You are in: Home > Air and Air Pollution Control > Air pollutant inputs
Last changed: 4/04/11
Air pollutants not only have direct effects via air, they also damage ecosystems after being removed from the air (deposition). They are deposited either in gaseous form, as particles, or dissolved in precipitation and fog.
Any input of airborne pollutants into ecosystems by means of precipitation (rain, snow) is called wet deposition. Its amount depends on the volume of precipitation at the testing site and the concentration of the pollutant in that precipitation.
Wet deposition is detected through measurements of pollutant concentrations in sampled precipitation. Several local, regional, and national monitoring programmes and networks take part in these measurements, resulting in a sufficiently dense and evenly distributed measurement network.
These concentration data are interpolated and multiplied with interpolated (to 1 x 1 km²) meteorological precipitation data for a given year to obtain wet deposition fields and thus enabling the production of maps.
Airborne particles and gases are also deposited into soil, vegetation, and other materials without rain and snowfall. Atmospheric conditions, the concentration of the pollutant in the atmosphere, and the receptor properties determine the amount of dry deposition. Size, shape, and composition of the receptor surface are most significant. Forest canopies are very effective in filtering out particles and droplets in addition to retaining large volumes of harmful compounds in the forest ecosystem through direct absorption on and into leaves.
Dry deposition in recorded regularly recorded at only a few measuring sites.
Land cover specific, high-resolution data on dry deposition (1 x 1 km²) is calculated based on modelling in Germany.
Atmospheric pollutants dissolve in fog and cloud droplets which are deposited to ecosystems. As with dry deposition the amount of occult deposition greatly depends on receptor characteristics. High-resolution (1 x 1 km²) model results are based on land use and meteorological data as well as pollutant concentrations for forest areas above 250 mean sea level.
Wet deposition only accounts for about one third of total deposition, whereas dry deposition accounts for the remaining two-thirds.
Total deposition is recorded as a combination of spatially interpolated measurements of wet deposition with modelled dry and occult depositions. It is mapped in high-resolution (1 x 1 km²) and specific to land use.