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| Titel |
Analysis of the impacts of major anion variations on surface water acidity particularly with regard to conifer harvesting: case studies from Wales and Northern England |
| VerfasserIn |
C. Neal, B. Reynolds, J. K. Adamson, P. A. Stevens, M. Neal, M. Harrow, S. Hill |
| 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 ; 2, no. 2/3 ; Nr. 2, no. 2/3, S.303-322 |
| Datensatznummer |
250000357
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| Publikation (Nr.) |
 copernicus.org/hess-2-303-1998.pdf |
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| Zusammenfassung |
| Data on the water quality of streams
draining a range of acidic and acid sensitive, mainly afforested, upland catchments in
mid- and north-Wales and northern-England are described to investigate the acidification
effects of conifer harvesting in relation to natural variability. Most sites show a large
range in pH and major cation and major anion concentrations. The waters draining from the
smaller catchments are more acidic and aluminium bearing reflecting a higher proportion of
runoff from the acidic soils in each area. However, there is often a less acidic component
of runoff under base-flow conditions due to ground-water contributions particularly within
the larger streams. Higher concentrations of nitrate occur for sites which have been
felled although declines in concentration occur several years after felling. Multiple
regression analysis reveals the importance of cation exchange and within catchment
acidification associated with sulphate and nitrate generation. Sulphate also has a
component associated with weathering but the patterns vary from catchment to catchment.
Analysis of the influence of changing anion concentrations associated with tree harvesting
reveals that the acidification induced by increases in nitrate can be offset or reversed
by the lowering of chloride and sulphate concentrations due to decreased atmospheric
scavenging by the vegetation, reduced evapotranspiration and increased surface runoff
diluting the acidity generated. It is concluded that contemporary UK forestry guidelines
with an emphasis on phased harvesting of catchments over several years and careful
harvesting methodologies can alleviate most problems of stream acidification associated
with felling activities and in some cases can reverse the acidification pattern. |
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