Abstract
An analytical method of vinylchloride (VC) and chloroethane (CA), i. e., degradation products of tetrachloroethylene (PCE), trichloroethylene (TCE) and 1, 1, 1-trichloroethane (TCA) in groundwater, was studied using a headspace/gas chromatography mass spectrometry (HS/GC/MS)
In order to analyze VC and CA, the GC column oven was kept at an initial temperature of -20°C for 2min to separate VOC peak and methanol peak, then ramped at a rate of 10°C /min to 200°C. The mass spectra were measured in the mass range 35-200 amu to avoid background noise. VC and CA were detected in the groundwater contaminated by cis-1, 2-dichloroethylene (cis-1, 2-DCE) . VC was detected more frequently in shallower wells (6 samples) than in deeper wells (6 samples) .
In the case of soil core samples contaminated by PCE, concentration of PCE, TCE and cis-1, 2-DCE were higher in the clay layer and the silt layer than in the sand layer. PCE concentration in the upper clay layer was higher than in the lower silt layer, but cis-1, 2-DCE concentration was almost equal between the two layers. The behavior of cis-1, 2-DCE in soil was different from that of PCE.
The results suggested that cis-1, 2-DCE in the upper clay layer transfered easily to the lower silt layer than PCE, and that the biodegradation of PCE proceeded in subsurface soil including organic carbon.
