Spreading of MTBE and Chlorinated Hydrocarbons in Groundwater: Comparison of Groundwater Transport and Plume Dimensions

Abstract

Based on a physical-chemical-biological database, the behavior of MTBE and CAH (chlorinated aliphatic hydrocarbons) in the subsoil is described and compared. In contrast to MTBE, CAH can form independent phase bodies that can infiltrate deep into aquifers. Due to its striking higher solubility, MTBE spreads much faster in groundwater. The longest CAH plume recorded in literature so far amounts to 10 000 km. The longest reported MTBE plume reaches 1 900 m. Interpreting the available worldwide data, spreading of MTBE groundwater contaminations leads plume lengths that fall rather into the category of the BTEX as into the class of CAH. A substantial reason for comparison with the lower CAH plume expansions might consist of the fact that MTBE plumes—due to high water solubility and thereby the connected fast development of the MTBE source transfer—progress comparatively fast into the stable and/or regressive status of the plume development. Beyond this, MTBE infiltrates as subordinated portion of gasolines (predominantly 1–3 wt % in regular grade fuel and/or premium fuel), in comparatively low quantities into the subsoil, so that these comparatively low quantities do not possess large source strengths over longer periods. Only spills with very large gasoline quantities may longer MTBE plumes develop under certain conditions.