Carbon burial potential of the surface sediment and its associated anthropogenic impacts in the semi-closed area of Bohai Bay

Abstract

Carbon burial potential in marine sediments plays an important role in global warming. However, they are easily disturbed by human activities in coastal areas. In this study, marine sediment samples were collected from the coastal area of Bohai Bay, and the effects of exogenous inputs on the carbon content and forms were evaluated. Results showed that the carbon content in sediments ranged from 12.45 g/kg to 19.14 g/kg, with an average of 16.23 g/kg ± 2.78 g/kg, and the average organic carbon (C-Org) content is 12.68 ± 1.14 g/kg, which accounts for about 75% of the total carbon storage in sediment. The content of inorganic carbon (CaCO3) did not change significantly, but the content of C-Org in the estuary area was significantly higher than that in other areas. The proportions of active components in C-Org such as light organic carbon (LOC) and neutral organic carbon (NOC) were relatively low, accounting for approximately 9.49% and 18.15% of the total organic carbon, respectively. The spatial distribution characteristics of LOC and NOC were similar to that of C-Org in the study area. This indicates that human activities have increased the content of C-Org and its active components in marine sediments. Although C-Org and its active components are of relatively low abundance, both are easily affected by human activities which increase pollutants associated with the active components of organic carbon in coastal sediments. Therefore, further consideration should be given to reducing the pollutants carried by exogenous inputs, so that cleaner carbon can be buried in the sediments of Bohai Bay.