Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
Proc Natl Acad Sci U S A. 2022 Jan 4;119(1). doi: 10.1073/pnas.2113263118. Epub 2021 Dec 22.
Planktonic organic matter forms the base of the marine food web, and its nutrient content (C:N:P) governs material and energy fluxes in the ocean. Over Earth history, C:N:P had a crucial role in marine metazoan evolution and global biogeochemical dynamics, but the geologic history of C:N:P is unknown, and it is often regarded constant at the "Redfield" ratio of ∼106:16:1. We calculated C:N:P through Phanerozoic time by including nutrient- and temperature-dependent C:N:P parameterizations in a model of the long-timescale biogeochemical cycles. We infer a decrease from high Paleozoic C:P and N:P to present-day ratios, which stems from a decrease in the global average temperature and an increase in seawater phosphate availability. These changes in the phytoplankton's growth environment were driven by various Phanerozoic events: specifically, the middle to late Paleozoic expansion of land plants and the Triassic breakup of the supercontinent Pangaea, which increased continental weatherability and the fluxes of weathering-derived phosphate to the oceans. The resulting increase in the nutrient content of planktonic organic matter likely impacted the evolution of marine fauna and global biogeochemistry.
浮游有机物是海洋食物网的基础，其营养成分（C:N:P）控制着海洋中的物质和能量流动。在地球历史上，C:N:P 在海洋后生动物的进化和全球生物地球化学动力学中起着至关重要的作用，但 C:N:P 的地质历史是未知的，通常被认为在“Redfield”比例（约 106:16:1）下是恒定的。我们通过在一个长时标生物地球化学循环模型中包含依赖营养和温度的 C:N:P 参数化，计算了整个显生宙时期的 C:N:P。我们推断出从古生代到现代 C:P 和 N:P 的比值降低，这归因于全球平均温度的降低和海水磷酸盐可用性的增加。浮游植物生长环境的这些变化是由各种显生宙事件驱动的：具体来说，中生代到古生代陆地植物的扩张和中生代末期泛大陆的分裂，增加了大陆的风化能力和风化衍生磷酸盐向海洋的通量。浮游有机物中营养成分的增加可能影响了海洋动物群的进化和全球生物地球化学。
