Testing contaminant mobility in soils and waste materials

Contaminant mobility in soils and waste materials is usually tested by stan dardized leaching procedures. In Germany, batch experiments are run for 24 h at a liquid/solid ratio of 10.1 (w/w). While the mobilities of metal(loid )s and hydrophilic organic compounds (e.g. phenols) can adequately be teste d by automatic titration stands, working at constant pH values (e.g. pH 4 o r 10), the mobility of hydrophobic organic chemicals like polycyclic aromat ic hydrocarbons (PAHs) or polychlorinated biphenyls (PCBs) is more difficul t to determine. Natural solubilizing agents have to be considered, when tes ting the mobility of hydrophobic organic chemicals. Several leaching experi ments utilizing natural and synthetic leaching solutions are presented. Exp erimental results show that sodium dodecyl sulfate (SDS) is a suitable refe rence leaching solution. The solubilizing potential of SDS is comparable to the one of the most potent natural leaching solutions (e.g. compost water) , and thus represents a worst case. Future leaching tests of the environmen tal mobility of hydrophobic contaminants should incorporate the solubilizin g effects of amphiphilic substances. (C) 1998 Elsevier Science B.V. All rig hts reserved.