Fate and behaviour of pharmaceutical residues in soils

in the frame of two research prejects, fate and behaviour of human and veterinary pharmaceutical residues in soils were investigated on the basis of sophisticated laboratory test systems. Target compounds were diclofenac, ibuprofen, ketoprofen, diazepam, paracetamol and sulfadiazine which were applied directly as C-14-labelled radiotracers or as defined aged residues in test sludge or test slurry. Soils under study were a clayey silt and a silty sand. Mobility in soils was tested by the determination of K-d values. In these equilibrium batch experiments, only ketoprofen (K-d: 2) was identified as a potential leacher. Otherwise, the impact of the test sludge application led to an enhanced mobility of diclofenac and diazepam, while mobility of ibuprofen and ketoprofen was reduced. Testing on degradability in soil was focused on microbial, chemical and photo-induced processes. Therefore, microbially active and inactive soil samples were incubated in the dark and under irradiation. First results showed that the metabolic fate of diclofenac is predominated by the formation of non-extractable residues in microbially active soils. Photo-induced impacts on degradation were of subordinate relevance in soils. Stability tests in bovine slurry revealed the persistence of sulfadiazine which showed a significant tendency of forming non-extractable residues in soil.