Dr. Jianghui Du is an Assistant Professor at Peking University's School of Earth and Space Sciences since 2024. He earned his B.S. (2009) and M.S. (2011) in Geology from Peking University and his Ph.D. in Oceanography from Oregon State University (2019), followed by postdoctoral research in Isotope Geochemistry at ETH Zurich (2019-2023).
His research focuses on marine biogeochemistry, with an emphasis on elemental exchange between the ocean and other Earth systems, the co-evolution of life and the environment, and the processes that maintain ocean and planetary habitability. His work has contributed to understanding millennial-scale Earth system coupling, trace-element and isotope cycling at the ocean-sediment interface, and quantitative modeling of redox, authigenic, and weathering processes in marine sediments. He has received honors including the Marie Sklodowska-Curie Individual Fellowship and ETH Fellowship. He serves as co-chair of the GEOTRACES Early Career Scientists Committee, and is a member of SCOR-China National Committee.
Trace elements and their isotopes (TEIs) are key tracers of ocean and Earth system processes, yet the mechanisms controlling their large-scale distributions remain uncertain. Conventional “top-down” frameworks emphasize surface inputs, biological uptake, and reversible scavenging by biogenic particles. However, recent field observations suggest that this paradigm cannot fully explain the behavior of particle-reactive TEIs such as the rare earth elements (REE) and neodymium isotopes (εNd), particularly in the deep Pacific Ocean.
Here we integrate water-column, sediment, and porewater REE and εNd measurements from the Pacific with diagenetic and ocean models to reassess the drivers of TEI cycling. Water-column profiles demonstrate that Mn oxides, though representing a minor fraction of suspended particles, dominate REE scavenging. When this process is represented realistically in ocean models, scavenging acts as a net sink throughout the water column, implying that additional sources are required to maintain observed Nd concentrations. Porewater data and modeling reveal a benthic flux generated by sediment diagenesis. This flux includes (1) a recycled component derived from elements previously scavenged from the water column and (2) a “new” component produced by marine silicate weathering within sediments. Although recycled fluxes dominate elemental budgets, the new component is essential for generating the radiogenic εNd signature characteristic of Pacific Deep Water. Ocean simulations that incorporate oxide-driven scavenging, benthic sources, and bottom-intensified mixing reproduce the observed vertical Nd concentration structure and non-conservative εNd patterns. These results highlight the central role of the seafloor sediment in shaping TEI distributions and challenge long-standing view based solely on surface-driven processes. Our findings support a bottom-up framework in which particle-type-dependent scavenging, diagenetic recycling, and marine silicate weathering collectively control TEI behavior, with implications for interpreting marine tracers and understanding Earth system dynamics.