Extrapolating mineralization rates from the ready Co2 screening test to activated sludge, river water, and soil

The objective of this research was to derive empirical extrapolation factors by concurrently measuring mineralization rates of nine diverse chemicals in a Ready CO2 test (modified Sturm) and realistic 14C tests using activated sludge, river water, and sludge-amended soil while holding other variables constant. All nine chemicals were mineralized in the Ready test and each of the compartments, but no significant statistical relationships existed between biodegradation rates in the various tests. Mineralization rates in the Ready test were on average 8.1, 2.5, and 1.2 times lower than the rates in realistic activated sludge, river water, and soil tests, but variability in the scaling factors spanned up to 1.5 orders of magnitude. The scaling factors for extrapolating from ready CO2 data ranged from 1.7 to 19 for activated sludge, from 0.1 to 5.6 for river water, and from 0.3 to 2.8 for soil. Correlation analysis revealed that the scaling factors from the CO2 test to activated sludge and river water were related to the quantitative structure-activity relationship based solubility and log Kow estimates for the test chemicals.