In this paper, the authors mainly discuss the distribution of total organic carbon (TOC) and its contributors. The results show that the concentrations of TOC are high in the southern and low in the northern part of the study area. Therefore, the authors removed the influence of inorganic nitrogen to the calculation.C/N ratios of samples in study area vary from 4 to 17 with an average at 9, suggesting the mixed origin of TOC from both marine and terrestrial sources. The contributions of terrestrial and marine sources to TOC were estimated, and the results indicate that the input of terrigenous organic carbon is the dominant contributor to the TOC in the study area, especially in the nearshore and estuarine areas.