Fractionation of 226Ra and Ba in the Upper North Pacific Ocean

Investigations conducted during the GEOSECS program concluded that radium-226 (T 1/2 = 1602 y) and barium are tightly correlated in waters above 2500 m Atlantic, Pacific Antarctic Oceans, with a fairly uniform 226 Ra/Ba ratio of 2.3 ± 0.2 dpm µmol -1 (4.6 nmol Ra/mol Ba). Here, we report new Ra Ba data obtained at three different stations Ocean: K1 K3 North-West station old Hale Aloha, off Hawaii Island. The relationship between found these is broadly consistent reported program. At investigated stations, however, find ratios significantly lower upper 500 water column than greater depths, pattern was overlooked program, either because precision measurements or relatively low sampling resolution m. Although not always apparent individual profiles, this trend noted before from non-zero intercept linear regression when plotting global set versus seawater concentration attributed, least part, to predominance surface input rivers for bottom sediments Ra. Similarly, have been other oceanic basins (e.g. Atlantic Ocean). Parallel seawater, higher were suspended particles collected This suggests fractionation two elements may contribute m, being preferentially removed water, possibly as result mass celestite formation by acantharians and/or barite precipitation, since both chemical similar ionic radius same configuration valence electrons. finding has implications dating marine carbonates Ra, which requires constant initial incorporated shells using an abyssal circulation mixing tracer.