首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 93 毫秒
1.
长江流域的昆虫病毒资源及其开发利用   总被引:1,自引:0,他引:1  
在长江流域已发现约130种昆虫病毒,其中多数属杆状病毒科。昆虫病毒作为杀虫剂在本地区广泛应用,防治棉花、森林、茶树、蔬菜和牧草上的害虫,克服了化学农药的一些缺点,取得了良好的生态效益和经济效益。近年来还进行了杆状病毒表达载体的研究,该系统的研制已用于高水平表达具有生物活性的外源基因产物,获得医药产品,或者组建更有效的基因工程病毒杀虫剂。  相似文献   

2.
我国棉铃虫病毒杀虫剂的研究开发和应用   总被引:9,自引:0,他引:9  
棉铃虫核型多角体病毒(NPv),从分离开始,经过实验室研究到工厂生产商品销售,至今历经了18个春秋。是中国生防史上第一次使一种昆虫病毒的研究,从技术上的成功转变成商业上的开发成功。从1988~1993年,总共生产棉铃虫病毒杀虫剂100t,使用面积7万ha,(100多万亩)。在防治棉花、烟叶、辣椒和蕃茄等作物上的棉铃虫和烟青虫方面,均获得了有效的控制。本文主要介绍该病毒的基本特性,生产工艺和应用效果,并展望未来的前景。  相似文献   

3.
跟踪拍照识别白鱀豚的研究   总被引:1,自引:0,他引:1  
作者从1986年起开展了照相识别白豚的研究。通过反复试验,采用多船弧形跟踪、单船切入拍照的方法,在观察到白豚的48天中,共拍得1600张照片并从中识别出10头白暨豚。除了白暨豚背鳍上的自然标记能有效地用于个体识别之外,豚体上的色斑、图象等亦能用于个体识别。作者由此获得了白豚群体组成变化和迁移距离等科学资料,对深入研究白暨豚生态学有重要意义。  相似文献   

4.
大九湖泥炭藓湿地对磷、铜污染物净化作用的模拟研究   总被引:1,自引:1,他引:0  
在大九湖泥炭藓沼泽湿地采用野外实地模拟方法,就泥炭藓湿地对铜、磷两种污染物的净化能力进行了研究。结果表明,磷污染物浓度分别为10,100,1 000 mg/L时,两小时后泥炭藓湿地对该污染物的净化率分别为939%,695%,663%;同样的浓度梯度下,对铜污染物的净化率分别为1000%,976%,880%。泥炭藓湿地对污染物具有很强的净化能力,其泥炭层部分在湿地净化污染物中起到重要作用。利用拟一级动力学模型、修改上限的拟一级动力学模型、拟二级动力学模型、Elovich模型、双常数速率模型、抛物线扩散模型等6个模型对泥炭藓湿地的净化进行动态研究,其中后4个模型均可模拟湿地净化的动态过程。长期预测以拟二级动力学模型为最佳。  相似文献   

5.
结合 1998年长江流域的特大洪水 ,提出了洪水成因链的概念 ,分析了各个物理因子对江淮洪水的影响。指出影响江淮洪水的物理因子都是层层相接、环环相扣的 ,它们组成了一个互相联系、互为因果的洪水成因链。成因链上物理因子之间的正反馈作用和消长作用 ,导致成因链上各个因子的致洪理论都不能完全地自圆其说 ,因而也无法完全确定地用于洪水预测。只有深入探讨洪水成因链上物理因子之间的正反馈作用和消长作用 ,对它们进行全面综合的诊断分析 ,才能提高江淮洪水预测的准确率。  相似文献   

6.
略论水资源费问题   总被引:1,自引:0,他引:1  
在水资源紧缺地区,征收水资源费是保持水资源永续利用,生态环境良性循环的经济措施。本文拟对有偿使用水资源的有关问题,按照水资源的自然、经济特点和供需矛盾程度,从理论和实践上进行探讨。其内容主要包括水资源费的构成和内涵,征收水资源费的依据和目的,确定水资源费的原则、标准和水资源费的使用原则等。  相似文献   

7.
如何确定湿地生态修复过程中底栖生物群落结构的变化及其影响因子对湿地生态系统操纵及生态修复效果有重要意义。研究以南汇东滩海三棱藨草湿地为对象,研究底栖生物群落结构的年度季节变化及空间格局。共鉴定大型底栖动物30种,四季都存在的优势种有光滑狭口螺、拟沼螺、堇拟沼螺和中国绿螂。春季以中国绿螂为主要物种,优势度大于0.4;夏季以拟沼螺和堇拟沼螺为主,优势度分别大于0.1和0.2;秋冬季优势种数目比春夏季高,均为13种,但优势种值较春夏季为低,且均匀。多样性、丰富度指数(p0.01)及均一性指数(p0.05)在空间上均具有显著性差异,其中多样性指数最高到达2.53。根据近岸海域环境监测规范(HJ442-2008),南汇东滩湿地生境质量从极差、差改善成等级一般,生境质量提高明显。底栖生物群落结构影响因素的排序分析表明,春夏秋三季大型底栖动物群落结构特征与植被指数及高程相关,其次是有机碳、含水率、导电率和硝氮,而冬季大型底栖动物群落结构特征受含水率、导电率和硝氮的影响最大。  相似文献   

8.
在2007年8月研究的基础上,于2008年7月在神农架大九湖泥炭藓沼泽湿地采用自制简易模拟装置进行现场模拟实验,深入研究了泥炭藓沼泽湿地对不同浓度的金属污染物镉(Ⅱ)、铜(Ⅱ)、铅(Ⅱ)、锌(Ⅱ)的净化作用。研究表明:泥炭藓沼泽湿地对各种金属污染物都有很强的去除能力,2小时后的去除效果强弱顺序为Pb>Cu>Cd>Zn;4种金属任一时刻的去除速率都随初始浓度的增加而增大,低初始浓度先于高初始浓度达到平衡;泥炭藓沼泽湿地的稀释功能在污染物去除中起着重要作用。通过双常数速率模型得到了去除速率与实验时间的关系;拟二级动力学模型和修改后的拟一级动力学模型能够很好地描述泥炭藓沼泽湿地去除金属污染物的动态过程,拟二级动力学模型的拟合效果更佳,通过修改后的拟一级动力学模型可以计算出稀释作用对湿地净化的贡献率。为评估泥炭藓沼泽湿地净水价值、保护和合理利用泥炭藓沼泽湿地提供科学依据。  相似文献   

9.
江淮流域大洪水的因子分析及成因链初步构造   总被引:6,自引:1,他引:5  
结合1998年长江流域的特大洪水,提出了洪水成因链的概念,分析了各个物理因子对江淮洪水的影响,指出影响江淮洪水的物理因子都是层层相接、环环相扣的,它们组成了一个互相联系、互为因果的洪水成因链,成因链上物理因子之间的正反馈作用和消长作用,导致成因链上各个因子的致洪理论都不能完全地自圆其说,因而也无法完全确定地用于洪水预测,只有深入探讨洪水成因链上物理因子之间的正反馈作用和消长作用,对它们进行全面综合的诊断分析,才能提高江淮洪水预测的准确率。  相似文献   

10.
根据2012年厦门市区空气中O3的监测数据及2013年4月至5月过氧乙酰硝酸酯(PAN)的在线监测结果,研究了厦门市O3和PAN的时空分布特征,揭示厦门市光化学污染特性及其污染物的传输规律;探讨厦门市的气候条件对光化学反应的影响,比较植物产生的挥发性有机物(VOCS)和厦门市工业排放的VOCS对光化学反应的影响。  相似文献   

11.
Indoor pesticide exposure is a growing concern, particularly for pyrethroids, a commonly used class of pesticides. Pyrethroid concentrations may be especially high in homes of immigrant farm worker families, who often live in close proximity to agricultural fields and are faced with poor housing conditions, potentially causing high pest infestation and pesticide use. We investigate levels of pyrethroids in the house dust of farm worker family homes in a study of mothers and children living in Mendota, CA, within the population-based Mexican Immigration to California: Agricultural Safety and Acculturation (MICASA) Study. We present pesticide use data and levels of pyrethroid pesticides in indoor dust collected in 2009 as measured by questionnaires and a GC/MS analysis of the pyrethroids cis- and trans-permethrin, cypermethrin, deltamethrin, esfenvalerate and resmethrin in single dust samples collected from 55 households. Cis- and trans-permethrin had the highest detection frequencies at 67%, with median concentrations of 244 and 172 ng/g dust, respectively. Cypermethrin was detected in 52% of the homes and had a median concentration of 186 ng/g dust. Esfenvalerate, resmethrin and deltamethrin were detected in less than half the samples. We compared the pyrethroid concentrations found in our study to other studies looking at both rural and urban homes and daycares. Lower detection frequencies and/or lower median concentrations of cis- and trans-permethrin and cypermethrin were observed in our study as compared to those studies. However, deltamethrin, esfenvalerate and resmethrin were detected more frequently in the house dust from our study than in the other studies. Because households whose children had higher urinary pyrethroid metabolite levels were more likely to be analyzed in this study, a positive bias in our estimates of household pyrethroid levels may be expected. A positive association was observed with reported outdoor pesticide use and cypermethrin levels found in the indoor dust samples (rs = 0.28, p = 0.0450). There was also a positive association seen with summed pyrethroid levels in house dust and the results of a pesticide inventory conducted by field staff (rs = 0.32, p = 0.018), a potentially useful predictor of pesticide exposure in farm worker family homes. Further research is warranted to fully investigate the utility of such a measure.  相似文献   

12.
For the first time, this work described pyrethroid bioaccumulation in edible river fish samples. We analyzed 42 whole fish samples collected in 4 different Iberian rivers. All samples were positive to these insecticides. Levels of concentration ranged from 12 to 4938 ng g 1 lipid weight (lw). Moreover, isomeric characterization was carried out. Our results remarked a general preference of cis isomers in bioaccumulation. Finally, the enantiomeric evaluation showed that there was an enantioselective bioaccumulation of some pyrethroids, depending on the studied species. Pyrethroid concentrations were compared with levels obtained for other common pollutants, such as flame retardants, personal care products, hormones and pharmaceuticals. The highest values corresponded to pyrethroid insecticides, even though, pyrethroid levels are safe for human consumption taken into account the current regulations.  相似文献   

13.
Pesticides are used in modern agriculture to increase crop yields, but they may pose a serious threat to aquatic ecosystems. Pesticides may enter water bodies through diffuse and point sources, but diffuse sources are probably the most important. Among diffuse pollution, surface runoff and erosion, leaching and drainage represent the major pathways. The most commonly used mitigation techniques to prevent pesticide input into water bodies include edge-of-field and riparian buffer strips, vegetated ditches and constructed wetlands. The first attempts to use wetland macrophytes for pesticide removal were carried out as early as the 1970s, but only in the last decade have constructed wetlands for pesticide mitigation become widespread. The paper summarizes 47 studies in which removal of 87 pesticides was monitored. The survey revealed that constructed wetlands with free water surface are the most commonly used type. Also, it has been identified that removal of pesticides is highly variable. The results of the survey revealed that the highest pesticide removal was achieved for pesticides of the organochlorine, strobilurin/strobin, organosphosphate and pyrethroid groups while the lowest removals were observed for pesticides of the triazinone, aryloxyalkanoic acid and urea groups. The removal of pesticides generally increases with increasing value of KOC but the relationship is not strong.  相似文献   

14.
Pyrethroid insecticides are widely used in agriculture and in homes. Despite the neurotoxicity of these insecticides at high doses, few studies have examined whether lower-level exposures could adversely affect children's neurodevelopment.The PELAGIE cohort included 3421 pregnant women from Brittany, France between 2002 and 2006. When their children reached their sixth birthday, 428 mothers from the cohort were randomly selected, successfully contacted and found eligible. A total of 287 (67%) mothers agreed to participate with their children in the neuropsychological follow-up. Two cognitive domains were assessed by the Wechsler Intelligence Scale for Children: verbal comprehension and working memory. Five pyrethroid and two organophosphate insecticide metabolites were measured in maternal and child first-void urine samples collected between 6 and 19 gestational weeks and at 6 years of age, respectively. Linear regression models were used to estimate associations between cognitive scores and urinary pyrethroid metabolite concentrations, adjusting for organophosphate metabolite concentrations and potential confounders.Maternal prenatal pyrethroid metabolite concentrations were not consistently associated with any children's cognitive scores. By contrast, childhood 3-PBA and cis-DBCA concentrations were both negatively associated with verbal comprehension scores (P-trend = 0.04 and P-trend < 0.01, respectively) and with working memory scores (P-trend = 0.05 and P-trend < 0.01, respectively). No associations were observed for the three other childhood pyrethroid metabolite concentrations (4-F-3-PBA, cis-DCCA, and trans-DCCA).Low-level childhood exposures to deltamethrin (as cis-DBCA is its principal and selective metabolite), in particular, and to pyrethroid insecticides, in general (as reflected in levels of the 3-PBA metabolite) may negatively affect neurocognitive development by 6 years of age. Whatever their etiology, these cognitive deficits may be of importance educationally, because cognitive impairments in children interfere with learning and social development. Potential causes that can be prevented are of paramount public health importance.  相似文献   

15.
16.
There is limited evidence about whether background exposure to organochlorine pesticides is related to impairment of cognitive function in general populations. This study was performed to investigate cross-sectional associations between serum concentrations of organochlorine pesticides and cognitive function, a predictor of dementia, among U.S. elders without overt dementia. Study subjects were 644 elders aged 60–85, participating in the National Health and Nutrition Examination Survey 1999–2002. We selected 6 organochlorine pesticides (p,p′-dichlorodiphenyltrichloroethane (DDT), p,p′-dichlorodiphenyldichloroethylene (DDE), trans-nonachlor, oxychlordane, heptachlor epoxide, and β-hexachlorocyclohexane) which were commonly detected in current general population. Cognitive function was assessed with the Digit-Symbol Substitution Test. All 6 compounds showed statistically significant or marginally significant inverse associations with cognitive score after adjusting for covariates including education levels. The strongest association was observed with p,p′-DDT. With the outcome of low cognitive score defined as < 25th percentile, elders in the highest quartile of p,p′-DDT, p,p′-DDE, and β-hexachlorocyclohexane had 2 to 3 times higher risks than those in the lowest quartile. In particular, when their concentrations were further divided with the cutoff points of 90th and 95th percentiles, p,p′-DDT in the highest 5th percentile showed 6.5 (95% confidence interval: 2.6–16.3) times higher risk of low cognitive score. On the other hand, non-persistent pesticides like organophosphates or pyrethroid showed little association with this cognitive score. The potential role of background exposure to organochlorine pesticides in the development of dementia should be explored in future prospective studies and in-vitro/in-vivo experimental studies.  相似文献   

17.
Surface waters located in intensive agricultural areas are more vulnerable to the pesticides contamination, which is a major concern if the water is intended to be used for human consumption. The aim of this study was to evaluate the presence and the distribution of pesticides in the Alqueva reservoir, an important source of water supply (South of Portugal), considering their representativeness in the agricultural practice of the area. For the analysis of pesticides risk impact we used the environmental quality standards in the field of water policy proposed recently by the European Commission. The pesticides belonging to the classes of phenylureas, triazines, chloroacetanilides, organophosphorous and thiocarbamates were analysed by on-line solid phase extraction-liquid chromatography-tandem mass spectrometry. The pesticides more frequently detected were atrazine, simazine, diuron and terbuthylazine. The highest levels of these pesticides were registered in spring, after pesticides treatment, namely in olive-tree and vine crops. The priority pesticides atrazine and diuron reached values above the annual average proposed in the European Union Legislation. The herbicide atrazine reached values that surpassed the proposed maximum allowable concentration (2 000 ng L? 1). The sampling stations most affected by these pesticides were Sra. Ajuda, Lucefecit and Alcarrache, located in the northern part of the reservoir, closer to Spain where the agricultural activity is more intensive.  相似文献   

18.
One of the biggest challenges faced by Sierra Leonean farmers is pest control. Birds, rodents, insects, crustaceans and other organisms can drastically reduce yields. In order to prevent these organisms from destroying their crop, farmers use pesticides. However there are reports that these chemicals are being misused and such misuse is having a negative impact on the environment and the health of the farmers.This research study aimed to investigate the use of pesticides in rice fields and its potential effects on the environment and on the farmers of Sierra Leone. Five hundred farmers and one hundred health workers across the country were interviewed. Fifty focus group discussions were also completed. Field observations were also undertaken to see how farmers apply pesticides to their farms and the possible threats these methods have on human health and the environment. It is clear that a wide range of pesticides are used by rice farmers in Sierra Leone with 60% of the pesticides used entering the country illegally. Most farmers have no knowledge about the safe handling of pesticides as 71% of them have never received any form of training. The pesticides kill both target and non-target organisms some of which enter the food chain.Cases of health problems such as nausea, respiratory disorders and blurred vision investigated in this research are significantly higher among farmers who use pesticides than those who do not use pesticides. Cases of pesticide intoxication are not investigated by health workers but results obtained from interviews with them also indicated that cases of pesticides related symptoms are significantly higher in environments where pesticides are used than those in which pesticides are not used.  相似文献   

19.
The U.S. EPA's SHEDS-Multimedia model was applied to enhance the understanding of children's exposures and doses to multiple pyrethroid pesticides, including major contributing chemicals and pathways. This paper presents combined dietary and residential exposure estimates and cumulative doses for seven commonly used pyrethroids, and comparisons of model evaluation results with NHANES biomarker data for 3-PBA and DCCA metabolites. Model input distributions were fit to publicly available pesticide usage survey data, NHANES, and other studies, then SHEDS-Multimedia was applied to estimate total pyrethroid exposures and doses for 3–5 year olds for one year variability simulations. For dose estimations we used a pharmacokinetic model and two approaches for simulating dermal absorption. SHEDS-Multimedia predictions compared well to NHANES biomarker data: ratios of 3-PBA observed data to SHEDS-Multimedia modeled results were 0.88, 0.51, 0.54 and 1.02 for mean, median, 95th, and 99th percentiles, respectively; for DCCA, the ratios were 0.82, 0.53, 0.56, and 0.94. Modeled time-averaged cumulative absorbed dose of the seven pyrethroids was 3.1 nmol/day (versus 8.4 nmol/day for adults) in the general population (residential pyrethroid use and non-use homes) and 6.7 nmol/day (versus 10.5 nmol/day for adults) in the simulated residential pyrethroid use population. For the general population, contributions to modeled cumulative dose by chemical were permethrin (60%), cypermethrin (22%), and cyfluthrin (16%); for residential use homes, contributions were cypermethrin (49%), permethrin (29%), and cyfluthrin (17%). The primary exposure route for 3–5 year olds in the simulated residential use population was non-dietary ingestion exposure; whereas for the simulated general population, dietary exposure was the primary exposure route. Below the 95th percentile, the major exposure pathway was dietary for the general population; non-dietary ingestion was the major pathway starting below the 70th percentile for the residential use population. The new dermal absorption methodology considering surface loading had some impact, but did not change the order of key pathways.  相似文献   

20.
Endocrine disrupting pesticides: implications for risk assessment   总被引:6,自引:1,他引:5  
Endocrine disrupting (ED) chemicals are compounds that alter the normal functioning of the endocrine system, potentially causing disease or deformity in organisms and their offspring. Pesticides are used widely to kill unwanted organisms in crops, public areas, homes and gardens and medicinally to kill parasites. Many are proven or suspected to be EDs. Ancient physiological similarities between different vertebrate groups suggest that disorders observed in wildlife may indicate risks to humans. This makes accurate risk assessment and effective legislation difficult. In this paper, the hazardous properties of pesticides which are known to have ED properties are reviewed in order to assess the implications for risk assessment. As well as data on sources of exposure in the United Kingdom (UK) an assessment of the evidence on the health effects of ED pesticides is also included. In total, 127 have been identified from the literature and their effects and modes of action are listed in this paper. Using the UK as a case study, the types and quantities of pesticides used, and their methods of application are assessed, along with their potential pathways to humans. In the UK reliable data are available only for agricultural use, so non-agricultural routes of pesticide exposure have been poorly quantified. The exposure of people resident in or visiting rural areas could also have been grossly under-estimated. Material links between ED pesticide use and specific illnesses or deformities are complicated by the multifactorial nature of disease, which can be affected by factors such as diet. Despite these difficulties, a large body of evidence has accumulated linking specific conditions to ED pesticides in wildlife and humans. A more precautionary approach to the use of ED pesticides, especially for non-essential purposes is proposed.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号