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| Titel |
Interpretation of trends in acidic deposition and surface water chemistry in Scotland during the past three decades |
| VerfasserIn |
R. Harriman, A. W. Watt, A. E. G. Christie, P. Collen, D. W. Moore, A. G. McCartney, E. M. Taylor, J. Watson |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 5, no. 3 ; Nr. 5, no. 3, S.407-420 |
| Datensatznummer |
250002563
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| Publikation (Nr.) |
 copernicus.org/hess-5-407-2001.pdf |
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| Zusammenfassung |
| Trends in major ionic components of bulk
precipitation were analysed for two sites, Faskally and Loch Ard forest in
Scotland, for the period 1972-2000. The pattern of change
was not linear. Large reductions in sulphur deposition occurred in the early
1980s and, to a lesser extent, during 1995-2000, with a
period of relative stability between 1988-95. pH increased significantly at both
sites but nitrate and ammonia only increased significantly
at Loch Ard forest. Long-term chemical data from a total of 37 streams and lochs
in four selected regions of Scotland were analysed over
three time periods (all available data (mostly 1978-2000), 1988-98 and
1995-2000) to match the deposition patterns. For the whole
study period a significant decline in non-marine sulphate was found at all sites
while the most consistent increases in pH and alkalinity
were recorded at all the high elevation loch sites in the Galloway area.
Significant reductions in toxic forms of aluminium were also recorded,
mostly at sites where pH had increased. Nitrate trends were equivocal except for
catchments with clear-felling operations. For these sites,
negative trends were found where felling occurred in the 1980s, while positive
trends were found at sites with felling in the 1990s. With
the exception of one site, dissolved organic carbon concentrations increased
significantly with moorland sites showing smaller increases
than forested sites. Associated with this change was a significant increase in
complexed forms of aluminium. Trends for the 1988-98 period were much smaller
than those for the whole study period and in many cases were insignificant. This
contrasts with the 1995-2000 period when large and
significant reductions in sulphate and nitrate were recorded along with
increases in marine salts, probably as a result of
climatically related events. Qualitative, experimental and monitoring data from
lochs in the Galloway area revealed evidence of recovery of
fish populations. Interpretation of chemical and biological trends was clearly
influenced by the choice of the time series, especially in relation
to deposition and climatic changes. Nevertheless, all the fresh waters included
in this study are currently in the best ecological condition
since the 1970s in the context of recovery from acidification.
Keywords: deposition, trends, acidification, forestry, recovery, fish, climate |
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