短链氯化石蜡在南瓜和大豆幼苗中的迁移和生物转化过程研究
发布时间：2018-09-01 12:33
【摘要】：新型持久性机污染物短链氯化石蜡(SCCPs)是一类直链氯化烷烃的复杂混合物,具有远距离环境迁移能力、环境持久性、生物蓄积性和较高的生物毒性,己经于2017年第8次《关于持久性有机污染物的斯德哥尔摩公约》缔约国大会上,被列入《公约》附件A受控POPs的清单。植物作为生态系统的生产者,在各种有机污染物的环境归趋和地球化学循环中起着重要作用,但植物与SCCPs之间的相互作用还知之甚少。南瓜对很多有机污染物,如PBDEs和DDT等具有较高的富集能力。大豆也被报道可以吸收和迁移氯丹、氯苯和8:2氟代调聚醇等。因此本研究选取南瓜(Cucurbita maxima × C.moschata)和大豆(Glycine maxL.Merrill)作为模型植物,通过相对简单的水培暴露体系首次研究了 SCCPs在不同植物中的吸收、迁移以及生物转化。主要内容如下:(1)SCCPs既可以通过大豆和南瓜幼苗的根也可以通过叶被植物吸收,并在植株体内发生迁移,迁移过程是双向的,包括从根向叶的迁移和从叶向根部的迁移。暴露组中主要是通过根部吸收SCCPs,再向上迁移到叶,并可通过叶部气孔散逸到气相中,而空白对照组主要是叶吸收气相中的SCCPs并向下迁移到根部。南瓜组织中根部富集的母体化合物含量最高,大于初始暴露量的23%。(2)SCCPs在大豆和南瓜植株中的吸收、迁移和植物挥发均受其链长和氯原子取代数的影响。当SCCPs含有相同的碳原子数时,南瓜幼苗富集母体化合物的含量和速度随着氯原子数的增加而增加,而当SCCPs含有相同的氯原子数时,富集量和速度随碳原子数的增加而增加。而碳链越短、氯原子取代数越少的SCCPs同系物越容易被植物体内传输和植物挥发,也更易于停留在空气中。(3)根据检测到的代谢产物,发现高氯代的SCCPs同系物在南瓜和大豆幼苗的作用下能够脱氯为低氯代同系物,并且在分子上发生氯原子重排。首次发现了南瓜和大豆作用下SCCPs的碳链断裂过程。(4)不同植物对SCCPs的迁移和转化能力有所不同。大豆体内SCCPs的迁移能力明显弱于南瓜,但其对SCCPs的生物转化能力显著高于南瓜。综上,本文首次报道了 SCCPs在活体植物中的环境行为,为今后SCCPs在生态系统中潜在的风险评估和人体健康危害提供了重要的理论依据。
[Abstract]:A novel persistent pollutant, SCCPs, (SCCPs) is a complex mixture of linear chlorinated alkanes with long-range environmental transport, environmental persistence, bioaccumulation and high biotoxicity. At the eighth Conference of the parties to the Stockholm Convention on persistent Organic pollutants, in 2017, it was included in the list of controlled POPs in Annex A to the Convention. As an ecosystem producer, plants play an important role in the environmental fate and geochemical cycle of various organic pollutants, but little is known about the interaction between plants and SCCPs. Pumpkin has high enrichment ability to many organic pollutants, such as PBDEs and DDT. Soybeans were also reported to absorb and migrate chlordane, chlorobenzene and 8:2 fluorinated polyols. In this study, pumpkin (Cucurbita maxima 脳 C.moschata and soybean (Glycine maxL.Merrill) were selected as model plants. The absorption, migration and biotransformation of SCCPs in different plants were studied for the first time through a relatively simple hydroponic exposure system. The main contents are as follows: (1) SCCPs can be absorbed not only through the roots of soybean and pumpkin seedlings, but also by the leaves of the plants. The migration process is bidirectional, including the migration from root to leaf and from leaf to root. In the exposed group, SCCPs, was absorbed by the root and then migrated up to the leaf, and then dispersed to the gas phase through the stomata of the leaf, while the blank control group absorbed the SCCPs in the gas phase and migrated down to the root. The concentration of parent compounds in the roots of pumpkin was the highest, which was more than 23% of the initial exposure. (2) the absorption, migration and volatilization of SCCPs in soybean and pumpkin plants were affected by the chain length and the number of chlorine substituents. When SCCPs contains the same number of carbon atoms, the content and rate of enrichment of parent compounds in pumpkin seedlings increase with the increase of the number of chlorine atoms, while when SCCPs contains the same number of chlorine atoms, the amount and speed of enrichment increase with the increase of the number of carbon atoms. The shorter the carbon chain, the more likely the SCCPs congeners with fewer chlorine atoms to be transported and volatilized by plants and more likely to remain in the air. (3) according to the detected metabolites, It was found that the high-chlorinated SCCPs congeners could be dechlorinated to low chlorinated congeners under the action of pumpkin and soybean seedlings, and chlorine rearrangement occurred on the molecular level. The carbon chain break process of SCCPs under the action of pumpkin and soybean was first found. (4) the migration and transformation ability of SCCPs was different among different plants. The migration ability of SCCPs in soybean was significantly weaker than that in pumpkin, but its biotransformation ability to SCCPs was significantly higher than that of pumpkin. In summary, the environmental behavior of SCCPs in living plants is reported for the first time, which provides an important theoretical basis for the potential risk assessment and human health hazard of SCCPs in ecosystem in the future.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S565.1;S642.1;X173
本文编号：2217211
[Abstract]:A novel persistent pollutant, SCCPs, (SCCPs) is a complex mixture of linear chlorinated alkanes with long-range environmental transport, environmental persistence, bioaccumulation and high biotoxicity. At the eighth Conference of the parties to the Stockholm Convention on persistent Organic pollutants, in 2017, it was included in the list of controlled POPs in Annex A to the Convention. As an ecosystem producer, plants play an important role in the environmental fate and geochemical cycle of various organic pollutants, but little is known about the interaction between plants and SCCPs. Pumpkin has high enrichment ability to many organic pollutants, such as PBDEs and DDT. Soybeans were also reported to absorb and migrate chlordane, chlorobenzene and 8:2 fluorinated polyols. In this study, pumpkin (Cucurbita maxima 脳 C.moschata and soybean (Glycine maxL.Merrill) were selected as model plants. The absorption, migration and biotransformation of SCCPs in different plants were studied for the first time through a relatively simple hydroponic exposure system. The main contents are as follows: (1) SCCPs can be absorbed not only through the roots of soybean and pumpkin seedlings, but also by the leaves of the plants. The migration process is bidirectional, including the migration from root to leaf and from leaf to root. In the exposed group, SCCPs, was absorbed by the root and then migrated up to the leaf, and then dispersed to the gas phase through the stomata of the leaf, while the blank control group absorbed the SCCPs in the gas phase and migrated down to the root. The concentration of parent compounds in the roots of pumpkin was the highest, which was more than 23% of the initial exposure. (2) the absorption, migration and volatilization of SCCPs in soybean and pumpkin plants were affected by the chain length and the number of chlorine substituents. When SCCPs contains the same number of carbon atoms, the content and rate of enrichment of parent compounds in pumpkin seedlings increase with the increase of the number of chlorine atoms, while when SCCPs contains the same number of chlorine atoms, the amount and speed of enrichment increase with the increase of the number of carbon atoms. The shorter the carbon chain, the more likely the SCCPs congeners with fewer chlorine atoms to be transported and volatilized by plants and more likely to remain in the air. (3) according to the detected metabolites, It was found that the high-chlorinated SCCPs congeners could be dechlorinated to low chlorinated congeners under the action of pumpkin and soybean seedlings, and chlorine rearrangement occurred on the molecular level. The carbon chain break process of SCCPs under the action of pumpkin and soybean was first found. (4) the migration and transformation ability of SCCPs was different among different plants. The migration ability of SCCPs in soybean was significantly weaker than that in pumpkin, but its biotransformation ability to SCCPs was significantly higher than that of pumpkin. In summary, the environmental behavior of SCCPs in living plants is reported for the first time, which provides an important theoretical basis for the potential risk assessment and human health hazard of SCCPs in ecosystem in the future.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S565.1;S642.1;X173
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