Abstract Introduction Site Desc. & Land Use Methods Results & Discussion Conclusions Acknowledgments References Figures, Tables, & Equations

Figures

Figure 1. Map of the MacArthur Agro-Ecology Research Center (MAERC) showing locations of three soil cores and locations of two pastures (S5, W4) where runoff water was collected.

Figure 2. Graphs showing concentrations of total phosphorus, nitrogen, sulfur, organic carbon, and uranium in soil profiles from improved pasture (S5), unimproved semi-native pasture (770), and native grassland (Lykes).

Figure 3. Graph showing variations of the U isotopic composition of soil extracts with depth in the three soil cores.

Figure 4. Graph showing the relation between organic carbon content of soil intervals and the percent of total U removed in a selective extraction with 0.1 M sodium bicarbonate.

Figure 5. Graphs showing the sulfur isotopic composition of soils from the three soil profiles with respect to (a) depth and (b) total S content.

Figure 6. Map showing locations of surface water samples collected north and west of Lake Okeechobee and described in Table IV.

Tables

Table I - Elemental analysis of soils and U isotopic analysis of soil extracts from selected intervals, MAERC

TABLE II - Uranium concentration and isotopic composition of phosphate-bearing fertilizers and cattle feed nutritional supplements used in the study area

TABLE III - Composition of runoff water from fertilized (S5) and unfertilized (W4) pastures

TABLE IV - Dissolved U concentration and U isotope composition of surface waters collected north and west of Lake Okeechobee

Equations

Sulfur Isotopic Composition Equation

Equation 1. If an extract contains a mixture of desorbed natural U and fertilizer-derived U, then the mass contribution of U from each component can be calculated using this standard isotope mass balance equation

Equation 2. Equation 1 solved for mass fraction of natural uranium from fertilizer