Early diagenesis in sediments from Danish coastal waters: Microbial activity and Mn-Fe-S geochemistry |
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| Institution: | 1. Dipartimento di Ingegneria dell''Innovazione, Università del Salento, via Monteroni, 73100 Lecce, Italy;2. Institute for Microelectronics and Microsystems, IMM-CNR, via Monteroni, 73100 Lecce, Italy;3. Elettra — Sincrotrone Trieste SCpA, SS14-Km163.5 in Area Science Park, 34149 Trieste, Italy;1. Neonatal Ward, Jining No. 1 People''s Hospital, Jining 272011, China;2. Department of PICU, The Affiliated Hospital of Jining Medical College, Jining 272000, China;3. Department of Pediatric Surgery, Jining No. 1 People''s Hospital, Jining 272011, China |
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| Abstract: | Depth distributions of bacterial respiration of O2, NO3− and SO42− were compared with geochemical data for Mn, Fe and S in coastal sediments from water depths between 26 and 520 m. As water depth increased, the zone of SO42− respiration was found deeper in the sediment and was eventually separated from the surface-located activity of O2 and NO2− respiration. At the deepest station additional SO42− reduction activity was observed in small, detrital aggregates on the sediment surface. Dissolved Mn2+ and Fe2+ appeared between the O2- plus NO3−-containing surface layer and the H2S-plus FeS-containing sediment below. This was a result of Mn and Fe reductions coupled to either the oxidation of sulfide or the mineralization of organic matter. Tracer experiments showed that both FeS, FeS2 and S0 were important radiolabelled products of sulfate respiration in this intermediate zone. In the same zone, the overall degradation of organic matter seemed to be underestimated by the assay of SO2-4 respiration and additional mineralization by Mn and Fe reductions was likely. |
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