Fate and behavior of organic compounds in an artificial saturated subsoil under controlled redox conditions: The sequential soil column system

A system was developed to investigate the fate and behavior of anthropogenic organic contaminants at concentrations present in polluted subsoils and aquifers. A sequential soil column system was constructed to simulate redox conditions from methanogenic, sulfate-reducing, denitrifying, to aerobic conditions which normally occur in a leachate pollution plume. This system allowed the simulation of subsurface pollution with a range of xenobiotics and the observation of the microbial response to this contamination. After an adaptation period of up to about 7 months, 2,4-dichlorophenol and 2-nitrophenol were eliminated and perchloroethene disappeared almost completely in the methanogenic column. Toluene was partially transformed under sulfate-reducing conditions, and nearly completely in the nitrate-reducing column. The same applied to naphthalene under denitrifying and aerobic conditions. Aerobically, a fraction of benzene was transformed, and 1,4-dichlorobenzene decreased to very low residual concentrations in one system. No significant transformation of 1,1-dichloroethene could be seen.