Trace Element Proxies of Carbon Flux and Bottom Water Oxygen Concentration

小行星9401138 铀通过化学还原沉积物中的沉淀而从海洋中去除。 在这里，我们提出了初步的结果，从亚南极洲的南大西洋显示高利率的自生铀沉积在冰川时代的沉积物。 在现代远洋沉积物中，没有类似的自生铀沉积速率如此之高。 所观察到的铀的埋藏意味着冰川海洋中存在两种情况之一：要么环极深水中氧含量大大减少（与现代超过200微摩尔的水平相比），要么亚南极表层沃茨的生物生产力大大增强。这两种情况都代表了冰川海洋碳循环的一个重要特征。 我们的假设是，亚南极洲沉积物持有的关键记录，这将导致长期寻求的解释较低的大气CO2浓度在冰河时代。 我们的目标不仅是检验这一假设，而且要获得有关冰河时期海洋生产力和深海O2含量的定量信息。

9401138 ARCHER Uranium is removed from the ocean by precipitation in chemically- reducing sediments. Here, we present preliminary results from the subantarctic South Atlantic showing high rates of authigenic U deposition in glacial-age sediments. There is no analog for such high rates of authigenic U deposition in modern pelagic sediments. The observed burial of uranium implies that one of two conditions existed in the glacial ocean: either greatly-reduced oxygen content of Circumpolar Deep Water (compared to modern levels in excess of 200 micromolar), or greatly-enhanced biological productivity of subantarctic surface waters. Either condition would represent a significant feature of the carbon cycle in the glacial ocean. Our hypothesis is that subantarctic sediments hold the key record which will lead to the long-sought explanation for lower atmospheric CO2 concentrations during the ice ages. Our goals are not only to test this hypothesis, but to derive quantitative information about ice-age ocean productivity and deep- sea O2 content.