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Free keywords:
north pacific
particulate matter
accumulation rates
pelagic
sediments
th-230
atlantic
sea
california
removal
pb-210
Abstract:
An ocean-wide study of the rates of removal of Be-10 and Pa-231 in the Pacific Ocean has identified intensified scavenging of the Be-10 and Pa-231 in several ocean margin areas, including the Northeastern and Northwestern Pacific, the Bering Sea, the Eastern Equatorial Pacific and the South Pacific Ocean. Scavenging rates of Be-10 and Pa-231 are clearly Correlated to particle flux. Principal component analysis further suggests that scavenging of Be-10 and Pa-231 may be related to opal productivity in surface waters. A simple box model was constructed to partition the deposition of Th-230, Pa-231 and Be-10 between open ocean and ocean margin sediments. Model parameters were constrained using measured values of Th-230 and Pa-231, which have a common source, and then applied to Be-10. An average Holocene Be-10 deposition rate for the entire Pacific Ocean is estimated to be approximately 1.5 x 10(6) atoms/cm2 yr-1, with approximately 70% of the total Be-10 supplied to the Pacific being deposited in margin sediments underlying only 10% of the ocean. The short residence times of Be-10 in ocean margin regions (from < 100 to approximately 200 yr) compared to the long Be-10 residence time in the central open Pacific Ocean (approximately 1000 yr) reflects the intensified scavenging of Be-10 in ocean margin waters. The results of this study suggest that the Pacific Ocean acts as a relatively closed basin with respect to the transport and burial of Be-10; therefore, the average Be-10 deposition rate in the Pacific Ocean can be used as an estimate of the global average production rate of Be-10 in the atmosphere during the Holocene period.
