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| Titel |
Response of a first-order stream in Maine to short-term in-stream acidification |
| VerfasserIn |
S. A. Norton, R. Wagai, T. Navrátil, J. M. Kaste, F. A. Rissberger |
| 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. 3 ; Nr. 4, no. 3, S.383-391 |
| Datensatznummer |
250001746
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| Publikation (Nr.) |
 copernicus.org/hess-4-383-2000.pdf |
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| Zusammenfassung |
| An experimental short-term acidification with HCl at a first-order stream in
central Maine, USA was used to study processes controlling the changes in stream
chemistry and to assess the ability of stream substrate to buffer pH. The
streambed exerted a strong buffering capacity against pH change by ion exchange
during the 6-hour acidification. Streambed substrates had substantial cation and
anion exchange capacity in the pH range of 4.1 to 6.5. The ion exchange for
cations and SO42- were rapid and reversible. The
speed of release of cations from stream substrates was
Na1+> Ca2+ > Mg2+ > Aln+ > Be2+,
perhaps relating to charge density of
these cations. Ca2+ desorption
dominated neutralisation of excess H+ for the first 2 hr. As the reservoir of
exchangeable Ca diminished,
desorption (and possibly dissolution) of Al3+ became the dominant neutralising
mechanism. The exchangeable (and possibly soluble) reservoir of Al was not
depleted during the 6-hour acidification. Sulphate adsorption during the
acidification reduced the concentration of SO42- in stream water by as much as
20 μeq L-1 (from 70 μeq L-1). Desorption of
SO42-
and adsorption of base cations after the artificial acidification resulted in a prolongation
of the pH depression. The streambed had the capacity to buffer stream water chemistry
significantly during an acidifying event affecting the entire upstream catchment.
Keywords: stream acidification; ion exchange; sediment; sulfate exchange; aluminium; beryllium |
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