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Research article - Peer-reviewed, 2016

Factors controlling phosphorus release from sediments in coastal archipelago areas

Puttonen, Irma; Kohonen, Tuula; Mattila, Johanna


In coastal archipelago areas of the northern Baltic Sea, significantly higher phosphate concentrations (6.0±4.5μmol/l, mean±SD) were measured in water samples close to the sediment surface compared with those from 1m above the seafloor (1.6±2.0μmol/l). The results indicated notable phosphate release from sediments under the bottom water oxygen concentrations of up to 250μmol/l, especially in areas that had experienced recent temporal fluctuation between oxic and hypoxic/anoxic conditions. No single factor alone was found to control the elevated PO4-P concentrations in the near-bottom water. In addition to the oxygen in the water, the contents of potentially mobile phosphorus fractions, grain-size, the organic content at the sediment surface, and the water depth were all important factors controlling the internal loading of phosphorus. The complexity of this process needs to be accounted for in assessments of the internal loading of phosphorus and in potential mitigation plans.


Baltic Sea; Internal loading; Sediment; Phosphorus fractions; Coastal zone; Hypoxia

Published in

Marine Pollution Bulletin
2016, volume: 108, number: 1-2, pages: 77–86

Authors' information

Puttonen, Irma
Åbo Akademi University
Kohonen, Tuula
Åbo Akademi University
Åbo Akademi University

Sustainable Development Goals

SDG6 Clean water
SDG14 Life below water

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