The aim of this work was to assess the effect of applying three different doses of fluxapyroxad on microbial activity, community structure and functional diversity as measured by respiration, microbial biomass C, phospholipid fatty acid(PLFA) and community-level physiological profiles(CLPPs). Our results demonstrated that substrate-induced respiration(on day 15) and microbial biomass C(on days 7 and 15) were inhibited by fluxapyroxad, but stimulation was observed thereafter. In contrast, fluxapyroxad addition increased the basal respiration and metabolic quotients(q CO2) and respiratory quotients(QR). Analysis of the PLFA profiles revealed that the total and bacterial biomass(both Gram-positive bacteria(GP) and Gram-negative bacteria(GN)) were decreased within the initial 15 days, whereas those as well as the GN/GP ratio were increased at days 30 and 60. F luxapyroxad input decreased the fungi biomass but increased the bacteria/fungi ratio at all incubation time. Moreover, high fluxapyroxad input(75 mg fluxapyroxad kg–1 soil dry weight) increased the microbial stress level. A principal component analysis(PCA) of the PLFAs revealed that fluxapyroxad treatment s ignificantly shifted the microbial community structure, but all of the observed effects were transient. Biolog results showed that average well color development(AWCD) and functional diversity index(H′) were increased only on day 60. I n addition, the dissipation of fluxapyroxad was slow in soil, and the degradation half-lives varied from 158 to 385 days depending on the concentration tested.
采用分散固相萃取(QuEChERS)样品前处理方法,建立了超高效液相色谱-串联质谱(UPLC-MS/MS)快速检测大豆和土壤中氟磺胺草醚的残留分析方法.大豆和土壤样品采用乙腈(含0.5%甲酸)提取,N-丙基乙二胺(PSA)或石墨化碳黑(GCB)净化,UPLC-MS/MS外标法检测定量.在0.005—0.5 mg.kg-1添加范围内,氟磺胺草醚在土壤、大豆和大豆植株中的平均回收率在79.4%—109.0%之间,变异系数在3.6%—10.1%之间.在山东、河南、吉林进行了氟磺胺草醚在大豆植株和土壤中的降解动态研究,结果表明,试验点中氟磺胺草醚在土壤中的降解半衰期为8.5—23.7 d;在大豆植株中的降解半衰期为2.7—9.8 d.
基于所建立的土壤中磺草酮残留的超高效液相色谱-串联质谱分析方法，通过土壤薄层层析试验研究了磺草酮在中国3种典型土壤中的淋溶特性。结果表明：添加水平为1和10 mg/kg时，磺草酮在土壤中的添加回收率为80％～104％，相对标准偏差为1.2％～8.1％，最低检测浓度为0.1 mg/kg。磺草酮在河北潮土、湖南红土和吉林黑土中的比移值（ R f ）分别为0.563、0.101和0.422，其在潮土和黑土中的移动性为中等，在红土中为不易移动；磺草酮在土壤中的淋溶特性与土壤理化性质密切相关，主要影响因素是土壤pH值及黏粒组分含量。
