Accounting for the dissociating properties of organic chemicals in LCIA: an uncertainty analysis applied to micropollutants in the assessment of freshwater ecotoxicity

摘要

In life cycle impact assessment (LCIA) models, the sorption of the ionic fraction of dissociating organicchemicals is not adequately modeled because conventional non-polar partitioning models are applied.Therefore, high uncertainties are expected when modeling the mobility, as well as the bioavailability foruptake by exposed biota and degradation, of dissociating organic chemicals. Alternative regressions thataccount for the ionized fraction of a molecule to estimate fate parameters were applied to the USEtoxmodel. The most sensitive model parameters in the estimation of ecotoxicological characterization factors(CFs) of micropollutants were evaluated by Monte Carlo analysis in both the default USEtox model andthe alternative approach. Negligible differences of CFs values and 95% confidence limits between the twoapproaches were estimated for direct emissions to the freshwater compartment; however the defaultUSEtox model overestimates CFs and the 95% confidence limits of basic compounds up to three ordersand four orders of magnitude, respectively, relatively to the alternative approach for emissions to theagricultural soil compartment. For three emission scenarios, LCIA results show that the default USEtoxmodel overestimates freshwater ecotoxicity impacts for the emission scenarios to agricultural soil by oneorder of magnitude, and larger confidence limits were estimated, relatively to the alternative approach.