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Isotopic disequilibrium in Globigerina bulloides and carbon isotope response to productivity increase in Southern Ocean

Prasanna, K and Ghosh, Prosenjit and Bhattacharya, SK and Mohan, K and Anilkumar, N (2016) Isotopic disequilibrium in Globigerina bulloides and carbon isotope response to productivity increase in Southern Ocean. In: SCIENTIFIC REPORTS, 6 .

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Official URL: http://dx.doi.org/10.1038/srep21533

Abstract

Oxygen and carbon isotope ratios in planktonic foraminifera Globigerina bulloides collected from tow samples along a transect from the equatorial Indian ocean to the Southern Ocean (45 degrees E and 80 degrees E and 10 degrees N to 53 degrees S) were analysed and compared with the equilibrium delta O-18 and delta C-13 values of calcite calculated using the temperature and isotopic composition of the water column. The results agree within similar to 0.25% for the region between 10 degrees N and 40 degrees S and 75-200 m water depth which is considered to be the habitat of Globigerina bulloides. Further south (from 40 degrees S to 55 degrees S), however, the measured delta O-18 and delta C-13 values are higher than the expected values by similar to 2% and similar to 1% respectively. These enrichments can be attributed to either a `vital effect' or a higher calcification rate. An interesting pattern of increase in the delta C-13(DIC) value of the surface water with latitude is observed between 35 degrees S and similar to 60 degrees S, with a peak at similar to 42 degrees S. This can be caused by increased organic matter production and associated removal. A simple model accounting for the increase in the delta C-13(DIC) values is proposed which fits well with the observed chlorophyll abundance as a function of latitude.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the NATURE PUBLISHING GROUP, MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND
Department/Centre: Division of Mechanical Sciences > Centre for Earth Sciences
Depositing User: Id for Latest eprints
Date Deposited: 02 Apr 2016 09:31
Last Modified: 02 Apr 2016 09:31
URI: http://eprints.iisc.ac.in/id/eprint/53462

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