Apparent Aging and Rejuvenation of Terrestrial Organic Carbon Along the River‐Estuary‐Coastal Ocean Continuum
Meng Yu, Timothy I. Eglinton, Pengfei Hou, Negar Haghipour, Hailong Zhang, Zicheng Wang, Meixun Zhao
Abstract
Abstract The fates of terrestrial organic carbon (OC terr ) during fluvial transport from land to ocean are still not well constrained. This study systematically examines the evolution and dynamics of OC terr along the river‐estuary‐coastal ocean continuum in three fluvial systems discharging to the Chinese marginal seas. The 14 C‐depleted characteristics of bulk OC and molecular components of riverine suspended sediments and marine sediments suggest that the Chinese marginal seas are a significant sink of pre‐aged OC terr . Our study reveals significant apparent aging of OC terr within estuaries, likely due to degradation of (younger) labile components, and apparent rejuvenation of OC terr in shelf systems, likely reflecting inputs of younger OC terr from proximal sources along the sediment dispersal pathway. The aging and rejuvenation of OC terr along the river‐ocean continuum confounds the use of plant wax lipid 14 C to constrain lateral transport times, and sheds light on more complex OC terr dynamics in marginal seas.