Abstract: A box model based on freshwater fraction method was used to estimate the freshwater residence time (FRT) in the Bohai Sea. The data used in this study
 include the evaporation, precipitation, river discharge, and salinity in the Bohai Sea and its surrounding region, the Yellow Sea. Sensitivity analysis was con
ducted to quantitatively assess the effects of freshwater flux on the water exchange between Bohai Sea and Yellow Sea. The results indicated that the interannua
l variability in the salinity in Bohai Sea was mainly caused by the freshwater supply from Yellow River, the largest river around Bohai Sea. During the periods
of 1965-1980, 1986-1992, 1994, and 1996, themean FRT in Bohai Sea was 2.6 years, and had a weak upward trend. In the 1960s, the FRT was 3.0 years; but in the 1980s, it increased to 4.6 years, with an increment of about 50%. The FRT decreased with increasing freshwater supply, and in general, was more sensitive to river discharge than to net precipitation flux (the difference between precipitation and evaporation), suggesting that sufficient attention should be paid on the formulation of environmental policy on the regulation of Yellow River water resources.

Key words: Momoge Lake, Paleo-plant community, Pollen record, Paleo-environment evolution