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Atmospheric deposition connects air quality, ecosystem health and climate
Citation:
Walker, J., C. Brümmer, J. Shen, M. Bell, T. Scheuschner, AND H. Fagerli. Atmospheric deposition connects air quality, ecosystem health and climate. IN: WMO Air Quality and Climate Bulletin, World Meteorological Organization, Geneva, Switzerland, (2):5-9, (2022).
Impact/Purpose:
This short article is a contribution to the 2022 World Meteorological Organization Air Quality and Climate Bulletin. The bulletin comprises several short sections (500-600 words) on scientific topics relevant to the activities of the WMO Global Atmosphere Watch. This article is one of six sections written for the 2022 bulletin. The article describes connections between air quality and ecosystem exposure (via critical load exceedance) in the US, Europe, and China and calls for expanded monitoring of wet and dry deposition to improve global measurement-model fusion methods for total atmospheric deposition of nitrogen and sulfur. All articles are peer reviewed for technical content by the Bulletin editorial board.
Description:
Gases and particles are deposited from the atmosphere to ecosystems via dry deposition (when gases or airborne particles leave the atmosphere by coming into contact with the surface of the Earth) or scavenging by precipitation (when gases or particles are removed from the atmosphere by raindrops or snowflakes). While deposition of many pollutants (e.g., ozone) is important, here we focus on nitrogen (N) and sulfur (S) compounds, which alone and in combination are sources of acidity in ecosystems and, in the case of N, also cause effects related to excess nutrients’ availability (i.e., eutrophication). Acidification of soils and waters can increase plant and aquatic life mortality and increase vulnerability to other ecosystem stressors (i.e., climate change). Additionally, N deposition can harm lichen, reduce soil microbial diversity, and alter plant community composition. These impacts affect the quality of services provided by healthy ecosystems, including biodiversity, clean drinking water, food and forest products, and carbon storage. Critical loads (CL), which are deposition amounts above which harmful effects might be expected, link ecosystem exposure to air pollution (i.e., air quality), via deposition, to its effect on the ecosystem. CLs have been developed for a range of ecosystem components and impacts from acidification and eutrophication are used to assess risk from current pollution and inform policy and management. Here we briefly assess trends in N and S emissions, deposition, and critical load exceedances in the U.S., Europe, and China.
