Uranium distribution in the coastal waters and pore waters of Tampa Bay, Florida

The geochemical reactivity of uranium (238U) and dissolved organic carbon (DOC), Fe, Mn, Ba, and V was investigated in the water column, pore waters, and across a river/estuarine mixing zone in Tampa Bay, Florida. This large estuary is impacted both by diverse anthropogenic activity and by extensive U-rich phosphatic deposits. Thus, the estuarine behavior of uranium may be examined relative to such known U enrichments and anthropogenic perturbations. Dissolved (diff) ranged from - 82.0 to 116.6 mol d- 1. It is likely that negative U fluxes imply seawater entrainment or infiltration (i.e., submarine groundwater recharge), which may contribute to the removal of water column uranium. For comparison, a bay-wide, Ra-derived submarine groundwater discharge estimate for Tampa Bay (8 L m- 2 d- 1) yielded an average, advective (JSGD) U flux of 112.9 mol d- 1. In Tampa Bay, the estuarine distribution of U indicates a strong natural, geologic control that may also be influenced by enhanced fluid transport processes across the sediment/water interface. © 2006 Elsevier B.V. All rights reserved.