A Numerical Study on Vertical Transport of Polychlorinated Biphenyls(PCBs)in East China Sea

摘要

Understanding the transport process and route of persistent organic pollutants(POPs)such as polychlorinated biphenyls(PCBs)in the ocean is important to assess their oceanic environmental impact and fate.In this study,a POPs transport model was constructed and applied to the East China Sea(ECS).This model includes four compartments namely:gas-phase POPs,dissolved phase POPs,phytoplankton POPs and detritus POPs,and was coupled with a high resolution ocean circulation model in the ECS.Together of this model,an air-water-plankton transport process of POPs,consisting of diffusive air-water exchange between air and water,effect of phytoplankton uptake,vertical sinking of phytoplankton,detritus originating from phytoplankton and decomposition of POPs.Moreover,transport processes from air to deep water and spatial distributions of PCBs are examined using this POPs model in the ECS.In the ECS,the diffusive air-water exchange,transport to deep water and vertical distribution of concentrations of dissolved and particulate phase PCBs are strongly influenced by phytoplankton uptake property and horizontal distribution of phytoplankton biomass.Especially,in coastal region of the ECS where primary production is higher,air-water flux of PCBs and sinking flux of particulate phase PCBs(phytoplankton and detritus PCBs)increases from the effect of phytoplankton uptake.This resulted to a major depositional sinking area of PCBs originating from atmosphere along the coastal area of the ECS.It is concluded that oceanic biochemical transport processes play an important role in controlling spatial distribution and formation of depositional sinking area of PCBs originating from atmosphere in the ECS.