title: Natural attenuation of MTBE at two petroleum-hydrocarbon spill sites.
abstract: Methyl tert-butyl ether (MTBE) has been used as a gasoline additive to improve the combustion efficiency and to replace lead since 1978. Because it is widely used and it has been disposed inappropriately, MTBE has become a prevalent groundwater contaminant worldwide. In this study, two petroleum-hydrocarbon contaminated sites (Sites A and B) were selected to evaluate the occurrence and effectiveness of natural attenuation of MTBE at these two sites. Field investigation results indicate that the natural attenuation mechanisms of MTBE at both sites were occurring with the first-order attenuation rates of 0.0021 and 0.0048 1day(-1) at Sites A and B, respectively. Results also reveal that the intrinsic biodegradation pattern was the most important mechanism among the natural attenuation processes at both sites. Results from BIOSCREEN simulation suggest that biodegradation was responsible for 78 and 59% of MTBE mass reduction at Sites A and B, respectively. Investigation results show that MTBE plume at Site B could be effectively controlled via natural attenuation processes. However, MTBE plume at Site A has migrated to a farther downgradient area and passed the boundary line of the site. Thus, more active groundwater remedial technologies should be applied at Site A to protect the downgradient environment. Results from this study suggest that natural attenuation might be feasible to be used as a remedial option for the remediation of MTBE-contaminated site on the premise that (1) detailed site characterization has been conducted and (2) the occurrence and effectiveness of natural attenuation processes have been confirmed.
authors.affiliation: Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
authors.forename: K F
authors.initials: KF
authors.lastname: Chen
authors.forename: C M
authors.initials: CM
authors.lastname: Kao
authors.forename: J Y
authors.initials: JY
authors.lastname: Wang
authors.forename: T Y
authors.initials: TY
authors.lastname: Chen
authors.forename: C C
authors.initials: CC
authors.lastname: Chien
mesh_terms: D001673:Biodegradation, Environmental; D004785:Environmental Pollutants; D004787:Environmental Pollution / Q000517:prevention & control*; D006838:Hydrocarbons / Q000737:chemistry*; D008738:Methyl Ethers / Q000737:chemistry*; D008956:Models, Chemical; D009994:Osmolar Concentration; D010578:Petroleum; D013624:Taiwan
chemical_list: D004785:Environmental Pollutants; D006838:Hydrocarbons; D008738:Methyl Ethers; D010578:Petroleum; C043243:methyl tert-butyl ether