publications > paper > fertilizer-derived uranium and sulfur in rangeland soil and runoff: a case study in central Florida
FERTILIZER-DERIVED URANIUM AND SULFUR IN RANGELAND SOIL AND RUNOFF: A CASE STUDY IN CENTRAL FLORIDA
ROBERT A. ZIELINSKI1, *, WILLIAM H. OREM2, KATHLEEN R. SIMMONS1 and PATRICK J. BOHLEN3
1U.S. Geological Survey, Denver, Colorado 80225, USA; 2U.S. Geological Survey, Reston, Virginia 20192, USA; 3MacArthur Agro-Ecology Research Center, Lake Placid, FL 33852, USA
(*author for correspondence, e-mail: firstname.lastname@example.org; Tel.: (303) 236-4719; Fax: (303) 236-3200)
|Posted with permission from Springer Science and Business Media. Journal of Water, Air, & Soil Pollution, Jan 2006. © Springer 2006.
Note: Paper is available from the Springer website (journal subscription is required)
Fertilizer applications to rangeland and
pastures in central Florida have potential impact on the nutrient-sensitive ecosystems of Lake Okeechobee and the Northern Everglades. To investigate the effects of fertilizer applications, three soil profiles from variably managed and improved rangeland, and four samples of surface runoff from both fertilized and unfertilized pasture were collected. In addition to determining nutrient concentrations, isotopic analyses of uranium (U) and sulfur (S) were performed to provide isotopic evidence for U derived from historically applied phosphate (P)-bearing fertilizer (234U/238U activity ratio = 1.0 ± 0.05), and S derived from recently applied ammonium sulfate fertilizer (34S = 3.5 per mil). The distribution and mobility of fertilizer-derived U in these samples is considered to be analogous to that of fertilizer-derived phosphate. Variations of U concentrations and 234U/238U activity ratios in soils indicate contribution of fertilizer-derived U in the upper portions of the fertilized soil (15-34 percent of total U). The U isotope data for runoff from the fertilized field also are consistent with some contribution from fertilizer-derived U. Parallel investigations of S showed no consistent chemical or isotopic evidence for significant fertilizer-derived sulfate in rangeland soil or runoff. Relatively abundant and isotopically variable S present in the local environment hinders detection of fertilizer-derived sulfate. The results indicate a continuing slow-release of fertilizer-derived U and, by inference, P, to the P-sensitive ecosystem, and a relatively rapid release of sulfate of possible natural origin.
Keywords: fertilizers, uranium, sulfur, isotopes, rangeland soil and runoff, Florida
(Received 22 November 2005; accepted 31 March 2006)