The environmental fate of butyl benzyl phthalate (BBP) was studied in two types of laboratory freshwater microcosms: (1) static single-dose ecocore microcosms designed to simulate fate processes in a lake and (2) renewal multiple-dose microcosms designed to simulate fate processes in a freshwater river. Both disturbed and undisturbed sediment cores were employed. BBP exposure concentrations ranged from 10 to 993 ppb.
Results indicated that BBP underwent rapid primary degradation in both microcosm designs with half-lives less than 2 days. Mineralization of BBP was measured in both systems by recovering 14C-CO2. The mineralization half-life is estimated to be 13 days. The data clearly indicated that the water transformation rate was rapid enough in both microcosm types to reduce sorption to sediments. Additionally, it was demonstrated that BBP was degraded when sorbed to sediments. Less than 0.2% of the total intact BBP was recovered from the sediments at the end of the experiments. BBP mass balance for both microcosm designs was 78% or higher. The use of complex microcosm studies in lieu of traditional biodegradation studies for obtaining chemical environmental fate data was discussed and it was concluded that microcosms can be an effective tool for evaluating chemical environmental fate, and environmental exposure, but are significantly more costly to use as a routine biodegradation screening test. A cost comparison for four types of biodegradation studies is provided.