Fog water chemical composition in different geographic regions of Poland

The fog water samples were collected with the use of both passive and active fog collectors during 2005-2006 at 3 sites: lowland in northern Poland (Borucino: 186 m a.s.l.), valley basin in southern Poland (Zakopane; 911 m a.s.l.) and mountain top (Szrenica Mt.; 1330 m a.s.l.) in south-western Poland. For all daily samples (Borucino-25; Zakopane-4 and Szrenica-155), electric conductivity, pH, and concentrations of some anions: Cl(-), F(-), Br(-), NO(2)(-), NO(3)(-), SO(4)(2-), PO(4)(3-) and cations: NH(4)(+), Ca(2)(+), K(+), Na(+) and Mg(2+) were measured. The selected ions were determined using ion suppressed chromatography (IC). Fog consists of a specific type of atmospheric phenomena. Results obtained on the basis of analysis of suitable fog samples can be treated as a source of valuable information on the chemistry of the atmosphere. Statistical analysis revealed significant differences depending on region, altitude, local morphology and, last but not least, fog origin. A distinct contrast is evident in the concentration and chemical composition between lowland radiation fog (represents lower layers of the atmosphere which are more influenced by continental emissions) versus orographic slope fog represented by a summit station, Mt Szrenica. It is partly induced by a distinction in weather conditions favouring fog existence, height of fog formation and its microphysical parameters. Acidity was associated with high concentrations of excess sulphate and nitrate in the fog water samples. Ammonium and calcium concentrations represent the most important neutralizing inputs. Collected cloud water at Szrenica Mt. includes solute contributions from emission sources located at much larger upwind distances. The fact that 95% of fog/cloud deposition is concentrated during SW-W-NW-N-NE, atmospheric circulation exerts an influence on the environmental quality of montane forests in the Sudety Mts. At numerous conspicuous convex landforms, where fog/cloud deposition becomes at least as important as wet deposition via atmospheric precipitation, a distinct difference in the health of coniferous forests is clearly visible, with the areas of the NW aspect being the worst affected, contrary to SE slopes with relatively healthy forest stands. (C) 2009 Elsevier B.V. All rights reserved.