Summer inputs of riverine nutrients to the Baltic Sea: Bioavailability and eutrophication relevance

R. Stepanauskas, N.O.G. Jørgensen, Ole Ritzau Eigaard, A. Zvikas, L.J. Tranvik, L. Leonardson

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Most nitrogen and phosphorus transported by world rivers to the oceans is associated with dissolved organic matter. However, organic matter as a potential source of N and P has hitherto been largely neglected in studies of coastal microbial food webs. We examined 50 rivers, draining a major part of the Baltic Sea watershed, with respect to summer concentrations, chemical composition, and biological availability of N and P. The broad spectrum of rivers studied enabled us to assess whether the input of terrigenous organic matter can be an important nutrient source, at various levels of anthropogenic loading of inorganic N and P. Concentrations of total N and P ranged from 9 to 220 mumol/L and from 0.14 to 5.56 mumol/L, respectively, with the highest concentrations in the southern part of the Baltic Sea drainage area and in several rivers on the Finnish western coast. Urea and dissolved combined amino acids (DCAA) each constituted 4-20% of dissolved organic nitrogen (DON), while dissolved free amino acids (DFAA) made up
Original languageEnglish
JournalEcological Monographs
Issue number4
Pages (from-to)579-597
Publication statusPublished - 2002

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