Multi-Medium Residues and Ecological Risk of Herbicides in a Typical Agricultural Watershed of the Mollisols Region, Northeast China

Abstract

The widespread use of herbicides impacts non-target organisms, promotes weed resistance, posing a serious threat to the global goal of green production in agriculture. Although the herbicide residues have been widely reported in individual environmental medium, yet their presence across multiple mediums has received scant attention, particularly in Mollisols regions with intensive agricultural application of herbicides. A systematic investigation was conducted in this study to clarify the occurrence of herbicide residues in soil, surface water, sediments, and grains from a typical agricultural watershed in the Mollisols region of Northeast China. Herbicide concentrations ranged from 0.30-463.49 μg/kg in soil, 0.31-29.73 μg/kg in sediments, 0.006-1.157 μg/L in water, and 0.32-2.83 μg/kg in grains, with Clomazone being the most priority herbicide detected in soil, sediments, and water, and Pendimethalin in grains. Crop types significantly affected the residue levels of herbicides in grains. Clomazone posed high ecological risks in soil and water, with 86.4% of water samples showing high risks from herbicide mixtures (RQ > 1). These findings aid in enhancing our comprehension of the pervasive occurrence and potential ecological risks of herbicides in multiple mediums within typical agricultural watersheds, providing detailed data to inform the development of targeted mitigation strategies.

Keywords: Multi-medium, Herbicide residues, Risk quotients, Mollisols region of China