We report measurements of strontium concentrations and Sr/Ca ratios in the Indian and Southern Oceans, which show that subtle geochemical variations along the main thermocline are the product of calcium carbonate (CaCO₃) and celestite (SrSO₄) precipitation and dissolution. Our calculations suggest that celestite skeletons precipitated by Acantharia contribute up to 10 mol % of the combined amount of carbonate and celestite shells precipitated in the Indian Ocean. The data suggest that the distribution of the concentration of strontium in the global ocean is governed by the different modes of deep-water formation in the Southern Ocean and North Atlantic. The formation of Antarctic bottom waters from strontium-rich, upwelled deep waters forms a southern end member contrasted with the strontium-depleted North Atlantic deep water. The difference in strontium concentrations and Sr/Ca ratios of the different water masses reported here is maintained by precipitation, export, and dissolution of CaCO₃ and SrSO₄. These preformed strontium concentrations correlate linearly with nitrate and phosphate concentrations in the Indian Ocean, but this correlation is weaker in low latitudes, where the mixotrophic lifestyle of Acantharia allows them to thrive in nutrient-depleted environments.

中文翻译：

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溶解的锶，Sr / Ca比值和印度洋和南洋棘皮的丰度

我们报告了印度洋和南洋中锶浓度和Sr / Ca比值的测量结果，这些结果表明沿主要温跃层的细微地球化学变化是碳酸钙（CaCO ₃）和天青石（SrSO ₄）沉淀和溶解。我们的计算表明，由棘棘沉淀的天青石骨架占印度洋沉淀的碳酸盐和天青石壳总含量的10 mol％。数据表明，全球海洋中锶的浓度分布受南大洋和北大西洋深水形成的不同模式的控制。与富含锶的北大西洋深水形成鲜明对比的是，富含锶的上涌深水形成的南极底部水形成了南端。此处报道的不同水团的锶浓度和Sr / Ca比值的差异通过CaCO ₃和SrSO _4的沉淀，输出和溶解得以维持。。这些预先形成的锶浓度与印度洋中的硝酸盐和磷酸盐浓度呈线性相关，但是在低纬度地区，棘层混养的生活方式使它们在营养贫乏的环境中壮成长，这种相关性较弱。