Anticipating Nationwide Risks to Drinking Water: Predicting Local Scale Contamination of Community Supply Wells by Gasoline Additives
نویسندگان
چکیده
Only ten years after the increased addition of methyl-tert-butylether (MTBE) to U.S. gasolines, nationwide MTBE contamination of thousands of drinking water supply wells has been widely documented, reflecting enormous environmental and economic costs. Due to its abundance in gasoline, high aqueous solubility, and slow degradation rate in aquifers, MTBE has migrated in significant quantities from subsurface gasoline spills to a substantial number of community and private drinking water wells in a short period of time. For the purposes of this project, it was hypothesized that the tendency for gasoline additives to contaminate subsurface drinking water resources could be accurately predicted a priori using a generalized transport model. A screening method was developed to predict both the migration times of gasoline constituents from a leaking underground fuel tank (LUFF) to a community drinking water supply well and expected contaminant levels in the well. A review of literature revealed that U.S. municipal drinking water supplies are typically found in shallow sand and gravel aquifers. A subsurface transport model was parameterized based on the proximity of community supply wells to LUFTs (1000 in); probable characteristics of sand and gravel aquifers; typical pumping rates of community supply wells (80 to 400 gal/min); and reasonable gasoline spill volumes from LUFTs (100 to 1000 gal). The transport model was tailored to individual solutes based on their estimated abundances in gasoline, gasoline-water partition coefficients (Kgw), and estimated organic matter-water partition coefficients (Kom). Transport calculations were conducted for 17 polar and four nonpolar compounds currently proposed for or found in contemporary U.S. gasolines, including MTBE, ethanol, and methanol. Subsurface degradation processes were not considered. The transport model predicted MTBE concentrations of 40 to 500 ppb in municipal wells, which compared favorably with observed well concentrations at a significant proportion of sites in the U.S. The transport model therefore captured the order of magnitude of observed MTBE contamination of municipal wells without any use of adjustable or "fitted" parameters. Subsurface transport calculations of gasoline constituents required prior knowledge or estimation of their gasoline-water partition coefficient and organic matterwater partition coefficients. In anticipation of the need to conduct transport calculations for novel or previously unstudied compounds, a review of methods for calculating or predicting solute partition coefficients in gasoline-water, organic matter-water, and octanol-water systems was conducted. Additionally, a new linear solvation energy relationship (LSER) was developed for estimating gasoline-water partition coefficients of organic compounds, having an estimated standard error of 0.22 log Kgw units. Thesis Supervisor: Dr. Philip M. Gschwend Title: Professor of Civil and Environmental Engineering
منابع مشابه
A physical-chemical screening model for anticipating widespread contamination of community water supply wells by gasoline constituents.
Continuing modifications of fuels like gasoline should include evaluations of the proposed constituents for their potential to damage environmental resources such as subsurface water supplies. Consequently, we developed a screening model to estimate well water concentrations and transport times for gasoline components migrating from underground fuel tank (UFT) releases to typical at-risk commun...
متن کاملGAO-02-753T ENVIRONMENTAL PROTECTION: MTBE from Underground Tanks
I am pleased to be here today to discuss the increasing concern that our nations waters are becoming contaminated with methyl tertiary butyl ether (MTBE). About a third of the states, in certain areas, use gasoline that contains MTBE to help them limit air pollution because it burns cleaner. However, the substance could also pose risks to human health, especially as a contaminant in drinking wa...
متن کاملFate of gasoline oxygenates in conventional and multilevel wells of a contaminated groundwater table in Düsseldorf, Germany.
In a gasoline-contaminated site in Düsseldorf, Germany a two-year monitoring program was carried out to determine the presence, behavior, and fate of 12 gasoline additives in a total of 96 samples from 14 groundwater wells. The origin of contamination was suspected to be a gasoline spill at a gas station. Target compounds were methyl-tert-butyl ether (MTBE), its main degradation products, tert-...
متن کاملGroundwater pollution assessment in urban areas of Qom City
Nowadays, it is vital to pay attention more seriously to the urban environmental risks because of its effects on citizens' lives. One of these problems is groundwater pollution which threatens much valuable water resources. Drinking water in Qom City is provided from different resources, such as watersheds and water wells which are located within the city. Although there is a shortage of water ...
متن کاملEvaluation of corrosion and scaling potential of drinking water supply sources of Marivan villages, Iran
Corrosion and scaling in drinking water sources can lead to economic and health damages. These processes produce by-products in distribution systems, reduce chemical water quality, and are the cause of health issues among consumers. The aim of this study was to evaluate the corrosion and scaling potential of water supply sources of Marivan villages, Iran. In total, 106 water samples were collec...
متن کامل