The evolving role of weather types on rainfall chemistry under large reductions in pollutant emissions

A - Papers appearing in refereed journals

Tso, M. C., Monteith, D., Scott, T., Watson, H., Dodd, B., Dos Santos Pereira, M. G., Henrys, P., Hollaway, M., Rennie, S., Lowther, A., Watkins, J, Killick, R. and Blair, G. 2022. The evolving role of weather types on rainfall chemistry under large reductions in pollutant emissions. Environmental Pollution. 299 (15 April), p. 118905. https://doi.org/10.1016/j.envpol.2022.118905

AuthorsTso, M. C., Monteith, D., Scott, T., Watson, H., Dodd, B., Dos Santos Pereira, M. G., Henrys, P., Hollaway, M., Rennie, S., Lowther, A., Watkins, J, Killick, R. and Blair, G.
Abstract

Long-term change and shorter-term variability in the atmospheric deposition of pollutants and 1 marine salts can have major effects on the biogeochemistry and ecology of soils and surface water 2 ecosystems. In the 1980s, at the time of peak acid deposition in the UK, deposition loads were highly 3 dependent on prevailing weather types, and it was postulated that future pollution recovery 4 trajectories would be partly dependent on any climate change-driven shifts in weather systems. 5 Following three decades of substantial acidic emission reductions, we used monitoring data collected 6 between 1992 and 2015 from four UK Environmental Change Network (ECN) sites in contrasting 7 parts of Great Britain to examine the trends in precipitation chemistry in relation to prevailing 8 weather conditions. Weather systems were classified on the basis of Lamb weather type (LWT) 9 groupings, while emissions inventories and clustering of air mass trajectories were used to interpret 10 the observed patterns. Concentrations of ions showed clear differences between cyclonic-westerly-11 dominated periods and others, reflecting higher marine and lower anthropogenic contributions in 12 Atlantic air masses. Westerlies were associated with higher rainfall, higher sea salt concentrations, 13 and lower pollutant concentrations at all sites, while air mass paths exerted additional controls. 14 Westerlies therefore have continued to favour higher sea salt fluxes, whereas emission reductions are 15 increasingly leading to positive correlations between westerlies and pollutant fluxes. Our results also 16 suggest a shift from the influence of anthropogenic emissions to natural emissions (e.g., sea salt) and 17 climate forcing as they are transported under relatively cleaner conditions to the UK. Westerlies have 18 been relatively frequent over the ECN monitoring period, but longer-term cyclicity in these weather 19 types suggests that current contributions to precipitation may not be sustained over coming years.

KeywordsRainfall Chemistry; Deposition; Major Ions; Lamb Weather Types; Climatic effects
Year of Publication2022
JournalEnvironmental Pollution
Journal citation299 (15 April), p. 118905
Digital Object Identifier (DOI)https://doi.org/10.1016/j.envpol.2022.118905
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeThe Rothamsted Long Term Experiments [2017-2022]
Publisher's version
Accepted author manuscript
Output statusPublished
Publication dates
Online15 Apr 2022
Publication process dates
Accepted24 Jan 2022
PublisherElsevier Science Bv
Elsevier Sci Ltd
ISSN0269-7491

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