Groundwater contamination with volatile organic compounds in urban and industrial areas: analysis of co-occurrence and land use effects

Abstract

Chlorinated solvents and trihalomethanes were the most frequently detected volatile organic compound (VOC) groups in groundwater in two metropolitan cities and three industrial complexes in Korea. Groundwater contamination with carbon tetrachloride and chloroform was noticeable in the industrial complexes, while MTBE was frequently detected only in metropolitan cities. In particular, groundwater was severely contaminated with chlorinated solvents and their dechlorination intermediates, including cis-1,2-DCE from TCE and 1,1-DCE from 1,1,1-TCA. Their co-occurrences were analyzed based on detection frequencies, rates of exceeding the water quality criteria, and a correlation matrix. Meanwhile, frequently co-occurring VOCs and VOC concentrations exceeding the water quality criteria were detected in only a few samples, which demonstrates the effects of land use due to the application of various types of VOCs. Thus, the effects of local land use were investigated by categorizing groundwater samples based on land use at the sampling locations; the effects of regional land use were assessed using factor analysis with administrative district statistics. The assessment results showed that public garages at the sampling locations were correlated with groundwater contamination. The detection of MTBE was correlated with vehicle use, while the detection of both toluene and chloroform was correlated with manufacturing and sewage collection and disposal systems; PCE was correlated with hazardous wastes. The contribution of this work is that the co-occurrence of some VOCs and persistent dechlorination intermediates was analyzed using a correlation matrix. Local and regional land uses were separately defined; their impacts on groundwater quality were assessed. Furthermore, a factor analysis included anthropogenic variables and VOC detection rates to better define latent variables.