961 resultados para pesticide contaminants
Resumo:
Accumulation and distributions of aliphatic and polyaromatic hydrocarbons (PAHs) and heavy metals were measured in tissues of the clam Ruditapes philippinarum collected from 5 sites in Jiaozhou Bay, Qingdao, China. The concentrations of total aliphatic hydrocarbon and PAHs ranged from 570 to 2 574 ng/gdw (gram dry weight) and from 276 to 939 ng/gdw, in the most and least polluted sites, respectively. The bio-accumulation of hydrocarbons and PAHs in the clams appeared to be selective. Aliphatic hydrocarbons were predominantly represented by short chain (< nC(23)) n-alkanes, suggesting that petroleum hydrocarbons were likely the major contamination source. The selective uptake of 3 and 4 ring PAHs, such as naphthalene, fluorene, phenanthrene, fluoranthene and pyrene, by the clams was probably related to the physiological and bio-kinetic processes that were energetically favorable for uptake of compounds with fewer rings. Accumulation of the metals Cd, Cu, Zn, Pb, Cr, Hg, and As in the clam tissues also showed high variability, ranging from 0.043 to 87 A mu g/gdw. Among the 7 detected metals, Zn, Cd, Cu, and As had a particularly high potential of accumulation in R. philippinarum. In general, a positive correlation was found between the tissue concentrations and sediment concentrations of hydrocarbons and of some metals. Our study suggests that moderate contamination with polyaromatic hydrocarbons, and low to moderate contamination with metals, currently exists for clam R. philippinarum in Jiaozhou Bay, in comparison with other regional studies. A long-term monitoring program is certainly needed for assessment of the potential ecological influence and toxicity of these contaminants of R. philippinarum in Jiaozhou Bay.
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Organochlorine contaminants including 12 polychlorinated biphenyl (PCB) congeners and 18 insecticides were determined in water, pore water and sediments of the Jiulong River Estuary and Western Xiamen Sea, China. The results showed that the levels of the total PCBs ranged from non-detectable to 1500 ngl(-1) in water, from 209 to 3870 ngl(-1) in pore water, and from 2.78 to 14.8 ng g(-1) dry weight in sediments. Total organochlorine insecticide concentrations were from below the limit of detection to 2480 ngl(-1) in water, from 267 to 33400 ngl(-1) in pore water, and from 4.22 to 46.3 ng g(-1) dry weight in sediments. Concentrations of PCBs and insecticides in pore water were significantly higher than those in surface water, due to the high affinity of these hydrophobic compounds for sediment phase. The PCB congeners with the highest concentrations were CB153, CB180 and CB194, which together accounted for 68-87% of total PCBs in water, pore water and sediment. Among the hexachlorocyclohexane (HCH) compounds, beta-HCH was found to be a major isomer. Analysis of 1,1,1-trichloro-2,2-bis-chlorophenyl-ethane (DDT) and its metabolites showed that 1, 1-dichloro-2[o-chlorophenyl]-2[p-chlorophenyl]-ethylene (DDE) was dominant in the group. In comparison to a 1998 study in the Western Xiamen Sea, levels of organochlorines were enhanced due probably to recent inputs and changes in sediments. (c) 2004 Elsevier Ltd. All rights reserved.
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To analyze and evaluate the status of organochlorine pollutants in the Changjiang (Yangtze River) estuary and adjacent waters, the concentrations of hexachlorocyclohexane (HCHs) and dichlorodiphenyltrichloroethane (DDTs) in shellfish collected in study area from 2006 to 2007 were determined with gas chromatography (GC). The concentration range of HCHs was (ND-12.13)x10(-3) mg/kg wet weight and averaged at 0.54x10(-3) mg/kg while the concentration of DDTs was in the range of (4.06-281.73) x10(-3) mg/kg with a mean of 57.52x10(-3) mg/kg in the survey areas. The concentrations of DDTs in the shellfish were higher than HCHs', so that DDTs could be considered as typical organochlorine pollutants in the areas. The concentrations of DDTs in the shellfish were higher than HCHs', so that DDTs could be considered as typical organochlorines pollutants. The HCHs in all the shellfish conformed to the first level of criterion (0.02 mg/kg) of the Marion Biology Quality (GB 18421-2001), and that of DDTs in most samples were beyond the first level (0.01 mg/kg) but conformed to the second level (0.10 mg/kg). On average, alpha-HCH and delta-HCH occupied the most part of HCHs, while O,P'-DDT and P,P'-DDT occupied the most part of DDTs. The concentrations of organocholorine pesticides in shellfish samples varied in site and in species. The highest level occurred at the Shengsi (SS), followed by Yangkougang (YKG), Lvsi (LS), Dongyuan (DY) and Beibayao (BBY), low concentrations were observed at Changsha (CS), Beidaodi (BDD), and Gouqi (GQ). The concentration of HCHs and DDTs in most sites decreased clearly from 2006 to 2007 except for YKG, DY, BDD, LYS, and SS. All of above results suggested that the study area was slightly affected by organochlorine pesticide, special by DDTs.
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Six domestic yaks aged 6 years, comprising three culling male and three culling female yaks, from the Qinghai Lake area and three male semi-wild yaks aged 6 months from Datong Yak Farm were used to detect the levels of amino acids, mineral elements, residual heavy metals and pesticides in yak meat. The results showed that there was little difference in amino acid levels for different types of yak by age and sex. The meat of the adult male yak was 7.35 mg/kg higher in calcium (P < 0.05) and 124 mg/kg higher in phosphorus (P < 0.01) than that of the adult female yak. There was an obvious difference in zinc content, and there was also a significant difference for copper and sulfur between adult male and female yaks (P < 0.01). Iron was 8.85 mg/kg higher in semi-wild yaks than in domestic yaks, but there were no differences for other minerals. The levels of residual heavy metals and residual pesticides were well within those allowed by the National Standard of China. Furthermore, the data showed that introducing wild yak's blood did not result in a quality change in the domestic yak meat. Yak meat from Qinghai Plateau has the characteristics of being non-polluted and rich in amino acids in comparison with local yellow cattle meat.
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A series of significant oil-gas exploration progresses have been achieved in Nanpu depression with 1.02 billion ton oil-gas reserves have been proven. It has been confirmed that Nanpu beach has a geologic condition to be a major field based on exhaustive research. This finding, which is integrated reservoir,great reserves, thick oil layer and high productivity in Nanpu depression, is the most excited success in Chinese oil-gas exploration in recent years. This abundant oilfield found is significant to the strategy of oil production stability in the east of China. Nanpu depression exploration is also a crucial exploration project for Petrochina. Based on the comprehensive research on Nanpu formation testing data, we reevaluate and analyze the reservoir property and the structure characteristics, and propose a series of testing technique that are suitable for Jidong oil field development. The results are summarized as follows: 1. The reservoir parameters and characters are defined by formation test data interpretation and systemic dynamic-static data comparison. 2. Based on sources analysis and statistical research related to formation contaminants, some technique measures, which can not only prevent or reduce invasion damage for different formations but also can effectively improve completion efficiency, are proposed. 3. By selecting the testing pressure drawdown, optimum working regulation and flow /shut-in duration, and adopting dynamic-static flow parameters correlation analysis to predict production, an optimum research on working regulation and flow /shut-in duration was accomplished. Optimization formation test principles suitable for any kinds of Nanpu oilfield are established, which can improve test quality, construction efficiency and data recording quality. 4. By reasonable selection of perforating gun and penetrating charge, the perforation penetration has been improved effectively and the flow channel of the oil gas have been expanded, so that the communication between formations and the wellbore is improved better. 5. One joint working procedure which combining formation test, perforation, unloading and stimulation treatment has become the dominant testing technology in the Nanpu offshore Oilfield. This combination technique can implement several procedures using one pipe string, and achieve rapid testing purpose.
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天然溶解有机质(natural dissolved organic matter,DOM)是由动植物残体经过复杂的物理、化学和生物过程形成的高分子有机混合物,它广泛分布于水体、土壤和沉积物中。DOM的结构十分复杂,分子量从几百到几十万不等,元素组成和化学结构随时空和来源不同而变化。腐殖物质是DOM的主要组成部分,以溶解有机碳计约占DOM总量的50%~80%。腐殖物质可以分为:富里酸(fulvic acid, FA任何pH值条件下都溶于水),腐殖酸(humic acid,HA在pH 1时不溶于水)和胡敏素(humin,任何pH条件下都不溶于水)。 DOM能影响许多生物地球化学过程。例如DOM是一个重要的碳汇,它能影响微生物的食物链和全球碳循环;DOM和营养元素含量、食物链结构等一起决定水生生态系统的属性和发展动态;它还能吸收自然光,从而影响紫外线在水中的穿透能力和浮游植物的光合作用;DOM含有多种弱酸和弱碱官能团,是天然水体pH的调节剂和控制因素;DOM和痕量金属离子或有机污染物发生作用,从而影响它们的形态、毒性、迁移转化和生物有效性;在饮用水消毒过程中,DOM能生成致癌物三卤甲烷和其它消毒副产物。 天然水体中的痕量金属离子(如Cu2+和Hg2+)主要以DOM络合态存在。在海水中DOM控制铜的主要存在形态;在淡水中 90%以上的铜离子与DOM发生配位。通过配位作用DOM能抑制浮游生物对Hg的吸收,增加鱼类对Hg的蓄积。目前,人们对金属离子在环境中的迁移转化机理的理解还不够深入,尤其是对有机质参与下的有毒重金属循环还缺乏必要地认识。条件稳定常数是描述重金属离子与DOM配位能力的基本参数。前人运用多种手段对DOM与金属离子的结合能力进行了研究,主要包括:离子选择性电极法、溶出伏安法、超滤及荧光淬灭滴定法等。紫外吸收滴定法可用于研究单一有机化合物和金属离子的相互作用,在这一领域的应用尚未报道。本文首次将紫外吸收滴定法应用于测定DOM与Cu2+和Hg2+的条件稳定常数。实验表明紫外吸收滴定法迅速、简便、可望成为研究DOM和痕量金属离子相互作用的有力工具。 药品和个人护理品(pharmaceuticals and personal care products,PPCPs)在环境中普遍存在。有证据表明,环境中的有些PPCPs能对生物体产生影响,如改变生物体的性别比例,影响植物生长,动物幼虫的孵化,甚至具有明显的致畸效应。卡马西平(Carbamazepine,CBZ)是一种常用的抗癫痫、止痛药物和抗抑郁药。毒理学实验表明,环境中的CBZ能严重影响鱼、蚌等水生生物的免疫和循环系统。CBZ使用量大,在环境中含量高,在地下水渗透过程和常规污水处理中保持稳定,因此CBZ成为衡量人类活动和污水处理工艺效率的标志物。但是目前人们对CBZ的环境地球化学循环知之甚少。DOM能与许多有机污染物发生相互作用,从而影响它们的生物环境地球化学行为,但DOM对CBZ的影响尚未见报道。本论文利用三维荧光光谱技术和同步荧光光谱技术,研究了DOM与CBZ的结合强度、结合类型、影响因素,并且初步总结了DOM对CBZ环境地球化学循环的影响。为理解其它PPCPs的生物地球化学循环,预测它们的迁移转化、归宿和环境毒性提供参考。 本文运用紫外吸收滴定法和荧光淬灭滴定法研究了不同来源的DOM和金属离子(Cu2+和Hg2+)的相互作用,运用三维荧光光谱法和同步扫描荧光光谱法研究了DOM和卡马西平的相互作用。主要成果简述如下: 1、本文首次将紫外吸收滴定法应用于测定金属离子和DOM的条件稳定常数,结果表明紫外吸收滴定法操作更简便、测定迅速、仪器普及率高,可在DOM含量很低(约10-5 ~ 10-7 mol/L)的情况下也可以直接进行测定,不必进行复杂的预富集。可望成为DOM和痕量有毒重金属离子相互作用的有力工具。 2、重金属离子(Hg2+和Cu2+)与DOM的羧基和酚羟基等基团配位。配位后电子的离域性增加,导致紫外吸收增加。与此同时配位后分子极性的改变和铜离子顺磁性作用,引起DOM荧光淬灭。在Cu2+和Hg2+的滴定过程中,紫外吸光度和荧光强度之间呈极显著线性负相关关系(R2=0.99,P<0.001)。这说明荧光和紫外从不同侧面揭示了DOM和金属离子的配位作用。 3、紫外吸收滴定法和荧光淬灭滴定法测定其条件稳定常数(log K)一致,介于3.5 ~ 5.5之间。强配位作用是DOM影响有毒重金属离子环境地球化学行为的根源。研究还表明配位作用的强弱受DOM来源和体系pH的影响。 4、 CBZ和DOM能发生强烈的相互作用,结合常数(log K)介于3.41 ~ 5.04之间。DOM能明显减少游离态CBZ的浓度,提高CBZ溶解度和迁移转化能力。这对认识CBZ和其它PPCPs的环境地球化学循环及其影响因素具有指导意义。 5、荧光光谱研究表明CBZ对DOM发射的荧光具有明显的猝灭作用,其猝灭机理为静态猝灭。疏水作用是CBZ和DOM之间的主要作用力。DOM-CBZ受pH值的影响不大, Cu2+对CBZ和DOM的结合有一定的影响。
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该论文测定了疏水性有机污染物在地质吸附剂上的吸附-解吸等温线,选用合适的模型拟合了这些等温线,并且研究了非线性吸附过程、解吸滞后现象与壤/沉积物异质性之间的关系;得到以下几点认识:1、利用红外光谱仪和核磁共振谱仪研究了土壤/沉积物有机质、土壤胡敏酸的组成.2、测定了菲、蔡、1,3,5-三氯苯在土壤/沉积物及处理样品上的吸附等温线.所有地质吸附剂上的吸附等温线表现出明显的非线性.Freundlic上模型能很好的拟合了有机物的吸附等温线,双区位反应模型(DRDM)能很好的拟合有机物在部分土壤/沉积物及处理样品上的吸附等温线,并且DRDM模型清楚的反映出有机物在低浓度和高浓度下不同的吸附特征.3、对相同土壤/沉积物样品,萘的吸附等温线要比菲的吸附等温线的线性要好些,这与它们的物化性质有关.4、对碱提取后残留土壤测定了菲、茶、1,3,5-三氯苯的吸附-解吸等温线.5、菲和萘在土壤/沉积物及处理样品上的吸附-解吸过程存在明显的滞后现象.
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A column method was developed to conveniently and reliably determine the soil organic partition coefficients (K-oc) of three insecticides (methiocarb, azinphos-methyl, fenthion), four fungicides (triadimenol, fuberidazole, tebuconazole, pencycuron), and one herbicide (atrazine), in which real soil acted as a stationary phase and the water solution of pesticide as an eluent. The processes of sorption equilibrium were directly shown through a breakthrough curve(BTC). The log K-oc values are 1.69, 1.95, 2.25, 2.55, 2.69, 2.67, 3.10, and 3.33 for atrazine, triadimenol, methiocarb, fuberidazole, azinphos-methyl, tebuconazole, fenthion and pencycuron, respectively.
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Com o objetivo de indicar pesticidas que devem ser monitorados em frutas, foi estimado o fator de bioconcentração (BCF) de 36 pesticidas em maçã selecionados do sistema de produção integrada de maçã (PIM). O BCF é um indicador da afinidade de substâncias por organismos. Para estimar o BCF foi utilizado o modelo FTM-p (Fruit Tree Model to Pesticide) [PARAÍBA, L.C. Pesticide bioconcentration modelling for fruit trees. Chemosphere, v.66, p.1468-1475, 2007] e um cultivo hipotético de macieiras. No modelo FTM-p, o valor do BCF foi correlacionado com características fisiológicas da planta e com propriedades físico-químicas dos pesticidas. Na estimativa foram utilizados os tempos de meia-vida no solo e na planta de cada um dos pesticidas. Da planta foram utilizados a biomassa seca, a taxa de transpiração de água e o volume do fluxo de água necessário para produzir um quilo de fruta fresca por planta. O coeficiente de partição tronco-água e o fator de concentração no fluxo de transpiração foram calculados por meio de expressões que correlacionam cada um desses parâmetros com o coeficiente de partição octanol-água do pesticida.
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2009
The total margin of exposure of ethanol and acetaldehyde for heavy drinkers consuming cider or vodka
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Heavy drinkers in Scotland may consume 1600 g ethanol per week. Due to its low price, cider may be preferred over other beverages. Anecdotal evidence has linked cider to specific health hazards beyond other alcoholic beverages. To examine this hypothesis, nine apple and pear cider samples were chemically analysed for constituents and contaminants. None of the products exceeded regulatory or toxicological thresholds, but the regular occurrence of acetaldehyde in cider was detected. To provide a quantitative risk assessment, two collectives of exclusive drinkers of cider and vodka were compared and the intake of acetaldehyde was estimated using probabilistic MonteeCarlo type analysis. The cider consumers were found to ingest more than 200-times the amount of acetaldehyde consumed by vodka consumers. The margins of exposure (MOE) of acetaldehyde were 224 for the cider and over 220,000 for vodka consumers. However, if the effects of ethanol were considered in a cumulative assessment of the combined MOE, the effect of acetaldehyde was minor and the combined MOE for both groups was 0.3. We suggest that alcohol policy priority should be given on reducing ethanol intake by measures such as minimum pricing, rather than to focus on acetaldehyde.
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Gustavo Chemale, Arjan J. van Rossum, James R. Jefferies, John Barrett, Peter M. Brophy, Henrique B. Ferreira, Arnaldo Zaha (2003). Proteomic analysis of the larval stage of the parasite Echinococcus granulosus: causative agent of cystic hydatid disease. Proteomics, 3(8), 1633-1636. Sponsorship: CNPq / PADCT/CNPq / FAPERGS (Brazil)/ BBSRC (UK) RAE2008
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Over the last 30 years, western European Song Thrush populations have declined with the steepest decline recorded on British farmland. Changes in agricultural practices have been implicated in these population declines. Ireland is an agriculturally dominated landscape but changes in agriculture here have occurred on a relatively slower rate and scale. Little is known about the ecology of the Song Thrush in Ireland, even though it is not classified as a species of conservation concern here. Some decline is thought to have occurred but the current breeding population appears to be stable and widespread. In light of these facts, this study investigated various aspects of Song Thrush ecology in relation to the Irish landscape from 2001-2003. The breeding season extended from mid March to late June, where mean clutch size was 4.1 and number of fledglings was 3.7. There were very few third broods. Daily nest survival rates were calculated for egg stage 0.9362, incubation stage 0.9505 and nestling stage 0.6909. Most nest failures were due to avian predation at both egg and chick stages. Most nests were located 1.3 -2.4m from the ground at trees, bushes or hedgerow. Clutch size was significantly higher on farmland than garden & parkland and woodland, and the number of fledglings was significantly lower in nests in trees than hedgerow and bush sites. Daily nest fail rates were significantly higher at tree sites and partly concealed nests. Nesting areas had significantly denser vertical vegetation than non-nesting areas. Mercury and the organochlorine HEOD were the most common contaminants in Song Thrush eggs and livers. However concentrations and occurrence were low and of no apparent biological or ecological concern. The presence of breeding Song Thrushes was influenced by mixed surrounding farmland, the absence of grass surrounding farmland, ditches especially wet ones, tall dense vegetation and trimmed boundaries. Song Thrush winter densities were predicted by ditches, with wet or dry, low thin vegetation and untrimmed boundaries. Winter densities were almost double that of the breeding season, probably due to the arrival and passage of migrating Song Thrushes through the country, especially in November. Changes in Irish agriculture did not differ significantly in areas of Song Thrush breeding population stability and apparent decline during 1970 1990. Even though the current breeding population heavily uses farmland, woodland, human and scrub habitats are more preferred. Nevertheless no farmland habitat was avoided, highlighting a positive relationship between breeding Song Thrushes and Irish agriculture. This appears to be in contrast with findings between breeding Song Thrushes and British agriculture. Theses findings are compared with other studies and possible influences by agricultural intensification, climate, latitude and insular syndrome are discussed. Implications for conservation measures are considered, especially for areas of decline. Even though Song Thrushes are currently widespread and stable here, future environmental consequences of longer-term changes in Irish agriculture and perhaps climate change remain to be seen.
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Globally, agriculture is being intensified with mechanization and increased use of synthetic fertilizers and pesticides. There has been a scaling up of production to satisfy the demands of supermarket distribution. Problems associated with intensification of production, trade globalisation and a larger market demand for greater volumes of fresh produce, include consumers' concern about pesticide residues and leaching of nutrients and pesticides into the environment, as well as increases in the transmission of human food-poisoning pathogens on raw vegetables and in fruit juices. The first part of this research was concerned with the evaluation of a biological control strategy for soil-borne pathogens, these are difficult to eliminate and the chemicals of which the most effective fumigants e.g. methyl bromide, are being withdrawn form use. Chitin-containing crustaceans shellfish waste was investigated as a selective growth substrate amendment in the field, in glasshouse and in storage trials against Sclerotinia disease of Helianthus tuberosus, Phytophthora fragariae disease of Fragaria vesca and Fusarium disease of Dianthus. Results showed that addition to shellfish waste stimulated substrate microbial populations and lytic activity and induced plant defense proteins, namely chitinases and cellulases. Protective effects were seen in all crop models but the results indicate that further trials are required to confirm long-term efficacy. The second part of the research investigated the persistence of enteric bacteria in raw salad vegetables using model food poisoning isolates. In clinical investigations plants are sampled for bacterial contamination but no attempt is made to differentiate between epiphytes and endophytes. Results here indicate that the mode isolates persist endophytically thereby escaping conventional chlorine washes and they may also induce host defenses, which results in their suppression and in negative results in conventional plate count screening. Finally a discussion of criteria that should be considered for a HACCP plan for safe raw salad vegetable production is presented.
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This thesis aimed to provide an understanding of how human-induced changes in the economic sectors of agriculture and transport affect carabid diversity, potential carabidmediated biocontrol and predator-pest interactions. The research involved both observational and manipulative laboratory and field-based studies. Observational research consisted of two large-scale investigations of (1) the impact of Miscanthus and oilseed rape production (n=45) and (2) the impact of horticultural and ecological based landscaping of roadside verges (n=64). This research is the first record of carabid diversity, potential biocontrol and community assemblage with respect to bioenergy crop production and roadside landscaping in an Irish context and it is also an important addition to the limited knowledge of carabid populations in these ecosystems internationally. Manipulative work involved the examination of the role predator identity, diversity and biomass play in the suppression of pollen beetle larvae (an economically damaging insect pest of oilseed rape in Europe), using a novel experimental design called ‘simplex’. To complement this research, an additional field study on the impact of low and high oilseed rape pesticide management on carabid species richness and abundance, and crop yield, was also conducted. This research is a great contribution to the existing understanding of what constitutes the important components of predator biodiversity and expands the knowledge of the usefulness of carabid predators in the context of pollen beetle larvae control. In particular, the work shows that the abundance or biomass of beetles has an effect that is far larger than the effect of diversity on the capacity of beetles to consume prey. In turn, the field study showed that pesticide applications had little impact on yield, or carabid richness, but that carabid abundance/biomass declined drastically. The work provides compelling evidence that management practices erode the useful components of biodiversity that are essential for the delivery of biocontrol services.