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) 是全球环境中广泛存在的持久性污染物，会产生一系列不利影响。长链全氟辛烷磺酸（> 7 个碳原子）的生态风险以及人类接触途径都有详细记录，导致人们呼吁对其生产进行更严格的监管。短链全氟辛烷磺酸受到的关注较少，但环境问题却日益受到关注。与长链物种一样，短链全氟辛烷磺酸在距离工业区很远的各个偏远地区（例如北极）也被检测到，表明它们是移动污染物。超短链全氟辛酸包括三氟乙酸 (TFA)、全氟丙酸 (PFP​​rA) 和全氟丁酸 (PFBA)，从大气到地表的沉积是这些污染物的主要生态系统来源（例如 Björnsdotter 等，2020）。在大气中，由于初级排放前体的氧化，可能会产生短链全氟辛烷磺酸，其中包括含氟调聚物醇（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。观测证据表明，近几十年来，短链全氟辛烷磺酸在地表的沉积量显着增加（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，长期以来所声称的 TFA 的重要自然来源现在受到质疑（Joudan 等人，2021 年），而对大气中沉积的 TFA 量的估计则不确定，因为 (1) 前体排放的量值、分布和趋势，(2) 前体氧化机制（以及全氟辛酸产量），以及 (3) 大气传输和其他过程的表示形式存在不确定性。 全球模型中的湿/干沉积（例如湿/干沉积）。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，需要进行紧急评估，从而为该主题带来进一步的政策相关性。为了了解短链全氟辛烷磺酸带来的环境风险，需要限制它们及其前体的大气预算。为此，该项目的主要目标是 (1) 开发 UCI 3-D 化学品传输模型，以包括主要的短链 PFCA 及其前体； (2) 量化短链全氟辛烷磺酸的全球/区域沉积，包括偏远的极地地区； (3) 探索短链 PFCA 源-受体途径的变异性对模型大气传输和化学/物理过程（例如对流层氧化剂、干/湿沉降处理）不确定性的影响； (4) 研究近几十年来短链 PFCA 沉积的趋势以及基于前体排放预测的未来可能的趋势（例如探索低 GWP HFO 制冷剂使用增长的影响）。