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Settling barium fluxes in the Arabian Sea: Critical evaluation of relationship with export production

DRS at CSIR-National Institute of Oceanography

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Title Settling barium fluxes in the Arabian Sea: Critical evaluation of relationship with export production
 
Creator Nair, T.M.B.
Ittekkot, V.
Shankar, R.
Guptha, M.V.S.
 
Subject biogeochemical cycle
barium
primary production
time series analysis
organic carbon
correlation
 
Description Time series measurement of biogenic and barium fluxes was made using nine sediment traps deployed in the western, central and eastern part of the Arabian Sea with the objective of evaluating barium as a proxy for surface ocean productivity. Our observations show a strong linear correlation between Ba sub(excess) fluxes and biogenic opal and organic carbon (C sub(org)) fluxes, indicating a biogenic origin of particulate Ba. However, the correlation between biogenic and Ba sub(excess) fluxes is remarkably strong in areas of uniform productivity like the central Arabian Sea, when compared to regions of episodic productivity. The processes that precipitate particulate Ba appear to be less active during periods of high biogenic flux. A large discrepancy is documented between the export flux calculated from the barium-based algorithm and from C sub(org) fluxes at different depths. However, approx. 35% increase in Ba fluxes and a concomitant increase in Ba/C sub(org) ratios are documented between 919 and 2002 m water depth in the western Arabian Sea. This increase may be due either to barite formation within the fecal pellets of mesozooplankton thriving at deeper levels or to scavenging of Ba by Mn oxyhydroxides. Manganese oxyhydroxides seem to act as a prominent scavenging phase for particulate Ba when the Mn sub(excess) content in the settling particles exceeds approx. 200 ppm, especially in the western and central Arabian Sea where in situ precipitation of Mn oxides is reported. The estimated preservation efficiency of Ba in the Arabian Sea sediments ranges between 50% and 61%. This is two-fold higher than the global average, suggesting that Ba may be a promising proxy for paleoproductivity estimation.
 
Date 2008-02-22T05:31:31Z
2008-02-22T05:31:31Z
2005
 
Type Journal Article
 
Identifier Deep-sea research. Part II. Topical studies in oceanography, Vol.52; 1930-1946p.
http://drs.nio.org/drs/handle/2264/985
 
Language en
 
Rights Copyright [2005]. It is tried to respect the rights of the copyright holders to the best of the knowledge. If it is brought to our notice by copyright holder that the rights are voilated then the item would be withdrawn.
 
Publisher Elsevier