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Monsoon related changes in sea surface productivity and water column denitrification in the Eastern Arabian Sea during the last glacial cycle

DRS at CSIR-National Institute of Oceanography

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Title Monsoon related changes in sea surface productivity and water column denitrification in the Eastern Arabian Sea during the last glacial cycle
 
Creator Banakar, V.K.
Oba, T.
Chodankar, A.R.
Kuramoto, T.
Yamamoto, M.
Minagawa, M.
 
Subject monsoons
water column
palaeo studies
palaeoclimate
carbon isotopes
nitrogen isotopes
denitrification
surface salinity
holocene
surface circulation
water mixing
glacial features
 
Description Sea surface salinity reconstruction for the Holocene and the Last Glacial Maximum (LGM) suggests that the LGM-Eastern Arabian Sea was more saline (by approx.5 psu) than the Holocene due to weakened freshwater flux to the region, and intensified winter monsoons. Time-series of sedimentary organic-carbon (C sub(org)), sigma alkenone and delta sup(13)C sub(org) for the last 100 kyr, together, indicate increased glacial productivity. Significantly reduced sedimentary-delta sub(15)N during the LGM indicates, however, diminished water column denitrification in spite of increased productivity. The distinct decoupling of denitrification from productivity during the LGM can be explained by vigorous ventilation of the thermocline as a result of simultaneously intensified formation of high-salinity water and deep-winter mixing in northern-Arabian Sea related to the extreme cold climate. The closely comparable time-series delta sup(15)N records across the Arabian Sea suggest basin-wide homogenisation of the isotopic signal. This probably resulted from combined monsoon-dependent surface water mixing, due to changes in the relative strength of reversing surface circulations, and intermediate water mixing, due to changes in north-south salinity gradient.
 
Date 2008-02-22T06:20:32Z
2008-02-22T06:20:32Z
2005
 
Type Journal Article
 
Identifier Marine geology, Vol.219; 99-108p.
http://drs.nio.org/drs/handle/2264/993
 
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 If it is brought to our notice by copyright holder that the rights are voilated then the item would be withdrawn.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