Temporal variation of mineralization rates and its influence on carbon storage over the last 50 years in Bohai Bay, China

Abstract

Recorded information on marine sediments is affected by mineralization. In this study, we collected sediment samples from Bohai Bay, where human interference is typically high. Overall, the CO2 fluxes in the columnar sediments decreased with increasing depth. The change in constants revealed a “C-curve” in which the mineralization rate first decreased significantly (i.e., from the 2020s to the 1980s) and subsequently increased slowly (i.e., from the 1980s to 1965). This may be explained by the fact that sediments from the 1980s–2020s were markedly influenced by the sedimentation rate, whereas sediments from the 1960s–1980s were predominantly influenced by microbial action. The loss of organic carbon due to mineralization accounted for approximately 15–20 % of the initial total organic carbon; therefore, when performing an inversion of the historical environment change using information derived from organic carbon in marine sediments, the influence of mineralization on this information should be fully considered.