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 NH þ 4 , Ca 2+ , K + , Mg 2+ , Na + , Cl − , NO À 3 , and SO 2À 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 NO À 3 and NH þ 4 as compared to the bulk samples during [2000][2001][2002]. NO À 3 are 5.7-10.7 times more concentrated in fog water and NH þ 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 NO À 3 , NH þ 4 , and SO 2À 4 , the contribution of fog deposition in total (bulk + fog) deposition is estimated as 54, 47, and 42%, respectively.
Future ground-level concentrations of phytotoxic ozone are projected to grow in the Northern Hemisphere, at a rate depending on emission scenarios. We explored the likely changes in net ecosystem production (NEP) due to the increasing concentration of tropospheric ozone by applying a Generalized Additive Mixed Model based on measurements of ozone concentration ([O3]) and stomatal ozone flux (FsO3), at a mountainous Norway spruce forest in the Czech Republic, Central Europe. A dataset covering the growing period (May-August 2009) was examined in this case study. A predictive model based on FsO3 was found to be marginally more accurate than a model using [O3] alone for prediction of the course of NEP when compared to NEP measured by the eddy covariance technique. Both higher [O3] and FsO3 were found to reduce NEP. NEP simulated at low, pre-industrial FsO3 (0.5 nmol m-2 s-1) was higher by 24.8% as compared to NEP assessed at current rates of FsO3 (8.32 nmol m-2 s-1). However, NEP simulated at high FsO3 (17 nmol m-2 s-1), likely in the future, was reduced by 14.1% as compared to NEP values at current FsO3. The interaction between environmental factors and stomatal conductance is discussed in this paper.
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