Factors controlling phosphorus release from sediments in coastal archipelago areas

Irma Puttonen, Tuula Kohonen, Johanna Mattila

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Abstract

In coastal archipelago areas of the northern Baltic Sea, significantly higher phosphate concentrations (6.0 ± 4.5 μmol/l, mean ± SD) were measured in water samples close to the sediment surface compared with those from 1 m above the seafloor (1.6± 2.0 μmol/l). The results indicated notable phosphate release from sediments under the bottom water oxygen concentrations of up to 250 μmol/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. In coastal archipelago areas of the northern Baltic Sea, significantly higher phosphate concentrations (6.0 ± 4.5 μmol/l, mean ± SD) were measured in water samples close to the sediment surface compared with those from 1 m above the seafloor (1.6± 2.0 μmol/l). The results indicated notable phosphate release from sediments under the bottom water oxygen concentrations of up to 250 μmol/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.
Original languageUndefined/Unknown
Pages (from-to)77–86
JournalMarine Pollution Bulletin
Volume108
Issue number1-2
DOIs
Publication statusPublished - 2016
MoE publication typeA1 Journal article-refereed

Keywords

  • Baltic Sea
  • Archipelago Sea
  • sediment phosphorus dynamics
  • Water quality
  • coastal eutrophication
  • Hypoxia

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