Ambient Temperature Modulates Dissipation and Redistribution of Chlorpyrifos and 3,5,6-Trichloro-2-Pyridinol in Paddy Field

ABSTRACT

Chlorpyrifos is an extensively used insecticide in the agriculture worldwide and was often detected in both surface waters and groundwater, posing threats to local residents’ health. Temporal changes and environmental fate of chlorpyrifos and 3,5,6-trichloro-2-pyridinol (TCP; the main degradation product of chlorpyrifos) were studied in field paddy lysimeters. On the other hand, batch sorption tests of both chlorpyrifos and TCP and dissipation test of chlorpyrifos under submerged condition were conducted for the paddy soil in the laboratory. Following field application, concentration of chlorpyrifos in the floodwater decreased rapidly by >90% of the initial concentration in the first two days. Higher temperature during the daytime, as compared to the nighttime, could not only lead to larger dissipation rates of chlorpyrifos and TCP in the floodwater in the first two days, but also cause greater release of TCP into the soil pore water for more days. A rain event at an early time (i.e., day 2) caused a transient peak release of chlorpyrifos and TCP into the soil pore water; however, no such changes occurred upon later rain or irrigation event(s). In future studies, due attention should be paid to the risk of the runoff and leaching of the weakly sorbing TCP.

KEYWORDS:

• Chlorpyrifos
• 3
• 5
• 6-trichloro-2-pyridinol
• paddy field
• lysimeter
• temperature

Acknowledgments

This study was supported by the National Key Research and Development Program of China (No. 2016YFD0800203), the National Natural Science Foundation of China (No. 42007361), the 135 Strategic Program of the CAS Institute of Mountain Hazards and Environment (No. SDS-135-1702), and the CAS Key Research Program of Frontier Sciences (No. QYZDJ-SSW-DQC006).

Disclosure statement

The authors declare that they have no competing interests.

Authors’ contributions

Ms. Liu, Dr. Guan, Dr. Cheng and Dr. Xian contributed to the field sampling and laboratory analyses, the processing of experimental data, and the drafting of this manuscript. Prof. Tang supervised all experimental and interpretative activities and completed the final version of the manuscript.

Additional information

Funding

This work was supported by the National Key Research and Development Program of China [2016YFD0800203]; National Natural Science Foundation of China [42007361]; 135 Strategic Program of the CAS Institute of Mountain Hazards and Environment [SDS-135-1702]; CAS Key Research Program of Frontier Sciences [QYZDJ-SSW-DQC006].