Simultaneous voltammetric determination of four triazine herbicides in water samples with the aid of chemometrics

A novel differential pulse voltammetry (DPV) method was developed for the simultaneous analysis of herbicides in water. A mixture of four herbicides, atrazine, simazine, propazine and terbuthylazine was analyzed simultaneously and the complex, overlapping DPV voltammograms were resolved by several chemometrics methods such as partial least squares (PLS), principal component regression (PCR) and principal component–artificial networks (PC–ANN). The complex profiles of the voltammograms collected from a synthetic set of samples were best resolved with the use of the PC–ANN method, and the best predictions of the concentrations of the analytes were obtained with the PC-ANN model (%RPE_T = 6.1 and average %Recovery = 99.0). The new method was also used for analysis of real samples, and the obtained results were compared well with those from the GC-MS technique. Such conclusions suggest that the novel method is a viable alternative to the other commonly used methods such as GC, HPLC and GC-MS.     

紫茎泽兰的化学防除及生态修复效果

紫茎泽兰是我国重要的外来入侵生物,一旦入侵,就排挤当地物种,很快成为优势种群,在西南地区已对当地的农业、畜牧业,以及生态环境造成严重的破坏.2年的试验和示范结果表明,磺酰脲类除草剂嘧磺隆187.5～375g/hm2(有效成分,下同)、噻吩磺隆375g/hm2、氯嘧磺隆375g/hm2和吡啶类除草剂氨氯吡啶酸1 080g/hm2对紫茎泽兰均有优异的防除效果.而2,4-滴1 500g/hm2、乙羧氟草醚150g/hm2、氟磺胺草醚500g/hm2、咪唑乙烟酸1 500g/hm2、嗪草酸甲酯50g/hm2、环嗪酮2 500g/hm2、氯草定750～1 500g/hm2不能完全杀死紫茎泽兰.针对山区水源短缺,运水不便的的问题,通过在除草剂中加入2 L/hm2机油乳油,采用很低容量喷雾法,用水量可由常量喷雾的900～1 200L/hm2减少到30～40L/hm2,施药效率较常量喷雾提高8～10倍.此外,还可将除草剂制成颗粒剂或采用毒土法撒施,不需施药器械,且可以节省大量水运输费用.紫茎泽兰用上述除草剂防除后,能选择性地促进非靶标植物的生长.大面积防除2年后,生态恢复率为40%～90%.     

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.     

FACTORS AFFECTING HERBICIDE YIELDS IN THE CHESAPEAKE BAY WATERSHED,JUNE 19941

ABSTRACT: Median concentrations and instantaneous yields of alachlor, metolachlor, atrazine, cyanazine, and simazine were generally highest at sites in the Lower Susquehanna River Basin and in agricultural subbasins. Instantaneous herbicide yields are related to land use, hydrogeologic setting, streamflow yield, and agricultural row cropping practices. The significance of these relations may be affected by the interdependence of the factors. The percentage of basin area planted in corn is the most influential factor in the prediction of herbicide yield. Instantaneous yields of all five herbicides measured in June 1994 related poorly to averaged 1990–94 herbicide use. Annually averaged herbicide-use data are too general to use as a predictor for short-term herbicide yields. An evaluation of factors affecting herbicide yields could be refined with more-current land use and land cover information and a more accurate estimate of the percentage of basin area planted in corn. Factors related to herbicide yields can be used to predict herbicide yields in other basins within the Chesapeake Bay watershed and to develop an estimate of herbicide loads to Chesapeake Bay.     

Effects of herbicides on Odonata communities in a rice agroecosystem

The effects of the five herbicides propanil, quinclorac, molinate/propanil, 2,4-D amine, and bensulfuron on Odonata diversity and abundance at the experimental rice plots was investigated. A total of 13 Odonata morphospecies belonging to two families have been identified. Treated plots exhibited higher species richness (up to 12 species) than the control plot (8 species). Ishnura spp. was the most abundant species in the treated plots with a mean density of 194.2 individuals per m², (ind m^?2) followed by Brachythemis contaminata (152 ind m^?2) and Agriocnemis spp. (124 ind m^?2). In the control plots, Agrocnemis spp. was the dominant species (153 ind m^?2) followed by Ishnura spp. (143 ind m^?2) and Neurothemis fluctuans (59 ind m^?2). In the propanil-treated plot, the highest number of odonate species (10 species) was recorded followed by the plots treated with quinclorax and molinate/propanil (9 species). On the 2,4-D amine or bensulfuron-treated plots as well as the control plot, only eight odonate species were recorded. This study revealed that herbicide application had a positive effect on Odonata diversity. This seems reasonable as Odonata are non-target organisms for herbicides. Furthermore, the decomposed weeds resulting from herbicide application would enrich the water with necessary organic matter.     

Environmental fate of pesticides used in Australian viticulture V. Behaviour of atrazine in the soils of the south Australian Riverland

The transport of the s‐triazine herbicide, atrazine, through the red, calcareous earth soils of the South Australian Riverland was investigated. Small, undisturbed soil cores were extracted from the inter‐row topsoil of a vineyard adjacent to the River Murray, approximately 10 km south‐west of Overland Corner, South Australia. The vines were grown in a deep (1–4 m) reddish brown, strongly alkaline, sandy loam with a low organic carbon content (<2%). Atrazine concentrations in the leachate were dependent on application rate and soil type. High application rates on subsoil gave high rates of leaching for a longer time compared to the same application rate on topsoil and/or lower application rates on either topsoil or subsoil. Overall, 37–65% of the applied atrazine was detected in the leachate from subsoil cores, 14–25% in topsoil core leachates. Small amounts of atrazine (< 10% of applied dose) were found only in the top 2 cm of the core profiles. The results suggest that this herbicide is somewhat mobile in such strongly alkaline, sandy loam soils and that the irrigated soils of this region are likely to be prone to leaching of atrazine, and therefore that groundwater supplies in this area may be at risk of contamination through use of triazine herbicides.     

Effects of Clear-Cutting and Plant Competition Control Methods on Carabid (Coleoptera: Carabidae) Assemblages in Northwestern Ontario

Total captures, species richness, diversity, and assemblages of adult carabids (Coleoptera: Carabidae) in a boreal mixed-wood ecosystem study were compared among unharvested, and clear-cut plots untreated or treated with herbicides (Vision® and Release®), mechanical treatments (brush saw and Silvana Selective). Carabids were sampled using unbaited pitfall traps for one growing season 7 and 9 years after clear-cutting, in the second growing season after competition control was applied. A total of 5032 individuals representing 30 species were collected between June 1 and September 25, 1995. Total catches were not affected by the harvest or the conifer release alternatives applied. Species richness and diversity increased following conifer release alternatives. Ten species showed habitat preferences after treatment whereas the remaining 20 species were not significantly affected by treatment.     

微板吸光法测定9种农药对斜生栅藻的抑制毒性

以斜生栅藻(Scenedesmus obliquus)为指示生物,96微孔板为暴露反应载体,SpectraMax M5酶标仪为吸光度测试设备,建立了测定毒物对藻生长抑制毒性的微板吸光法.论文系统研究了微板吸光法中斜生栅藻的可见吸收光谱和生长曲线以及pH和暴露时间对藻生长的影响,同时应用该方法成功测定了环嗪酮、阿特拉津、西草净、扑灭通、苯嗪草酮、敌草快、草甘膦7种除草剂和磷胺、甲胺磷2种杀虫剂对斜生栅藻的剂量-效应曲线(DRC).通过对剂量-效应数据进行非线性最小二乘模拟,获得了这些农药的半数效应浓度EC50及置信区间.对比标准锥形瓶栅藻毒性试验,微板吸光法具有测试简便快速,所需样品体积少,便于多次平行毒性测试等优点.     

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%.     

Air concentrations of currently used herbicides and legacy compounds in the Canadian prairies,subarctic, and arctic

Passive air samplers were installed in the summers of 2005 and 2007 for 90 days at four locations in the agricultural region of the Canadian Prairies and at five locations in the Canadian Subarctic and Arctic. The presence and masses of ten currently used herbicides and three legacy compounds in the polyurethane foam disks were quantified. Herbicides 2,4-D, bromoxynil and MCPA were detected at all locations in the Canadian Prairies and in both years because these herbicides are widely applied to control broadleaf weeds in cereal crops that are an integral part of Prairie agricultural production systems. MCPA was also detected at one location in the Arctic in 2007. The detection of the other seven herbicides in the 2 years combined ranged from no detections (atrazine only) to five detections for the relatively volatile herbicides trifluralin and triallate. Triallate was the only other herbicide detected in the Arctic (2005). Legacy compounds were either not detected (alachlor) or at levels near their detection level (γ-HCH and α-HCH). γ-HCH and α-HCH were more frequently detected in 2005 than in 2007 indicating that their concentrations in Canadian air have decreased over time. γ-HCH, widely used as an insecticide in Prairie oilseed production until 2002, was detected at larger concentrations in the Canadian Prairies than in the Subarctic and Arctic. α-HCH, a manufacturing by-product in technical HCH prior to 1971 in Canada, was not detected in the Canadian Prairies but was at detectable levels in the Subarctic and Arctic as the Arctic Ocean is reported to be a major source of α-HCH to the atmosphere. We conclude that some of the most widely used herbicides in Canadian agriculture today are commonly present in the air in regions where they are applied and that a portion of these herbicides may be traveling as parent molecules to the Canadian Arctic. To the authors’ knowledge, this is the first evidence of the presence of MCPA and triallate in Arctic air samples, perhaps because previous research has seldomly monitored for currently used herbicides in this region.