d）and digestion rate constant（0.688 8~0.985 2 d-1）of chlorpyrifos in the overlying water were similar at the three tested temperatures. The added chlorpyrifos was easily converted into 3, 5, 6-trichloro-2-pyridinol（TCP） and accumulated in the overlying water. Chlorpyrifos degradation was significantly affected by temperature. After 60 d of incubation, 17.3%~25.5% of chlorpyrifos was degraded into TCP at 40 ℃. The accumulation of chlorpyrifos in the surface soil（0~3 cm）was significantly affected by temperature. In the unsterilized treatment, the chlorpyrifos residue in the surface soil at 15, 25 ℃, and 40 ℃ was 163.66, 80.29 μmol·kg-1 and 34.95 μmol·kg-1, respectively, approximately 57.38%, 28.15% and 12.25% of the initial amount of chlorpyrifos added, respectively. Overall, in the soil-overlying water system, only 0.39%~2.24% of the added chlorpyrifos remained in the overlying water after 60 d, 10.18%~58.32% migrated into the soil, and 0.47%~25.53% degraded into TCP in the overlying water. The residual rate of chlorpyrifos in the overlying water was lower than that in the soil, and its enrichment in the surface layer was distinct. Temperature and microorganisms synergistically affect chlorpyrifos dissipation. |
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