RT Journal Article
T1 Manganese diagenesis in different geochemical environments of the ria de Vigo (Galicia, NW Iberian Peninsula)
A1 Otero Pérez, Xosé Lois
A1 Ramírez Pérez, Alexandra María
A1 Abernathy, M.
A1 Ying, S.C
A1 Queiroz, Hermano M.
A1 Ferreira, Tiago Osório
A1 Huerta Díaz, M.A.
A1 De Blas Varela, María Esther
K1 Mn speciation
K1 Methane
K1 Pyritization
K1 Anaerobic oxidation of methane (AOM)
AB Manganese is one of the most abundant elements in marine sediments and plays an essential role in sediment redox processes. However, unlike Fe or S, the Mn cycle has not received the same attention. Mn is a ubiquitous redox-active metal in marine systems; however, its influence on C and S cycling is still poorly understood. In particular, we hypothesize that conditions that favor high H2S production can lead to high Mn pyritization. In the Ria de Vigo, large methane fields have been identified at different depths within sediments, ranging from the surface to 2 m below the surface. Four sediment cores from different locations (outermost, middle, and innermost) within the Ria de Vigo were analyzed. Samples were subjected to a general characterization and a five-step Mn sequential extraction procedure, and analyses were complemented with X-ray absorption spectroscopy (EXAS). The results showed that the main geochemical forms of Mn undergo intense spatial and depth-related variations in sediments. Two geochemical scenarios were identified: one corresponding to the innermost section and another one to the middle and outermost sections of the ria. The former was characterized by intense Mn pyritization and by the absence of the Mn‑carbonate fraction due to the high production of H2S because of anaerobic oxidation of methane. The formation of Mnsingle bondS bonds was only identified by EXAS. Conversely, in the middle and outermost part of the ria, with or without the presence of methanogenesis in deep sediment layers, the Mn‑carbonate fraction was dominant even at depth, along with the presence of methane, high concentrations of H2S and, therefore, high degrees of Fe pyritization. These results suggest that, once Mn‑carbonate is formed under suboxic conditions (with low or no presence of H2S) at or near the surface, it remains stable after burial, even under conditions of high H2S concentration
PB Elsevier
SN 0025-3227
YR 2024
FD 2024
LK http://hdl.handle.net/10347/33827
UL http://hdl.handle.net/10347/33827
LA eng
NO Marine Geology, Volume 470, 2024, 107250
NO This research was co-funded by the Spanish Ministry of Economy and Competitiveness (CGL2012–33584) and the Consellería de Educación, Universidade e Formación Profesional-Xunta de Galicia (Axudas á consolidación e estruturación de unidades de investigación competitivas do SUG do Plan Galego IDT, Ambiosol Group ref. ED431C 2022/40). Thanks are due to María José Santiso for her assistance with laboratory work. The use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515
DS Minerva
RD 22 abr 2026