An understanding of the geochemistry of the cosmogenic radioisotope 10Be (t 1 2 = 1.5 My) and the stable isotope 9Be is necessary for the development of their use in deep-sea sediments as a geochronometer and as a monitor of variations in cosmogenic nuclide production. We examined these isotopes in oceanic regions strongly influenced by input of continental materials; the effects of atmospheric aerosols were studied through examination of the water column chemistry of the Mediterranean (a basin strongly influenced by Saharan dust) while salinity transects through the Amazon and Ganges-Brahmaputra estuaries were used to investigate riverine fluxes to the oceans. These results were used to quantify riverine and eolian fluxes; they indicate that eolian dust is probably the most significant source of 9Be to the oceans. Changes in 10Be:9Be in the marine sedimentary record which are not associated with radioactive decay or variability in 10Be production can thus result from local or regional changes in dust inputs.
Bibliographical noteFunding Information:
Land Reclamation Project of Bangladesh provided logistical support for the fieldwork in the Ganges-Brahmaputra estuary. Reviews by E.R. Sholkovitz and an anonymous referee improved the manuscript. This work was supported by the NSF through a graduate fellowship (ETB) and through grants OCE-8614336, OCE-8717227 and INT-8816770 (JME) and by the MIT/WHOI Joint Program Education Office. Tandetron operation is supported by CNRS, CEA and IN2P s.