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| Titel |
Determination of the historical variation of the trophic state in lakes using sediment stratigraphies |
| VerfasserIn |
G. Olli |
| 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 ; 11, no. 6 ; Nr. 11, no. 6 (2007-11-06), S.1747-1756 |
| Datensatznummer |
250009538
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| Publikation (Nr.) |
 copernicus.org/hess-11-1747-2007.pdf |
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| Zusammenfassung |
| Biogenic silica (BSi) and phosphorous (P) accumulation were investigated in
sediment cores from Karlskärsviken, a bay of Lake Mälaren. The aim
was to make use of BSi and P relations in sediment stratigraphies in order
to investigate the historical nutrient trophy in a near shore lake
environment since the Middle Ages, with focus on industrial times, and to
evaluate anthropogenic influences on the bay's trophic state. The BSi
accumulation in the sediments is a better indicator of former nutrient
pelagic trophy than P accumulation in sediments and for this reason a BSi
inferred P (BSi-P) water concentration is calculated. This method enables
the determination of the background total phosphorous (TP) concentration
(which is related to the reference conditions) in the investigated bay; this
background TP is determined equal to 0.020–0.022 mg L−1. There is an
increasing trend of BSi-P concentration in the bay since the Middle Ages to
the present, about 0.025 mg L−1, with a small decrease in the inner bay
section during the last decades. The P accumulation rate is not found to
have changed since the 1960s and 1970s, which indicates that the P loading
to Karlskärsviken has not decreased. In Karlskärsviken, the shallow
inner section of the bay, where the water quality is dominated by loading
from the bay catchment area, is less nutritious than the water in the outer
section, which is influenced by the main streams from the western part of
Lake Mälaren. |
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