甲黄隆,氯黄隆,苄嘧黄隆及其降解产物对蛋白核小球藻生长的效应

本文研究了甲黄隆、氯黄隆、苄嘧黄隆及其降解产物对蛋白核小球藻（Chlorellapyrenoidosa）的96h生长抑制急性毒性和化合物氮的生物可获得性。急性毒性试验表明:黄隆的毒性比其降解产物取代磺胺和氮杂环化合物大得多（EC_(50)相差2—3个数量级）,降解产物取代磺胺、均三嗪、取代嘧啶存在明显的低浓度促进生长现象,氮的生物可获得性试验表明:小球藻能有效利用低浓度取代磺胺、均三嗪、取代嘧啶化合物中的氮促进生长,促进程度:氯磺胺>苄磺胺≈二甲氧基嘧啶>甲磺胺>均三嗪。     

Laboratory study on leachability of five herbicides in South Australian soils

Abstract

Norflurazon, oxadiazon, oxyfluorfen, trifluralin and simazine are herbicides widely used in the vineyards of the Barossa Valley, South Australia. The leaching behaviour of norflurazon, oxadiazon, oxyfluorfen and trifluralin was investigated on four key soils in the Barossa Valley. Leaching potential on packed soil columns and actual mobility using intact soil columns were investigated. On the packed soil columns, norflurazon was the most leachable herbicide. More of the herbicides were detected in the leachates from the sandy soils (Mountadam and Nuriootpa) than from the clayey soils (Lyndoch and Tanunda). Organic matter is generally low in soils in the Barossa region. Porosity and saturated conductivity significantly affect herbicide movement and in the sandy Mountadam and Nuriootpa soils, the water flux is greater than for the higher clay content Lyndoch and Tanunda soils. Increasing the time interval between herbicide application and the incidence of “rainfall”; reduced the amounts of herbicides found in the leachates. The use of intact soil columns and including simazine for comparison showed that both norflurazon and simazine were present in the leachates. Simazine was the first herbicide to appear in leachates. Sectioning of the intact soil columns after leaching clearly demonstrated that norflurazon and simazine reached the bottom of the soil columns for all soils studied. Greater amounts of norflurazon were retained in the soil columns compared with simazine. The other herbicides were mostly retained in the initial sections of the soil columns.     

Effect of humic acids on photodegradation of chloroacetanilide herbicides under UV irradiation

The effects of two humic acids (HAs) of different origins on the photodegradation of the chloroacetanilide herbicides acetochlor, propisochlor and butachlor were investigated in this study. One of the tested HAs was a standard sample that was purchased from a commercial source, and the other was isolated from the black soil of Northeast China. The photolysis of all three herbicides followed pseudo-first-order kinetics under ultraviolet (UV) irradiation conditions, regardless of whether HAs were present or not. Both HAs improved the photolysis rates of acetochlor in a dose-reversed way, whereas they inhibited butachlor degradation under all experimental concentrations. The two HAs differed in their effects on propisochlor photolysis, changing from enhancement to inhibition, depending on the origin and concentration of HAs. Element and Fourier Transform Infrared spectroscopy analyses showed that the isolated HAs had more polysaccharides and less aliphatic groups than the commercial HAs, and it was indicated that some characteristic radicals (C═O, O─H and phenolic hydroxyls) in HAs were involved in the photolysis of the herbicides. Gas chromatography/mass spectrometry (GC/MS) analyses indicated that the presence of HAs had no effects on the photolysis pathway and photoproduct species of the three herbicides.     

Trace level determination of selected sulfonylurea herbicides in wetland sediment by liquid chromatography electrospray tandem mass spectrometry

Sulfonylurea herbicides are widely used in crop production on the Canadian prairies and a portion of these herbicides applied to cropland are inevitably lost to surrounding aquatic ecosystems. Little is known regarding the presence of sulfonylurea herbicides in wetlands located amongst cropland. This paper describes a new analytical method for the extraction and the determination of seven sulfonylurea herbicides (thifensulfuron-methyl, tribenuron-methyl, ethametsulfuron-methyl, metsulfuron-methyl, rimsulfuron, nicosulfuron and sulfosulfuron) in wetland sediment. The method provided > 85% analyte recovery from fortified sediment for six of the seven sulfonylurea herbicides with a limit of quantification (LOQ) of 1.0 μ g kg^{? 1}. Tribenuron-methyl had significantly lower recovery compared to the other six sulfonylurea herbicides (LOQ = 2 μ g kg^{? 1}). Mean recovery standard deviations were < 10%. This methodology was used to quantify sulfonylurea herbicide residues in sediment samples collected from prairie wetlands situated within the agricultural landscape of Saskatchewan and Manitoba, Canada. This is the first-known detection of sulfonylurea herbicide residues in prairie wetland sediments. Ethametsulfuron-methyl, sulfosulfuron and metsulfuron-methyl, the three most environmentally persistent of the seven sulfonylurea herbicides monitored in the surveillance component of this study, were most frequently detected in wetland sediment with mean concentrations ranging from 1.2 to 10 μ g kg^{? 1}.     

Fast determination of phenoxy acid herbicides in carrots and apples using liquid chromatography coupled triple quadrupole mass spectrometry

A fast, simple and inexpensive method has been developed for the analysis of phenoxy acid herbicides: 2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-2-methylphenoxyacetic acid (MCPA), 2-(4-chloro-o-tolyloxy)propionic acid (MCPP), 2-(4-aryloxyphenoxy)propionic acid (Fluazifop) and 2-(4-aryloxyphenoxy)propionic acid (Haloxyfop) in carrots and apples by liquid chromatography coupled to triple quadrupole mass spectrometry (LC/MS/MS). The compounds were analyzed by QuEChERS (quick, easy, cheap, effective, rugged, safe) methodology without cleanup.

The recoveries were performed at two spiked levels (0.05 and 0.5 mg/kg) for both matrices with six replicates for each level. The mean recoveries ranged from 70–92% for both apples and carrots. The precision of the method expressed as relative standard deviation (RSD%) was found to be in the range 3–15%. For all compounds, good linearity (r² > 0.99) was obtained over the range of concentration from 0.05 μ g/mL to 0.5 μ g/mL, corresponding to the pesticide concentrations of 0.05 mg/kg and 0.5 mg/kg, respectively. The determination limits (LOQs) ranged from 0.01 ng/mL to 1.3 ng/mL in solvent, whereas, the LOQs calculated in matrix ranged from 0.05 ng/g to 21.0 ng/g for apples and from 0.06 ng/g to 10.2 ng/g for carrots. The developed methodology combines the advantages of both QuEChERS and LC/MS/MS producing a very rapid, sensitive and cheap method useful for the routine analytical laboratories.     

Impact of Sublethal Doses of 2,4-D,Simulating Drift,on Tomato Yield

Abstract

Tomato is considered one of the most sensitive crops regarding 2,4-D drift. In many cases, such susceptibility has led to important restrictions in the use of 2,4-D based products. Field experiments were carried out for two consecutive years in tomato, by applying sublethal doses of 2,4-D (ranging from 0.42 to 13.44 g a.i. ha^?1) directly to plants, at different stages of growth, as a simulation of eventual drifts to the crop. The range of rates was based on the assumption of a 0.0625–2.0% drift level of a 1 L ha^?1 of the most common formulated herbicides. For this crop, the range of rates between 0.42 and 13.44 g a.i ha^?1 applied at the beginning of flowering caused a linear crop reduction. On the other hand, rates ≤13.44 g a.i. ha^?1 applied after full development of fourth truss stage or latter had no effect on crop yield or development. For tomato, tolerance to 2,4-D strongly increases with plant age.     

Spiking solvent, humidity and their impact on 2,4-D and 2,4-DCP extractability from high humic matter content soils

The 2,4-dichlorophenoxyacetic acid (2,4-D) is a hormone-like herbicide widely used in agriculture. Although its half life in soil is approximately two weeks, the thousands of tons introduced in the environment every year represent a risk for human health and the environment. Considering the toxic properties of this compound and its degradation products, it is important to assess and monitor the 2,4-D residues in agricultural soils. Furthermore, experiments of phyto/bioremediation are carried out to find economic and environmental friendly tools to restore the polluted soils. Accordingly, it is essential to accurately measure the amount of 2,4-D and its metabolites in soils. There is evidence that 2,4-D extraction from soil samples seriously depends on the physical and chemical properties of the soil, especially in those soils with high content of humic acids. The aim of this work was to assess the variables that influence the recovery and subsequent analysis of 2,4-D and its main metabolite (2,4-dichlorophenol) from those soils samples. The results showed that the recovery efficiency depends on the solvent and method used for the extraction, the amount and kind of solvent used for dissolving the herbicide and the soil water content at the moment of spiking. An optimized protocol for the extraction and quantification of 2,4-D and its main metabolite from soil samples is presented.     

氯代酰胺类除草剂降解菌的分离及降解性能

从生产乙草胺的农药厂废水生物处理池活性污泥中分离到一株氯代酰胺类除草剂降解细菌,命名为Y3B-1.根据表型特征、生理生化特性和16S rDNA序列系统发育分析,将其鉴定为副球菌属(Paracoccus sp.).研究了菌株Y3B-1在不同条件下对多种氯代酰胺类除草剂的降解性能.结果表明:菌株Y3B-1能以乙草胺为碳源生长,并能降解乙草胺、丁草胺和丙草胺,3 d对这3种氯代酰胺类除草剂的降解率分别达到86.7%、65.5%和69.1%,不能降解异丙甲草胺.该菌降解乙草胺的最适温度为30℃,最适pH为7.0,对乙草胺的降解效果与接种量成正相关,对较低浓度的乙草胺有很好的降解效果,过高的起始浓度抑制其对乙草胺的降解,外加营养如酵母膏和土壤悬液则显著促进其对乙草胺的降解.图7参23     

固相萃取-高效液相色谱法同时测定水中12种磺酰脲类除草剂

采用固相萃取-高效液相色谱法同时测定水中12种磺酰脲类除草剂,样品经磷酸调节pH值为2后,经Watens Oasis HLB SPE柱净化浓缩,乙腈洗脱,选择检测波长为230 nm,以乙腈-水溶液(0.02%磷酸)为流动相梯度洗脱,保留时间在14 min～32 min范围内.12种磺酰脲类除草剂在0.050 mg/L～...