Transport and Fate of Pharmaceuticals in the Environment

With sustainable agricultural practices increasingly incorporating waste materials as soil amendments and fertilizers, concerns about potential environmental and ecological effects of pharmaceutical exposure have been raised. In order to more fully understand the effects of pharmaceutical contamination in the environment, research on human and veterinary pharmaceutical transport, sorption to soil/soil constituents as well as uptake into plants is needed.;The application of biochar, produced via pyrolysis of waste biomass, is a potential strategy to minimize the mobility and phytoaccumulation of organic pharmaceuticals present in biosolids. Sorption of pharmaceuticals (antibiotic, ciprofloxacin; antibacterial agents, triclocarban, triclosan), and heavy metals (Cu, Cd, Ni, Pb) to biochar (wood, walnut shell), kaolinite, activated carbon, and biochar/biosolid/soil mixtures was examined. All contaminants exhibited significant sorption to activated carbon and walnut shell biochar, while kaolinite and wood biochar had significantly lower sorption. The differences in biochar sorption demonstrate the need to consider biochar source materials, when using it as a soil amendment with the purpose of sequestering contaminants.;Greenhouse experiments were conducted to determine the effect of biochar amendments on the uptake of ciprofloxacin, triclocarban and triclosan in lettuce and carrot plants grown in biosolid amended soil. The effect of biochar and biosolid amended soil on lettuce and carrot growth and vigor was also determined. The addition of biochar to biosolid amended soil (10 t ha-1) reduced the concentration of ciprofloxacin and triclocarban in lettuce shoots by 75 and 45 %, respectively, and triclosan in carrot roots by 75 %. Biochar addition to biosolid amended soil did not negatively affect plant growth.;Limited transport of veterinary pharmaceuticals chlortetracycline, oxytetracycline, and ivermectin from manure was demonstrated in packed soil boxes and surface runoff plot experiments. Less than 4.2 % of the applied pharmaceuticals were detected in surface runoff from the soil boxes and less than 0.1 % of applied pharmaceuticals were detected in runoff water from the plots, attributed to their high sorption to manure and soil (Kd range: 280-63020 L kg -1). Up to 99 % of applied pharmaceuticals were retained in the dried manure or in the upper 5 cm of soil directly beneath the manure deposits in the runoff plots. Under the conditions examined, the risk of significant chlortetracycline, oxytetracycline and ivermectin transport to surface water from cattle manure on irrigated pasture was shown to be low.