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| Titel |
pH modelling in aquatic systems with time-variable acid-base dissociation constants applied to the turbid, tidal Scheldt estuary |
| VerfasserIn |
A. F. Hofmann, J. J. Middelburg, K. Soetaert, F. J. R. Meysman |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 6, no. 8 ; Nr. 6, no. 8 (2009-08-07), S.1539-1561 |
| Datensatznummer |
250003946
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| Publikation (Nr.) |
 copernicus.org/bg-6-1539-2009.pdf |
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| Zusammenfassung |
| A new pH modelling approach is presented that explicitly quantifies
the influence of biogeochemical processes on proton cycling and pH
in an aquatic ecosystem, and which accounts for time variable
acid-base dissociation constants. As a case study, the method is
applied to investigate proton cycling and long-term pH trends in the
Scheldt estuary (SW Netherlands, N Belgium). This analysis
identifies the dominant biogeochemical processes involved in proton
cycling in this heterotrophic, turbid estuary. Furthermore, information on the factors controlling the longitudinal pH
profile along the estuary as well as long-term pH changes are obtained. Proton production by nitrification is identified as the
principal biological process governing the pH. Its acidifying effect
is mainly counteracted by proton consumption due to CO2
degassing. Overall, CO2 degassing generates the largest proton
turnover in the whole estuary on a yearly basis. The main driver of
long-term changes in the mean estuarine pH over the period 2001 to
2004 is the decreasing freshwater flow, which influences the pH
directly via a decreasing supply of dissolved inorganic carbon and
alkalinity, and also indirectly, via decreasing ammonia loadings and
lower nitrification rates. |
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