IV. CHEMICAL COMPOSITION OF DENSE ATMOSPHERIC PRECIPITATIONS IN TRANSBOUNDARY MOUNTAINS SITES OF THE CZECH REPUBLIC

The composition of atmospheric precipitations on the territory of the Czech Republic has been monitored for a long time and surveys of the average contents of ions are published annually. Ion concentrations (cations of macro-elements, heavy metals and anions) are measured in precipitation in locations spread over the whole territory of the Czech Republic. Data presented in this article were obtained solely from samples of snow and ice accretions. The data were gathered under the EU-funded project, �Monitoring of trans-boundary air pollution by isotope fingerprinting of sources�. Ten new monitoring sites were established at the altitude of about 1000 m along the border of the Czech Republic (see Fig. IV.1 and Tab. IV.1). The sampling sites were chosen in locations remote from any human dwellings to eliminate the possibility of contamination and overprinting of regional pollution from distant sources. Sampling is also conducted in this way. Samplers avoid anything that could contaminate the samples and record any traces which indicate human activity close to the sites. Possible contamination of the samples during their collection, transport or in the laboratory is checked using blind samples. The sampling takes place in roughly 10-day intervals. The project is planned for three years. Regular sampling enables recalculating concentration data to seasonal fluxes of contaminants. The data presented in this paper show results of the first year of the project (2009) when the samples were collected between January and April. At each site 3-7 snow samples were collected (depending on the snow conditions of each location) and 1-6 samples of the ice accretions. If possible, three replicas of the sample were collected (see Fig. IV.2). Each sample was then analyzed, both the liquid part and the solid part obtained by filtering the sample. Using the ICP-MS method concentrations of 19 elements were measured.

In this article we present an overview of the concentration data of elements, which were selected on the basis of the importance of their influence of the environment.

Results

The Table IV.2 shows the amounts which were calculated as the average of all the amounts obtained by the analysis of the snow and ice accretion in a given location. The total number of samples is also given.

The results show that the horizontal depositions (ice accretions) are generally more concentrated than vertical depositions. It is difficult to define the location with the highest pollution. However it is possible to identify amounts which clearly top the rest. For example the content of As in the ice accretion samples from the Giant Mountains (Krkonoše). Similar maximal amounts can be found at the location Pramenáč in the Krušné Mountains, where the content of Cd in ice accretion and the content of Al in snow are high.
Locations in the south of the Český Les and Bohemian Forest (Šumava) can be called the cleanest. Where the content of Cd does not reach the 0.1 ppm mark in either the snow nor the ice accretion samples and where the content of other elements is generally lower than in the other locations.

Lower pollution is expected in the South of Bohemia but low content of samples from Zaječí Hora in the Krušné Mountains quite surprising and interesting.

Tab. IV.1 Sampling sites description

Tab. IV.2 Mean concentrations of elements in dense atmospheric precipitation collected in the first half-year of 2009 – wet deposition

Fig. IV.1 Map of the sites

Fig. IV.2 Jizerské hory – Bukovec, sampler installation