Understanding the ocean's biogeochemical cycles of trace elements has significant scientific and societal implications. First, many trace elements are vital nutrients for marine organisms. As a result, they can drive evolutionary processes, influence surface climate and environmental conditions by participating in global biogeochemical cycles of carbon and oxygen, and play a key role in maintaining the health of marine ecosystems. Second, trace elements serve as essential tools for investigating the ocean system and tracking its interactions with the biosphere, atmosphere, and lithosphere. Importantly, the isotopic compositions of many trace elements often provide scientists with the only means to reconstruct past ocean environmental conditions, enabling us to study how historical ocean changes have affected the origin and evolution of life on Earth.
Consequently, there is a growing effort to incorporate marine trace elements into state-of-the-art global models, aiming to enhance our ability to predict future changes in ocean chemistry and climate. However, these efforts have faced challenges due to our limited understanding of the sources and sinks of dissolved trace elements in the ocean. Recent findings specifically indicate that sedimentary source and sink fluxes may play significantly larger roles in shaping the distributions of marine trace elements than previously assumed. Yet, our knowledge of these fluxes and the relevant sediment biogeochemical processes remains insufficient, resulting in substantial uncertainties in the modern and paleo-applications of trace elements in the field of ocean biogeochemistry. The project aims to characterize the sedimentary processes and fluxes of these trace elements and isotopes, develop new modeling tools to study their biogeochemical cycling in marine sediments and understand the role of sedimentary processes in their global ocean cycles. The project is focused on the rare earth elements and transition metals.
The project has concluded that the sedimentary fluxes of trace elements and isotopes are regulated by diagenetic processes including organic matter remineralization, redox cycling, authigenesis, marine silicate weathering and reverse weathering; the sedimentary fluxes contribute significantly to the elemental and isotopic budgets of trace elements and isotopes; including sedimentary processes and fluxes in ocean models is needed to fully explain the distributions of trace elements and isotopes in the ocean.
