Trends in soil water composition at a heavily polluted site-effects of decreased s-deposition and variations in precipitation

摘要

Precipitation, soils and soil water in a forested catchment in western Poland have been studied during the period 1992 - 96 (see also Vogt et al., this conf.). The S-deposition in the area during the study period was 2 - 3g S m{sup}(-2)yr{sup}(-1). In spite of decreasing anthropogenic enussions the S-deposition in the area did not change much during the study period mainly because the first years were exceptionally dry". However, the S-deposition was considerably higher during the previous decade. Based on Soil water sulphate concentration, pH, acid neutralising capacity and the ratio of Al{sup}(3+)/(Ca{sup}(2+) + Mg{sup}(2+)), there is apparently an amelioration in the conditions. A study using inter alia principal component analysis, indicates that this improvement is mainly due to more precipitation in the later part of the study period. Variations in precipitation amount have a pronounced effect on the soil-water chemistry, which makes it difficult to establish trends caused by changes in anthropogenic deposition. Long time series are therefore necessary to establish recovery due to reduced S-emissions.