典型有机氯农药在颤蚓-锦鲤体内富集、消除及毒性效应研究

发布时间：2018-04-03 01:40

本文选题：有机氯农药　切入点：颤蚓　出处：《中国农业大学》2017年博士论文

【摘要】：大部分有机氯农药属于持久性污染物,具有疏水性、生物累积性、持久性和长距离迁移性等,虽然已被禁用几十年,但在各种环境介质中仍有检出,如食物网、沉积物、水和空气等,此外,一些有机氯农药具有手性特征,手性污染物的对映异构体在环境中可能表现出不同的环境行为,尤其是在生物体内这个大的手性环境下,对映异构体通常会表现出不同的毒性毒理、生物活性及富集代谢等行为,有时甚至表现出截然相反的生理效应。因此,研究有机氯农药的环境行为及毒性效应,有助于全面理解其环境归趋情况,并做出正确的风险评估。在此基础上,我们选取颤蚓这种特殊的底栖生物进行研究,颤蚓对水质和底质两方面污染反应都很敏感,可以综合地反映出水体和沉积物的污染情况及污染物毒性。颤蚓作为食物链中重要的一环,可以被许多鱼类捕食,如锦鲤,锦鲤处于食物链中间位置,利于评估污染物的生物放大效应及环境风险。基于这两种研究生物,我们主要研究了 4种HCH异构体,DDT及其代谢物DDD和DDE,其中α-HCH和o,p,-DDT、o,p'-DDD为手性农药。围绕HCH异构体我们开展了以下研究,1.HCH异构体经水暴露在颤蚓体内的选择性行为及其毒性效应,研究发现颤蚓对HCH异构体有较强的富集及消除能力,但对α-HCH对映体无选择性富集消除,且HCH异构体对颤蚓有一定的毒性效应,均可导致颤蚓体内MDA含量增加,引发氧化损伤从而对颤蚓健康造成不利影响。2.HCH异构体经沉积物暴露在颤蚓体内的选择性行为,研究发现在颤蚓体内,HCH异构体富集趋势呈M型,这种富集趋势可能与颤蚓尾部的自割和再生有关,颤蚓的存在可以加速沉积物中HCH异构体的耗散,对环境中HCH异构体的消除具有重要意义,同时,颤蚓可以选择性的富集α-HCH对映体。3.颤蚓扰动作用对HCH异构体向沉积物中转移和分布影响,研究发现颤蚓可以加速上层水中β-HCH向沉积物中转移。4.HCH异构体经水暴露在颤蚓-锦鲤食物链中的选择性行为,研究发现颤蚓与锦鲤体内HCH异构体富集趋势相似,但颤蚓富集HCH异构体的能力强于锦鲤,且HCH异构体经食物链向上传递,产生生物放大效应;在锦鲤排泄物中发现较高浓度的HCH,这将对其它生物产生风险,致使HCH重新进入食物链;颤蚓和锦鲤体内HCH异构体的消除较快,半衰期小于2.5天;同时,颤蚓选择性富集、消除α-HCH对映体,导致锦鲤中出现选择性,这种选择性可能会改变污染物对生物的毒性效应。围绕DDT我们开展了以下研究,1.不同暴露途径及生物效应对锦鲤富集DDT行为的影响,研究发现不同暴露途径影响DDT及其代谢物(DDD和DDE)在锦鲤体内的富集代谢行为,同时,颤蚓和锦鲤可以选择性的富集代谢o,p'-DDT和o,p'-DDD对映体。2.DDT经食物链暴露在锦鲤体内组织分布及其毒性效应,研究发现DDT及其代谢物(DDD和DDE)在锦鲤体内不同组织中的浓度变化趋势不同,且对锦鲤组织有一定的毒性效应,其中锦鲤的鳃和肾脏是主要的靶器官。
[Abstract]:Most of the organochlorine pesticides are persistent pollutants, with hydrophobic, bioaccumulation, persistence and long distance migration, although has been disabled for decades, but in various environmental media are still positive, such as food, water and air, sediment, in addition, some organochlorine pesticides with chiral characteristics the enantiomers of chiral pollutants may exhibit different environmental behavior in the environment, especially in the organism the chiral environment, enantiomers often exhibit different toxicological, biological activity and accumulation of metabolic behavior, sometimes even showing the opposite physiological effects. Therefore, environmental behavior and toxic effects of organochlorine pesticides, contribute to the comprehensive understanding of the environmental fate, and make proper risk assessment. Based on this, we selected t.tubifex this special research of benthos The tubifex on water and sediment pollution in two reactions are very sensitive and can reflect the situation of pollution and toxicity of pollutants in water and sediment. Tubifex as an important link in the food chain, can be a lot of fish predation, such as Koi, Koi in the middle of the food chain, for assessment of pollutants the amplification effect and environmental risk. These two kinds of biological research based on, we mainly study the 4 isoforms of HCH, DDT and its metabolites DDD and DDE, the alpha -HCH and O, P, -DDT, O, p'-DDD around the HCH isomers of chiral pesticides. We carried out the following studies, 1.HCH isomers by exposure to water selective behavior in tubifex and its toxic effects, study found that tubifex has the strong ability of accumulation and elimination of HCH isomers, but the alpha -HCH selectivity of enantiomerically enriched and eliminate HCH isomers on tubifex have toxic effects, which can lead to Increase the content of MDA in tubifex, causing oxidative damage to health caused by adverse effects on tubifex.2.HCH isomers by sediment exposure in selective behavior in tubifex tubifex, found in vivo, HCH isomer enrichment trend was M type, this trend may be related to autotomy and regeneration enrichment of tubifex tubifex tail. The presence of HCH can accelerate the dissipation of heterogeneous sediments in the body, is of great significance, for the elimination of HCH in heterogeneous environment. At the same time, tubifex can selectively enriched alpha -HCH enantiomer.3. Tubificid bioturbation effect on HCH isomers to the sediment transfer and distribution effect, study found that tubifex can accelerate the upper water P -HCH to the sediment transfer of.4.HCH isomers by water selective exposure behavior in the food chain - Koi in tubifex tubifex, found in HCH and Koi isomers enrichment trend is similar, but the tubifex enrichment of HCH isomers The ability to carp and HCH isomers through the food chain to transfer, to produce biological amplification; found that higher concentration of HCH in Koi excretions, which will produce a risk to other organisms, causing HCH to enter the food chain; tubifex and Koi in vivo HCH isomers eliminated more quickly, the half-life is less than 2.5 day; at the same time, selective enrichment of tubifex, elimination of alpha -HCH enantiomers, leading to selective appear Koi may change, the selective toxicity of pollutants on organisms around DDT. We carried out the following studies, effects of 1. different exposure pathways and biological effects on Koi enriched DDT behavior, the study found that different exposure pathways affected by DDT and its metabolites (DDD and DDE) and in vivo metabolic behavior, enrichment of carp and Koi, tubifex can metabolize o selective enrichment, p'-DDT and O, p'-DDD enantiomers.2.DDT through the food chain exposure in Koi tissues Distribution and toxicity, studies have found that DDT and its metabolites (DDD and DDE) of different concentration changes in different tissues in vivo and Koi, had certain toxic effects on koi carp tissues, the gills and kidneys are the main target organs.

【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TQ450.261

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