Calcium isotope ratios in the world's largest rivers: A constraint on the maximum imbalance of oceanic calcium fluxes

Tipper, E. T. and Gaillardet, J. and Galy, A. and Louvat, P. and Bickle, M. J. and Campas, F (2010) Calcium isotope ratios in the world's largest rivers: A constraint on the maximum imbalance of oceanic calcium fluxes. Global Biogeochemical Cycles, 24. GB3019. DOI 10.1029/2009GB003574

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Abstract

The oceanic mass balance of calcium (Ca) is de¯ned by a bal- ance between the inputs (rivers and hydrothermal) and outputs (bulk carbonate) of Ca. Large rivers were analysed for Ca isotope ratios (44Ca/42Ca,expressed as ±4442 Ca) to investigate the source and cycling of riverine Ca, and to add an isotopic mass balance constraint to the oceanic budget of Ca. The new data accounts for approximately one-third of the total Ca supplied to the oceans by rivers. Inter-sample and seasonal variability was assessed by analysing more than one sample for many rivers. The range in the ±4442Ca of large rivers at high water stand is extremely narrow at 0.27h. Variations in ±4442Ca do not correlate with proxies for carbonate, silicate or evaporite derived Ca, and are more likely related either to inherent variability in the lithological sources of Ca or to process related fractionation. The spread in riverine ±4442Ca overlaps with the spread in marine limestone ±4442Ca consistent withmost riverine Ca coming from the recycling of limestones.

Item Type: Article
Uncontrolled Keywords: 2010AREP; IA61;
Subjects: 02 - Geodynamics, Geophysics and Tectonics
Divisions: 02 - Geodynamics, Geophysics and Tectonics
Journal or Publication Title: Global Biogeochemical Cycles
Volume: 24
Page Range: GB3019
Identification Number: 10.1029/2009GB003574
Depositing User: Sarah Humbert
Date Deposited: 13 Aug 2010 12:04
Last Modified: 23 Jul 2013 10:00
URI: http://eprints.esc.cam.ac.uk/id/eprint/1908

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