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| Titel |
Critical loads of sulphur and nitrogen for freshwaters in Great Britain and assessment of deposition reduction requirements with the First-order Acidity Balance (FAB) model |
| VerfasserIn |
C. Curtis, T. Allott, J. Hall, R. Harriman, R. Helliwell, M. Hughes, M. Kernan, B. Reynolds, J. Ullyett |
| 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 ; 4, no. 1 ; Nr. 4, no. 1, S.125-140 |
| Datensatznummer |
250001524
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| Publikation (Nr.) |
 copernicus.org/hess-4-125-2000.pdf |
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| Zusammenfassung |
| The critical loads approach is widely used within Europe to
assess the impacts of acid deposition on terrestrial and freshwater ecosystems.
Recent work in Great Britain has focused on the national application of the
First-order Acidity Balance (FAB) model to a freshwaters dataset of 1470 lake
and stream water chemistry samples from sites across Britain which were selected
to represent the most sensitive water bodies in their corresponding 10 km grid
square. A ``Critical Load Function" generated for each site is compared with
the deposition load of S and N at the time of water chemistry sampling. The
model predicts that when catchment processes reach steady-state with these
deposition levels, increases in nitrate leaching will depress acid neutralizing
capacity (ANC) below the critical threshold of 0 μeql-1 at more than
a quarter of the sites sampled, i.e. the critical load of acid deposition is
exceeded at these sites. The critical load exceedances are generally found in
upland regions of high deposition where acidification has been previously
recognised, but critical loads in large areas of western Scotland are also
exceeded where little biological evidence of acidification has yet been found.
There is a regional variation in the deposition reduction requirements for
protection of the sampled sites. The FAB model indicates that in Scotland, most
of the sampled sites could be protected by sufficiently large reductions in S
deposition alone. In the English and Welsh uplands, both S and N deposition must
be reduced to protect the sites. Current international commitments to reduce S
deposition throughout Europe will therefore be insufficient to protect the most
sensitive freshwaters in England and Wales.
Keywords: critical loads; acidification; nitrate; FAB model;
acid deposition |
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