지하유류저장시설에 의한 지하수의 탄화수소 오염

Abstract

Underground oil storage cavern uses groundwater as a barrier for oil and oil-derived vapor leakage. And there exists concern for groundwater contamination. This study investigated status of polycyclic aromatic hydrocarbons (PAHs) contamination and tried to find out possible input sources of PAHs into the underground environment. Groundwater samples were taken from groundwater level monitoring wells and 16 EPA priority PAHs and alkylated PAHs were analyzed. Sum of 16 PAHs concentration ranged 0.04 ~ 7.29 ug/L with a mean of 0.63 ug/L, 0.05 ~ 0.37 ng/L with a mean of 0.16 ug/L, 0.01 ~ 1.75 ug/L with a mean of 0.68 ug/L in the groundwater samples from monitoring wells in the first, second and third cavern system, respectively. Though the third cavern is being built and does not contain any crude oil, PAHs levels in the third cavern are comparable with the results of the first cavern. Sum of alkylated PAHs (C1 ~ C4 naphthalene, C1 ~ C4 phenanthrene, C1 ~ C3 dibenzothiophene) ranged 0.04 ~ 10.6 ug/L with a mean of 1.21 ug/L, 0.03 ~ 2.9 ug/L with a mean of 0.76 ug/L, 1.26 ~ 99.8 ug/L with a mean of 20.1 ug/L in the first, second and third cavern system, respectively. Profiles of 24 PAHs provide first clue for the input sources. The first cavern was dominated by low molecular weight PAHs, while the third cavern by middle and high molecular weight PAHs and the second cavern showed mixed pattern of the first and the third. The difference between the first and other caverns were more distinct in alkyl homologue series pattern. PAHs chromatogram pattern of groundwater in the first storage cavern was compared with those of Dubai crude, major stockpiling oil, and untreated wastewater which contact crude oils. Due to the cracks and other structural defects, small amounts of water soluble fractions were supposed to be diffused into the surrounding underground environment. In case of the second and third cavern, drilling process unintentionally introduced cutting oils to groundwat