Chemical Characterization of Rain and Fog Water in the Cervenohorske Sedlo (Hruby Jesenik Mountains, Czech Republic)

Abstract

Field study at the Cervenohorske sedlo (1,013 m a.s.l.) (Hruby Jesenik Mountains, the Czech Republic, Central Europe) during 1999–2002 has been conducted in order to analyse the chemistry of rain/snow water using bulk and throughfall collector and fog/cloud water using modified passive Grunow collector. Fog water input to coniferous forest (Picea abies) was quantified using canopy balance method. For all samples pH, and the concentrations of ${\text{NH}}^{{\text{ + }}}_{{\text{4}}}$, Ca²⁺, K⁺, Mg²⁺, Na⁺, Cl⁻, ${\text{NO}}^{{\text{ - }}}_{{\text{3}}}$, and ${\text{SO}}^{{{\text{2 - }}}}_{{\text{4}}}$ were measured. The volume-weighted mean pH value varied from 4.92 to 5.43 in open bulk precipitation, from 4.30 to 4.71 in throughfall and from 4.66 to 5.23 in fog water. The fog droplets generally contain higher ion concentrations than rainwater. The related enrichment factors lie between 1.1 and 10.7 for the relevant species. The fog samples exhibit higher concentrations of ${\text{NO}}^{{\text{ - }}}_{{\text{3}}}$ and ${\text{NH}}^{{\text{ + }}}_{{\text{4}}}$ as compared to the bulk samples during 2000–2002. ${\text{NO}}^{{\text{ - }}}_{{\text{3}}}$ are 5.7–10.7 times more concentrated in fog water and ${\text{NH}}^{{\text{ + }}}_{{\text{4}}}$ are 3.4–7.2 times more concentrated in fog water. These differences may result from the height and characteristics of formation of the droplets. Based on canopy balance method, the annual fog water inputs were estimated to be 22 and 19% of rain and snow annual amounts in 1999 and 2000, respectively. For ${\text{NO}}^{{\text{ - }}}_{{\text{3}}}$, ${\text{NH}}^{{\text{ + }}}_{{\text{4}}}$, and ${\text{SO}}^{{{\text{2 - }}}}_{{\text{4}}}$, the contribution of fog deposition in total (bulk + fog) deposition is estimated as 54, 47, and 42%, respectively.