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- Andersson, Ulla-Maria, et al.
(författare)
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Hydrochemical investigations in three representative basins in Sweden
- 1978
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- SummaryDuring the IHD-period 1965—1974 chemical investigations were carried out in the three representative basins Velen, Kassjöån and Lappträsket, mainly to obtain balances of common constituents in surface waters, taking into account deposition from the atmosphere.As to the seasonal variation of concentrations in discharge from the basins and sub-basins it is remarkably suppressed compared to variations in discharge rates. This can be explained by the storage in lakes and as groundwater which tend to smooth rapid fluctuations in concentrations. However, it also indicates that surface run-off during snow-melt is in no way a dominant process. The largest fluctuations are found for the nitrogen compounds ammonia and nitrate where complex biological processes may at times either "fix" or release nitrogen compounds from organic matter.Considering balances of incoming — outflowing constituents, sulphur and nitrogen compounds always show a deficit; much more is deposited from the atmosphere than carried away from the basins by run-off. There are two possible mechanisms which explain this. One is a loss as volatile sulphur and nitrogen compounds from soils due to microbiological processes in reducing environments. The other possibility is a steady increase in soil sulphur and nitrogen (bound in organic matter) revealing an ongoing adjustment of soil sulphur and nitrogen to the increasing levels of atmospheric deposition of these.As to the balances of calcium, magnesium, sodium and potassium they indicate losses in the ground due to weathering. There are differences in the rates of weathering in the three basins which can be explained on basis of differences in the mineralogical composition of the hard rocks which are so common in Sweden.
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