Impact of methane occurrence on iron speciation in the sediments of the Gdansk Basin (Southern Baltic Sea)

Olga Brocławik , Katarzyna Łukawska-Matuszewska , Aleksandra Brodecka-Goluch , Jerzy Bolałek


Due to changing climate conditions, such inland seas as the Baltic are expected to become more eutrophicated and less saline (causing lower availability of sulphates). This may promote methanogenesis as the main process of organic matter (OM) degradation in marine sediments. Presence of methane, in turn, may affect biogeochemical cycling of many elements, including iron. Thus, in the present study we attempted to investigate the influence of CH4 on the Fe forms in marine sediments. Sediment cores were collected from three physico-chemically different stations within the Southern Baltic, taking into account such parameters as water depth, OM content, bottom zone oxygenation and distance from the Vistula River (main source of anthropogenic material). At two sampling stations methane was present in shallow sediments (P1, MET2) and at one station (W6) any traces of this gas were not determined. Iron species (FeCARB, FeOX1, FeOX2, FeMAG, FePRS, FeT, FeFeS2, FeFeS) in sediments were investigated using the sequential extraction. Pore water was analysed to obtain vertical profiles of hydrogen sulphide, sulphate and dissolved inorganic carbon (DIC). Additionally, such parameters as water and OM content, CH4 and Eh in sediments were determined. Results showed that methanogenesis affects the biogeochemical iron cycling in sediments of the Southern Baltic, leading to the increase of carbonates containing ferrous iron (as a result of DIC production during intensive OSR, AOM and methanogenesis) and decrease of ferric iron compounds used in the AOM. Moreover, in the areas of lower salinity, pyrite formation is limited by an insufficient amount of hydrogen sulphide, leading to the situation when a significant part of Fe is accumulated in the form of monosulphides. In turn, in the areas of higher salinity, where oxygen deficiencies occur more often, more hydrogen sulphide is present in pore water. Pyrite formation is then limited by iron, not by sulphur.
Author Olga Brocławik (FOG/IO/DMChEP)
Olga Brocławik,,
- Division of Marine Chemistry and Environmental Protection
, Katarzyna Łukawska-Matuszewska (FOG/IO/DMChEP)
Katarzyna Łukawska-Matuszewska,,
- Division of Marine Chemistry and Environmental Protection
, Aleksandra Brodecka-Goluch (FOG/IO/DMChEP)
Aleksandra Brodecka-Goluch,,
- Division of Marine Chemistry and Environmental Protection
, Jerzy Bolałek (FOG/IO/DMChEP)
Jerzy Bolałek,,
- Division of Marine Chemistry and Environmental Protection
Journal seriesScience of the Total Environment, ISSN 0048-9697, e-ISSN 1879-1026, (N/A 200 pkt)
Issue year2020
Publication size in sheets0.65
Article number137718
Keywords in Englishanaerobic methane oxidation, iron speciation, marine sediment, methanogenesis, pore water, Baltic Sea
ASJC Classification2304 Environmental Chemistry; 2305 Environmental Engineering; 2310 Pollution; 2311 Waste Management and Disposal
Languageen angielski
LicenseOther; published final; Uznanie Autorstwa - Użycie Niekomercyjne - Bez utworów zależnych (CC-BY-NC-ND); with publication
Score (nominal)200
Score sourcejournalList
ScoreMinisterial score = 200.0, 14-04-2020, ArticleFromJournal
Publication indicators Scopus SNIP (Source Normalised Impact per Paper): 2016 = 1.849; WoS Impact Factor: 2018 = 5.589 (2) - 2018=5.727 (5)
Citation count*1 (2020-08-05)
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