Determination of organophosphorus pesticides in cucumber and potato by stir bar sorptive extraction

Organophosphorus pesticides (OPPs) in vegetables were determined by stir bar sorptive extraction (SBSE) and capillary gas chromatography with thermionic specific detection (TSD). Hydroxy-terminated polydimethylsioxane (PDMS) prepared by sol-gel method was used as extraction phase. The effects of extraction temperature, salting out, extraction time on extraction efficiency were studied. The detection limits of OPPs in water were <= 1.2 ng/l. This method was also applied to the analysis of OPPs in vegetable samples and matrix effect was studied. Linear ranges of OPPs in vegetable samples were 0.05-50 ng/g with detection limits <= 0. 15 ng/g and the repeatability of the method was less than 20% relative standard deviation. (c) 2005 Elsevier B.V. All rights reserved.

Detection of polybrominated diphenyl ethers in tilapia (Oreochromis mossambicus) from O'ahu, Hawai'i

Polybrominated diphenyl ethers (PBDEs) have been detected for the first time at a range from 231.58 to 685.61 ng g(-1) lipid weight in the muscles of tilapia ( Oreochromis mossambicus) collected from O'ahu, an island of the geographically isolated Hawaiian archipelago.

Body loadings and health risk assessment of polychlorinated dibenzo-p-dioxins and dibenzofurans at an intensive electronic waste recycling site in China

This study is one of the very few investigating the dioxin body burden of a group of child-bearing-aged women at an electronic waste (e-waste) recycling site (Taizhou, Zhejiang Province) (24 +/- 2.83 years of age, 40% were primiparae) and a reference site (Lin'an city, Zhejiang Province, about 245 km away from Taizhou) (24 +/- 2.35 years of age, 100% were primiparae) in China. Five sets of samples (each set consisted of human milk, placenta, and hair) were collected from each site. Body burdens of people from the e-waste processing site (human milk, 21.02 +/- 13.81 pg WHO-TEQ(1998/g) fat (World Health Organization toxic equivalency 1998); placenta, 31.15 +/- 15.67 pg WHO-TEQ(1998/g) fat; hair, 33.82 +/- 17.74 pg WHO-TEQ(1998/g) dry wt) showed significantly higher levels of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurnas (PCDD/Fs) than those from the reference site (human milk, 9.35 +/- 7.39 pg WHO-TEQ(1998/g) fat, placenta, 11.91 +/- 7.05 pg WHO-TEQ(1998/g) fat; hair, 5.59 +/- 4.36 pg WHO-TEQ(1998/g) dry wt) and were comparatively higher than other studies. The difference between the two sites was due to e-waste recycling operations, for example, open burning, which led to high background levels. Moreover, mothers from the e-waste recycling site consumed more foods of animal origin. The estimated daily intake of PCDD/Fs within 6 months by breast-fed infants from the e-waste processing site was 2 times higher than that from the reference site. Both values exceeded the WHO tolerable daily intake for adults by at least 25 and 11 times, respectively. Our results implicated that e-waste recycling operations cause prominent PCDD/F levels in the environment and in humans. The elevated body burden may have health implications for the next generation.

Determination of 266 pesticide residues in apple juice by matrix solid-phase dispersion and gas chromatography-mass selective detection

A macro matrix solid-phase dispersion (MSPD) method was developed to extract 266 pesticides from apple juice samples prior to gas chromatography-mass selective detection (GC-MSD) determination. A 10 g samples was mixed with 20 g diatomaceous earth. The mixture was transferred into a glass column. Pesticide residues were leached with a 160 mL hexane-dichloromethane (1:1) at 5 mL/min. Two hundred and sixty-six pesticides were divided into three groups and detected by GC-MSD under selective ion monitoring. The proposed method takes advantage of both liquid-liquid extraction and conventional MSPD methods. Application was illustrated by the analysis of 236 apple juice samples produced in Shaanxi province China mainland this year. (C) 2004 Elsevier B.V. All rights reserved.

Toxicity of cypermethrin to Daphnia magna HB

The acute toxic effect of the pesticide cypermethrin to Daphnia magna HB was examined. D. magna HB was exposed to cypermethrin at concentrations of 0, 1, 3, 5, 7, and 9 mg/L for 24 In. Data showed that the 24 h-LC50 of cypermthrin on D. magna HB was 4.81 mg/L. In contrast, the 24 h-LC50 of K2Cr2O7 (the national standard toxicant) to Daphnia magna was 0.38 mg/L in the current study. Results indicated that the Daphnia magna was very sensitive to pesticides. In addition, the effects of the culture condition(such as hardness, temperature and DO etc.) on Daphnia magna HB was also studied.

Cloning of biologically active genomes from a Helicoverpa armigera single-nucleocapsid nucleopolyhedrovirus isolate by using a bacterial artificial chromosome

Purification of genotypes from baculovirus isolates provides understanding of the diversity of baculoviruses and may lead to the development of better pesticides. Here, we report the cloning of different genotypes from an isolate of Helicoverpa armigera single-nucleocapsid nucleopolyhedrovirus (HaSNPV) by using a bacterial artificial chromosome (BAC). A transfer vector (pHZB10) was constructed which contained an Escherichia coli mini-F replicon cassette within the upstream and downstream arms of HaSNPV polyhedrin gene. Hz2e5 cells were co-transfected with wild-type HaSNPV DNA and pHZB10 to generate recombinant viruses by homologous recombination. The DNA of budded viruses (BVs) was used to transform E. coli. One of the bacmid colonies, HaBacHZ8, has restriction enzyme digestion profiles similar to an in vivo cloned strain HaSNPV-G4, the genome of which has been completely sequenced. For testing the oral infectivity, the polyhedrin gene of HaSNPV was reintroduced into HaBacHZ8 to generate the recombinant bacmid HaBacDF6. The results of one-step growth curves, electron microscopic examination, protein expression analysis and bioassays indicated that HaBacDF6 replicated as well as HaSNPV-G4 in vitro and in vivo. The biologically functional HaSNPV bacmids obtained in this research will facilitate future studies on the function genomics and genetic modification of HaSNPV. (C) 2003 Elsevier B.V. All rights reserved.

Environmental threats to children's health in Southeast Asia and the Western Pacific

The Southeast Asia and Western Pacific regions contain half of the world's children and are among the most rapidly industrializing regions of the globe. Environmental threats to children's health are widespread and are multiplying as nations in the area undergo industrial development and pass through the epidemiologic transition. These environmental hazards range from traditional threats such as bacterial contamination of drinking water and wood smoke in poorly ventilated dwellings to more recently introduced chemical threats such as asbestos construction materials; arsenic in groundwater; methyl isocyanate in Bhopal, India; untreated manufacturing wastes released to landfills; chlorinated hydrocarbon and organophosphorous pesticides; and atmospheric lead emissions from the combustion of leaded gasoline. To address these problems, pediatricians, environmental health scientists, and public health workers throughout Southeast Asia and the Western Pacific have begun to build local and national research and prevention programs in children's environmental health. Successes have been achieved as a result of these efforts: A cost-effective system for producing safe drinking water at the village level has been devised in India; many nations have launched aggressive antismoking campaigns; and Thailand, the Philippines, India, and Pakistan have all begun to reduce their use of lead in gasoline, with resultant declines in children's blood lead levels. The International Conference on Environmental Threats to the Health of Children, held in Bangkok, Thailand, in March 2002, brought together more than 300 representatives from 35 countries and organizations to increase awareness on environmental health hazards affecting children in these regions and throughout the world. The conference, a direct result of the Environmental Threats to the Health of Children meeting held in Manila in April 2000, provided participants with the latest scientific data on children's vulnerability to environmental hazards and models for future policy and public health discussions on ways to improve children's health. The Bangkok Statement, a pledge resulting from the conference proceedings, is an important first step in creating a global alliance committed to developing active and innovative national and international networks to promote and protect children's environmental health.

Xenobiotics removal from polluted water by a multifunctional constructed wetland

Removal efficiencies on xenobiotics from polluted water in a twin-shaped constructed wetland consisting of a vertical flow chamber with the crop plant Colocasia esculenta L. Schott and a reverse vertical flow one with Ischaemum aristatum var. glaucum Honda, were assessed by chemical analysis and bioassays. After a four-month period of application, removal efficiencies of the applied pesticides parathion and omethoate were 100%, with no detectable parathion and omethoate in the effluent. For the applied herbicides, the decontamination was less efficient with removal efficiencies of 36% and 0% for 4-chloro-2-methyl-phenoxyacetic acid and dicamba, respectively. As shown by toxicity assay with duckweed Lemna minor L., growth retardation may occur if the water treated for herbicide removal is used in irrigation of sensitive cultivars in agriculture or horticulture. In contrast to I. aristatum var. glaucum Honda, the crop C esculenta L. Schott has a high yield in biomass production as a valuable source of renewable energy. (C) 2002 Elsevier Science Ltd. All rights reserved.

Analysis of organchlorine compounds in water by solid phase microextraction and gas chromatography

In this work, both,solid phase microextraction (SPME) and solid phase extraction(SPE) were used to enrich organochlorine compounds in water samples and analyzed by gas chromatography with electron capture detector. The operating conditions of SPME have been studied and different kinds of solid phase were compared. Linear alkybenzene sulfonate(LAS) was added to the samples to investigate its effect on the analysis. The results indicated that polyacrylate was better than other commercial solid phases in extraction of moderated polar organic compounds and the sensitivity of SPME was higher than SPE. LAS affect much in liquid-liquid extraction and headspace SPME; but it has little effect on SPE and direct-SPME method. The applications showed that SPME was a fast and effective method in sample preparation.

草甘膦的土壤酶效应研究

为了探讨当今世界使用量最大的除草剂——草甘膦的土壤环境效应,本文采用室内模拟方法,较为系统地研究了我国4类土壤:褐土、黄绵土、风沙土和红壤,共11个土样中4种主要酶类(脲酶、转化酶、磷酸酶以及脱氢酶)活性与草甘膦间的关系,计算并得到了能够表征土壤轻度污染的生态剂量值ED10。结果表明:非缓冲液法较好地反映了土壤酶的实际情况;草甘膦总体上激活土壤脲酶、转化酶和脱氢酶活性,最大增幅分别为190%、1372%和42%;抑制磷酸酶活性,最大幅度为35%;磷酸酶与草甘膦间为完全抑制作用机理;激活脱氢酶活性揭示出草甘膦导致了土壤中微生物活性增强,从侧面反映出草甘膦是一种毒性较低的农药。计算获得4类供试土壤褐土、黄绵土、风沙土和红壤ED10值分别为168.3、438.5、35.1和141.4mg·kg-1;在一定程度上用土壤酶活性比生物来表征土壤污染程度更敏感。土壤性质对草甘膦的毒性有重要影响。

辽北农田土壤农药残留特征及其对农产品安全影响

农药对产地环境，特别是对土壤的广泛污染严重威胁农产品安全和人类健康。因此，本文采用建立的除草剂和有机氯农药（OCPs）残留分析方法，开展了辽北地区土壤农药残留特征、阿特拉津和乙草胺田间消解动力学、土壤农药残留对农产品安全影响等方面研究。主要研究结果如下： 1. 分别建立了土壤、大米、蔬菜、玉米中3种除草剂和8种OCPs多残留分析方法。方法检出限介于0.04~1.30 ng•g-1之间；11种农药在0.01 (0.02)~1.0 (2.0) mg•L-1范围内线性良好，相关系数介于0.9963-0.9998之间；平均回收率介于71%-117%之间、相对标准偏差小于14.4%。 2. 阿特拉津和乙草胺在辽北农田土壤普遍残留；丁草胺、六氯苯、狄氏剂和艾氏剂在部分土壤有残留；乙草胺和丁草胺相对其它农药残留较高；阿特拉津、六氯苯、狄氏剂和艾氏剂残留量与相关报道和标准相比较低。除艾氏剂外，检出农药残留量经Box-Cox变换后，均服从正态分布。阿特拉津、乙草胺、丁草胺、六氯苯在不同土壤利用类型之间存在显著差异（P<0.05）。 3. 玉米地土壤中阿特拉津和乙草胺消解动态符合一级反应动力学模式，阿特拉津消解半衰期在12.2~59.8d之间，乙草胺在18.5~54.6d之间。喷施地阿特拉津和乙草胺消解速率约为对照地的2~5倍，且喷施量越大，消解越快。 4. 11种农药在辽北蔬菜、大米、玉米中残留较低，仅阿特拉津、六氯苯、乙草胺和丁草胺在部分农产品中有残留，其在土壤中残留通过蔬菜、大米和玉米给消费者带来的总膳食风险较低。大田试验进一步说明在试验区域喷施4倍最大推荐剂量阿特拉津或乙草胺也不会对玉米安全产生影响。

铜-农药污染的土壤生态化学脱毒行为研究

通过开展Cu与农药甲胺磷、草甘嶙吸附／解吸试验、Cu和甲胺磷的大豆根际行为试验，以及农药脱毒生态化学指示（土壤酶、有效P）试验，对东北地区典型土壤—黑土与棕壤污染物的化学脱毒行为进行研究，为东北地区农业清洁生产提供理论参考。污染物的吸附／解吸行为是土壤物理化学脱毒的体现。试验结果表明，Cu2＋的吸附／解吸等温线与Freundiich方程有较好的拟合性。黑土对cu2＋的吸附脱毒能力高于棕壤，且解吸率更低。Cu2＋的解吸量与吸附量之间呈二次幂函数关系。描述Cu2＋吸附／解吸动力学过程的最优模型为双常数方程。两种农药在土壤原胶体及去有机质土壤上的吸附仍符合Freundllch方程，但有机质去除后吸附量大为降低。无机矿物是甲胺磷吸附的主要载体，而有机质对草甘麟的吸附脱毒则更为重要。在土壤一农药-Cu2＋共存体系中，Cu2+的吸附量降低，解吸量增加。由于较强的络合能力，草甘麟对Cu2+吸附确军吸行为的影响大于甲胺磷。根际和土壤酶通过生物化学机制对污染物进行脱毒。大豆根系通过将Cu2＋转化为铁锰氧化物结合态和有机质结合态而减少吸收。同时，甲胺磷在大豆根际环境中的降解速率显著加快。土壤脱氢酶对农药反应敏感，多数情况表现出抑制作用。酸性磷酸酶在甲胺磷加入初期被刺激，随后被部分抑制；随着草甘磷浓度的升高，酸性磷酸酶的抑制作用增强。农药的施入增加了土壤有效P含量，但对有效P的贡献率仍较低。

Preparation of stir bars for sorptive extraction using sol-gel technology

A sol-gel coating method for the preparation of extractive phase on bars used in sorptive microextraction is described. The extraction phase of poly(dimethylsiloxane) is partially crosslinked with the sol-gel network, and the most part is physically incorporated in the network. Three aging steps at different temperatures are applied to complete the crosslinking process. Thirty-micrometer-thick coating layer is obtained by one coating process. The improved coating shows good thermal stability up to 300degreesC. Spiked aqueous samples containing n-alkanes, polycyclic aromatic hydrocarbons and organophosphorus pesticides were analyzed by using the sorptive bars and GC. The results demonstrate that it is suitable for both aploar and polar analytes. The detection limit for chrysene is 7.44 ng/L, 0.74 ng/L for C-19 and 0.9 ng/L for phorate. The extraction equilibration can be reached in less than 15 min by supersonic extraction with the bars of 30 mum coating layer. (C) 2004 Elsevier B.V. All rights reserved.