Submarine reverse weathering and its effect on oceanic elements cycling

Reverse weathering in the marine environment refers to the process in which silicon reacts with soluble cations to form authigenic aluminosilicate minerals (clays), while consuming ocean alkalinity and releasing CO₂. The reverse weathering hypothesis was proposed in 1966 and has attracted rapidly increasing research attention over the last two decades. It has been regarded as an important mechanism regulating global carbon, oceanic silicon and key element cycles, and ocean alkalinity. Reverse weathering can occur in various marine environments including estuarine deltas and marginal seas, hydrothermal or deeply buried diagenetic environments, and deep oceans. The reaction timescales of reverse weathering vary widely, ranging from days to millions of years, and the controlling factors of the reactions are also significantly different in different marine environments. The major research methods of reverse weathering include direct observation of authigenic silicate minerals, chemical analysis of pore water and sediments, and experimental simulation and modelling, etc. The quantification of the degree of reverse weathering, the determination of limiting factors, and evaluation of its influence on the key element cycling have always been the key issues in the research of reverse weathering. The rapid development of non-traditional stable (metal) isotopes may allow us to better constrain the reverse weathering research. The East Asian continental margin is featured by the world's largest river delta, wide continental shelf, and characteristic hydrothermal activity, whose unique muddy sedimentary systems and active interface reactions and processes make the continental margin a natural laboratory for the integrated study of reverse weathering.