固相萃取-高效液相色谱法测定水中磺酰脲类除草剂

建立了固相萃取-高效液相色谱测定水中7种磺酰脲类除草剂的方法,考察了降解作用及滤膜对测定的影响.方法在0.30 mg/L～5.00 mg/L之间线性关系良好,7种磺酰脲类除草剂的检出限为0.32 μg/L～0.62 μg/L,RSD为4.4%～7.6%,平均加标回收率为87.9%～102%.     

EFFECTS OF FOREST HERBICIDE APPLICATIONS ON STREAMWATER CHEMISTRY IN SOUTHWESTERN BRITISH COLUMBIA1

ABSTRACT: The herbicide glyphosate was applied to portions of two watersheds in southwestern British Columbia to kill vegetation that was competing with Pseudotsuga menziesii (Douglas-fir) plantations. This application had little significant effect on streamwater chemistry (K⁺, Na²⁺, Mg²⁺, Ca²⁺, Cl^-, NOs₃^-, NH₄⁺, PO4^3-, SO₄⁼, and SiO₂ concentrations, electrical conductivity, and pH) when vegetation cover in a watershed was reduced by 4%, but had significant (P>0.05) effects, which lasted for at least five years, when cover was reduced by 43%. In this case, most parameters increased in value following the application, with K⁺ and Mg²⁺ concentrations and pH values exhibiting the most prolonged increases and NO₃^- concentrations exhibiting the greatest percentage increases. Sulphate and dissolved SiO₂ concentrations decreased following the application. Streamwater chemical fluxes showed similar trends to concentrations except that changes in fluxes were less significant and no decreases were observed. Forest management induced losses of NO₃-N in streamwater during the first five post-treatment years in the study area decreased in the order: herbicide application (approximately 40 kg/ha) < clearcutting and slashburning (approximately 20 kg/ha) < clearcutting (approximately 10 kg/ha). In watersheds similar to those of the study area, herbicide application is likely to have a greater impact on streamwater chemistry, in general, than would clearcutting or clearcutting followed by slashburning.     

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.     

Systematic review and meta-analysis of glyphosate exposure and risk of lymphohematopoietic cancers

This systematic review and meta-analysis rigorously examines the relationship between glyphosate exposure and risk of lymphohematopoietic cancer (LHC) including NHL, Hodgkin lymphoma (HL), multiple myeloma (MM), and leukemia. Meta-relative risks (meta-RRs) were positive and marginally statistically significant for the association between any versus no use of glyphosate and risk of NHL (meta-RR = 1.3, 95% confidence interval (CI) = 1.0–1.6, based on six studies) and MM (meta-RR = 1.4, 95% CI = 1.0–1.9; four studies). Associations were statistically null for HL (meta-RR = 1.1, 95% CI = 0.7–1.6; two studies), leukemia (meta-RR = 1.0, 95% CI = 0.6–1.5; three studies), and NHL subtypes except B-cell lymphoma (two studies each). Bias and confounding may account for observed associations. Meta-analysis is constrained by few studies and a crude exposure metric, while the overall body of literature is methodologically limited and findings are not strong or consistent. Thus, a causal relationship has not been established between glyphosate exposure and risk of any type of LHC.     

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.     

Droplet trajectories and deposition with an airblast forestry sprayer

Abstract

The characteristics of the air pattern and spray droplet trajectories from the Algonquin airblast forestry sprayer were investigated. An experiment with water and Rhodamine tracer dye was conducted in a shelterwood location to evaluate droplet deposition on Kromekote^® card targets above and within a canopy of poplar saplings. Computer simulation of a free jet was used to model the airblast in order to investigate droplet trajectories. Measured deposits indicated that the effective swath width is 14 m from the blower outlet. Mean simulated droplet trajectory data were in good agreement with the droplet density data observed in the field. Both sets of results predicted a very low level of spray deposition beyond 14 m.     

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％。     

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。     

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.