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（PFCAs）是一种广泛存在于全球环境中的持久性污染物，具有一系列不利影响。长链全氟化学品（>7个碳原子）的生态风险沿着人类接触的途径都有详细记录，因此要求对其生产进行更严格的监管。短链PFCAs受到的关注较少，但越来越受到环境关注。与长链物种一样，短链全氟氯化碳也在距离工业区很远的各个偏远地区（如北极）被检测到，这表明它们是移动的污染物。超短链PFCA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这些污染物的主要生态系统来源（例如，Björnsdotter等人，2020年）。在大气中，由于一次排放的前体（包括氟调聚物醇）的氧化，可能发生短链全氟化碳的二次产生（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而引入的气体（某些氟氯烃、氢氟碳化合物）。观测证据表明，近几十年来，短链全氟化学品在地表的沉积显著增加（Pickard等人，2020; Garnett等人，2022年），但其全球预算存在很大的不确定性。例如，长期以来声称的TFA的重要天然来源现在受到质疑（Joudan等人，2021年），而大气中沉积的TFA量的估计是不确定的，原因是（1）前体排放的幅度，分布和趋势，（2）前体氧化的机制（以及PFCA产量），以及（3）全球模型中大气传输和其他过程（例如湿/干沉积）的代表性。此外，越来越多地使用超低全球升温潜能值制冷剂（包括氢氟烯烃、氢氟烯烃）作为TFA和其他全氟化学品的来源，迫切需要对这一问题进行评估，从而进一步提高这一问题的政策相关性。为了了解短链全氟化学品造成的环境风险，有必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三维化学迁移模型，以纳入主要的短链全氟化学品及其前体;（2）量化短链全氟化学品的全球/区域沉积，包括在偏远的极地地区;（3）探索短链全氟乙酸源-受体途径的可变性，以应对模式大气迁移和化学/物理过程中的不确定性（如对流层氧化剂、干/湿沉降的处理）;（4）根据前体排放预测，审查近几十年来短链全氟乙酸沉降的趋势和未来可能的趋势（如探讨日益使用低全球升温潜能值的氢氟烯烃制冷剂的影响）。