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| Item Type: | Dataset |
|---|---|
| Title: | Persistent seasonal deoxygenation alters benthic metabolic processes and accelerates hypoxia feedbacks in the Baltic Sea |
| Abstract: | Nutrient enrichment (and warming cause widespread costal deoxygenation leading to hypoxia (oxygen below 63 micromolar) or anoxia (no oxygen) bottom waters. The benthic-water-column-feedbacks that developed under persistent seasonal oxygen depletion and amplify hypoxia remain poorly constrained. A 15-month study of seasonally hypoxic/anoxic costal system in the southwestern Baltic Sea combining water column monitoring, sediment chemistry, metabolic rates and microbial analyses with historic data, reveal pronounced seasonal shifts in sediment processes. During winter oxygenation, organic matter degradation, fermentation, aerobic respiration, nitrate- and iron-reduction and microbial competition increased. Re-ventilation following anoxia did not "re-set" sediment biogeochemistry, but initiated intensified oxygen consumption, microbial biosynthetic activity and anaerobic carbon re-cycling. Reactive iron-(oxyhydr)oxides became exhausted, the sulfidic zone shoaled and sulfate reduction and pyrite formation rates increased through fall. These processes reinforced benthic feedbacks, progressively reducing the sediment's capacity to retain sulfide over years. This weakening of sedimentary resilience exacerbates sulfide accumulation in eutrophic costal environments with growing chances of sulfidic deep-water upwelling. |
| Source: | BioProject |
| Publisher: | National Center for Biotechnology Information (NCBI) |
| Date: | 4 July 2025 |
| External Fulltext: | View full text on external repository or document server |
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