The flux of226Ra from deep-sea sediments |
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| Authors: | J Kirk Cochran |
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| Institution: | Department of Geology and Geophysics, Yale University, New Haven, CT 06520 U.S.A. |
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| Abstract: | The flux of226Ra from bottom sediments has been determined from patterns of226Ra/230Th disequilibrium in ten deep-sea cores from the world oceans. Values range from ? 0.0015 dpm/cm2 yr (in the Atlantic) to 0.21 dpm/cm2 yr (in the north equatorial Pacific). The flux is poorly related to sediment type, but is inversely correlated in a non-linear fashion with sediment accumulation rate. There is a direct relationship between the production rate of226Ra near the sediment-water interface (i.e. the integrated230Th activity in the biologically mixed zone) and the226Ra flux. The226Ra concentration in near-bottom water follows the geographic variation in the226Ra flux. The high flux from north equatorial Pacific sediments especially is reflected in the high bottom water226Ra concentrations in that area. The data suggest that both rate of circulation and the magnitude of the radium flux influence the near-bottom226Ra concentration. |
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