Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen, 361021, China.
Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, China.
Environ Sci Pollut Res Int. 2020 May;27(14):17370-17381. doi: 10.1007/s11356-020-07679-7. Epub 2020 Mar 10.
Pesticide chlorothalonil is widely applied in tea agroecosystem, potentially disturbing soil microbial-mediated nitrogen cycle. The underlying toxicity mechanism, however, is not well explored. Here, we investigated the long-term effects of chlorothalonil on soil microbial denitrification and NO emission pattern in a tea field after 40 days of exposure. Results showed that chlorothalonil inhibited denitrification process but remarkably promoted NO emission by 380-830%. Chlorothalonil significantly inhibited NO reductase activity but did not affected nosZ abundance. Our results further revealed that chlorothalonil influenced soil denitrification by directly suppressing microbial electron transport system activity, and decreasing electron donor nicotinamide adenine dinucleotide (NADH) and energy source adenosine triphosphate (ATP) levels. Additionally, chlorothalonil also downregulated denitrifying functional genes (narG, nirS, and norB) and declined the relative abundances of potential denitrifiers (i.e., Pseudomonas and Streptomyces). Stepwise regression and path modeling suggested that nitrate reductase was the most significant factor in explaining denitrification rate under chlorothalonil applications. This study provides important information for revealing the chronic impacts of pesticide on tea soil denitrification and NO emission on the basis of electron transport mechanism. Most significantly, NO emission is underestimated in chlorothalonil-treated soils, which suggests that future estimations of NO emission from agricultural lands should take account of pesticide dependency conditions.
杀菌剂百菌清广泛应用于茶园生态系统，可能会扰乱土壤微生物介导的氮循环。然而，其潜在的毒性机制尚未得到充分探索。在这里，我们研究了百菌清在暴露 40 天后对茶园土壤微生物反硝化和 NO 排放模式的长期影响。结果表明，百菌清抑制了反硝化过程，但显著促进了 380-830%的 NO 排放。百菌清显著抑制了硝酸还原酶活性，但对 nosZ 丰度没有影响。我们的结果进一步表明，百菌清通过直接抑制微生物电子传递系统的活性，降低电子供体烟酰胺腺嘌呤二核苷酸（NADH）和能源三磷酸腺苷（ATP）水平，从而影响土壤反硝化作用。此外，百菌清还下调了反硝化功能基因（narG、nirS 和 norB），降低了潜在反硝化菌（如假单胞菌和链霉菌）的相对丰度。逐步回归和路径建模表明，在百菌清处理下，硝酸盐还原酶是解释反硝化速率的最显著因素。本研究基于电子传递机制，为揭示农药对茶园土壤反硝化和 NO 排放的慢性影响提供了重要信息。最重要的是，在百菌清处理的土壤中，NO 排放被低估了，这表明未来对农业用地 NO 排放的估计应考虑到农药的依赖条件。
