气相色谱-火焰光度法测定土壤中有机磷农药残留

土壤样品用正己烷-丙酮(体积比为1∶1)混合溶液提取,配合硅胶小柱净化,用乙酸乙酯洗脱,再用气相色谱-火焰光度法测定待测液中14种有机磷农药残留,方法在0.100 mg/L~1.00 mg/L范围内线性良好,当取样量为10 g时,方法检出限为1.3μg/kg~2.3μg/kg。用该方法测定有机磷的有证标准溶液,结果均在保证值范围内,RSD为2.2%~6.7%。实际土壤样品的13种有机磷农药加标回收率为59.2%~125%(敌百虫除外),敌百虫回收率为0,说明目标物在测定过程中被降解,该方法不适用于敌百虫的测定。     

3种农药及其复配剂对日本鹌鹑的急性毒性比较

采用"经口灌胃法"测定了3种农药及其复配剂对鹌鹑的24 h、48 h、72 h和168 h急性毒性,根据我国《化学农药环境安全评价实验准则》中对鸟类的急性经口毒性划分的规定,3种农药及其复配剂对鹌鹑的毒性等级如下:35%精甲霜灵悬浮种衣剂对鸟类的24 h、48 h、72 h和168 h-LD_(50)均大于500 a.i.mg·kg~(-1)bw(以单位体重计),属"低毒"级,25 g·L~(-1)咯菌腈悬浮种衣剂对鸟类的24 h、48 h、72 h和168 h-LD_(50)也均大于500 a.i.mg·kg~(-1)bw,属"低毒"级,25%噻虫嗪水分散粒剂对鸟类的24 h、48 h、72 h和168 h-LD_(50)分别是695 mg·kg~(-1)bw、587 mg·kg~(-1)bw、502 mg·kg~(-1)bw、502 mg·kg~(-1)bw,属于"低毒"级;25%噻虫嗪·咯菌腈·精甲霜灵悬浮种衣剂对鸟类的24 h、48 h、72 h和168 h-LD_(50)分别是754 mg·kg~(-1)bw、504 mg·kg~(-1)bw、504 mg·kg~(-1)bw、504mg·kg~(-1)bw,也属于"低毒"级。     

3种农药对大型溞的急性毒性比较

采用"半静态法"测定了3种农药及其混剂对大型溞的24 h、48 h急性毒性,根据我国《化学农药环境安全评价实验准则》中的毒性等级标准,它们对大型溞的毒性等级如下:精甲霜灵悬浮种衣剂对大型溞的24 h、48 h-EC_(50)均大于10 a.i.mg·L~(-1),属"低毒"级,咯菌腈悬浮种衣剂对大型溞的24 h、48 h-EC_(50)分别是0.339 mg·L~(-1)、0.246 mg·L~(-1),根据0.1 a.i.mg·L~(-1)EC_(50)(48 h)≤1.0 a.i.mg·L~(-1)判断,属"高毒"级。嘧菌酯水分散粒剂对大型溞的24 h、48 h-EC_(50)分别是0.389 mg·L~(-1)、0.286 mg·L~(-1),根据0.1a.i.mg·L~(-1)EC_(50)(48 h)≤1.0 a.i.mg·L~(-1)判断,属"高毒"级。精甲霜灵·咯菌腈·嘧菌酯悬浮种衣剂对大型溞的24 h、48 h-EC_(50)分别是0.292 mg·L~(-1)、0.228 mg·L~(-1),根据0.1 a.i.mg·L~(-1)EC_(50)(48 h)≤1.0 a.i.mg·L~(-1)判断,属"高毒"级。精甲霜灵·咯菌腈·嘧菌酯悬浮种衣剂和嘧菌酯水分散粒剂都属"高毒",但比较具体数值,发现精甲霜灵·咯菌腈·嘧菌酯悬浮种衣剂毒性相对更大,原因是其中还含有"高毒"的咯菌腈。     

极性有机物整合采样技术在监测水环境中农药的应用

明确水环境中农残的污染状况对研究其环境行为和生态风险至关重要。传统主动采样法耗能、耗力且单次采样仅获得瞬时浓度值。被动采样节能、方便且为时间加权平均浓度,利于大规模采样。极性有机物整合采样技术(polar organic chemical integrative sampler,POCIS)是针对极性有机物的被动采样技术,近年来在水环境中农药监测的运用越来越广泛。本文概述了POCIS结构、原理和校正方法,探讨了环境因素(如水流速率、温度、p H、溶解性有机质、盐度和膜污染)、化合物性质及POCIS结构对农药采样速率(Rs)的影响。此外,综述了POCIS在监测水环境中农药的应用,展望了POCIS在该领域中的问题、解决方式及前景。     

长三角地区池塘养殖水产品体内农药类污染与食用风险评价

为了解池塘养殖水产品体内的农药污染情况,以便为水产品质量评价及保障当地居民的饮食健康提供科学依据,本研究采用气相色谱质谱联用法(GC-MS)对长三角地区13个养殖池塘中5类(蟹类、鳖类、蚌类、虾类、鱼类)水产品体内9种有机磷农药(OPPs)、8种有机氯农药(OCPs)以及4种拟除虫菊酯类农药(SPs)进行了检测,并初步分析了其污染来源。结果表明,水产品体内3类农药均有检出,但残留水平均不高,OPPs残留总量为未检出至299 ng·g-1(dw),三唑磷、伏杀硫磷、喹硫磷和毒死蜱较易在水产品体内蓄积;OCPs残留总量为16~82 ng·g-1(dw),主要污染物为六六六(HCHs),主要来自历史残留;SPs残留总量为44~89 ng·g-1(dw),主要污染物为高效氯氟氰菊酯。水产品体内的农药污染可能与养殖池塘中的沉积物污染密切相关。5类水产品体内3类农药的总风险指数(HI)为0.0020~0.046,远小于1,因此,长三角地区由3类农药造成的健康风险处于安全水平。     

南充农村土壤中有机氯农药残留现状分析

本研究以四川省南充市某农村土壤为研究对象,于2010年和2011年连续两年对土壤中有机氯农药(HCH,DDT)残留情况进行了定点监测。研究结果表明,试区土壤HCHs在2011年基本未检出。两年的DDTs的检出率均为100%。OCPs主要残留物为p,p’-DDE,占残留总量75%以上。不同利用类型土壤中有机氯残留总量排序为:菜地>重点污染场地>基本农田>居民聚集区。所有土壤样品中的HCHs含量均达到国家《土壤环境质量标准》(GB15618-1995)一级标准(<0.05mg/kg),DDTs含量均达到二级标准(<0.50mg/kg)。残留污染较轻。     

Determination of organochlorine pesticide residue in sediment and water from the Densu river basin, Ghana

The distribution of organochlorine pesticides in the aquatic ecosystem from the Densu river revealed varying levels of concentration in water and the sediment samples. Three locations were sampled along the river to evaluate the levels of organochlorine pesticide residue in the river. Sediment and surface water samples were extracted by soxhlet and liquid-liquid extraction respectively and analyzed using Gas Chromatograph coupled with electron capture detector. The detectable organochlorine pesticides were gamma-hexachlorocyclohexane (HCH), delta-hexachlorocyclohexane, heptachlor, aldrin and dieldrin. The other pesticides that were investigated are gamma-chlordane, alpha endosulfan, endosulfan sulfate, p,p′-DDT and its metabolite p,p′-DDE, methoxychlor, endrin and its metabolite endrin aldehyde and endrin ketone. The order of increasing frequency of detection of samples was higher in sediment than water. In sediment, the mean concentration ranged from 0.030 μg kg⁻¹ dry weight (endrin) to 10.98 μg kg⁻¹ dry weight (aldrin). The highest detected concentration of organochlorine in water was endosulfan sulfate with mean concentration of 0.185 μg L⁻¹. Analysis of variance indicated significant differences for most organochlorine pesticide residue in the sediment sampled from the various locations. Some of the levels of organochlorine pesticides detected in water were relatively high compared to guideline values set by World Health Organization and Australia and thus could be harmful if the trend is not checked.     

Heterogeneous reactions of suspended parathion, malathion, and fenthion particles with NO(3) radicals

Organophosphorus pesticides (OPPs) emit into the atmosphere in both gas and particulate phases via spray drift from treatments and post-application emission, but most of their degradations in the atmosphere are not well known. In this study, the heterogeneous reactions of nitrate (NO₃) radicals with three typical OPPs (parathion, malathion, and fenthion) absorbed on azelaic acid particles are investigated using an online vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS). The reaction products observed with the VUV-ATOFMS are identified on the basis of GC/MS analysis of the products in the reaction between NO₃ radicals and the coating of the pesticide. Paraoxon is identified as the only product of parathion; malaoxon and bis(1,2-bis-ethoxycarbonylethyl)disulfide as the products of malathion; fenoxon, fenoxon sulfoxide, fenthion sulfoxide, fenoxon sulfone, and fenthion sulfone as the products of fenthion. The degradation rates of parathion, malathion, and fenthion under the experimental conditions are 5.5 × 10⁻³, 5.6 × 10⁻², and 3.3 × 10⁻² s⁻¹, respectively. The pathways of the heterogeneous reactions between the three OPPs and NO₃ radicals are proposed. The experimental results reveal the possible transformations of these OPPs through the oxidation of NO₃ radicals in the atmosphere.     

Role of Riparian Areas in Atmospheric Pesticide Deposition and Its Potential Effect on Water Quality

Riparian buffers are known to mitigate hydrologic losses of nutrients and other contaminants as they exit agricultural fields. The vegetation of riparian buffers can also trap atmospheric contaminants, and these pollutants can subsequently be delivered via rain to the riparian buffer floor. These processes, however, are poorly understood especially for pesticide residues. Therefore, we conducted a four‐year study examining stemflow and throughfall to a riparian buffer which was adjacent a cultured Zea mays field treated with atrazine and metolachlor. Stemflow is rain contacting the tree canopy traveling down smaller to larger branches and down the tree trunk, whereas throughfall is rain that may or may not contact leaves and branches and reaches the earth. Stemflow concentrations of the herbicides were larger than throughfall concentrations and accounted for 5‐15% of the atrazine and 6‐66% of the metolachlor depositional fluxes under the canopy. Larger depositional fluxes were measured when leaves were more fully emerged and temperatures and humidity were elevated. Rain collected outside the riparian buffer on the field side and on the back side revealed the trees trapped the herbicide residues. Herbicide loading to the riparian buffer stream was found to be linked to tree canopy deposition and subsequent washoff during rain events. These results indicate that in agricultural areas canopy washoff can be an important source of pesticides to surface waters.     

ASE提取GPC净化双塔双柱气相色谱法测定土壤中有机氯农药

对土壤中8种有机氯农药(α-HCH、β-HCH、γ-HCH、δ-HCH、p,p’-DDE、p,p’-DDD、o,p’-DDT、p,p’-DDT)进行了分析,使用加速溶剂萃取(ASE)仪对土壤样品中的目标组分进行萃取、凝胶渗透色谱(GPC)仪对萃取液净化、双塔双柱同时进样分析,采用双电子捕获检测器(ECD)同时定性定量测定。结果表明,该方法检测效果较好,8种有机氯农药的回收率在81.3%～88.6%,相对标准偏差为3.9%～5.7%,检出限为0.18～0.37μg/kg。与传统的方法相比,该方法操作简便、重复性好,定性定量更准确。