Sulfamethazine and flubendazole in seepage water after the sprinkling of manured areas Original Research Article

Pharmaceuticals are widely used in modern livestock production and can reach the environment via the application of manure containing excreted drugs. Limited information is available on the transport and fate of veterinary medicines applied to soils. Therefore, we assessed the potential for the sulphonamide antibiotic sulfamethazine (SMT) and the antiparasitic drug flubendazole (FLUB) including their metabolites to move from agricultural manure to drainage waters at 1 m depth. A comparison was made of losses from sites under different land use (grassland versus arable cropping) as well as losses from neighbouring plots under the same land use. Liquid manure from pigs treated with SMT and FLUB was spread on 10 × 30 m2 plots (750 l per plot). SMT concentration in slurry ranged from 600 to 1700 μg l−1 (metabolite acetyl-SMT 280–1700 μg l−1) and FLUB concentration ranging from 25 to 56 μg l−1 (metabolite amino-FLUB 32-110 μg l−1, hydroxy-FLUB 19–38 μg l−1). About 1 h after application heavy rainfall (50 mm in 2.5 h) was simulated by sprinkler irrigation. Drainage flow started within 1 h after the commencement of sprinkling. SMT and FLUB concentrations in leachate reached values of up to 16 μg l−1 and 0.3 μg l−1, respectively. Loss rates (relative to the applied amounts) from the neighbouring sites under arable cropping ranged from 2.8% to 5.4% for SMT and 0.8% to 3.1% for FLUB (including metabolites). On the permanent grassland plot, due to its multitude of macropores, loss rates reached values up to 10% for SMT and 16% for FLUB (including metabolites). These results demonstrate that the variability in leaching of veterinary drugs may be high even between large neighbouring plots, depending on site heterogeneity and land use.