title: Factors controlling phosphorus release from sediments in coastal archipelago areas.
abstract: 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.
authors.affiliation: Åbo Akademi University, Environmental and Marine Biology, Tykistökatu 6, FI-20740 Turku, Finland. Electronic address: irma.puttonen@abo.fi.
authors.forename: Irma
authors.initials: I
authors.lastname: Puttonen
authors.affiliation: Åbo Akademi University, Environmental and Marine Biology, Tykistökatu 6, FI-20740 Turku, Finland.
authors.forename: Tuula
authors.initials: T
authors.lastname: Kohonen
authors.affiliation: Åbo Akademi University, Environmental and Marine Biology, Tykistökatu 6, FI-20740 Turku, Finland.
authors.forename: Johanna
authors.initials: J
authors.lastname: Mattila
mesh_terms: D001267:Atlantic Ocean; D019015:Geologic Sediments; D010100:Oxygen; D010758:Phosphorus; D012623:Seawater; D014874:Water Pollutants, Chemical
chemical_list: D014874:Water Pollutants, Chemical; D010758:Phosphorus; D010100:Oxygen
keywords: Baltic Sea; Coastal zone; Hypoxia; Internal loading; Phosphorus fractions; Sediment