a Laboratory of Ecotoxicology, Center for Nuclear Energy in Agriculture , University of Sao Paulo Piracicaba , São Paulo , Brazil.
b Former research fellow at Center for Nuclear Energy in Agriculture , University of Sao Paulo Piracicaba , São Paulo , Brazil.
J Environ Sci Health B. 2019;54(7):560-568. doi: 10.1080/03601234.2019.1620043. Epub 2019 Jun 27.
After application, herbicides often reach the soil and affect non-target soil microorganisms, decreasing their population, diversity or affecting metabolic activity. Therefore, laboratory studies were performed to evaluate the effects of diuron, hexazinone and sulfometuron-methyl alone and mixed upon carbon transformation by soil microorganisms in clayey and sandy soils and the effect on bacterial diversity and structure. Control treatment without herbicide application was also performed. Sub-samples from the control and herbicide treatments (10 g - in triplicate) were collected before herbicide application and 7, 14, 28 and 42 days after treatment (DAT), then 1 mL of C-glucose solution was applied. The released CO was trapped in 2 M NaOH solution and the radioactivity was analyzed by liquid scintillation counting (LSC), 12 h after glucose application. The effect of herbicides on bacterial diversity was evaluated by The experiment was conducted in a complete randomized design. Hexazinone did not affect CO evolution. Diuron showed a greater CO evolution in sandy and clayey soil, while sulfometuron-methyl led to an increase in sandy soil, at 42 DAT. A greater evolution of carbon was observed in the treatment with herbicide mixture in sandy soil, compared with the same treatment in clayey soil or control. However, the herbicide mixture application did not affect the soil biological activity measured by the respiration rate induced by substrate. On the other hand, the herbicide mixtures affected the bacterial diversity in both soils, being the strongest effect to diuron and sulfometuron-methyl in clayey soil and hexazinone in sandy soil.
施药后，除草剂通常会到达土壤并影响非靶标土壤微生物，降低其种群数量、多样性或影响代谢活性。因此，进行了实验室研究以评估单独和混合施用敌草隆、六嗪酮和甲磺隆甲酯对粘壤土和沙壤土中土壤微生物碳转化的影响，以及对细菌多样性和结构的影响。还进行了不施药的对照处理。在施药前和施药后 7、14、28 和 42 天（DAT）从对照和除草剂处理的亚样本（一式三份，每份 10 g）中采集，然后应用 1 mL C-葡萄糖溶液。释放的 CO 被捕获在 2 M NaOH 溶液中，并在葡萄糖应用 12 小时后通过液体闪烁计数（LSC）分析放射性。通过实验评估除草剂对细菌多样性的影响。实验采用完全随机设计进行。六嗪酮对 CO 释放没有影响。敌草隆在沙壤土和粘壤土中表现出更大的 CO 释放，而甲磺隆甲酯在 42 DAT 时导致沙壤土中 CO 释放增加。与粘壤土中相同处理或对照相比，在沙壤土中施用除草剂混合物的处理中观察到更大的碳释放。然而，除草剂混合物的施用并没有影响通过底物诱导的呼吸速率测量的土壤生物活性。另一方面，除草剂混合物影响了两种土壤中的细菌多样性，对粘壤土中敌草隆和甲磺隆甲酯以及沙壤土中六嗪酮的影响最大。
