Risk assessment of organic contamination in shallow groundwater around a leaching landfill site in Kaifeng, China

Subsoil and shallow groundwater surrounding the Luhuagang landfill site (LLS) have been contaminated by leachate that contains organic chemicals in Kaifeng, China. The composition and spatial distribution of organic pollutants in shallow groundwater near the LLS was investigated by analyzing 28 shallow groundwater samples that were collected in May 2010. The ambient severity method was used to evaluate the potential risks to human health and the environment from organic contaminants in the shallow groundwater. Volatile and semi-volatile organic compounds in the groundwater samples were screened using full-scan gas chromatography–mass spectrometry, and seven organic compounds were detected. 1,2-dichlorobenzene (1,2-DB), 1,2,3-trichlorobenzene (1,2,3-TCB), and 1,2,4-trichlorobenzene (1,2,4-TCB) were detected in all groundwater samples, while naphthalene was detected in 13 samples (detection rate 46.4 %). The highest 1,2-DB concentration was 277.45 μg/L, and all 1,2-DB concentrations were below the Chinese drinking water quality threshold of 1000 μg/L. Concentrations of 1,2,4-TCB, 1,2,3-TCB and naphthalene exceeded the Chinese drinking water quality limit in 6 samples, 3 samples, and 1 sample, respectively. 1,2-DB, 1,2,3-TCB, and 1,2,4-TCB have already formed a small contamination plume close to the landfill; however, their concentrations decrease in a northwest/southeast direction. Shallow groundwater around the LLS is severely contaminated by 1,2,4-TCB and 1,2,3-TCB, mainly as a result of either leachate from the landfill or refuse from the village. There are greater potential risks to human health and the environment from 1,2,4-TCB than from 1,2-DB and 1,2,3-TCB. These results will help support management of groundwater resources in this area.