Short-term response of soil enzymatic activities and respiration to atrazine in fluvio-aquic soil in the Huang-Huai-Hai Plain

【Objective】Atrazine is a widely used herbicide whose ecological impacts on fluvio-aquic soils remain insufficiently understood. This study aims to evaluate the effects of atrazine on soil biogeochemical properties and to identify sensitive biomarkers capable of indicating atrazine pollution level.【Method】A controlled culture experiment was conducted using six atrazine concentrations 0 (CK), 0.6 (T1), 2.5 (T2), 10 (T3), 50 (T4), and 100 mg/kg (T5). The changes in soil enzyme activities (urease, sucrase, amylase, alkaline phosphatase, and catalase) were measured daily from the onset of the experiment to elucidate the temporal variations in their response to atrazine application. The IBRv2 index was used to evaluate the comprehensive toxicity of atrazine to soil biogeochemical processes.【Result】Atrazine significantly stimulated soil urease activity, but the effect varied with atrazine concentration. Soil sucrase activity was significantly inhibited on day 14 after atrazine application but returned to CK levels after 28 days. Increasing atrazine concentrations strongly inhibited soil amylase activity during the early incubation period, with the inhibition positively correlated with atrazine concentration. The activity of alkaline phosphatase did not show a noticeable change in the first 7 days after atrazine application, but became significant between day 14 and day 21 before being inhibited. Atrazine significantly stimulated catalase activity except in T1 treatment, with the activation increasing with atrazine concentration. Soil respiration started to increase significantly 28 days after atrazine application, and it was positively correlated with atrazine concentration. IBRv2 analysis showed that increasing atrazine concentrations resulted in an increase in soil toxicity.【Conclusion】The activity of soil urease, amylase and catalase responded rapidly and sensitively to atrazine application, with the changes in activity level depending on atrazine concentration. These enzymes can serve as biomarkers to assess the impact of atrazine on biogeochemical processes in fluvio-aquic soils.