BackgroundThis project was aimed at investigations into the fate and transport of veterinary pharmaceuticals (VPs) in soil and water. There has been relatively little work done in this area, especially specific to Canadian conditions. More information is required to determine the extent to which VPs persist in agricultural soil and runoff, and what risks are posed by their presence.
Research ProgressManure from Quebec poultry farms feeding one of 3 coccidiostats (monensin, narasin and salinomycin) was applied to soil at 10 Mg/ha (~4.5 ton per acre). The soil was previously free of poultry manure for 10 years. Specially designed devices, known as lysimeteres, were used to track the movement of these VPs through the soil and into ground water. Rainfall was simulated to represent the 50-year maximum in the area over 3 months (July to September). Soil samples were collected from the surface and at three depths (0.1, 0.3, 0.5m), and leachate (water runoff) was collected 0.9m below the surface throughout the experiment. Monensin persisted at various soil depths for over 60 days. At the surface, it decreased from 16.1 mg/kg on day 0 to 1.54 mg/kg on day 60. At other depths, monensin levels initially increased, and then decreased. The pharmaceutical was detected at all four soil sampling depths from day 7 through day 60. A small amount of monensin was also observed in drainage waters from day 3 to day 15. At the soil surface, narasin levels declined from 11.08 mg/kg on day 0 to 0.036 mg/kg on day 30, while below the soil surface and in drainage water, it only persisted until day 15. Salinomycin at the soil surface, initially at 8.5 mg/kg dropped to 0.72 mg/kg by day 3, and was undetectable thereafter. While below the soil surface, salinomycin only remained detectable until day 7 it remained detectable in drainage water until day 60, where its concentration (1.56 mg/L) was greater than that of either monensin (0.34 mg/L) or narasin (0.32 mg/L). It appears that whereas monensin could persist in soil over a longer period, salinomycin is more mobile and may present a greater threat to water resources. Studies are also underway to investigate the effect of VP-manure on the half-life of commonly used herbicides. Initial results indicate that half-lives of three herbicides (atrazine, metolachlor, and metribuzin) increased with the presence of VPs in soil. One of the primary mechanisms of pesticide degradation in soil is microbial degradation and the presence of VPs in soil may be affecting microbial survival in soil. However, more work needs to be done in this area before any concrete conclusions can be drawn.
Future WorkIt took longer than expected to develop and refine techniques for VP extraction. The objective of testing the project’s data against a mathematical model was therefore not achieved in the expected timeframe. This work is, however, currently underway. It is hoped that information gathered during ongoing work will lead to Best Management Practices designed to mitigate any negative effects of VPs in the environment.
Funding$114,000 (CPRC $38,000, NSERC/AAFC $76,000)
Kim, S.-H., M. Fan, S. O. Prasher, R.M. Patel, and S.A. Hussain. 2011. Fate and transport of atrazine in a sandy soil in the presence of antibiotics in poultry manures. Agricultural Water Management, Vol. 98(2011): 653-660.
Ramaswamy. R., S.O. Prasher, R. Kaur, and R.M. Patel. 2011. Effect of soil pH on sorption of salinomycin in clay and sandy soils. African Journal of Environmental Science and Technology, Vol. 5(9):661-667.
Ramaswamy, J., S.O. Prasher, R.M. Patel, S.A. Hussain, and S.F. Barrington. 2010. The effect of composting on the degradation of a veterinary pharmaceutical. Bioresource Technology, Vol. 101(7): 2294-2299.