A simple model to predict compound loss processes in aquatic ecotoxicological tests : calculated and measured Triphenyltin levels in water and biota

A new simple model, based on the fugacity approach, has been developed to provide a predictive tool useful in the planning phase of aquatic ecotoxicological tests for assessing the actual daily concentrations in water. In our experiments, three nominal concentrations (100, 225, and 500 ng L -1) of triphenyltin chloride (TPT-Cl) were employed for an exposure period of 28 days in 50 L aquaria with the echinoderm Antedon mediterranea as test species. Extracts from water and biota samples collected during the experiments were analysed by GC-MS/MS, after the extraction/derivatization step. An indicative mean BCF (V/V) on a fresh weight base of 3.5 × 10 4 ± 0.8 × 104 (standard deviation) could be calculated for A. mediterranea. Three different compartments (air, water and biota) and main advection/reaction processes are taken into account in the model design, and the comparison between predicted and measured concentrations in both water and biota for the three concentrations tested confirmed that the assumptions given in our model application were valid and useful for further applications.