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Study examines fate of antimicrobials used in dairies

November 12, 2010 – A
recent study has found that antimicrobials used on two California dairies can
be recovered from surface soil and manure lagoons, but that groundwater
contamination was limited.
November 12, 2010 – A
recent study has found that antimicrobials used on two California dairies can
be recovered from surface soil and manure lagoons, but that groundwater
contamination was limited.

Dr. Thomas Harter, PhD, a
faculty member with the Department of Land, Air, and Water Resources at the
University of California – Davis, said the researchers detected all 13
antimicrobials used on two free-stall dairies in the dairies’ surface soil and
lagoons, and they found low concentrations of two sulfonamides and lincomycin
in the first 20 feet of groundwater below the dairies. The groundwater
concentrations were typically an order of magnitude less than those seen in
manure lagoons, and affected groundwater was primarily in the immediate
vicinity of the manure lagoons or near irrigation valves on manure-irrigated
fields.

University information
indicates many of the antimicrobials, while frequently found in corrals and
manure flush lanes, degraded within the first foot of soil.

The researchers selected
sites in the San Joaquin Valley that have sandy loam soil, high levels of
irrigation, and groundwater located in a sandy aquifer between 10 and 30 feet
below the surface. Dr. Harter said the sites were chosen on the basis of their
high risk of groundwater contamination.

The results from the
research conducted by University of California – Davis and U.S. Geological
Survey Water Science Center employees has been published online by the journal
Environmental Science & Technology. The text is available at http://pubs.acs.org/doi/full/10.1021/es100834s.