Abstract
First of all, 1,1,1-trichloroethane (MCF), tetrachloroethylene (PCE) and trichloroethylene (TCE) concentrations of 51 well waters in Nagaoka City of Japan were measured in 1989. Maximum, minimum and average concentrations of MCF were 20.0, below 0.1 and 1.8μg·l-1. Those for PCE were 2.27, below 0.02 and 1.26μg·l-1, and for TCE were 2.29, below 0.01 and 1.17, respectively. Many wells at Sekihara area, which is in the west of the city, were contaminated exclusively with MCF.
Next, detailed study of the groundwater quality at Sekihara area was carried out both in 1989 and 1991. The number of the wells was 17 in 1989 and 24 in 1991. The maximum, minimum and average concentrations of MCF were 18.6, below 0.1 and 2.9 in 1989, and 173.4, 0.1 and 9.2 in 1991. No decrease in the MCF concentration between 1989 and 1991 was observed at all. The source of the MCF was suspected to be an electric factory in this area.
Last, halogenated organic chemicals in the wastewater discharged from the factory were analyzed in two drain ditches. Sampling was carried out at the interval of 3 hours for a day. Considerable amount of MCF and total organic halogens (TOX) was detected.The TOX amount in a ditch, of which water is originally coming from groundwater, was 9.3g in a day and in another one for rainwater drain was 144g during the run-off of 6 hours' rainfall. The ratio of MCF to TOX was very small in the both case.
