Preliminary results from a field experiment investigating the fate of some creosote components in a natural aquifer

Creosote, a distillation product of coal tar, is made up of an extremely complex mixture of phenols and polycyclic aromatic compounds (PAC) which include polycyclic aromatic hydrocarbons (PAH) and nitrogen, sulphur and oxygen (NSO) containing heterocyclics. It is considered to be an environmental hazard. This report presents some preliminary results from a large field experiment that is evaluating the mobility, persistence and fate in groundwater of compounds present in coal tar creosote. This involved setting up a long-term field experiment where a limited plume of contaminated ground water was created by placing creosote into an extremely well characterized sand aquifer. The original creosote was dominated by PAH components with minor amounts of NSO containing PAC. The concentration of the dominant nitrogen heterocyclic (quinoline) was only 10% of the abundance of the major PAH components (naphthalene and phenanthrene). Analysis of groundwater samples collected 278 days after the emplacement of the creosote shows that with increasing distance from the source the concentration of naphthalene is reduced while that of quinoline increases, eventually becoming dominant. A similar trend was also observed for samples collected after 471 days and this can be related to the relative aqueous solubilities and mobility of the two compounds. Also observed in the outermost 471 day samples was the presence of quinolinone which is believed to be an aerobic metabolite of quinoline. Strategies for the final part of the project which involve cleaning up the Borden experimental site are briefly discussed in light of these results.