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Origin and fate of dissolved organic matter in four shallow Baltic Sea estuaries

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  • Maren Voss, Leibniz Institute for Baltic Sea Research
  • ,
  • Eero Asmala, University of Helsinki
  • ,
  • Ines Bartl, Leibniz Institute for Baltic Sea Research
  • ,
  • Jacob Carstensen
  • Daniel J. Conley, Lund University
  • ,
  • Joachim W. Dippner, Leibniz Institute for Baltic Sea Research
  • ,
  • Christoph Humborg, Stockholms Universitets Östersjöcentrum
  • ,
  • Kaarina Lukkari, Finnish Environment Institute
  • ,
  • Jolita Petkuviene, Klaipeda University
  • ,
  • Heather Reader, Memorial University of Newfoundland
  • ,
  • Colin Stedmon, Technical University of Denmark
  • ,
  • Irma Vybernaite-Lubiene, Klaipeda University
  • ,
  • Nicola Wannicke, Leibniz Institute for Baltic Sea Research, Leibniz Institute for Plasma Science and Technology
  • ,
  • Mindaugas Zilius, Klaipeda University

Coastal waters have strong gradients in dissolved organic matter (DOM) quantity and characteristics, originating from terrestrial inputs and autochthonous production. Enclosed seas with high freshwater input therefore experience high DOM concentrations and gradients from freshwater sources to more saline waters. The brackish Baltic Sea experiences such salinity gradients from east to west and from river mouths to the open sea. Furthermore, the catchment areas of the Baltic Sea are very diverse and vary from sparsely populated northern areas to densely populated southern zones. Coastal systems vary from enclosed or open bays, estuaries, fjords, archipelagos and lagoons where the residence time of DOM at these sites varies and may control the extent to which organic matter is biologically, chemically or physically modified or simply diluted with transport off-shore. Data of DOM with simultaneous measurements of dissolved organic (DO) nitrogen (N), carbon (C) and phosphorus (P) across a range of contrasting coastal systems are scarce. Here we present data from the Roskilde Fjord, Vistula and Öre estuaries and Curonian Lagoon; four coastal systems with large differences in salinity, nutrient concentrations, freshwater inflow and catchment characteristics. The C:N:P ratios of DOM of our data, despite high variability, show site specific significant differences resulting largely from differences residence time. Microbial processes seemed to have minor effects, and only in spring did uptake of DON in the Vistula and Öre estuaries take place and not at the other sites or seasons. Resuspension from sediments impacts bottom waters and the entire shallow water column in the Curonian Lagoon. Finally, our data combined with published data show that land use in the catchments seems to impact the DOC:DON and DOC:DOP ratios of the tributaries most.

Original languageEnglish
JournalBiogeochemistry
Volume154
Issue2
Pages (from-to)385-403
Number of pages19
ISSN0168-2563
DOIs
Publication statusPublished - Jun 2021

Bibliographical note

Publisher Copyright:
© 2020, The Author(s).

Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.

    Research areas

  • Baltic Sea, Coastal systems, Dissolved organic matter, Riverine input

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