Regional Monitoring of Natural Environment 2004, No 5 129-138
TEMPORAL TRENDS IN THE CHEMICAL COMPOSITION OF PRECIPITATION, SOIL SEEPAGE AND STREAMWATER IN TWO FORESTED CATCHMENTS IN THE BLACK FOREST AND THE EASTERN ORE MOUNTAIS (GERMANY)
Martin Armbruster, Karl-Heinz Feger
This paper focuses on the temporal trends in the composition of precipitation, throughfall affected by atmospheric deposition-load and the consecutive modifactions in soil seepage and stream water chemistry of two forested catchments in Germany. The catchment ‘Schluchsee’ (Black Forest; SW Germany) has been exposed to relatively low atmospheric inputs lasting until a few years ago whereas Rotherdbach (Ore Mountains; E Germany) received considerable amounts of acid deposition (mainly originating from SO2 emissions). Both sites reveal decreases in S deposition and cojoined acidity during the 1990s which ensue also the general trends in Europe. In response to the decline in atmospheric, S deposition, soil solution and stream-water SO42- concentrations decreased significantly in the investigation period 1988-1998. In this time, the level of N deposition was more or less constant at both sites. At Schluchsee, NO3– concentration in stream water remained more or less unchanged, whilst a decrease at Rotherdbach was observed. Remarkable recovery of alkalinity was found in seepage water as indicated by increasing acid neutralizing capacity (ANC). Stream-water ANC increased only in the permanently acidified Rotherdbach. A change of ANC was observed in the Schluchsee stream, which was characterized by episodic acidification during high-flow conditions. Nevertheless, the key factor controlling the recovery from surface water acidification was the type, amount and distribution of stored S pools in the ecosystem. Thus, time series analysis of long-term data of input-output chemistry can be a valuable instrument in order to improve the understanding of linked terrestrial-aquatic systems and give useful clues for modeling efforts.