The evolving role of weather types on rainfall chemistry under large reductions in pollutant emissions.
The evolving role of weather types on rainfall chemistry under large reductions in pollutant emissions.
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DOI：
10.1016/j.envpol.2022.118905
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发表时间：
2022-01
影响因子：
8.9
通讯作者：
Chak‐Hau Michael Tso;D. Monteith;T. Scott;H. Watson;Beverley Dodd;M. Pereira;P. Henrys;M. Hollaway;S. Rennie;Aaron Lowther;J. Watkins;Rebecca Killick;Gordon S. Blair
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作者：
Chak‐Hau Michael Tso;D. Monteith;T. Scott;H. Watson;Beverley Dodd;M. Pereira;P. Henrys;M. Hollaway;S. Rennie;Aaron Lowther;J. Watkins;Rebecca Killick;Gordon S. Blair
污染物和海洋盐分在大气中沉积的长期变化和短期变化会对土壤和地表水生态系统的生物地球化学和生态产生重大影响。 20 世纪 80 年代，英国酸沉降高峰期，沉降负荷高度依赖于当时的天气类型，据推测，未来的污染恢复轨迹将部分依赖于任何气候变化驱动的天气系统变化。经过三十年大幅减少酸性排放之后，我们使用 1992 年至 2015 年从英国不同地区的四个英国环境变化网络 (ECN) 站点收集的监测数据来研究与主要天气条件相关的降水化学趋势。天气系统根据兰姆天气类型 (LWT) 分组进行分类，同时使用排放清单和气团轨迹聚类来解释观测到的模式。离子浓度在气旋西风主导时期与其他时期之间表现出明显差异，反映出大西洋气团中海洋贡献较高，人为贡献较低。西风带与所有地点较高的降雨量、较高的海盐浓度和较低的污染物浓度有关，而气团路径则施加额外的控制。因此，西风带继续有利于较高的海盐通量，而排放量减少则日益导致西风带和污染物通量之间的正相关性。我们的结果还表明，当它们在相对清洁的条件下运输到英国时，人为排放的影响转向自然排放（例如海盐）和气候强迫。在 ECN 监测期间，西风带相对频繁，但这些天气类型的长期周期性表明，目前对降水的贡献在未来几年可能不会持续。
Long-term change and shorter-term variability in the atmospheric deposition of pollutants and marine salts can have major effects on the biogeochemistry and ecology of soils and surface water ecosystems. In the 1980s, at the time of peak acid deposition in the UK, deposition loads were highly dependent on prevailing weather types, and it was postulated that future pollution recovery trajectories would be partly dependent on any climate change-driven shifts in weather systems. Following three decades of substantial acidic emission reductions, we used monitoring data collected between 1992 and 2015 from four UK Environmental Change Network (ECN) sites in contrasting parts of Great Britain to examine the trends in precipitation chemistry in relation to prevailing weather conditions. Weather systems were classified on the basis of Lamb weather type (LWT) groupings, while emissions inventories and clustering of air mass trajectories were used to interpret the observed patterns. Concentrations of ions showed clear differences between cyclonic-westerly-dominated periods and others, reflecting higher marine and lower anthropogenic contributions in Atlantic air masses. Westerlies were associated with higher rainfall, higher sea salt concentrations, and lower pollutant concentrations at all sites, while air mass paths exerted additional controls. Westerlies therefore have continued to favour higher sea salt fluxes, whereas emission reductions are increasingly leading to positive correlations between westerlies and pollutant fluxes. Our results also suggest a shift from the influence of anthropogenic emissions to natural emissions (e.g., sea salt) and climate forcing as they are transported under relatively cleaner conditions to the UK. Westerlies have been relatively frequent over the ECN monitoring period, but longer-term cyclicity in these weather types suggests that current contributions to precipitation may not be sustained over coming years.