A methodology for modelling the contamination of moving organisms in water bodies with spatial and time dependent pollution levels

The contamination of non-stationary fishes living in large water bodies may depends on the migration through areas characterised by heterogeneous pollution levels. A methodology to link biota movement models with biological uptake models for predicting the levels of concentration of contaminant substances in migrating aquatic species is discussed. Three cases of possible biota movement are analysed: (a) floating organisms transported by water currents; (b) stationary organisms such as rooted plants; and (c) swimming organisms. The methodology allows the development of models for predicting the contamination levels of aquatic species by accounting for their migratory habits. Examples of applications to random walk and translation movements of fish are presented. The effects of the mobility of organisms on the predicted contamination levels are discussed. An application to the contamination of fishes in river Yenisey is described to demonstrate that the methodology supplies results coherent with experimental evidences.