Reduction of performance time for microbial respiration in the context of on-site analysis

The microbial respiration activity in soil can be used as an indicator for the presence of toxic substances and easily degradable carbon sources. If standardized methods are applied, the preparation of samples (sieving, determination of maximum water holding capacity, determination and adjustment of water content) and the subsequent measurement of respiration requires about one week. In the context of on-site analysis it is important to obtain results quickly and with minimal effort. This especially applies to the monitoring of remediation processes. We therefore tried to improve the preparation and measurement of samples to reduce the time needed for respirometric determinations required for on-site analyses. Three measuring devices suitable t o determine the respiration activity were applied, which differed in their grade of automation and principle of measurement . For all investigations several soils with different physiochemical properties and differing microbial activity were used. The results demonstrate that the application of an adequately sensitive but robust measuring device allows to obtain sufficiently precise data for on-site analyses in not more than two days. This even applies to soils with a very low microbial respiration activity.