Aquivalence revisited - New model formulation and application to assess environmental fate of ionic pharmaceuticals in Hamilton Harbour, Lake Ontario

► Fugacity-type models are widely used but are inappropriate for non-volatile compounds. ► “Aquivalence” is an alternative to fugacity for modeling non-volatile chemicals. ► An aquivalence model is presented to include differing fates of interconverting species. ► Model is applied to pharmaceuticals ibuprofen, gemfibrozil, naproxen, triclosan. ► The model estimated that half-lives in water ranged from 2-147 d for the compounds.