Abstract
Groundwater pollution with tetrachloroethylene (or perchloroethylene, PCE) has been found in several sites in Kanazawa City from 1982. In this study, the concentrations of PCE and its degradation products (trichloroethylene (TCE), and cis-1,2-dichlorothylene (cis-DCE) in well water samples in two contaminated areas in Kanazawa City were analyzed. One is area T located in the center of the city, and another is area I located in the southwest of the city. Groundwater was sampled at 19 existing wells at area T and at 5 existing wells at area I. Using the result of the analysis of the total molar concentration of the three compounds and the degradation ratio calculated from the molar fraction of the products (TCE+cis-DCE), contaminations were evaluated in two areas. In area T, 1) although the polluted area increased until 2000, it was decreased in 2003. This tendency was influenced by the relationship between the total concentration of VOCs and the distance from the tentative contamination source. 2) The decrease in the area polluted with PCE described above might be due to pumping of the polluted groundwater from August 2000. 3) The increase in the degradation ratio of PCE suggested that the nonaqueous PCE liquid phase had already disappeared at the contamination source. In the area I, 4) the decrease in the PCE concentration and the increase in the PCE degradation ratio suggested that the original liquid PCE did not exist at the contamination source. 5) The distribution of the degradation ratio of PCE suggested that the contamination source existed in the east-southeast direction of this group of research wells.
