大气中有机氯农药分析方法研究

采用GC-ECD标准曲线法测定大气中17种有机氯农药,采用索氏提取、旋转蒸发仪和氮吹仪浓缩前处理方法,测定空白加标精密度、准确度,样品加标精密度、准确度和方法检出限,结果表明大气中空白加标精密度、准确度分别在7.4～19.5%和81.7～114%之间,检出限在0.06～0.23 ng/m3之间。     

Comparison of Two Parametric Methods to Estimate Pesticide Mass Loads in California’s Central Valley1

Saleh, Dina K., David L. Lorenz, and Joseph L. Domagalski, 2010. Comparison of Two Parametric Methods to Estimate Pesticide Mass Loads in California’s Central Valley. Journal of the American Water Resources Association (JAWRA) 00(0):1‐11. DOI: 10.1111/j.1752‐1688.2010.00506.x Abstract: Mass loadings were calculated for four pesticides in two watersheds with different land uses in the Central Valley, California, by using two parametric models: (1) the Seasonal Wave model (SeaWave), in which a pulse signal is used to describe the annual cycle of pesticide occurrence in a stream, and (2) the Sine Wave model, in which first‐order Fourier series sine and cosine terms are used to simulate seasonal mass loading patterns. The models were applied to data collected during water years 1997 through 2005. The pesticides modeled were carbaryl, diazinon, metolachlor, and molinate. Results from the two models show that the ability to capture seasonal variations in pesticide concentrations was affected by pesticide use patterns and the methods by which pesticides are transported to streams. Estimated seasonal loads compared well with results from previous studies for both models. Loads estimated by the two models did not differ significantly from each other, with the exceptions of carbaryl and molinate during the precipitation season, where loads were affected by application patterns and rainfall. However, in watersheds with variable and intermittent pesticide applications, the SeaWave model is more suitable for use on the basis of its robust capability of describing seasonal variation of pesticide concentrations.     

降尘中多溴联苯醚及有机氯农药的分析方法

利用硅胶吸附色谱和凝胶渗透色谱结合净化的方法,实现了对降尘中有机氯农药和多溴联苯醚的同时分离净化,有效地避免了降尘中干扰物质对有机氯农药和多溴联苯醚检测时产生的干扰.在优化的条件下,浮尘样本中有机氯农药和多溴联苯醚的添加回收率分别在65.8%—115%和58.6%—112%之间,检测限分别在0.002—0.011 n·...     

8种中药提取物对植物病原真菌的抑制活性

研究目的是改良植物源杀菌剂的筛选思路,降低植物源农药的毒残留,寻找效果较持久的植物源杀菌剂.通过筛选提取常见且具有强抗逆性的植株如柳、盐肤木等植物叶中活性抑菌成分,寻找低毒持效的杀菌剂.从试验数据分析得出,在粗提物质量浓度为50mg/mL时,连翘、盐肤木对3种供试植物病原菌抑制效果显著,抑制率均在65%以上,柳叶、马尾松针、臭椿、茵陈蒿的粗提物对至少两种植物病原菌的菌丝生长速率抑制率在50%以上;香槐和枫杨叶活性较低,仅对其中一种病原菌活性达到50%;柳叶、马尾松针、臭椿叶对两种病原菌气生菌丝的生长状况具有明显的抑制作用;盐肤木粗提物的抑制作用具有较好的延续性,因此连翘、盐肤木作为植物源杀菌剂具有深入研究的价值.     

细胞色素P450酶代谢新烟碱类农药N-脱烷基反应的机制研究：以噻虫嗪为例

生物转化是影响有机污染物毒性的重要过程,细胞色素P450酶在其中起着关键作用.新烟碱类农药对于哺乳动物毒性较低,但是经过P450酶的转化后,可能会产生毒性增强的代谢产物,提高环境和健康风险.本研究以噻虫嗪（TMX）为例,采用计算模拟的方法研究P450酶催化下TMX的代谢路径和产物,探讨该类污染物N-脱烷基的反应机制.计算结果表明,P450酶代谢TMX有两条不同路径：一条是经过两次O-亚甲基羟基化后通过水桥开环生成毒性减小的噻虫胺（CLO）;另一条是通过氢提取/羟基反弹羟基化甲基的过程,然后经水桥转移氢质子发生N-脱甲基反应,生成去甲基噻虫嗪（dm-TMX）,据前人实验报道该产物会导致肝肿瘤发生率的增加,具有明显的健康风险.鉴于其他烷基胺类化合物具有类似的代谢机理,进一步通过C—H键解离能(BDE_C-H)与氢提取反应的活化能（ΔE^*）建立了N-脱烷基化反应活性的预测模型,R²=0.932,平均绝对误差MAE=1.75 kcal·mol^-1,模型的稳健性良好,可以快速有效地为该类污染物的代谢活性研究提供...     

太原市污灌区有机氯农药垂直分布特征及源解析

采用气相色谱-电子捕获检测器（GC-ECD）方法分析了太原市小店污灌区9个土壤剖面中有机氯农药（OCPs）的垂直分布特征.结果表明,OCPs主要积累在土壤上层0～30 cm,含量最大值为98.56 ng·g-1,其中六六六（HCHs）、滴滴涕（DDTs）、硫丹（endosulfans）和甲氧滴滴涕（methoxychlor）为主要污染物质,占总有机氯农药的85.1%,其它有机氯农药物质相对含量较少.绝大部分剖面土中OCPs含量随着深度增加而明显减少,β-HCH和DDE（o,p＇-DDE＋p,p＇-DDE）在HCH农药和DDT农药中占主要成分.组分分析表明,清灌区和沼泽区中最近可能有新的DDT源输入,其它剖面土中HCH和DDT主要来自历史使用残留.研究区内绝大部分土壤为粉砂壤土;污灌区和清灌区中ΣOCPs含量与总有机碳（TOC）均表现出明显正相关性,但沼泽区和背景点与TOC相关性不显著.     

含13种有机氯农药土壤标准样品的研制

采用分级稀释混合法将来自不同采样点的含不同种类和浓度的有机氯农药(OCPs)的样品进行混合制得含13种OCPs的土壤标准样品。根据GB/T 15000《标准样品工作导则》系列标准对土壤标准样品进行均匀性检验、稳定性检验,并和16家实验室协作定值。实验结果表明:土壤标准样品中13种OCPs指标均匀性良好,保证土壤标准样品足够均匀的最小取样量为0.50 g;在室温(不超过30℃)避光贮存条件下,在为期12个月的稳定性检验期间,该土壤标准样品中13种OCPs稳定性良好。该土壤标准样品中13种OCPs指标的含量范围为0.08~5.23μg/g,扩展不确定度为0.014~0.82μg/g,基本满足我国土壤、沉积物等环境样品中OCPs的质量控制检测需求。     

一体式粉末活性炭-微滤组合工艺的除污染效能

研究了一体式粉末活性炭-微滤(PAC-MF)组合工艺对有机物、农药和氨氮的去除效果,并量化了粉末活性炭-微滤工艺中PAC、微生物和MF分别对去除污染物的贡献.结果表明,PAC-MF组合工艺对TOC、UV254、以及THMFP和HAAFP的平均去除率分别为73.56%、96.75%、77.64%、83%,对敌敌畏的平均去除率为95.1%,对氨氮的平均去除率可达98%.粉末活性炭-微滤工艺中,活性炭能够使膜的有机负荷降至膜直接过滤工艺的28.32%,膜表面的炭层对污染物有去除作用;活性炭在一次性高浓度的投加方式下,可以提高活性炭对氨氮的吸附作用,使对氨氮的去除率达44.5%.     

Concentration and fate of persistent organochlorine pesticides in estuarine sediments using headspace solid-phase microextraction

The concentration and fate of persistent organochlorine pesticides (OCPs) in estuarine surface sediments in Erh-jen and Lan-yang rivers, Taiwan were investigated using headspace solid-phase microextraction (HSSPME) method to evaluate the possible pollution potential and guideline for OCP concentrations in Taiwan. The HSSPME method exhibits a good analytical performance with low detection limits for OCP determination in sediment. In addition, results obtained using the developed HSSPME method were in good agreement with those obtained using Soxhlet extraction in a certified sample. The developed analytical method was further applied to the determination of concentrations of OCP residues in surface sediments from the estuaries of the selected rivers in Taiwan. A total of 20 surface sediments from each river was collected from 10 sampling stations. The total OCP concentrations in sediments from Erh-jen River ranged from 0.17 to 5.04 ng/g-dw with the mean values of 0.25–1.24 ng/g-dw for HCHs, 0.10–0.89 ng/g-dw for cyclodienes and 0.16–0.64 ng/g-dw for DDTs. The concentrations of OCPs in sediments from Lan-yang River were in the range 0.37–0.9 ng/g-dw with an average of lower than 0.5 ng/g-dw. HCHs and DDTs were abundant in the estuarine sediments from the selected rivers. Results obtained in this study show that the origin of OCPs in the surface sediments from Erh-jen River is a combination of erosion of the weathered soils and long-range atmospheric transport, while the OCP concentrations found in Lan-yang River could be regarded as the background levels of OCPs in Taiwan.     

Organochlorine pesticides in the ambient air of Chiapas, Mexico

Organochlorine (OC) pesticides were measured in the ambient air of Chiapas, Mexico during 2000-2001. Concentrations of some OC pesticides (DDTs, chlordanes, toxaphene) were elevated compared with levels in the Great Lakes region, while those of other pesticides were not (hexachlorocyclohexanes, dieldrin). While this suggests southern Mexico as a source region for the former group of chemicals, comparably high levels have also been reported in parts of the southern United States, where their suspected sources are soil emissions (DDTs, toxaphene) and termiticide usage (chlordane). Ratios of p,p'-DDT/p,p'-DDE and trans-chlordane/cis-chlordane/trans-nonachlor (TC/CC/TN) in Chiapas suggest a mixture of fresh and weathered sources, while congener profiles of toxaphene suggest emission of old residues from soils. This is supported by air parcel back trajectory analysis, which indicated that air masses over Chiapas at the time of sampling had previously passed over areas of continuing or recent use of some OC pesticides as well as areas of past use.