Silicic-Acid Dependence of Oxygen-Isotope Fractionation in Diatom Opal and its Bearing on Isotopic Paleoclimatology

新的分析方法使高 高质量、可重复的硅藻二氧化硅18 O/16 O分析。 这些技术可应用于硅藻类沉积物 从海洋和湖泊环境中获得详细的 古气候和气候变化信息。 但是，在这方面， 一些证据表明氧气的分馏 生物蛋白石和水之间的同位素可能是动力学 控制。 如果是这样的话，硅藻18 O可能部分取决于 硅藻从中提取的水中的草酸含量 他们的硅。 因为古代的二氧化硅浓度 湖泊和海洋将很少知道，硅酸 依赖性--如果存在的话--可能会降低 很有前途的古温度计 在这 调查，海洋和湖泊硅藻将是 培养了解他们的18 O是否取决于 环境水的酸性含量。 动力学 如果一个依赖性是 硅藻二氧化硅是宝贵的信息来源 应用于古水文学研究。

New analytical approaches have made possible the high quality, reproducible 18O/16O analysis of diatom silica. These techniques could be applied to diatomaceous sediments from oceanic and lacustrine environments to obtain detailed information on paleoclimate and climate change. However, some evidence suggest that the fractionation of oxygen isotopes between biogenic opal and water may be kinetically controlled. If so, diatom 18O may depend partly on the silicic acid content of the water from which diatoms extract their silica. Because the silica concentration of ancient lakes and seas would seldom be known, a silicic-acid dependence--if on exists--could diminish the precision of an otherwise promising paleothermometer. In this investigation, marine and lacustrine diatoms will be cultured to learn whether their 18O depends on the silicic acid content of the environmental water. A kinetic fractionation model will be developed if a dependence is found. Diatom silica is valuable source of information having application to paleohydrologic studies.