New Constraints on the Physical and Biological Controls on the Silicon Isotopic Composition of the Arctic Ocean
New Constraints on the Physical and Biological Controls on the Silicon Isotopic Composition of the Arctic Ocean
复制标题
DOI：
10.3389/fmars.2021.699762
复制
发表时间：
2021-08
期刊：
影响因子：
--
通讯作者：
M. Brzezinski;I. Closset;Janice L. Jones;Gregory F. de Souza;C. Maden
中科院分区：
文献类型：
--
作者：
M. Brzezinski;I. Closset;Janice L. Jones;Gregory F. de Souza;C. Maden
北冰洋深处的硅酸δ30Si(OH)4的硅同位素组成与其他深海盆地相比异常重。为了进一步评估导致这种情况的机制，我们在US GEOTRACES剖面GN01上对从白令海峡到北极的δ30Si(OH)4进行了研究。极地混合层同位素值显示出强烈的跨极漂移影响。漂水含有较高的[Si(OH)4], δ30Si(OH)4较重，这与河流源水的高硅酸盐和欧亚大陆架上强烈的生物Si(OH)4消耗相一致。加拿大盆地双盐斜内硅酸浓度最大值[Si(OH)4]形成了局部δ30Si(OH)4最小值，并扩展到整个加拿大盆地，反映了高[Si(OH)4]的太平洋源水和楚科奇海底栖输入的Si(OH)4。随着中深水[Si(OH)4]含量的增加，δ30Si(OH)4变轻；加拿大盆地深水和欧亚盆地深水均比其他洋盆深水重。结合所有可用的北极δ30Si(OH)4数据的初步同位素预算证实了同位素重流入对形成北极深部异常Si同位素特征的重要性，但也揭示了与穿越连接北极与太平洋和大西洋的主要门户的流出相比，主要流入的同位素组成惊人地相似。这种相似性意味着生物生产力和蛋白石埋藏在去除从河流进入北冰洋的轻同位素方面发挥了重要作用。
The silicon isotope composition of silicic acid, δ30Si(OH)4, in the deep Arctic Ocean is anomalously heavy compared to all other deep ocean basins. To further evaluate the mechanisms leading to this condition, δ30Si(OH)4 was examined on US GEOTRACES section GN01 from the Bering Strait to the North Pole. Isotope values in the polar mixed layer showed a strong influence of the transpolar drift. Drift waters contained relatively high [Si(OH)4] with heavy δ30Si(OH)4 consistent with the high silicate of riverine source waters and strong biological Si(OH)4 consumption on the Eurasian shelves. The maximum in silicic acid concentration, [Si(OH)4], within the double halocline of the Canada Basin formed a local minimum in δ30Si(OH)4 that extended across the Canada Basin, reflecting the high-[Si(OH)4] Pacific source waters and benthic inputs of Si(OH)4 in the Chukchi Sea. δ30Si(OH)4 became lighter with the increase in [Si(OH)4] in intermediate and deep waters; however, both Canada Basin deep water and Eurasian Basin deep water were heavier than deep waters from other ocean basins. A preliminary isotope budget incorporating all available Arctic δ30Si(OH)4 data confirms the importance of isotopically heavy inflows in creating the anomalous deep Arctic Si isotope signature, but also reveals a surprising similarity in the isotopic composition of the major inflows compared to outflows across the main gateways connecting the Arctic with the Pacific and the Atlantic. This similarity implies a major role of biological productivity and opal burial in removing light isotopes entering the Arctic Ocean from rivers.