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Artificially induced migration of redox layers in a coastal sediment from the Northern Adriatic
ID Metzger, Eduard (Avtor), ID Langlet, D. (Avtor), ID Viollier, E. (Avtor), ID Koron, Neža (Avtor), ID Riedel, Bettina (Avtor), ID Stachowitsch, Michael (Avtor), ID Faganeli, Jadran (Avtor), ID Tharaud, M. (Avtor), ID Geslin, E. (Avtor), ID Jorissen, F. (Avtor)

URLURL - Predstavitvena datoteka, za dostop obiščite http://www.biogeosciences.net/11/2211/2014/bg-11-2211-2014.html Povezava se odpre v novem oknu

Izvleček
Long-term experimental studies suggest that, under transient anoxic conditions, redox fronts within the sediment shift upwards, causing sequential rise and fall of benthic fluxes of reduced species (Mn(II), Fe(II) and S(-II)). Infaunal benthic organisms are associated with different redox fronts as micro-habitats and must be affected by such changes during natural hypoxia events. In order to document the geochemical evolution of the sediment during prolonged anoxia in the framework of an in situ experiment designed to mimic natural conditions, benthic chambers were deployed on the seafloor of the Northern Adriatic and sampled after 9, 30 and 315 days of incubation. Oxygen and sulfide were measured continuously in the early stages (9 days) of the experiment. High-resolution pore water profiles were sampled by DET probes and redox-sensitive species (S(VI), Mn(II)and Fe(II)) and alkalinity were measured. Starting oxygen saturation was about 80% within the chamber. After 7 days, anoxia was established in the bottom waters within the chambers. Mn(II) and Fe(II) started diffusing towards the anoxic water column until they reached the surficial sediment. Being reoxidized there, Mn and Fe reprecipitated, giving a rusty coloration to the seafloor. Infaunal species appeared at the sediment surface. After 20 days, all macro-organisms were dead. Decomposition of macroorganisms at the sediment–water interface generated S(-II) within the entire height of the chamber, leading to a downward flux of sulfides into the sediment, where they were quickly oxidized by metallic oxides or precipitated as FeS. S(-II) was below detection in the water column and pore waters at the end of the experiment. Our results suggest that S(-II) enrichment in the water column of coastal systems, which are episodically anoxic, is strongly controlled by the biomass of benthic macrofauna and its decay during anoxia, whereas its residence time in the water column is controlled by iron availability (as solid oxides or as dissolved reduced cations) within the sediment, even without water circulation.

Jezik:Angleški jezik
Ključne besede:Jadransko morje, sedimenti, morski sedimenti, anoksija, pomanjkanje kisika, morje
Vrsta gradiva:Delo ni kategorizirano (r6)
Tipologija:1.01 - Izvirni znanstveni članek
Organizacija:BF - Biotehniška fakulteta
Leto izida:2014
Št. strani:Str. 2211-2224
Številčenje:Vol. 11, no. 8
UDK:551.44(497.4)
ISSN pri članku:1726-4170
COBISS.SI-ID:3105103 Povezava se odpre v novem oknu
Datum objave v RUL:10.07.2015
Število ogledov:896
Število prenosov:326
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Naslov:Biogeosciences
Skrajšan naslov:Biogeosciences
Založnik:Copernicus
ISSN:1726-4170
COBISS.SI-ID:3667320 Povezava se odpre v novem oknu

Sekundarni jezik

Jezik:Neznan jezik
Ključne besede:Adriatic Sea, marine sediments, anoxia, Northern Adriatic

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