Stable oxygen isotope data of Thoracosphaera heimii in surface sediment samples of the equatorial Atlantic and South Atlantic

To investigate the potential use of the stable isotope composition of the vegetative cysts of the photosynthetic dinoflagellate Thoracosphaera heimii for quantitative palaeotemperature reconstructions a method has been developed to purify T. heimii cysts from sediment samples. Stable oxygen and carbon isotopes have been measured on T. heimii cysts from 21 surface sediment samples from the equatorial Atlantic and South Atlantic Oceans. Calculated temperatures based on the palaeotemperature equation for inorganic calcite precipitation generally reflect mean annual temperatures of the upper water column, notably of thermocline depths. Although the present results suggest that the isotopic composition of T. heimii shells might be formed in equilibrium with the seawater in which the shells are being formed, future investigations are required to determine possible effects of metabolic and kinetic processes on the fractionation process. […]

为探究光合裸藻 Thoracosphaera heimii 营养 cysts 中稳定同位素组成在定量古温度重建中的潜在应用，已开发出一套从沉积物样本中纯化 T. heimii cysts 的方法。对来自赤道大西洋和南大西洋表层沉积物的 21 个 T. heimii cysts 样本进行了稳定氧和碳同位素的测量。基于无机方解石沉淀的古温度方程计算出的温度通常反映了上层水柱的平均年温度，尤其是温度跃层深度。尽管目前的结果表明，T. heimii 壳体的同位素组成可能与其形成过程中的海水处于平衡状态，但仍需未来的研究来确定代谢和动力学过程对同位素分馏过程可能产生的影响。