Immission Mapping
Air pollution immission maps are an important tool which authorities use for planning purposes, performance control of air quality measures and information of the general public. According to pollutant and spatial as well as temporal scale, we utilize different methodologies for mapping. Here we present some examples.
Modeling of PM10 and NO2 pollution
On behalf of the Swiss Federal Office for the Environment (FOEN) and together with the firm Infras, METEOTEST has developed a distribution model for PM10. The model is implemented within the Geographical Information System ArcInfo®. The spatial distributions of the emissions from different sources are calculated from the emission sum for Switzerland, based on land use and census information. With regional transfer functions, emissions are converted to PM10 immissions. Secondary particles are determined from the immissions of their predecessors.
METEOTEST has modeled and mapped the results of FOEN report No. 169. Maps showing yearly mean values are published on the FOEN website. An analogous project was carried out for NO2. The environmental department of the canton of Solothurn has summarized and commented the results. PDF (German only)
Ozone exposition of the Swiss forest 2004-2006
Interpolation of ozone measurements
Based on interpolation routines METEOTEST produces spatial maps of parameters that are important in the scope of air quality control. The interpolations are based on measurements of the cantonal air monitoring stations and the National Air Pollution Monitoring Network (NABEL).
For example, the ozone impact on forests was displayed on maps using the AOT40f index. AOT40f is the sum of the ozone impact above a threshold of 40 ppb during the forest's vegetation period between April 1 and September 30.
The air pollution maps were mapped on the basis of statistical correlations between AOT40f and spatial information with ArcGIS® and can be viewed on the FOEN website.
Nitrogen deposition 2000
Modeling of nitrogen deposition
Nitrogen deposition from the atmosphere can have undesireable fertilizing or acidifying effects in nature-near, low nutrient ecosystems such as forests, fens as well as dry meadows and pastures. In order to quantify these effects, the concept of Critical Loads is employed in the UNECE convection on large-scale transnational air pollution (LRTAP).
The following nitrogen components are taken into consideration: Ammonia, ammonium, nitrogen dioxide, nitrate and nitric acid. Component fluxes are calculated on a 1x1 km raster. For all of Switzerland, a sum of 68'500 t nitrogen per year (2006) was determined, which corresponds to an average deposition of 17 kg nitrogen par ha and year. A possible use of the nitrogen deposition map is for calculatong the exceedance of critical loads.
In 1996, METEOTEST wrote the FOEN report "Critical Loads of Nitrogen and their Exceedances" (Environmental Series No. 275), in which the current state of nitrogen deposition and exceedance of critical loads was recorded. Since then numerous improvements have been performed for mapping critical loads and nitrogen depositions (CCE status report 2008; Stickstoffhaltige Luftschadstoffe in der Schweiz). Currently, a project for updating the pollution maps is underway.
Yearly means of ammonia immissions 2000
Modeling of ammonia immissions
METEOTEST utlizes an ammonia dispersion model in different projects. It is implemented in the Geographical Information System ArcInfo®.
On behalf of the FOEN, the spatial distribution of different ammonia sources was determined based on land use statistics and an agricultural census. Using transfer functions, the ammonia emissions are transferred to ammonia immissions.
According to the latest calculations of the simulation model Agrammon, gaseous ammonia emissions amounted to 51'300 t NH3 in the year 2007. 95% of them originate from agricultural activities such as animal farming as well as storage and distribution of organic fertilizer. The critical levels for ground vegetation and lichens are 3 and 1 µg/m3, respectively. Approximately half of the emitted NH3-gasses are deposed in a perimeter of a few kilometers. The other half is transformed to more stable ammonium compounds (NH4+) and is transported hundreds of kilometers in the atmosphere.