The Isotopic Signature of Fallout North Pacific
نویسنده
چکیده
Plutonium analyses of a dated coral record from the French Frigate Shoals in the central North Pacific indicate that there are two major sources of PM in this basin: close-in (troposphertc) fallout from nuclear weapons testing at the Pact& Proving Grounds in the Marshall Islands in the 1950s and global (stratospheric) fallout which peaked in 1962. Furthermore, the 240Pu/239Pu atom ratio of fallout ,from the Pacific Proving Grounds is characteristically higher (0.24) than that of global jhllout Pu (O.l8+I9). Seawater and sediment samples from the North Pacific exhibit a wide range of “40Pu/239Pu values (0.19-+34), with a trend towards higher ratios in the subsurface waters and sediment. Deep water 240Pul”39Pu ratios are higher in the vicinity of the Marshall Islands relative to stations further from this close-in fallout source. These preliminary data suggest that fallout Pu from the Pacific Proving Grounds is more rapidly removed from the surface waters than is global fallout Pu. Plutonium geochemistry appears to be related to the physical/chemical form of PM-bearing particles generated by dtfferent ,fallout sources. (‘ 1997 Elsevier Science Limited.
منابع مشابه
Radiogenic isotopic mapping of late Cenozoic eolian and hemipelagic sediment distribution in the east-central Pacific
Pelagic clay of the east-central Pacific province is shown to be a mixture of three primary detrital components, reflecting continental source areas in Asia, North America, and Central and South America. Relative contributions from each source area are a function of geography, and this distribution appears to have remained constant over the past five million years, despite changing flux rates. ...
متن کاملar X iv : a st ro - p h / 01 06 20 5 v 2 3 1 Ju l 2 00 1 Experimental Limit to Interstellar 244 Pu Abundance
Short-lived nuclides, now extinct in the solar system, are expected to be present in interstellar matter (ISM). Grains of ISM origin were recently discovered in the inner solar system and at Earth orbit and may accrete onto Earth after ablation in the atmosphere. A favorable matrix for detection of such extrater-restrial material is presented by deep-sea sediments with very low sedimentation ra...
متن کاملar X iv : a st ro - p h / 01 06 20 5 v 3 2 5 A ug 2 00 1 Experimental Limit to Interstellar 244 Pu Abundance
Short-lived nuclides, now extinct in the solar system, are expected to be present in interstellar matter (ISM). Grains of ISM origin were recently discovered in the inner solar system and at Earth orbit and may accrete onto Earth after ablation in the atmosphere. A favorable matrix for detection of such extrater-restrial material is presented by deep-sea sediments with very low sedimentation ra...
متن کاملar X iv : a st ro - p h / 01 06 20 5 v 1 1 2 Ju n 20 01 Experimental Limit to Interstellar 244 Pu Abundance
Short-lived nuclides, now extinct in the solar system, are expected to be present in the interstellar medium (ISM). Grains of ISM origin were recently discovered in the inner solar system and at Earth orbit and may accrete onto Earth after ablation in the atmosphere. A favorable matrix for detection of such extraterrestrial material is presented by deep open-sea sediments with very low sediment...
متن کاملArrival of the Fukushima radioactivity plume in North American continental waters.
The large discharge of radioactivity into the northwest Pacific Ocean from the 2011 Fukushima Dai-ichi nuclear reactor accident has generated considerable concern about the spread of this material across the ocean to North America. We report here the first systematic study to our knowledge of the transport of the Fukushima marine radioactivity signal to the eastern North Pacific. Time series me...
متن کامل