Thorium isotopes in the western Mediterranean Sea: an insight into the marine particle dynamics
Thorium isotopes in the western Mediterranean Sea: an insight into the marine particle dynamics
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DOI：
10.1016/s0012-821x(01)00606-9
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发表时间：
2002-03
影响因子：
5.3
通讯作者：
M. Roy‐Barman;L. Coppola;M. Souhaut
中科院分区：
文献类型：
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作者：
M. Roy‐Barman;L. Coppola;M. Souhaut
我们提出了西地中海 230Th-232Th 系统学的详细视图，以限制水和粒子通量。在区域范围内获得的结论在全球范围内也具有相关性，尽管在公海中可能更难以确定。230Th 和 232Th 对在利古里亚海、阿尔博兰海和爱奥尼亚海收集的粒度分级海水和海洋颗粒样品进行了分析。由于深水的形成，DYFAMED 和阿尔沃兰海域的 230Thxs（海水中 234U 放射性衰变产生的 230Th）剖面不是线性的。这两个地点230Thx浓度的差异与水团的老化和不同的清除条件有关。 230Th/232Th 比率在混合过程中用作示踪剂，以提供有关水柱中物质所遵循路径的信息。在 DYFAMED 中，过滤（<0.2 μm）和超滤（<1 kDa）溶液具有相似的 230Th/232Th 比率，表明真正溶解的 Th 与胶体 Th 之间存在平衡。 8 月份在 200 m 至 1000 m 之间观察到的 Th 通量和捕获颗粒 230Th/232Th 比率的变化最好是通过过滤后的大颗粒在捕获颗粒上的聚集来解释的。过滤后的大颗粒相对于捕获颗粒上的聚集的停留时间约为 8-80 天。地中海西部 230 钍和 232 钍输入的综合预算需要溶解与所有大陆颗粒输入（包括边缘隔离的颗粒）相关的 3-5% 的钍，这表明风成输入并不是地中海难熔元素的唯一来源，而且可能是整个海洋的难熔元素的唯一来源。
We present a detailed view of the230Th–232Th systematics in the western Mediterranean Sea in order to constrain water and particle fluxes. The conclusions obtained at the regional scale are also relevant at a more global scale although they may be more difficult to establish in the open ocean.230Th and232Th were analyzed in size-fractionated seawater and marine particle samples collected in the Ligurian, Alboran and Ionian seas. The230Thxs(230Th produced by the radioactive decay of234U in seawater) profiles at DYFAMED and in the Alboran sea site are not linear due to the formation of deep waters. The difference of230Thxsconcentration between these two sites is related to the aging of the water masses and to different scavenging conditions. The230Th/232Th ratio is used as a tracer during mixing processes to provide information on the pathways followed by the matter in the water column. At DYFAMED, filtered (<0.2 μm) and ultrafiltered (<1 kDa) solutions have similar230Th/232Th ratios, suggesting that an equilibrium exists between truly dissolved and colloidal Th. The change of the Th flux and of the230Th/232Th ratio of trapped particles observed in August between 200 m and 1000 m is best explained by aggregation of filtered large particles on the trapped particles. The residence time of filtered large particles with respect to aggregation on trapped particles is of the order of 8–80 days. The combined budget of230Th and232Th inputs to the western Mediterranean Sea requires the dissolution of 3–5% of the Th associated with all the continental particulate inputs (including particles sequestered in margins) suggesting that eolian inputs are not the only source of refractory elements to the Mediterranean Sea and may be to the whole ocean.