izpis_h1_title_alt

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

URLURL - Presentation file, Visit http://www.biogeosciences.net/11/2211/2014/bg-11-2211-2014.html New window

Abstract
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.

Language:English
Keywords:Jadransko morje, sedimenti, morski sedimenti, anoksija, pomanjkanje kisika, morje
Work type:Not categorized (r6)
Tipology:1.01 - Original Scientific Article
Organization:BF - Biotechnical Faculty
Year:2014
Number of pages:str. 2211-2224
Numbering:Vol. 11, no. 8
UDC:551.44(497.4)
ISSN on article:1726-4170
COBISS.SI-ID:3105103 Link is opened in a new window
Views:464
Downloads:173
Metadata:XML RDF-CHPDL DC-XML DC-RDF
 
Average score:(0 votes)
Your score:Voting is allowed only to logged in users.
:
Share: Bookmark and Share

Record is a part of a journal

Title:Biogeosciences
Shortened title:Biogeosciences
Publisher:Copernicus
ISSN:1726-4170
COBISS.SI-ID:3667320 New window

Secondary language

Language:Unknown
Keywords:Adriatic Sea, marine sediments, anoxia, Northern Adriatic

Similar documents

Similar works from RUL:
Similar works from other Slovenian collections:

Comments

Leave comment

You have to log in to leave a comment.

Comments (0)
0 - 0 / 0
 
There are no comments!

Back