The impact of induced redox transitions on nutrient diagenesis in coastal marine sediments (Gulf of Trieste, northern Adriatic Sea)

2015 ◽  
Vol 15 (12) ◽  
pp. 2443-2452 ◽  
Author(s):  
Neža Koron ◽  
Nives Ogrinc ◽  
Edouard Metzger ◽  
Bettina Riedel ◽  
Jadran Faganeli
Keyword(s):  
Marine Sediments ◽  
Adriatic Sea ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Coastal Marine Sediments ◽  
Gulf Of Trieste ◽  
Coastal Marine ◽  
Redox Transitions ◽  
The Impact

Oxic - anoxic transition of benthic fluxes from the coastal marine environment (Gulf of Trieste, northern Adriatic Sea)

2009 ◽  
Vol 60 (7) ◽  
pp. 700 ◽  
Author(s):  
Jadran Faganeli ◽  
Nives Ogrinc
Keyword(s):  
Adriatic Sea ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Sedimentary Environments ◽  
Gulf Of Trieste ◽  
Coastal Marine ◽  
Incubation Experiments ◽  
O2 Concentration ◽  
Recovery Response ◽  
Dissolved O2

The influence of O2 concentration on mineralisation processes was examined by sediment incubation experiments under controlled laboratory conditions over a sequence of oxic, anoxic and then reoxidising conditions. Sediments were studied from five locations representing marine, lagoonal and brackish environments in the Gulf of Trieste (northern Adriatic Sea). A complete depletion of dissolved O2 and nitrate were observed after ~6 –15 days in marine and lagoonal sediments, and after 5 days in brackish sediments. During the reoxygenation phase, nitrification occurred at some sites, as evidenced by increases in NO3– concentrations, but not at other sites, indicating an inhibited recovery response to intermittent oxic conditions. NH4+ and PO43– regeneration during mineralisation was much more extensive in sediments overlain by oxygen-depleted waters, driving additional eutrophication. During reoxygenation, an influx of phosphate was observed in all three sedimentary environments, removing soluble phosphorus through coagulation and finally precipitation. Two degraded organic matter (OM) types could be distinguished: OM degraded under oxic conditions in marine and brackish sediments v. OM rapidly degraded under anoxic conditions in lagoon sediments.

scholarly journals Microbial dark carbon fixation fueled by nitrate enrichment

2021 ◽  
Author(s):  
Joseph H. Vineis ◽  
Ashley N. Bulseco ◽  
Jennifer L. Bowen
Keyword(s):  
Microbial Communities ◽  
Marine Sediments ◽  
Salt Marshes ◽  
Carbon Fixation ◽  
Niche Partitioning ◽  
Coastal Marine Sediments ◽  
Functional Relationships ◽  
Coastal Marine ◽  
Dark Carbon Fixation ◽  
The Impact

Anthropogenic nitrate amendment to coastal marine sediments can increase rates of heterotrophic mineralization and autotrophic dark carbon fixation (DCF). DCF may be favored in sediments where organic matter is biologically unavailable, leading to a microbial community supported by chemoautotrophy. Niche partitioning among DCF communities and adaptations for nitrate metabolism in coastal marine sediments remain poorly characterized, especially within salt marshes. We used genome-resolved metagenomics, phylogenetics, and comparative genomics to characterize the potential niche space, phylogenetic relationships, and adaptations important to microbial communities within nitrate enriched sediment. We found that nitrate enrichment of sediment from discrete depths between 0-25 cm supported both heterotrophs and chemoautotrophs that use sulfur oxidizing denitrification to drive the Calvin-Benson-Bassham (CBB) or reductive TCA (rTCA) DCF pathways. Phylogenetic reconstruction indicated that the nitrate enriched community represented a small fraction of the phylogenetic diversity contained in coastal marine environmental genomes, while pangenomics revealed close evolutionary and functional relationships with DCF microbes in other oligotrophic environments. These results indicate that DCF can support coastal marine microbial communities and should be carefully considered when estimating the impact of nitrate on carbon cycling in these critical habitats.

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