PAHs Appraisal,Distribution And Source Appointment Identification In The Open Seawater From Northern South China Sea And Coastal Seawater,Pearl River Delta

The seawater samples were collected during the year spring time,March 2014 in the northern South China Sea.Two voyage was carried out at that time.The first one was for the coastal area near pearl river basin and the second one was for the sampling in marginal northern south china sea area.This study was carried out for the analysis of concentration,horizontal and vertical distribution and sources of PAHs in the coast and open sea in the northern South China Sea.In addition,the hydrological process and biological pump was taken into attention in order to discuss the potential impacts on the spatial distribution of PAHs in the study area.And hence,it is good to have deep insight of the pollution status of dissolved PAHs in northern SCS.The primary assumptions from this study are as followed:The concentration of dissolved PAHs in the coast of northern SCS was 8.79 ng/L?46.59 ng/L(middling 23.3 8 ng/L)and in the marginal sea area the concentration of PAHs was 6.22 ng/L-41.37 ng/L(average 13.44 ng/L).In general,SCS can be regarded as a medium PAH-contamnated region on a global scale.With the distance from seashore increasing,the concentrations of dissolved PAHs showed a declining trend in the northern SCS.The dissolved PAHs concentrations decrease in horizontal direction with distance far away from the coast in the northern SCS.This trend,however,is probably due to the input of runoff and atmosphere from the anthropogenic activity center.The distribution patterns of dissolved PAHs in the northern SCS are relevant to the runoff,coastal current,Kuroshio,warm current of SCS and eddy.The primary influence factors could be the industrial and agricultural emissions and oil or gas exploitation in the nearby countries and regions.The PAHs pollution in this area is aggravated increasingly,which may be closely related to the development of China,Philippines,and Vietnam as well as other areas in Southeast Asia.In this current study,dissolved PAHs content in shallower water near 200 m was higher than that below 200 m.It is because,PAHs was "pumped" into suspended particulate matter,which can be settled into the deep ocean by the biological pump,resulting in the decrease of dissolved PAHs in the northern SCS.In the northern South China Sea,the upwelling,sediment resuspension,biological pump and PAHs input were significant factors for the vertical distribution of PAHs.Atmospheric PAHs input would lead to higher PAHs concentration in the surface water,while resuspension would cause higher PAHs contents in bottom water.Sinking of particulate matter such as zooplankton fecal pellets was related with high PAHs value in the open ocean upper 200 m.The study also carried for source identification by using some compound ratio in that area.The PAHs sources in the waters of the Pearl river delta estuary and northern South China Sea were analyzed by the ratio of Phennanthrene/Anthracene(Phen/Ant),Fluorine/Pyrene(Fluo/Pyr),Ant/(Ant+Phen)along with Flu/(Flu+Pyr).Those ratio suggested that PAHs in the SCS were mainly originated from the input of combustion sources,and PAHs were originated from pyrolytic source as well as some are petrogenic source of origin.From this study we can believe that the source of PAHs in northern SCS was originated for the most part from the input of Pearl River,which was mainly influenced by the development of the Pearl River Delta Economic Zone.