PRIMING EFFECT OF SUBSTRATE ADDITION IN SOIL-BASED BIODEGRADATION TESTS

To test whether substrate addition changes background CO2 evolution of soil, we measured both (CO2)-C-14 and net CO2 evolution from various test compounds. Glucose caused a priming effect, defined as substrate- stimulated soil organic matter mineralization, Formate, benzoate, n-he xadecane, and his (2-ethylhexyl)phthalate caused no priming, and pheno l caused only a transient one, The priming effect of glucose appears t o be unusual and does not require a general rejection of net CO2 evolu tion measurements in biodegradability testing.