The sediment accumulation rates and dating studies in the aquatic environments have significant importance on understanding of the relationship between human activities and aquatic medium. In this study, sediment accumulation rates and Pb-210 fluxes were calculated by using excess Pb-210 profile distributions and C.R.S. model together, and the dating of each layer was determined in three sediment cores where were sampled from east side of Van Lake. 210Pb activity was obtained from activities which was measured with alpha spectroscopy of the Po-210. Average sediment accumulation rates in the cores were found as 0.031 +/- 0.011, 0.046 +/- 0.021 and 0.077 +/- 0.051 g.cm(-2).y(-1). It was observed that sediment accumulation rates were found as significantly high levels in the areas where had high human activities and transportations from agricultural areas via stream erosion. In addition to, it was investigated the distributions of the Cs-137 isotop which is a fission product along two sediment core, and it was determined the concentrations of Cs-137 at certain levels which were spreaded to area because of the nuclear weapon tests conducted in 1954-1963 and Chernobyl nuclear plant accident in 1986. According to the general trend of Cs-137 distribution, it has pointed out that entry of Cs-137 to the lake from the environment continuous already now Furthermore, heavy metal concentrations (Cd, Cr, Cu, Pb) which was related to industrial, urban, agricultural wastes and geology of the basin were evaluated.