REMOVAL OF TH-230 AND PA-231 AT OCEAN MARGINS
REMOVAL OF TH-230 AND PA-231 AT OCEAN MARGINS
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DOI：
10.1016/0012-821x(83)90127-9
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发表时间：
1983-01-01
影响因子：
5.3
通讯作者：
BREWER, PG
中科院分区：
文献类型：
--
作者：
ANDERSON, RF;BACON, MP;BREWER, PG
通过在巴拿马盆地部署沉积物捕集器以及在巴拿马和危地马拉盆地现场过滤大量海水，测量了收集的颗粒物中的铀、钍和钚同位素。在原地抽水系统中，溶解的Th和Pa的浓度是通过放置在过滤器后面的MnO2吸附装置来测定的。巴拿马和危地马拉盆地中溶解的230Th和231Pa的浓度低于公海，而溶解的230Th/231Pa值等于或略高于公海的比值。沉积物捕捉器样品中的颗粒~(230)Th/~(231)Pa值介于4到8之间，而在以前研究的开阔海域，这一比值为30或更高。在巴拿马盆地和危地马拉盆地最靠近大陆边缘的地方，通过过滤收集的颗粒物含有与沉积物陷阱样品中的比率相似的230Th/231Pa值。靠近大陆边缘的悬浮颗粒物对Th或Pa的吸附没有表现出偏好，因此在化学上一定不同于远洋中的颗粒物，后者表现出强烈的吸附Th的偏好。以巴拿马和危地马拉盆地为代表的海洋边缘，相对于230Th而言，是231Pa的优先汇。此外，边缘是230Th的汇，更大程度上是由开阔海洋的水平混合输送的231Pa汇。
Uranium, thorium and protactinium isotopes were measured in particulate matter collected by sediment traps deployed in the Panama Basin and by in-situ filtration of large volumes of seawater in the Panama and Guatemala Basins. Concentrations of dissolved Th and Pa isotopes were determined by extraction onto MnO2adsorbers placed in line behind the filters in the in-situ pumping systems.Concentrations of dissolved230Th and231Pa in the Panama and Guatemala Basins are lower than in the open ocean, whereas dissolved230Th/231Pa ratios are equal to, or slightly greater than, ratios in the open ocean. Particulate230Th/231Pa ratios in the sediment trap samples ranged from 4 to 8, in contrast to ratios of 30 or more at the open ocean sites previously studied. Particles collected by filtration in the Panama Basin and nearest to the continental margin in the Guatemala Basin contained230Th/231Pa ratios similar to the ratios in the sediment trap samples. The ratios increased with distance away from the continent.Suspended particles near the margin show no preference for adsorption of Th or Pa and therefore must be chemically different from particles in the open ocean, which show a strong preference for adsorption of Th. Ocean margins, as typified by the Panama and Guatemala Basins, are preferential sinks for231Pa relative to230Th. Furthermore, the margins are sinks for230Th and, to a greater extent,231Pa transported by horizontal mixing from the open ocean.