Assessment of Photodegradation of Herbicide Prometryn in Soil

Jiang, Chen; Li, Xuejing; Wang, YaRu; Ma, Liya; Wang, YaKun; Lu, Yichen; Yang, Hong

Assessment of Photodegradation of Herbicide Prometryn in Soil

2017

Prometryn has been used in crop (e.g., corn and sorghum) field to prevent growth of annual grasses and broadleaf weeds for many years. As a moderately persistent herbicide in soil, prometryn may exert detrimental effects on environmental safety and crop production. The present study assessed the photodegradation of prometryn residues in soil by exploring a variety of factors such as soil moisture, temperature, and light exposure that potentially affect prometryn photodegradation. The dissipation rate of prometryn during a 14-day period of study was more than 90% under 15 (low pressure), 100, and 300 W (medium pressure) UV light exposure. The half-life of prometryn decay under UV light (53.5–116.4 h) was far less than that under xenon light (1131.6 h) and dark (3138.7 h) conditions. When the soil moisture (clay loam) was 60% of the field moisture capacity, it was most effective for prometryn photodegradation. The prometryn photodegradation on soil with 60% moisture level was increased with temperature and prometryn concentrations. The theoretical optimization scheme for eliminating prometryn in soil was recommended. The degraded products of prometryn under UV light and darkness were characterized using ultra high-performance liquid chromatography coupled to a linear ion trap-orbitrap hybrid mass spectrometer (UPLC-LTQ-orbitrap-MS/MS) and showed that prometryn decay in soil was through hydroxylation, dealkylation, and dethiomethylation pathways.

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