Article (Scientific journals)
Physical and bacterial controls on inorganic nutrients and dissolved organic carbon during a sea ice growth and decay experiment
Zhou, Jiayun; Delille, Bruno; Kaartokallio, Hermanni et al.
2014In Marine Chemistry, 166, p. 59-69
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Abstract :
[en] We investigated how physical incorporation, brine dynamics and bacterial activity regulate the distribution of inorganic nutrients and dissolved organic carbon (DOC) in artificial sea ice during a 19-day experiment that included periods of both ice growth and decay. The experiment was performed using two series of mesocosms: the first consisted of seawater and the second consisted of seawater enriched with humic-rich river water. We grew ice by freezing the water at an air temperature of -14 °C for 14 days after which ice decay was induced by increasing the air temperature to -1 °C. Using the ice temperatures and bulk ice salinities, we derived the brine volume fractions, brine salinities and Rayleigh numbers. The temporal evolution of these physical parameters indicate that there was a succession of 3 stages in the brine dynamics: forced-convection, followed by bottom convection during ice growth, and then brine stratification during ice decay. The major findings are: (1) the incorporation of dissolved compounds (nitrate, nitrite, ammonium, phosphate, silicate, and DOC) into the sea ice was not conservative (relative to salinity) during ice growth. Brine convection clearly influenced the incorporation of the dissolved compounds, since the non-conservative behavior of the dissolved compounds was particularly pronounced in the absence of brine convection. (2) Bacterial activity further regulated nutrient availability in the ice: ammonium and nitrite accumulated as a result of remineralization processes, although bacterial production was too low to induce major changes in DOC concentrations. (3) Different forms of DOC have different properties and hence incorporation efficiencies. In particular, the terrestrially-derived DOC from the river water was less efficiently incorporated into sea ice than the DOC in the seawater. Therefore the main factors regulating the distribution of the dissolved compounds within sea ice are clearly a complex interaction of brine dynamics, biological activity and in the case of dissolved organic matter, the physico-chemical properties of the dissolved constituents themselves.
Disciplines :
Earth sciences & physical geography
Author, co-author :
Zhou, Jiayun ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Océanographie chimique
Delille, Bruno  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Océanographie chimique
Kaartokallio, Hermanni
Kattner, Gerhard
Kuosa, Harri
Tison, Jean-Louis
Autio, Riitta
Dieckmann, Gerhard S.
Evers, Karl-Ulrich
Jorgensen, Linda
Kennedy, Hilary
Kotovitch, Marie ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Océanographie chimique
Luhtanen, Anne-Mari
Stedmon, Colin A.
Thomas, David N.
More authors (5 more) Less
Language :
English
Title :
Physical and bacterial controls on inorganic nutrients and dissolved organic carbon during a sea ice growth and decay experiment
Publication date :
22 November 2014
Journal title :
Marine Chemistry
ISSN :
0304-4203
Publisher :
Elsevier, Netherlands
Volume :
166
Pages :
59-69
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 01 October 2014

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