Abstract : 1B.6
Precipitation chemical composition in Bulgarian mountains

Liliana Iordanova
National Institute of Meteorology and Hydrology, Bulgarian Academy of Sciences

The precipitation chemistry network of NIMH (National Institute of Meteorology and Hydrology) comprises 3 mountain stations – on Musala mount (Rila Mountain, 2925 m), on Cherni Vruh mount (Vitosha Mountain, 2290 m) and on Rojen mount (Rhodope Mountains, 1430 m). The samples are obtained at main synoptical hours 00, 06, 12 and 18 UTC as well as the 6-hourly precipitation amount. The precipitation acidity (in pH-units) is measured with portable pH-metre on-site immediately after sample taking and the data are transmitted in a special group by the code SYNOP. The rest of the sample is conserved in appropriate conditions and all samples are transported monthly to the nearest NIMH’s laboratory for nitrates (NO3-), sulphates (SO42-) and conductivity analysis. The chemical composition of the rainfall there is considered to bear the characteristics of the regions over which the cyclone’s frontline has formed and passed. The investigation suggests that the background concentrations are significantly lower in the rain systems formed and passed over the Mediterranean, rather than over West and Central Europe. There are exceptions which might be explained with significant regional sources of pollution, for example - a Mediterranean cloud system with exceptionally high level of sulfates in the precipitation over Mount Cherni Vruh, could be explained with the working of 'Maritsa' power complex.