我国微生物农药的应用现状

对微生物农药的概念、种类及其作用机理进行了综述,其中重点介绍了微生物农药的分类,同时对我国目前使用的几类微生物农药的研究应用状况进行了阐述,并提出微生物农药现存的问题及其解决方案,指出微生物农药的发展前景是乐观的。     

饮用水中苯基脲除草剂的分子印迹固相萃取方法研究

以N-（4-异丙基苯基）-N-亚丁基脲分子印迹聚合物为吸附剂,建立了饮用水中苯基脲除草剂的分子印迹固相萃取方法。上样后固相萃取柱依次用2．5mL0．1mol／L盐酸和2．5mL去离子水淋洗,然后氮气吹干,再用1mL含8％乙腈的甲苯溶液淋洗,最后用2mL甲醇洗脱。将建立的方法用于自来水中异丙隆、非草隆、甲氧隆、绿麦隆、枯莠隆、灭草隆、伏草隆、草不隆等8种苯脲类除草剂的测定,除伏草隆和草不隆的回收率较低外,其余6种除草剂的回收率均〉60％。     

Field evaluation and determination of four herbicides in a wheat ecosystem by a simple and versatile QuEChERS method with liquid chromatography-tandem mass spectrometry

Wheat products are consumed worldwide and every day; therefore, herbicides misuse in the wheat ecosystem has become a global food safety issue. Here, a simple and versatile method, QuEChERS (quick, easy, cheap, effective, rugged, and safe) with liquid chromatography-tandem mass spectrometry was developed to measure four herbicides in soil, wheat, and wheat straw – florasulam, carfentrazone-ethyl, fluroxypyr-meptyl, and fluroxypyr. By adjusting the amount of graphitized carbon black from 0 to 10 mg, the herbicides could be extracted with satisfactory recoveries of 80%–110%. Application of two water-dispersible granules showed first-order kinetics as well as half-lives between 1.2 and 5.1 d under open-field conditions. The dissipation kinetics of the four herbicides differed in the soil, wheat, and wheat straw, with residual concentrations in straw at 2 h after application being higher than in soil and faster degradation occurring in straw. The terminal residues in soil, wheat grain, and wheat straw were all below the maximum residue limits. The developed method was easy to handle and versatile; thus, it will facilitate regulation and inspection for possible misuse against Good Agriculture Practices. Moreover, the results of this study will contribute to global environmental protection as well as food safety issues.     

Estimating Contributions of Nitrate and Herbicides From Groundwater to Headwater Streams,Northern Atlantic Coastal Plain,United States1

Abstract: Groundwater transport often complicates understanding of surface‐water contamination. We estimated the regional flux of nitrate and selected herbicides from groundwater to nontidal headwater streams of the Atlantic Coastal Plain (New Jersey through North Carolina) based on late‐winter or spring base‐flow samples from 174 streams. Sampled streams were selected randomly, and flux estimates are based on resulting population estimates rather than on empirical models, which have been used previously for similar estimates. Base‐flow flux in the estimated 8,834 headwater streams of the study area are an estimated 21,200 kg/day of nitrate (as N) and 5.83, 0.565, and 20.7 kg/day of alachlor, atrazine, and metolachlor (and selected degradates), respectively. Base‐flow flux of alachlor and metolachlor is <3% of the total base‐flow flux of those compounds plus degradates. Base‐flow flux of nitrate and herbicides as a percentage of applications is typically highest in well‐drained areas and lowest in areas with abundant poor drainage and anoxic conditions. In Coastal Plain watersheds of Albemarle and Pamlico Sounds, <2% of applied nitrogen reaches headwater streams as base flow. On the Delmarva Peninsula part of the Chesapeake Bay watershed, however, more than 10% of such applications are transported through groundwater to streams, and base‐flow nitrate flux represents 70% of total nitrogen flux in headwater streams.     

Residual tembotrione and atrazine in carrot

Carrot (Daucus carota L.) is a vegetable crop that is grown throughout the year across various regions of Brazil in rotation or in succession to other cultures. Herbicide residual effect has emerged as a concern, because of the possibility of carryover. Thus, the objective of this study was to evaluate the effect of tembotrione and atrazine residues – in mixture and isolated – on carrot planted in succession to corn. The experiment was designed in randomized blocks with five replications. Treatments consisted of tembotrione (50.4 g ha^?1), tembotrione (100.8 g ha^?1), tembotrione + atrazine (50.4 g ha^?1+ 2 L ha^?1), tembotrione + atrazine (100.8 g ha^?1+ 2 L ha^?1), and atrazine (2.00 L ha^?1) applied eight months before carrot seeding, plus a control treatment with no herbicide application. Investigated variables were shoot dry mass, productivity, and classification of carrot roots. The presence of atrazine and tembotrione decreased dry mass in the area, and only tembotrione reduced total root productivity. Thus, there is a carryover effect to tembotrione application that reduces the dry matter accumulation of shoot and total productivity, and an atrazine + tembotrione (100.8 g ha^?1) mixture reduces the total productivity after application of these herbicides to soil.     

高效薄层析进行农药吸附态光解的研究

研究了绿麦隆和消草醚２种除草剂在硅胶Ｇ高效薄层上的光稳定性,提出应用高效薄层析技术作为农药吸附态光解的一种试验方法。在高效薄层上直接点样,同一薄层上包括照光、黑暗对照和定量曲线样品,原始剂量４００—８００ｎｇ·１×５ｍｍ斑点－１,照光后直接展开和扫描定量测定,最低检测量可达２０ｎｇ·斑点－１。本方法无须对样品进行提取、净化等处理,具有快速高效、重复性好,且可直观光解产物等优点。     

Contaminant Retention Potential of Forested Filter Strips Established as SMZs in the Piedmont of Georgia1

Abstract: It is common practice in the United States and elsewhere to maintain vegetated filter strips adjacent to streams to retain contaminants in surface runoff. Most research has evaluated contaminant retention in managed agricultural field strips, while relatively few studies have quantified retention in forested filter strips, particularly for dissolved contaminants. Plot‐scale overland flow experiments were conducted to evaluate the efficiency of natural forested filter strips established as streamside management zones (SMZs) for retaining phosphorus (P), atrazine, and picloram transported in runoff. Retention was evaluated for five different slope classes: 1‐2, 5‐7, 10‐12, 15‐17, and 20‐22%; two cover conditions: undisturbed forest floor (O horizon intact) and forest floor removed by raking; and two periods with contrasting soil moisture conditions: summer‐dry and winter‐wet season. Surface flow was collected at 0, 2, 4, 6, and 10 m within the filter strip to evaluate changes in solution concentration as it moved through the O horizon and the surface soil horizon mixing zone. On average, a 10 m length of forested SMZ with an undisturbed forest floor reduced initial solution concentration of total dissolved P by 51%, orthophosphate P by 49%, atrazine by 28%, and picloram by 5%. Percentages of mass retention through infiltration of water plus concentration reductions in runoff were 64% for total dissolved P, 62% for orthophosphate P, 47% for atrazine, and 28% for picloram for undisturbed forest floor conditions. Lower retention occurred following forest floor removal, particularly for P. Average dissolved P retention was 16% lower following forest floor removal. For undisturbed sites, differences in retention were more closely related to forest floor depth than to slope or antecedent soil moisture. These results indicate that forested SMZ filter strips provide a significant measure of surface water protection from dissolved P and herbicide delivery to surface water.     

FACTORS AFFECTING PESTICIDE OCCURRENCE AND TRANSPORT IN A LARGE MIDWESTERN RIVER BASIN1

ABSTRACT: Several factors affect the occurrence and transport of pesticides in surface waters of the 29,400 km² White River Basin in Indiana. A relationship was found between pesticide use and the average annual concentration of that pesticide in the White River, although this relationship varies for different classes of pesticides. About one percent of the mass applied of each of the commonly used agricultural herbicides was transported from the basin via the White River. Peak pesticide concentrations were typically highest in late spring or early summer and were associated with periods of runoff following application. Concentrations of diazinon were higher in an urban basin than in two agricultural basins, corresponding to the common use of this insecticide on lawns and gardens in urban areas. Concentrations of atrazine, a corn herbicide widely used in the White River Basin, were higher in an agricultural basin with permeable, well‐drained soils, than in an agricultural basin with less permeable, more poorly drained soils. Although use of butylate and cyanazine was comparable in the White River Basin between 1992 and 1994, concentrations in the White River of butylate, which is incorporated into soil, were substantially less than for cyanazine, which is typically applied to the soil surface.     

Pesticides residues in vegetables in and around Delhi

This article presents the development of a multiresidue method forthe estimation of 30 insecticides, 15 organochlorineinsecticides and 6 organophosphorus insecticides, 9 syntheticpyrethriods and 2 herbicides and their quantificationin vegetables. The monitoring study indicates that though allthe vegetable samples were contaminated with pesticides, only31% of the samples contained pesticides above the prescribedtolerance limit.     

Concurrent Exposure Assessments of Atrazine and Metolachlor in the Mainstem, Major Tributaries and Small Streams of the Chesapeake Bay Watershed: Indicators of Ecological Risk

The goals of this study were to: (1) measure atrazine and metolachlor concentrations during both high and low use periods in the Chesapeake Bay's mainstem/major tributaries, smaller tributaries and representative small agricultural streams during 1995 and 1996; (2) compare these exposure data with toxicity benchmarks for each herbicide to predict ecological risk and (3) use in-stream fish community data collected in the streams to provide supportive data for ecological risk characterization. Spatially, atrazine (<0.10–98 g/L) and metolachlor (<0.10–68 g/L) concentrations were highest in the streams, followed by the small tributaries (<0.10–11 g/L atrazine; <0.10–8.6 g/L metolachlor) with the lowest concentration in the mainstem Bay/larger tributaries (<0.10–0.22 g/L atrazine; <0.10–0.24 g/L metolachlor). Temporally, concentrations of both herbicides were greatest in all three types of habitats in the late spring and early summer. Concentrations of atrazine and metolachlor were very low or non-detectable in all habitats sampled from early August to mid-April. Toxicity benchmarks of 20 g/L for atrazine based on an ecological No Observed Effect Concentration (NOEC) for microcosm/mesocosm studies and an acute 10th percentile of 53 g/L for metolachlor (protection of ninety % of the species) based on laboratory toxicity data were selected to assess annual and seasonal ecological risk. Both of these toxicity benchmarks were conservative estimates of ecological risk designed to protect the trophic group (plants) most sensitive to these herbicides. Based on a comparison of these toxicity benchmarks with two years of exposure data, the ecological risk from both atrazine and metolachlor exposure in the mainstem Chesapeake Bay/large tributaries, small tributaries and representative agriculturally dominated streams was generally judged to be low. During one 72-h stream rain event in 1995, the atrazine toxicity benchmark (20 g/L) was exceeded during part of the event. However, long-term permanent ecological effects are not expected based on the documented recovery potential of the most sensitive trophic group (plant communities) to the concentrations of atrazine reported and the transient nature of the atrazine pulses. Fish communities at the stream sites receiving the highest concentrations of both herbicides were judged to be healthy based on an Index of Biotic Integrity (IBI) developed for Maryland's coastal plain.