Temporal uranium variations in the Brazos River

Dissolved uranium concentrations of 21 Brazos River samples taken between March 1971 and February 1972 ranged from 0.6 to 2.7 μg/l. The highest uranium concentrations were observed in the spring. From the correspondingly high spring fluxes for nitrate, phosphorus and uranium during peak flows from overland runoff, dissolution of phosphate fertilizer appears to be responsible for the increased uranium concentrations in the Brazos River. Comparison of peak fluxes of potential agriculturally derived ions with those of geologically derived bicarbonate, sulfate and chloride further indicates that fertilizer is a source of uranium in the Brazos River