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Titolo:
SEDIMENT-WATER FLUXES OF NUTRIENTS IN AN ANTARCTIC COASTAL ENVIRONMENT - INFLUENCE OF BIOTURBATION
Autore:
NEDWELL DB; WALKER TR;
Indirizzi:
UNIV ESSEX,DEPT BIOL COLCHESTER CO4 3SQ ESSEX ENGLAND
Titolo Testata:
Polar biology
fascicolo: 1, volume: 15, anno: 1995,
pagine: 57 - 64
SICI:
0722-4060(1995)15:1<57:SFONIA>2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
MARINE-SEDIMENTS; SIGNY-ISLAND; ESTUARINE SEDIMENT; NITROGEN UPTAKE; AMMONIUM UPTAKE; UREA PRODUCTION; ORGANIC-CARBON; AARHUS BIGHT; WEDDELL SEA; PHYTOPLANKTON;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
53
Recensione:
Indirizzi per estratti:
Citazione:
D.B. Nedwell e T.R. Walker, "SEDIMENT-WATER FLUXES OF NUTRIENTS IN AN ANTARCTIC COASTAL ENVIRONMENT - INFLUENCE OF BIOTURBATION", Polar biology, 15(1), 1995, pp. 57-64

Abstract

Rates of exchanges of nitrate and ammonium across the sediment-water interface were measured in an inshore marine environment at Signy Island, South Orkney Islands, Antarctica, over 6 months from August 1991 to February 1992. The sediment was a source of ammonium to the water column but a sink of nitrate, although nitrate exchange rates were very variable. Concentration profiles of nitrate and ammonium in the sediment porewater corroborated the measured vertical exchanges. Bioturbation, by a largely amphipod benthic infauna which was confined to the top2 cm of sediment, was investigated experimentally. Removal of bioturbation depressed sedimentary O2 uptake by 33% and sedimentary release of NH4+ by 50%. In contrast, in the absence of bioturbation, the removal of NO3- from the water column by the sediment increased in rate. Themeasured fluxes of ammonium and nitrate from the sediment did not match with the amount of nitrogen mineralised within the sediment, and urea may account for the difference. It is suggested that the export of nitrogen from the bottom sediment may be significant in sustaining primary production in the Antarctic inshore environment. Ammonium and urea are preferred to nitrate as a nitrogen source by phytoplankton. The nitrate concentrations in the sediment porewater were low, but a largepool of nitrate was identified in the top 0-2 cm layer, which was released by KCl extraction or by freezing of the sediment. This extractable pool of nitrate did not equilibrate with the soluble nitrate pool in the sediment, but seemed to be released from components of the benthic infauna, which were also largely confined to the top 0-2 cm. The physiological role of this nitrate is unknown.

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Documento generato il 31/03/20 alle ore 10:17:01