Investigation of country-scale cadmium pollution levels in Poland continued. This work is carried out in close cooperation of MSC-E and national experts from Institute for Environmental Protection - National Research Institute (IEP-NRI) of Poland (http://www.ios.edu.pl/). Three main objectives are formulated for the country-specific case study of cadmium pollution in Poland:
1) Testing the model ability to simulate pollution levels on new EMEP grid with fine (0.1° x 0.1°) spatial resolution.
2) Analysis of factors affecting cadmium pollution levels in Poland, taking into account national data on emission and monitoring and modelling results.
3) Preparation detailed policy-oriented information on cadmium pollution in Poland with fine spatial resolution.
National experts from Poland provided MSC-E with national data on emissions of cadmium with spatial resolution 0.1° x 0.1°. Emission data are subdivided according to source categories. Additionally, emissions from large point sources are presented.
Spatial distribution of cadmium emission in Poland from source categories “Industry” (left) and “Other Stationary Combustion” (right) in 2014. Please note that colour palettes of these two maps are different.
Measurements of concentrations of cadmium in air are available at 84 stations of national monitoring network. Among them there are three background regional, two sub-urban and 79 urban stations. Besides, information on wet deposition fluxes was from 23 stations also provided by national experts.
Location of stations measuring concentrations of cadmium in air (left) and wet deposition fluxes (right) of national monitoring network. In the left map purple circles depict urban, green square – sub-urban and red triangles – background regional stations
Annual mean concentrations in air calculated on new grid with fine spatial resolution were compared with the concentrations obtained on old EMEP grid. Besides, the results of modelling on old and new grid were compared with air concentrations measured at the EMEP monitoring stations and regional background and suburban national stations. It was shown that transition from old (50x50km2) to new (0.1°x0.1°) EMEP grid resulted to some improvement of quality of mean annual modelled concentrations at background regional stations in Poland and neighbouring areas.
Annual mean modelled (50x50 km2, 0.1°x0.1°) and observed concentrations of cadmium at the EMEP and national Polish background regional and suburban stations
In spite of improvement of the model performance due to transition from old to new grid, overall underestimation of measured air concentrations remains. Comparison of monthly mean modelled and observed air concentrations demonstrates that at most of stations modelled and observed air concentrations are close in warm period. However, in cold period the model underestimates the observed levels
The following possible reasons leading to underestimation in cold period were examined. They include:
1) Seasonal changes of atmospheric boundary layer height
2) Seasonal changes of cadmium emissions
3) Episodic transboundary transport from polluted regions
It was shown that heavy metal emissions from some source categories (e.g. residential combustion) can have significant uncertainties and need further refinement. Besides, the need to revise emissions data for Eastern Europe was demonstrated to improve quality of the model assessment.
Time series of modelled and observed concentrations of cadmium at the EMEP station PL5 (Diabla Gora) in 2014
It is planned that further work in the framework of case study will include:
· Analysis of emission sectors and their effect on modelling results.
· Involvement of information on wet deposition in the analysis of pollution levels in Poland and in evaluation of the model performance.
· Preparation of country-specific policy-oriented information on pollution levels with fine spatial resolution. This information will include source-receptor matrices, contribution to pollution levels in national administrative regions from foreign emission sources, large point sources (LPS), key emission source categories etc.
· Joint report on the results of the case study