A stepwise procedure for assessment of the microbial respiratory activity of soil samples contaminated with organic compounds

Soil respiration measurements are used frequently for the characterization of soil samples. Identical methods are used for the ecotoxicological charac terization of contaminated soil samples as well as for quantification of th e active microbial biomass in agriculturally used soils. In this study four soil samples contaminated with large amounts of volatile organic compounds , polyaromatic hydrocarbons, or nitroaromatic compounds are characterized a fter stepwise addition of carbon, nitrogen, and phosphorus. The respiration kinetics are assessed over a period of 5 days. By means of qualitative eva luation of the results, it is demonstrated that this stepwise addition allo ws one to distinguish between growth-promoting effects of biodegradable org anic compounds on the one hand and the toxic influence of these compounds o n the other hand. Finally it is stated that a comprehensive ecotoxicologica l characterization cannot be performed routinely using only one or several parameters of respiration curves. There is need for further research and va lidation if soil respiration measurements are to be performed quantitativel y in the future, (C) 2000 Academic Press.