Long-time respiration of contaminated soil samples during laboratory storage under different conditions

Soil samples have to be stored during transportation and investigation in the laboratory if they are not analyzed directly at the site. Existing standards and investigations give no recommendations on handling and storage of soil materials for (eco-)toxicological investigations. The objective of this investigation was to determine if microbial turnovers and losses of volatile organic compounds mainly cause storage-dependent changes in soil samples. Furthermore, recommendations are given for storage of soil reserve samples for toxicological investigations. During 18 months of storage, the microbial respiration of six highly contaminated soil samples was determined. Physicochemical characteristics, such as contaminant and nutrient content, were analyzed before and after storage. From the investigations it can be concluded that the oxygen consumption depends on the storage temperature, organic matter content, nutrient content, and total content of toxic substances. Based on the results, a flow scheme was derived that could be a useful tool for a sequential approach to determine the storage capacity of contaminated soil samples and sites for toxicological investigations.