REMOVAL OF TH-230 AND PA-231 FROM THE OPEN OCEAN
REMOVAL OF TH-230 AND PA-231 FROM THE OPEN OCEAN
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DOI：
10.1016/0012-821x(83)90067-5
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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
在马尾藻海（S2站）、北赤道大西洋（E站）和北赤道太平洋（P站）的沉积物收集器收集的颗粒物中以及在E站通过原位过滤收集的颗粒物中测量了230 Th和231 Pa的浓度。在P站和D站用二氧化锰吸附柱提取溶解态Th和Pa，发现P站和D站溶解态230 Th/231 Pa活度比为3-6。相比之下，对于所有沉积物收集器样品从大于2000米，uncalled 230 Th/231 Pa的比值为22-35（平均29.7）。在较浅深度取样的颗粒物中，比率较低。在3600米和5000米处过滤的颗粒在站点E的比率为50和40。结果表明，相对于Pa，大洋中悬浮颗粒物优先清除Th.大部分234 U在开阔海洋中衰变产生的230 Th通过沉降颗粒物的吸附而被去除。相比之下，由235 U衰变产生的231 Pa只有不到50%通过这种机制从水柱中去除。混合过程将剩余物输送到其他汇。
Concentrations of230Th and231Pa were measured in particulate matter collected by sediment traps deployed in the Sargasso Sea (Site S2), the north equatorial Atlantic (site E), and the north equatorial Pacific (Site P) as well as in particles collected by in situ filtration at Site E. Concentrations of dissolved Th and Pa were determined by extraction onto manganese dioxide adsorbers at Site P and at a second site in the Sargasso Sea (site D).Dissolved230Th/231Pa activity ratios were 3–6 at Sites P and D. In contrast, for all sediment trap samples from greater than 2000 m, unsupported230Th/231Pa ratios were 22–35 (average 29.7). Ratios were lower in particulate matter sampled at shallower depths. Particles filtered at 3600 m and 5000 m at Site E had ratios of 50 and 40. Results show that suspended particulate matter in the open ocean preferentially scavenges Th relative to Pa. Most of the230Th produced by decay of234U in the open ocean is removed by adsorption to settling particulate matter. In contrast, less than 50% of the231Pa produced by decay of235U is removed from the water column by this mechanism. Mixing processes transport the remainder to other sinks.