Title: Photochemical behaviour of pretilachlor on black soil surface

Authors: Virendra Kakotiya; Partha P. Choudhury

Addresses: Department of Soil Science and Agril. Chemistry, Jawaharlal Nehru Krishi Vishwavidyalaya, Jabalpur, MP-482004, India ' ICAR-Directorate of Weed Research, Jabalpur, MP, PIN-482004, India; Division of Basic Sciences, ICAR-IIHR, Bangalore-560089, India

Abstract: In any agricultural soil, humic-substances are the storehouse of multiple chromophores, which may degrade soil-applied herbicides under sunlight. In the present study, the role of humic acid (HA) on the photolysis of pretilachlor in soil was investigated. Experiments on the photolysis of pretilachlor were conducted on the surfaces of glass, HA-coated glass, black soil, organic matter free (OMF) black soil, and HA-coated OMF-black soil. The half-life values were found 27.72, 43.31, 115.5, 63.00, 138.6 hour, respectively. Thus, the rates of reaction on HA-containing surfaces were slower than that on surfaces devoid of HA, because HA provided either a quenching or shielding effect protecting pretilachlor from sunlight. The photoreaction of pretilachlor generated at least 12 photoproducts through two major routes - the deacylation on amide linkage and the cleavage of the ether linkage. The product 2,6-diethylaniline, one of the photoproducts characterised, is a potent mutagen and has the capacity to contaminate groundwater.

Keywords: black soil; chloroacetanilide herbicide; 2,6-diethylaniline; humic acids; photodegradation; photolysis; pretilachlor.

DOI: 10.1504/IJGENVI.2020.115906

International Journal of Global Environmental Issues, 2020 Vol.19 No.4, pp.306 - 318

Accepted: 17 Nov 2020
Published online: 05 Jul 2021 *

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