Abstract

Contamination of groundwater by volatile organic compouds (VOCs) was investigated for 168 grounwater wells in Ulsan area to study the natural attenuation of organic compounds in the aquifers. As groundwater contamination by VOCs is closely related to land use, 168 groundwater samples were classified into 4 different groups:agricultural, forestry, industrial, and residential & business. From analysis 65 out of 168 groundwater samples contained more than one VOC. Analysis of samples were performed for 36 halogenated airphatic hydrocarbons and 25 petroleum hydrocarbons set up by NAWQA of US geological survey. Twelve petroleum hydrocarbons were detected in 26 groundwater wells, but their concentrations were less than 1.5g/L except for MTBE. Twenty three chlorinated aliphatic hydrocarbons, composed of 11 methans and 6 ethenes, were detected in 63 groundwater samples. The range of methanes concentration was ND~330 g/L, ethanes ND~84 g/L, and PCE and their derivatives ND~62 g/L. As the study area was comprised of the aerobic. denitrification zones and Fe⁺³ redox condition, most of petroleum hydrocarbons were degraded well, while halogenated hydrocarbons were slowly biodegraded.

Keywords groundwater, land use, VOCs, biodegradation