Field studies of creosote contamination

Since very little is known about actual concentrations of aromatic heterocyclic NSO-sompounds and their metabolites in contaminated groundwater, characterization is carried out at several field sites. In addition to the organic analysis, the redox state and the number of microorganisms is determined. Toxicity tests are also used to detect any toxic pollutants which have not been detected by the chemical analysis.
Although the concentrations of phenolics and mono- and polyaromatic hydrocarbons are commonly measured at creosote sites, the variability og the concentrations versus distance from the source, the giological protection level, the redox state, etc. is poorly known. Statistical analysis of field data is therefore done based on information from field investigations made by consultant engineering firms.
A field site investigation at a coal-gassification plant in England including carefull analysis for contaminants in the groundwater from the sandstone aquifer revealed strong contamination with ammonia from the process wash-water, whereas the content of organic coal-tar compounds in the groundwater was insignigicant in spite of the presence of free phase coal-tar in the unsaturated zone and a high content of phenolic coal-tar compounds in the raw wash-water. Laboratory scale biodegradation studies have been carried out to obtain knowledge of the degradation potential for organic coal-tar compounds and of the competition between microorganisms degrading organic coal-tar compounds and ammonia. The research has demonstrated that the natural attenuation is very efficient and phenol, the cresols, and the xylanols are effectively degraded in the subsurface, even under mixed denitrifying and ironreducing conditions.