研究人员开发了一个磷酸盐、碳、氧和钙耦合循环的统计模型，以约束显生宙时期(5.41亿年前至今)风化衍生的通量和磷酸盐的海水浓度。统计模型包括输入参数和来自地质和地球化学数据的时变作用力。研究发现，低温流体对洋壳化学风化的气候敏感性对磷酸盐的有效性起一级控制作用。具体来说，大陆风化是限制性营养磷酸盐的来源，但海底风化被认为是一个较小的磷酸盐汇。因此，在地球历史上，海底风化占总风化(海底+大陆)很大一部分的时期，也是磷酸盐流入海洋和在海洋中浓度相对较低的时期。在此期间，较低的海水磷酸盐水平可能导致较低的初级生产力以及海洋和大气氧浓度。
据介绍，磷酸盐是所有生物的必须常量营养素，在确定海洋初级生产力水平方面起着关键作用。尽管磷酸盐对海洋生物地球化学循环非常重要，并在塑造海洋生物进化方面发挥作用，但在地质时间尺度上控制磷酸盐生物有效性的因素仍然知之甚少。
附：英文原文
Title: Rates of seafloor and continental weathering govern Phanerozoic marine phosphate levels
Author: Sharoni, Shlomit, Halevy, Itay
Issue&Volume: 2022-12-22
Abstract: Phosphate is an essential macronutrient for all organisms with a key role in setting levels of marine primary productivity. Despite its importance for marine biogeochemical cycles and its role in shaping the evolution of marine organisms, the factors controlling phosphate bioavailability on geologic timescales remain poorly understood. Here we develop a statistical model of the coupled cycles of phosphate, carbon, oxygen and calcium to constrain the weathering-derived fluxes and seawater concentrations of phosphate through Phanerozoic time (541 million years ago to the present). Our model includes input parameters and time-dependent forcings derived from geologic and geochemical data. We find that the climate sensitivity of chemical weathering of the oceanic crust by low-temperature fluids exerts a first-order control on phosphate availability. Specifically, continental weathering is a source of the limiting nutrient phosphate, but seafloor weathering is considered to be a minor phosphate sink. Consequently, times in Earth history during which seafloor weathering constituted a large fraction of the total (seafloor+continental) weathering were also times during which phosphate influxes to and concentrations in the ocean were relatively low. Lower seawater phosphate levels during those times probably resulted in lower primary productivity and oceanic and atmospheric oxygen concentrations.
DOI: 10.1038/s41561-022-01075-1
Source: https://www.nature.com/articles/s41561-022-01075-1