抄録
The carbon isotopic compositions (δ13C) of suspended particulate and sedimentary organic matters (POM and SOM, respectively) collected in August and September 2000 at Hakata Bay and its surrounding watershed were measured to clarify the dynamics of organic carbon. The δ13C values of POM at the watershed were typical values of C3 plants with an average of -26.6±1.6‰ (n=17). There was little difference between the δ13C values of POM and SOM from the watershed. On the other hand, the δ13C values of POM in the central area of the Bay ranged from -17.4‰ to -16.3‰ ad were considerably higher than those of general phytoplankton (-20‰). This might be attributed to the limitation of the rate of CO2 diffusion into the cells because of the abrupt growth of phytoplankton in summer. The δ13C values of SOM at the Bay ranged from -21.0‰ to -20.1‰ and did not reflect those of POM. The fraction of terrestrial organic carbon in the SOM of the Bay were estimated using the δ13C values of two end members of terrestrial and marine organic matters.
