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Seasonal and spatial variations in settling manganese fluxes in the northern Arabian Sea

DRS at CSIR-National Institute of Oceanography

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Title Seasonal and spatial variations in settling manganese fluxes in the northern Arabian Sea
 
Creator Nair, T.M.B.
Ramaswamy, V.
Shankar, R.
Ittekkot, V.
 
Subject manganese
sediment traps
suspended particulate matter
seasonal variations
spatial variations
denitrification
 
Description Particulate manganese (Mn) fluxes measured with six time series sediment traps showed that the annual settling fluxes were 3-6 times higher in the west compared to those in the east and central Arabian Sea. Annual detrital Mn (Mn sub(dt)) flux was nearly the same in the eastern and western Arabian Sea, but excess Mn (Mn sub(ex)) fluxes were much higher (> 4 times) in the western Arabian Sea. Atmospheric inputs cannot account for these high-Mn fluxes. Central and eastern Arabian Sea traps are overlain by a thick and intense denitrification layer, which may cause reductive dissolution of Mn oxides from settling particles and consequently low Mn sub(ex) fluxes. As the exchange of intermediate waters between the Arabian Sea and the rest of the Indian Ocean is confined largely to the western Arabian Sea, relatively more oxic and dynamic conditions prevail in this region. Increased oxidizing conditions coupled with higher inputs of dissolved Mn through intermediate and surface advective processes might have led to in situ oxidation of Mn, thus resulting in higher vertical fluxes on Mn sub(ex). Mn sub(ex) fluxes in traps at approx 1000 m depth exhibited seasonal variability with a minimum during the winter monsoon (January-February) and maximum during the pre- and early- south-west monsoon (March-June). This variation is correlated with water mass movements and bacterial abundance observed during the Joint Global Ocean Flux Study (JGOFS). The possible involvement of bacteria and the microbial loop is suggested for the concentration and vertical transport of excess Mn
 
Date 2009-01-10T10:20:25Z
2009-01-10T10:20:25Z
1999
 
Type Journal Article
 
Identifier Deep-Sea Research (I: Oceanographic Research Papers), Vol.46; 1827-1839p.
http://drs.nio.org/drs/handle/2264/1751
 
Language en
 
Rights Copyright [1999]. 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 Pergamon