Spatiotemporal variations and driving factors of buried organic carbon in mangrove sediments of China: Based on δ13C values

Abstract

Mangroves, as significant coastal carbon reservoirs, play a pivotal role in the global carbon cycle. However, the detailed data on mangrove organic carbon (OC) burial is patchy in China, owing to regional discrepancies in spatiotemporal variations and driving factors. To fill this gap, the end-member mixing models based on δ¹³C and C/N values were used to calculate the relative contributions of terrestrial, mangrove, and marine OC, based on 28 sediment cores collected from five typical mangroves in China. The organic carbon burial flux (OCBF) and stocks (OCS) were calculated to be 133.93 ± 106.56 (n = 28) g C m⁻² yr⁻¹ and 126.91 ± 52.45 (n = 28) Mg C ha⁻¹, respectively, which were lower than the global averages. The study indicated that there were no significant latitudinal variations in mangrove OCS. The reason was that these sampling sites in high latitudes were mostly located at estuaries, exhibiting relatively higher sedimentation rates. The increase in terrestrial OC derived from river inputs effectively offset the decline in mangrove productivity. Therefore, sedimentation rates should be the main driving factor for spatiotemporal variations of mangrove OC burial in China.