PLUTONIUM AND AMERICIUM IN ANOXIC MARINE-SEDIMENTS - EVIDENCE AGAINST REMOBILIZATION
PLUTONIUM AND AMERICIUM IN ANOXIC MARINE-SEDIMENTS - EVIDENCE AGAINST REMOBILIZATION
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DOI：
10.1016/0016-7037(81)90022-3
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发表时间：
1981-01-01
影响因子：
5
通讯作者：
BEASLEY, TM
中科院分区：
文献类型：
--
作者：
CARPENTER, R;BEASLEY, TM
摘要 在缺氧的萨尼奇湾沉积物中，发现 239+ 240 Pu 活性为 100-450dpm/kg，深达 15-18 厘米，在未受干扰的沉积物中具有地下最大值。萨尼奇湾 (Saanich Inlet) 的两个缺氧沉积物岩心和 65 公里外的华盛顿州达博布湾 (Dabob Bay) 的一个含氧沉积物岩心中都存在与交付估计重叠的综合 239+ 240 Pu 库存。萨尼奇湾沉积物中的 241 Am 239+ 240 Pu 比率与中北纬度未分级沉降物、华盛顿大陆架的含氧沉积物以及南加州和墨西哥附近两个盆地的缺氧沉积物中的比率重叠。萨尼奇湾沉积物三个区间的 239+ 240 Pu 137 Cs 比率也与先前报道的含氧沿海海洋沉积物的比率一致。 Pu 库存、Am Pu 和 Pu Cs 比率以及 Saanich Inlet Dabob Bay 的比较都表明，Pu 不会在缺氧沉积物中快速重新流动。地下 239+ 240 Pu 活动最大值与 1963-1964 年 Pu 沉降峰值的历史记录不一致，除非我们的 210 Pb 沉积速率不正确地高。然而，它们与萨尼奇湾先前的 210 Pb 和 varve 年表非常一致，并且还给出了 239+ 240 Pu 和 SNAP-9A 提供的 238 Pu 首次出现在沉积物中的合理日期。我们得出的结论是，他们正确地确定了 1970-1973 年沉积物 239+240 Pu 活动的最大值，并寻求对峰值沉降后 7-10 年滞后的解释。卡里亚科海沟东部盆地的一处岩心和杜尔塞湾的两处岩心中含有 239+ 240 Pu 库存。当使用过量的 210 Pb 库存和通量来验证至少最近沉积的沉积物的主要部分的恢复时，哥斯达黎加太平洋沿岸的缺氧盆地也与这些纬度的沉降物输送情况合理一致。
Abstract 239+ 240 Pu activities of 100–450dpm/kg are found down to 15–18 cm in anoxic Saanich Inlet sediments, with a subsurface maximum in undisturbed deposits. Integrated 239+ 240 Pu inventories which overlap delivery estimates are present both in two cores of anoxic sediments from Saanich Inlet and in one core of oxic sediments 65 km away in Dabob Bay, Washington. 241 Am 239+ 240 Pu ratios in Saanich Inlet sediments overlap ratios in unfractionated midnorthern latitude fallout, in oxic sediments from the Washington continental shelf, and in anoxic sediments from two basins off southern California and Mexico. The 239+ 240 Pu 137 Cs ratios in three intervals of Saanich Inlet sediments are also in agreement with ratios previously reported for oxic coastal marine sediments. The Pu inventories, the Am Pu and Pu Cs ratios, and the Saanich Inlet Dabob Bay comparison all argue that Pu is not rapidly remobilized in anoxic sediments. The subsurface 239+ 240 Pu activity maximum is not in agreement with the historical record of peak Pu fallout in 1963–1964 unless our 210 Pb-derived sedimentation rates are incorrectly high. However, they are in good agreement with previous 210 Pb and varve chronologies in Saanich Inlet, and also give reasonable dates for times when 239+ 240 Pu and SNAP-9A supplied 238 Pu first appear in the sediments. We conclude they properly date the maximum in sedimentary 239+ 240 Pu activity at 1970–1973, and seek explanations for the 7–10yr time lag after peak fallout. 239+ 240 Pu inventories in one core from the eastern basin of the Cariaco Trench and in two cores from Golfo Dulce. an anoxic basin off the Pacific coast of Costa Rica, are also in reasonable agreement with fallout delivery to these latitudes when excess 210 Pb inventories and fluxes are used to verify recovery of at least a major fraction of the most recently deposited sediments.