| Abstract: | 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 (< 0.45??m) uranium exhibited both removal and enrichment processes across the Alafia River/estuarine mixing zone relative to conservative mixing. Such non-conservative U behavior may be attributed to: i) physical mixing processes within the river; ii) U carrier phase reactivity; and/or iii) fluid exchange processes across sediment/water interface. In the bay proper, U concentrations were ?????2 to 3 times greater than those reported for other estuarine systems and are likely a result of erosional inputs from the extensive, underlying U-rich phosphatic deposits. Whereas dissolved U concentrations generally did not approach seawater values (13.6??nM) along the Alafia River salinity transect, water column U concentrations exceeded 16??nM in select regions of the bay. Within the hydrogeological framework of the bay, such enriched U may also be derived from advective fluid transport processes across the sediment/water interface, such as submarine groundwater discharge (SGD) or hyporheic exchange within coastal rivers. Pore water profiles of U in Tampa Bay show both a flux into and out of bottom sediments, and average, diffusive U pore water fluxes (Jdiff) 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. |
| Genre: | Article |
| ProdID: | 70028771 |
| Citation Author: | Swarzenski, P. W.; Baskaran, M. |
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| Citation End Page: | 266 |
| Citation Issue: | 3-4 |
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| Citation Language: | English |
| Citation Larger Work Title: | Marine Chemistry |
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| Citation Number Of Pages: | 15 |
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| Citation Search Results Text: | Uranium distribution in the coastal waters and pore waters of Tampa Bay, Florida; 2006; Article; Journal; Marine Chemistry; Swarzenski, P. W.; Baskaran, M. |
| Citation Start Page: | 252 |
| Citation Volume: | 102 |
| Citation Year: | 2006 |
| Type: | citation/reference |
| Text: | Uranium distribution in the coastal waters and pore waters of Tampa Bay, Florida; 2006; Article; Journal; Marine Chemistry; Swarzenski, P. W.; Baskaran, M. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DIGITAL OBJECT IDENTIFIER): | http://dx.doi.org/10.1016/j.marchem.2006.06.016 |
| Date Other: | Sun, 1 Jan 2006 00:00 -0600 |
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