The Mesoproterozoic Era (1,600-1,000 million years ago (Ma)) has long been considered a period of relative environmental stasis with biological evolutionary stagnation (Cawood & Hawkesworth, 2014). However, decimeter-scale multicellular fossils have been discovered in the 1,560 million-year-old Gaoyuzhuang Formation of the Yanliao Basin, North China Craton (Zhu et al., 2016). This advanced evolution of complex multicellular eukaryotes to the early Mesoproterozoic. K. Zhang et al. (2018) established a link between rising oxygen levels and the emergence of multicellular eukaryotic life in the early Mesoproterozoic. Furthermore, except for the Yanliao Basin, the Ruyang Group (∼1,750-1,400 Ma) in the southwestern margin of the North China Craton (Agić et al., 2017), the Kotuidan Formation (∼1,500 Ma) on the Northern Siberia Platform (Vorob'eva et al., 2015), and the Roper Group (∼1,500 Ma) in northern Australia (Javaux et al., 2001) have also been reported to preserve a high abundance and diversity of eukaryotic organisms in the early Mesoproterozoic. This evidence suggests that biological evolution during this time was far more active. During the deposition from the Wumishan Formation to the Hongshuizhuang Formation in the Yanliao Basin, a transition from organic-poor to organic-rich deposition leaves much unknown in ocean chemical conditions. Fixed nitrogen (N) in the euphotic zone, including nitrate and ammonium, is essential to life (Koehler et al., 2017). Ocean chemical conditions can influence the availability of nitrogen. In ferruginous upwelling systems, euphotic waters overlying upwelling water mass with NO 3 − reduction to N 2 and NH 4 + take place at relatively high rates due to the persistent Fe(II) electron donors supply (Michiels et al., 2017). NO 3 − reduction to NH 4 + through