This paper studied the content of organic matter and stable carbon isotope composition(?13C)of suspended particulate organic matter in water column and sediment organic matter in sediment cores,according to the spatial and temporal distribution characteristic,we got these findings:1.?13CPOC in the study area ranged from-26.2 to-19.2‰,averaged-23.4±1.3‰,and decreased with the increasing depth and distance from the coast.The ?13C indicating a mainly marine source organic matter.2.In the euphotic zone,?13CPOC had positive correlation with POC concentration and Ch1 a concentration,indicating the distritution of ?13CPOC was to a great extent controlled by phytoplankton primary production,and then we estimated the phytoplankton photosynthesis fractionation factor to be 16.4‰.3.The ?13C of sediment organic matter in the study area ranged from-21.9 to-20.5‰ in the recent 100 years,and showed obviously increasing trend in the recent 60 years.Biogenic silica flux and sediment diatom abundance also increased since 1950?1960,indicating an increasing primary production.We speculated the main reason of increasing primary production was the increasing atmospheric nitrogen deposition.The intensifying coastal erosion bringing more nutrients probably also made contribution to the increasing primary production,but its influence remained to be clarified. |