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Fluctuations in productivity and denitrification in the southeastern Arabian Sea during the Late Quaternary

DRS at CSIR-National Institute of Oceanography

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Title Fluctuations in productivity and denitrification in the southeastern Arabian Sea during the Late Quaternary
 
Creator Kessarkar, P.M.
Rao, V.P.
Naqvi, S.W.A.
Chivas, A.R.
Saino, T.
 
Subject stable isotopic
marine isotope stage
primary productivity
Palaeoproductivity proxies
 
Description Sedimentological and stable isotopic characteristics of sediments have been studied in a core from the southeastern Arabian Sea containing records of the past 70 ka. Palaeoproductivity proxies such as organic carbon (C sub(org)), total nitrogen (TN) and calcium carbonate (CaCO sub(3)) contents, show high values at the core top and during the Last Glacial Maximum (LGM) and marine isotope stage (MIS) 4, suggesting high productivity, whereas low C sub(org) and CaCO sub(3) contents are associated with the MIS 1/2 and mid-MIS 3, indicating reduced productivity. The delta sup(18)O values in planktonic foraminifera range between - 2.7 ppt and - 0.1 ppt, with a large glacial-interglacial amplitude delta sup(18)O of approx. 2.6 ppt, suggesting changes related to monsoonal precipitation/ runoff. The delta sup(15)N values fluctuate between 5.4 ppt and 7.3 ppt, signifying variation in denitrification intensity. The delta sup(15)N indicates an overall increase in denitrification intensity during MIS 1 and MIS 3 and, reduced intensity during MIS 1/2, LGM and mid-MIS 3. Higher primary productivity and reduced denitrification intensity during LGM and MIS 4 might be due to convective winter mixing and more oxygenated subsurface waters. Reduced primary productivity during MIS 1/2 and mid-MIS 3 might be the effect of enhanced precipitation associated with the intensified southwest monsoon fortifying near-surface stratification.
 
Date 2010-09-01T07:28:50Z
2010-09-01T07:28:50Z
2010
 
Type Journal Article
 
Identifier Current Science, vol.99(4); 485-491
http://drs.nio.org/drs/handle/2264/3704
 
Language en
 
Rights Copyright [2010]. All efforts have been made to respect the copyright to the best of our
knowledge. Inadvertent omissions, if brought to our notice, stand for correction and withdrawal of document from this repository.
 
Publisher Current Science Association