Meteorological situations in 2007 and their implications for the cycling of selected chemical elements in a Central Bohemian forested catchment

Comparison of the annual bulk precipitation in the Lesní potok experimental catchment (Central Bohemia, Czech Republic) in the hydrological year 2007 (758.8 mm) with the average annual value between the years 1995 and 2006 (737.4 mm) indicates almost similar values, whereas the stream water discharge in 2007 amounts to only 38.2% of the average annual value of the comparable time span. It has been found that the low discharge in 2007 resulted from the extremely temperate winter and from the anomalous distribution of the precipitation events throughout the year. These factors, together with higher pH values of stream water in 2007, reduced the output of elements from the catchment. The output of dissolved Al, Be, Cd, Mn, Ni, Pb, and Zn through the stream water in 2007 is amounted to only 15 to 20% of their annual output in 1995-2006. The unusually low output of the elements distinctly affected their budgets in the catchment changing towards more positive mass balance values. This holds especially for the major base cations Ca, Mg, and Na (e.g. shift from -1460 to -127 mg/m2year for Ca and from -572 to +15 mg/m2year for Mg) and also for the trace elements Be, Mn, Ni, and Sr (e.g. shift from -368 to +144 μg/m2year for Be, from 2820 to 14 300 μg per m2year for Mn, and from 191 to 7 790 μg/m2year for Sr). The meteorological conditions in 2007 induced, to a certain extent, the recovery of the acid-sensitive ecosystem disturbed by a long-term high input of acid precipitation.