Hong Qingquan, Cheng Yilin, Qu Yang, Wei Lin, Liu Yumeng, Gao Jianfeng, Cai Pinghe, Chen Tianyu
State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering and Frontiers Science Center for Critical Earth Material Cycling, Nanjing University, Nanjing, 210023, China.
State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361005, China.
Nat Commun. 2024 May 10;15(1):3966. doi: 10.1038/s41467-024-48297-y.
Rhenium (Re) and uranium (U) are essential proxies in reconstructing past oceanic oxygenation evolution. However, their removal in continental shelf sediments, hotspots of early diagenesis, were previously treated as quantitatively unimportant sinks in the ocean. Here we examine the sedimentary reductive removal of Re and U and their coupling with organic carbon decomposition, utilizing the Ra/Th disequilibria within the East China Sea shelf. We identified positive correlations between their removal fluxes and the rates of sediment oxygen consumption or organic carbon decomposition. These correlations enable an evaluation of global shelf reductive sinks that are comparable to (for Re) or higher than (~4-fold for U) previously established suboxic/anoxic sinks. These findings suggest potential imbalances in the modern budgets of Re and U, or perhaps a substantial underestimation of their sources. Our study thus highlights shelf sedimentary reductive removal as critical yet overlooked sinks for Re and U in the modern ocean.
铼（Re）和铀（U）是重建过去海洋氧化演化的重要指标。然而，它们在大陆架沉积物（早期成岩作用的热点区域）中的去除，以前被视为海洋中数量上不重要的汇。在此，我们利用东海陆架内的镭/钍不平衡，研究了铼和铀的沉积还原去除及其与有机碳分解的耦合关系。我们确定了它们的去除通量与沉积物耗氧率或有机碳分解率之间的正相关关系。这些相关性使得能够评估全球陆架还原汇，其与先前确定的亚oxic/缺氧汇相当（对于铼）或更高（对于铀约为4倍）。这些发现表明铼和铀的现代收支可能存在不平衡，或者可能严重低估了它们的来源。因此，我们的研究强调了陆架沉积还原去除是现代海洋中铼和铀的关键但被忽视的汇。
