Occurrence, spatial distribution, and multicriteria prioritization of current-use herbicides in agricultural surface...

Herbicides are commonly used in crop production and pose environmental threats. Currently, Chinese researches on herbicide residues in agricultural soils focused on Northeast China, with information lacking for most other major crop-producing regions. In this study, topsoil samples were collected from 391 fields in Chinese mainland, and the concentrations of 33 current-use herbicides and two metabolites were quantified. The results revealed herbicides were commonly found in the farmland topsoil in China. The total concentration of the 35 herbicides (i.e., Σ₃₅herbicides) ranged from 0.354 to 2694 μg/kg. And the atrazine was the most frequently detected herbicide. Herbicide concentrations and compositions varied across 31 provinces. The highest median concentration of the Σ₃₅herbicides was detected in Heilongjiang at 33.7 μg/kg, while Tibet had the lowest median concentration (0.514 μg/kg). It might be due to regional differences in herbicide application and degradation conditions. Additionally, the Σ₃₅herbicides concentration in the topsoil cultivated with grain (median: 13.9 μg/kg) was higher than in that cultivated with vegetables (median: 3.20 μg/kg) and fruits (median: 2.05 μg/kg, p < 0.05), mainly because grains require more herbicide application. Overall, the Σ₃₅herbicides concentration in the topsoil of both mulched (median: 11.2 μg/kg) and non-mulched (median: 8.62 μg/kg) farmlands was higher than that in greenhouse farmlands (median: 3.11 μg/kg, p < 0.05), possibly because of the differences in the types and extent of the crops cultivated in these systems. Finally, this study was the first to list ten prioritized herbicides based on measured concentration data in China through a multicriteria approach.