Fog deposition to Norway Spruce stands at high-elevation sites in the Eastern Erzgebirge (Germany)

Abstract

Fog deposition was quantified by comparing the water budget of a small head-water catchment with direct measurements of evapotranspiration by the eddy-covariance-energy-budget-(ECEB)-method and with results of a resistance model. Results from the model showed a distinct altitudinal gradient in fog deposition mirroring different fog frequencies. For two water budget years the model amounted to 270 mm of occult precipitation, while the water budget comparison reached 215 mm. To characterize its contribution to element deposition fog was collected by active and passive samplers. Element fluxes were calculated by multiplying concentrations with modeled water fluxes stratified by wind directions in order to account for the influence of the Bohemian Industrial Basin. Element deposition through fog was in the case of SO 4 2−–S, NH 4 +–N and K + higher than wet deposition. Fog deposition is so an important path within bulk deposition for forested hill sites. The measured ion concentrations in fog water have declined considerably (60–90%) over the last 10 years at the same site. This trend confirms with other measurements of air pollution and atmospheric deposition in the Eastern Erzgebirge.