Rapid method for assessing pollution-induced community tolerance in contaminated soil



Using the pollution-induced community tolerance (PICT) concept, this article presents a rapid method for detecting toxic effects of contaminated soil on soil microbial communities and for elucidating the causal relationship between exposure history and toxic effects in exposed microbial communities. The method is based on the use of multiwell plates (Biolog®) for producing concentration versus effect relationships for (maximally) 95 different microbial metabolic activities. For this, artificial exposure in the multiwell plate is established to the contaminant supposedly causing toxic effects in the field. The method was tested in a gradient of zinc-contaminated field plots by studying community tolerance to zinc. For most substrates the metabolic activities showed an increased community tolerance for zinc with increased zinc concentration in the field. Consequently, PICT has evolved after 2.5 years of zinc exposure under field conditions. The perspectives for future use of the PICT concept in combination with the multiwell technique for demonstrating ecotoxicological effects at contaminated sites is exemplified by the comparison of Dutch soil quality criteria for zinc with the collected data. This comparison showed that the evolution of microbial-PICT for zinc has occurred at environmental concentrations near the Dutch intervention value, a quality criterion linked to remediation urgency.