甲氧基丙烯酸酯类杀菌剂对土壤微生物的生态毒性效应与机制

Strobilurin fungicides are currently the most widely used new fungicide. Azoxystrobin, pyraclostrobin and fluoxastrobin are the major varieties. Much attention has been paid to the effect of this kind of pesticides on the ecological environment. Now some toxicity studies of the three pesticides about the aquatic organisms and earthworms have been reported, but studies about the soil microorganisms are rarely reported. In this study, the three mentioned pesticides are taken as the target. The method of high-throughput sequencing is used to study the effect of these pesticides on the diversity of soil microbial community structure. The impact on the functional microorganism AOA and AOB is measured by the method of quantitative polymerase chain reaction (PCR). The method of Biolog is used to study the impact on soil microbial activity and determinate the activity of urease, phosphatase, dehydrogenase. The GC-MS-MS and HPLC-MS-MS are used to measure the residue dynamic of these pesticides on the soil and the degradation products. From the residue dynamic and degradation products, we can know the residual half-life and degradation rate constant, clarify the degradation mechanism and degradation pathway. The single cell gel electrophoresis experiment and broad bean root tip micro nuclear test are used to determinate the ecological toxicity and biological validity. Based on the above research results, we can screen out the main controlling factor that decides the soil microorganisms are sensitive to this kind of fungicides and obtain the threshold dose. According to comprehensive comparison of the effect of three pesticides, this study provides the basis for choosing pesticide that cause low environmental effect in the production.

甲氧基丙烯酸酯类杀菌剂是目前使用最广泛的新型杀菌剂,其中嘧菌酯、吡唑醚菌酯和氟嘧菌酯是主要品种.该类农药使用后对生态环境影响备受关注,已有其对水生生物和蚯蚓的毒性研究,但对土壤微生物的影响研究鲜有报道.本研究以上述三种药剂为对象,采用高通量测序方法研究对土壤微生物群落结构多样性的影响,采用定量PCR方法研究对功能微生物AOA和AOB的影响;采用Biolog方法研究对土壤微生物活性影响并测定对脲酶、磷酸酶和脱氢酶活性影响;采用GC-MS-MS和HPLC-MS-MS测定其在土壤中残留动态和降解产物,得出其残留半衰期和降解速率常数,明确降解机制和降解途径.采用单细胞凝胶电泳实验和蚕豆根尖微核实验测定其生态毒性和生物有效性.根据以上研究结果,筛选得出土壤微生物对该类杀菌剂影响敏感的主控因子,得出阈剂量,综合比较三种药剂对土壤微生物的毒性影响,为生产中选用低环境影响农药品种提供依据.

甲氧基丙烯酸酯类杀菌剂是目前使用最广泛的新型杀菌剂，其中嘧菌酯、吡唑醚菌酯和氟嘧菌酯是其主要品种。该类农药使用后对生态环境影响备受关注，已有其对水生生物和蚯蚓的毒性研究，但对土壤微生物的影响研究鲜有报道。本研究以上述三种药剂为对象，采用高通量测序方法研究了对土壤微生物群落结构多样性的影响，采用定量PCR方法研究了对功能微生物AOA和AOB的影响；采用Biolog方法研究了对土壤微生物活性影响并测定对脲酶、磷酸酶和脱氢酶活性影响；采用HPLC-MS-MS测定了其在土壤中残留动态，得出其残留半衰期和降解速率常数，明确降解机制和降解途径。结果发现①甲氧基丙烯酸酯类杀菌剂施用降低了土壤微生物多样性，但随着时间的推移，不利影响会逐渐恢复。②甲氧基丙烯酸酯类杀菌剂施用降低了土壤可培养微生物数量和土壤微生物活性。③甲氧基丙烯酸酯类杀菌剂施用对土壤硝化功能相关的微生物丰度和土壤酶活性有一定不利影响，但该影响是可接受的。④将微生物指标分为微生物数量、酶活性、氮循环功能基因丰度和碳循环功能基因丰度这几大类，土壤可培养真菌数量、土壤脲酶活性、nirK基因丰度和cbbLG基因丰度分别是这几类微生物指标中对甲氧基丙烯酸酯类杀菌剂响应最敏感的。⑤推荐剂量的嘧菌酯、吡唑醚菌酯、氟嘧菌酯在小麦田土壤中的半衰期分别为9.8 d、38.93 d和15.7 d，在玉米田土壤中的半衰期分别为8.0 d、2.33 d和22 d。推荐剂量倍量的嘧菌酯、吡唑醚菌酯、氟嘧菌酯在小麦田土壤中的半衰期分别为8.2 d、37.06 d和22.5 d，在玉米田土壤中的半衰期分别为9.9 d、2.16 d和16.2 d。本研究为生产中选用低环境影响农药品种提供了依据。