The proximity of aquifer systems to sources of contamination exposes them to severe environmental threats. Pollutants that leak from petrol stations, industrial areas and landfills eventually seep through the vadose zone to reach shallow groundwater, leading to groundwater contamination. One of these pollutants is Methyl Tertiary-Butyl Ether (MTBE), which is a polar organic compound that is volatile at room temperature. As a result of its high solubility compared to other gasoline additives, MTBE can cause serious environmental issues. The aims of this study were to characterize the extent of MTBE in groundwater and characterize natural attenuation in a Saudi Arabian MTBE and methanol manufacturing company.
The aims were achieved by analyzing monthly MTBE concentrations (to observe the seasonal changes of MTBE) and annual MTBE concentrations (to observe long-term changes) in 5 out of 18. Groundwater samples were collected, and in each year the MTBE, Total organic carbon (TOC) and Electrical conductivity (EC) concentrations were recorded. Because of inconsistency in the data, the results for the monthly data were from 2007 to 2010, and from 2007 to 2012 for the annual data. The results indicated a positive relationship between MTBE and TOC, and as a result TOC can be used to monitor and indicate the presence of MTBE. There was plume growth in 2 of the 5 wells (well 4 and well 14) with well 4 recording the highest MTBE concentration in all years. The reason for the high concentration might be because of spillages during truck loading. The other 3 wells showed signs of natural attenuation. Results from seasonal data suggested that temperature influences MTBE concentrations and therefore the rate of natural attenuation. There are many methods to remediate MTBE and each of them is site specific, but bioremediation was recommended for this site due to its cost-effectiveness.