TY - JOUR
T1 - Qualitative variability of dissolved organic matter in the Baltic Sea sediments apparent from fluxes and optical properties
AU - Loginova, Alexandra N.
AU - Wünsch, Urban J.
AU - Zabłocka, Monika
AU - Cherkasheva, Aleksandra
AU - Szymczycha, Beata
AU - Kuliński, Karol
AU - Winogradow, Aleksandra
AU - Kowalczuk, Piotr
PY - 2024
Y1 - 2024
N2 - The release of dissolved organic matter (DOM) from sediments serves as an important part of the carbon cycle. Here, we address pore water DOM quality and its release from shallow sediments (0–10 cm) of the central and southern Baltic Sea - Gdansk, Bornholm, and Eastern Gotland Basins - using excitation–emission matrix spectroscopy and size-exclusion chromatography. DOM release from sediments displayed spatial variability, with diffusive DOC fluxes ranging from 0.02 to 1.06 mmol m−2 d−1, and basin-averaged fluxes increased in the order Gotland < Bornholm < Gdansk. DOM qualitative characteristics also varied among investigated basins. In the oxygen-limited study sites from the Gdansk Basin, we observed elevated abundances of low apparent molecular weight DOM fraction and proteinaceous-like fluorescent DOM, while in the Bornholm Basin, pore water DOM was generally more humic-like and of higher apparent molecular weight. Pore waters from the deepest study sites in the Gotland Basin were qualitatively very similar to those of the pore waters from the upper sediment layers (0–4 cm) from all other investigated sites, suggesting little organic matter reworking at depth at those stations. Our results suggest that the spatial variability in the magnitude of DOM release may be linked to the qualitative differences of DOM in sediments.
AB - The release of dissolved organic matter (DOM) from sediments serves as an important part of the carbon cycle. Here, we address pore water DOM quality and its release from shallow sediments (0–10 cm) of the central and southern Baltic Sea - Gdansk, Bornholm, and Eastern Gotland Basins - using excitation–emission matrix spectroscopy and size-exclusion chromatography. DOM release from sediments displayed spatial variability, with diffusive DOC fluxes ranging from 0.02 to 1.06 mmol m−2 d−1, and basin-averaged fluxes increased in the order Gotland < Bornholm < Gdansk. DOM qualitative characteristics also varied among investigated basins. In the oxygen-limited study sites from the Gdansk Basin, we observed elevated abundances of low apparent molecular weight DOM fraction and proteinaceous-like fluorescent DOM, while in the Bornholm Basin, pore water DOM was generally more humic-like and of higher apparent molecular weight. Pore waters from the deepest study sites in the Gotland Basin were qualitatively very similar to those of the pore waters from the upper sediment layers (0–4 cm) from all other investigated sites, suggesting little organic matter reworking at depth at those stations. Our results suggest that the spatial variability in the magnitude of DOM release may be linked to the qualitative differences of DOM in sediments.
KW - Dissolved organic matter
KW - Porewater DOM
KW - DOM molecular weight
KW - Sediment release
KW - Baltic Sea
KW - FDOM
U2 - 10.3389/fmars.2024.1433199
DO - 10.3389/fmars.2024.1433199
M3 - Journal article
SN - 2296-7745
VL - 11
JO - Frontiers in Marine Science
JF - Frontiers in Marine Science
M1 - 1433199
ER -