The joint effects of atmospheric dry and wet deposition on organic carbon cycling in a mariculture area in North China

In this research, the atmospheric dry and wet deposition fluxes of particulate organic carbon (POC) over the coastal waters around the Yangma Island in North Yellow Sea were investigated. Combining the results of this research and previous reports about the wet deposition fluxes of dissolved organic carbon (DOC) in precipitation (FDOC-wet)and dry deposition fluxes of water-dissolvable organic carbon in atmospheric total suspended particles (FDOC-dry) in this area, a synthetic assessment of the influence of atmospheric deposition on the eco-environment was conducted. It was found that the annual dry deposition flux of POC was 1097.9 mg C m-2 a-1, which was approximately 4.1 times that of FDOC-dry (266.2 mg C m-2 a-1). For wet deposition, the annual flux of POC was 445.4 mg C m-2 a-1, accounting for 46.7 % that of FDOC-wet (954.3 mg C m-2 a-1). Therefore, atmospheric POC was mainly deposited through dry process with the contribution of 71.1 %, which was contrary to the deposition of DOC. Considering the indirect input of organic carbon (OC) from atmospheric deposition, that is, the new productivity supported by nutrient input from dry and wet deposition, the total OC input from atmospheric deposition to the study area could be up to 12.0 g C m-2 a-1, highlighting the important role of atmospheric deposition in the carbon cycling of coastal ecosys-tems. The contribution of direct and indirect input of OC through atmospheric deposition to the dissolved oxygen con-sumption in total seawater column was assessed to be lower than 5.2 % in summer, suggesting a relatively smaller contribution to the deoxygenation in summer in this region.

Automated summary

This research investigated the impact of atmospheric dry and wet deposition on particulate organic carbon (POC) in the coastal waters of Yangma Island in the North Yellow Sea. The findings showed that POC was primarily deposited through dry processes, accounting for 71.1% of the deposition. The total input of organic carbon (OC) from atmospheric deposition to the study area was estimated to be up to 12.0 g C m-2 a-1, indicating the important role of atmospheric deposition in coastal ecosystem carbon cycling. The contribution of atmospheric deposition to dissolved oxygen consumption in the seawater column was found to be lower than 5.2% in summer, suggesting a relatively minor impact on summer deoxygenation in the region.