Occurrence of 13 veterinary drugs in animal manure-amended soils in Eastern China

The occurrence of 13 veterinary drugs were studied in soil fertilized with animal manures in Eastern China. The 69 soil samples were obtained from twenty-three vegetable fields in 2009 and analysed for selected veterinary drugs by HPLC-MS/MS at soil depths of 0-20, 20-40 and 40-60 cm, and two additional samples were re-analysed from an earlier study from November 2011. Results showed that animal wastes, especially those from poultry farms, were one of pollution sources of veterinary drugs in soil. The detection frequency of veterinary drugs in soil was 83%, 91% and 87% in the three soil depths, respectively. The detection rates for the five classes of drugs in soils followed the rank order cyromazine > tetracyclines > sulfonamides > fluoroquinolones > florfenicol. Veterinary drugs were detected in soil layers at 20-40 and 40-60 cm depth to a greater extent than at 0-20 cm depth. The results of the same point in years 2009 and 2011 indicated that veterinary drugs accumulate easily and persist in the deeper soil. In addition, residue levels of veterinary drugs in soil were related to the animal species the manure was derived from. Overall, the predominance of tetracyclines in sampled soils underscored the need to regulate their veterinary use in order to improve the management and treatment of associated releases.