Key Laboratory of Orogenic Belts and Crustal Evolution, MOE & School of Earth and Space Sciences, Peking University, Beijing, 100871, China.
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation & Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu, 610059, China.
Sci Rep. 2020 Apr 2;10(1):5794. doi: 10.1038/s41598-020-62816-z.
Organic matter production and decomposition primarily modulate the atmospheric O and CO levels. The long term marine primary productivity is controlled by the terrestrial input of phosphorus (P), while the marine P cycle would also affect organic matter production. In the past 540 million years, the evolution of terrestrial system, e.g. colonization of continents by vascular land plants in late Paleozoic, would certainly affect terrestrial P input into the ocean, which in turn might have impacted the marine primary productivity and organic carbon burial. However, it remains unclear how the marine P cycle would respond to the change of terrestrial system. Here we reconstruct the secular variations of terrestrial P input and biological utilization of seawater P in Phanerozoic. Our study indicates that riverine dissolved P input and marine P biological utilization (i.e. the fraction of P being buried as organophosphorus) are inversely correlated, suggesting the coupling of continental P input and marine P cycle. We propose an increase of P input would elevate surface ocean productivity, which in turn enhances marine iron redox cycle. Active Fe redox cycle favors the scavenging of seawater P through FeOOH absorption and authigenic phosphate formation in sediments, and accordingly reduces the bioavailability of seawater P. The negative feedback of marine P cycle to terrestrial P input would keep a relatively constant organic carbon burial, limiting the variations of surface Earth temperature and atmospheric O level.
有机质的产生和分解主要调节大气中的 O 和 CO 水平。长期以来，海洋初级生产力受陆地磷（P）输入的控制，而海洋 P 循环也会影响有机质的产生。在过去的 5.4 亿年中，陆地系统的演化，例如晚古生代维管陆地植物的大陆殖民化，肯定会影响陆地 P 向海洋的输入，这反过来又可能影响海洋初级生产力和有机碳埋藏。然而，海洋 P 循环将如何响应陆地系统的变化仍不清楚。在这里，我们重建了显生宙陆地 P 输入和海水 P 生物利用的季节性变化。我们的研究表明，河流溶解态 P 输入与海洋 P 生物利用（即 P 作为有机磷埋藏的部分）呈负相关，表明大陆 P 输入与海洋 P 循环的耦合。我们提出，P 输入的增加会提高海洋表面生产力，进而增强海洋铁的氧化还原循环。活跃的 Fe 氧化还原循环有利于通过 FeOOH 吸收和沉积物中自生磷酸盐的形成来清除海水中的 P，从而降低海水中 P 的生物利用度。海洋 P 循环对陆地 P 输入的负反馈作用会保持相对稳定的有机碳埋藏，限制地表地球温度和大气 O 水平的变化。
