Bio-reactivity of refractory humic-like dissolved organic matter found to increase in energy-limiting deep-sea sediments

Humic-like dissolved organic matter (DOM) is a major component of DOM in marine sediment pore waters. It is usually regarded as refractory for their complex molecular structures and long residence time in natural environments. However, its bio-reactivity remains poorly explored, especially in depositional settings with different organic matter availability, which makes its roles in supporting deep life and regulating long-term oceanic carbon cycling elusive.