短链（C2-C6）全氟羧酸及其共通前体物在大气-土壤-植物体系迁移转化

Due to the substitution of products in perfluoroalkyl substances and refrigerants, short-chain (C4-C6) perfluoroalkyl carboxylic acids (PFCAs) have become the dominant compounds detected in the environment, replacing the middle and long-chain analogues. The concentrations of “super” short-chain （C2-C3）PFCAs are even higher due to their additional sources such as refrigerants, and will increase dramatically in near future. The sources of C2-C3 and C4-C6 PFCAs are overlapped and their environmental behaviors should be different from the corresponding long chain analogues, which have not been elucidated clearly. This project plans to select (super) short-chain PFCAs (C2-C6) and their overlapped classic precursors (6:2 fluorotelomers and N-methyl perfluorobutane sulfonamidoethanol) as target compounds, and the system of atmosphere–soil-plants as the object system, and to conduct the following researches. 1) To investigate the contamination characteristics of the target compounds in atmosphere, wet and dry precipitation, and surface environment and plant samples in classic areas in China, and analyze the mechanism for the interchange of source and sink. 2) To check the change of adsorption and leaching of C2-C6 PFCAs and the corresponding controlling mechanisms with the carbon length and influencing factors. 3) To analyze plant absorption path and transformation potential of the target compounds and precursors using a sealed microcosm technology. The results of this project will gain new knowledge on the contamination characteristics and key environmental processes of the target compounds, provide scientific foundation for the evaluation of environmental effects of the substitution strategies, and contribute to enriching the theory exploring in the field of environmental geochemistry.

由于全氟化合物与制冷剂的产品替代，短链（C4-C6）全氟烷基酸类逐渐替代中长链成为环境优先检出物；而超短链（C2-C3）全氟羧酸由于制冷剂等额外来源在环境中的浓度更高，并将进一步大幅提高。超短链与短链全氟羧酸具有一些共通来源，环境行为有别于中长链，一些环境过程尚认知不清。本项目以（超）短链（C2-C6）全氟羧酸及典型共通前体物（6:2氟调醇与N甲基全氟丁基磺酰胺乙醇）为目标物，以大气-土壤-植物体系为对象，开展以下研究，调查研究目标物在我国典型地区的大气、干湿沉降及各类地表环境与植物中的污染特征，并分析其源汇机制；阐明目标物在土壤中吸附/淋滤及其主控机理随链长的变化与影响因素；利用密闭微宇宙技术，研究目标物与前体物在植物体内的吸收路径与转化潜力。本项目将加深对目标物在我国环境污染特征与关键环境过程的认知，为评价相关替代政策的环境效应提供科学依据，并为丰富环境地球化学的理论探索做出贡献。

由于全氟化合物与制冷剂的产品替代，短链（C4-C6）全氟烷基酸类逐渐替代中长链成为环境优先检出物；而超短链（C2-C3）全氟羧酸由于制冷剂等额外来源在环境中的浓度更高，并将进一步大幅提高。超短链与短链全氟羧酸具有一些共通来源，环境行为有别于中长链，一些环境过程尚认知不清。本项目以（超）短链（C2-C6）全氟羧酸及共通前体物为目标物，以大气-土壤-植物体系为对象，开展以下研究，调查研究目标物在我国典型地区的大气、干湿沉降及各类地表环境与植物中的污染特征，并分析其源汇机制；阐明目标物在土壤中吸附/淋滤及其主控机理随链长的变化与影响因素；利用密闭微宇宙技术，研究目标物与前体物在植物体内的吸收路径与转化潜力。研究结果表明，短链全氟烷基酸在各种环境介质中被广泛检出，其中TFA在各种介质中的浓度要比其它长链PFAAs高出1-3个数量级；干湿沉降是地表环境中PFASs的一个重要来源；污水处理厂、垃圾填埋场和氟化工厂可以向大气直接排放离子型PFASs；C4-C12 PFCAs的固-水分配系数和颗粒物-大气分配系数随着链长的增加而增加，TFA则展示出与PFOA等长链PFCAs相似的吸附性。离子型PFASs主要通过根部吸收和颗粒物的叶片吸收进入到植物体，中性前体物主要通过植物叶片进入到植物体。在小麦根部吸收PFASs的过程中，除主动运输外，离子通道和水通道也起到关键作用。本项目将加深对目标物在我国环境污染特征与关键环境过程的认知，为评价相关替代政策的环境效应提供科学依据，并为丰富环境地球化学的理论探索做出贡献。