Understanding the atmospheric transport and fate of fluorinated Persistent Organic Pollutants with global models

利用全球模型了解氟化持久性有机污染物的大气迁移和归宿

• 批准号: 2898143
• 金额: --
• 依托单位: Lancaster University
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2898143
• 关键词: Understanding; atmospheric; transport; fate; fluorinated

Perfluorocarboxylic acids (PFCAs) are persistent pollutants found widely in the global environment where they have a range of adverse effects. Ecological risks from long-chain PFCAs (>7 carbon atoms), along with routes for human exposure, are well documented, leading to calls for more stringent regulation on their production. Short-chain PFCAs have received less attention but are of increasing environmental concern. Like long-chain species, short-chain PFCAs are detected in various remote regions (e.g. the Arctic) vast distances from industrial areas, indicating that they are mobile contaminants. Ultra-short chain PFCAs include trifluoroacetic acid (TFA), perfluoropropionic acid (PFPrA), and perfluorobutanoic acid (PFBA), with deposition from the atmosphere to the surface a major ecosystem source of these contaminants (e.g. Björnsdotter et al., 2020). In the atmosphere, secondary production of short-chain PFCAs may occur due to the oxidation of primary-emitted precursors, including fluorotelomer alcohols (e.g. Ellis et al., 2004) and gases that were introduced to replace ozone-depleting substances now banned by the Montreal Protocol (certain HCFCs, HFCs). Observational evidence shows deposition of short-chain PFCAs to the surface increased markedly in recent decades (Pickard et al., 2020; Garnett et al., 2022), but there are large uncertainties in their global budget. For example, a long purported significant natural source of TFA is now questioned (Joudan et al., 2021), while estimates of the amount of TFA deposited from the atmosphere are uncertain due to uncertainty in (1) the magnitude, distribution and trends of precursor emissions, (2) the mechanisms of precursor oxidation (and thus PFCA yields), and (3) the representation of atmospheric transport and other processes (e.g. wet/dry deposition) in global models. Moreover, the growing use of ultra-low GWP refrigerants (including hydrofluoroolefins, HFOs) as a source of TFA and other PFCAs requires urgent evaluation, bringing further policy relevance to this topic. To understand environmental risks posed by short-chain PFCAs there is a need to constrain their atmospheric budget and that of their precursors. To that end, key objectives of this project are to (1) develop the UCI 3-D chemical transport model to include major short-chain PFCAs and their precursors; (2) quantify global/regional deposition of short-chain PFCAs, including in remote polar regions; (3) explore variability in short-chain PFCA source-receptor pathways to uncertainties in model atmospheric transport and chemical/physical processes (e.g. tropospheric oxidants, treatment of dry/wet deposition); and (4) examine trends in short-chain PFCA deposition over recent decades and possible future trends based on precursor emission projections (e.g. explore the impact of the growing use of low-GWP HFO refrigerants).

全氟羧酸 (PFCA) 是在全球环境中广泛存在的持久性污染物，长链 PFCA（> 7 个碳原子）及其人类接触途径会带来一系列不利影响，这些危害已得到充分记录。短链全氟辛烷磺酸受到的关注较少，但与长链物种一样，短链全氟辛烷磺酸在各个偏远地区（例如北极）也被发现。距工业区的距离，表明它们是移动污染物，包括三氟乙酸（TFA）、全氟丙酸（PFPrA）和全氟丁酸（PFBA），从大气到地表的沉积是主要的生态系统来源。这些污染物（例如 Björnsdotter 等人，2020）在大气中可能会二次产生短链全氟辛烷磺酸。发生的原因是初级排放前体的氧化，包括含氟调聚物醇（例如 Ellis 等人，2004 年）和为取代《蒙特利尔议定书》现已禁止的臭氧消耗物质（某些 HCFC、HFC）而引入的气体。近几十年来，短链全氟辛烷磺酸在表面的沉积显着增加（Pickard 等人，2020 年；Garnett 等人， 2022 年），但其全球预算存在很大的不确定性，例如，长期声称的 TFA 重要天然来源现在受到质疑（Joudan 等人，2021），而对大气中沉积的 TFA 数量的估计也不确定。 (1) 前体排放的量值、分布和趋势，(2) 前体氧化机制（以及 PFCA 产量），以及 (3) 大气传输和其他过程的表征的不确定性此外，越来越多地使用超低 GWP 制冷剂（包括氢氟烯烃、HFO）作为 TFA 和其他 PFCA 的来源，需要紧急评估，从而进一步了解这一主题的政策相关性。鉴于短链 PFCA 带来的环境风险，需要限制其大气预算及其前体的预算，为此，该项目的主要目标是 (1) 开发 UCI 3-D 化学品传输。模型包括主要的短链 PFCA 及其前体；(2) 量化短链 PFCA 的全球/区域沉积，包括偏远极地地区；(3) 探索模型中的短链 PFCA 源-受体途径的可变性大气传输和化学/物理过程（例如对流层氧化剂、干/湿沉积的处理）；(4) 研究近几十年来短链全氟辛烷磺酸沉积的趋势以及基于前体排放预测的未来可能的趋势（例如探讨低全球升温潜能值 HFO 制冷剂的使用增加的影响）。