Isotopic composition and environmental behavior of dissolved inorganic carbon in brackish surface water

In the present study,δ13C of the Dissolved Inorganic Carbon(DIC) in brackish surface waters of Tianjin were measured to investigate its potential sources and cycling mechanism.The results show that δ13C values of DIC in the Tianjin surface waters range from 0.27‰ to –14.9‰,displaying a wide range comparing to most of other surface water of the world.The concentrations of DIC also show very high values that range from 155 mg/L to 1000 mg/L,mainly from 200 mg/l to 500 mg/L.Those δ13C values and concentrations of DIC indicated that atmospheric CO2 and organic carbon decomposition were two major sources of DIC for the Tianjin surface waters.