SWETHRO,
Swedish Throughfall Monitoring Nework
A collaboration between Air Quality Associations, County Administrative Boards,
the Swedish Environmental Protection Agency, as well as different companies.
SWETHRO is a national network that measure air concentrations, deposition in open areas and as throughfall as well as soil water chemistry all over Sweden. These measurements provide important data used in regional and national environmental quality standards. The aim of SWETHRO is to describe conditions, regional differences, temporal trends, and the effects of the deposition of acidifying and eutrophying substances. SWETHRO is managed by IVL Swedish Environmental Research Institute in collaboration with Lund University and is primarily funded by various air quality associations, county administrative boards, and the Swedish Environmental Protection Agency. The measurements began in 1985.
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Air concentrations
Air quality measurements are conducted within SWETHRO, Swedish Throughfall Monitoring Nework, at measurement plots throughout Sweden. The monthly measurements include sulfur dioxide, nitrogen dioxide, ammonia, and ozone. Concentrations of air pollutants are measured using diffusion samplers, "passive samplers." This means that the gas is captured on a filter impregnated with a chemical that quantitatively absorbs the gas to be analyzed.
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Deposition
Air pollution deposition is measured monthly within the SWETHRO, Swedish Throughfall Monitoring Nework, both in open areas and under tree canopies in the forest. In open areas, deposition is measured using bulk collectors, while deposition in forest ecosystems is measured as throughfall. Some substances interact with the tree canopies, and therefore string samplers are also used to determine the dry deposition of these substances.
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Soil water chemistry
Deposition measurements are used to quantify the air pollution load on forest ecosystems, while the environmental condition of forest ecosystems is quantified through measurements of soil water chemistry. The chemistry of the soil water is the first to be affected by the deposition of air pollutants as the water makes its way towards groundwater and surface water.
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