Understanding nitrogen (N) and sulfur (S) cycle dynamics during the past hyperthermal is essential to predict how the current global warming impacts ocean chemistry and marine ecosystems. The Cretaceous oceanic anoxic event at the Cenomanian-Turonian transition (OAE-2, ~94 Ma) is an episode of typical marine anoxia under a warm climate. This time interval is characterized by rising sea surface temperature, enhanced marine biological productivity, and widespread occurrence of organic-rich black shale. With the export of biological production to the deep ocean, organisms consume vast amounts of oxygen and subsequently utilize nitrate and sulfate as electron acceptors during organic matter degradation, thereby affecting the ocean's internal biogeochemical cycles. Due to a lack of comprehensive compilation of global geochemical records, how the N and S cycles respond to warming climate and oxygen loss and their characteristics through time and space are yet to elucidate. To bridge this gap, we compile the marine N and S isotope data from worldwide locations across the Cenomanian-Turonian boundary and discuss the current model interpretation with the goal to reconstruct the magnitude, distribution, and evolution of ocean anoxia. This study aims to provide a global picture of changes in the N and S cycles through the OAE-2 with implications for the potential deterioration of future marine environments.

硫循环,大洋缺氧事件,氮循环,白垩纪