Hydrogeochemical controls on uranium in aquifers of the Jacobsville Sandstone
- 出版日期：2004.
- 页数：1 v. :
- 第一责任说明：Heidi M. Sherman.
- 分类号：a272
- ISBN：0496007939(ebk.) :
MARC全文
02h0029441 20120614110301.0 cr un||||||||| 120614s2004 xx ||||f|||d||||||||eng | 3143314 0496007939(ebk.) : CNY371.35 NGL NGL NGL a272 Sherman, Heidi M. Hydrogeochemical controls on uranium in aquifers of the Jacobsville Sandstone [electronic resource] / Heidi M. Sherman. 2004. 1 v. : digital, PDF file. Adviser: Gierke, John S. Thesis (Ph.D.)--Michigan Technological University, 2004. The occurrence of elevated uranium U) in sandstone aquifers was investigated in the Upper Peninsula of Michigan, focusing on aquifers of the Jacobsville Sandstone. The hydrogeochemical controls on groundwater U concentrations were characterized using a combination of water sampling and spectral gamma-ray logging of sandstone cliffs and residential water wells. 235U/ 238U isotope ratios were consistent with naturally occurring U. Approximately 25% of the 270 wells tested had U concentrations above the U.S. Environmental Protection Agency Maximum Contaminant Level MCL) of 30 mug/L, with elevated U generally occurring in localized clusters. Water wells were logged to determine whether groundwater U anomalies could be explained by the heterogeneous distribution of U in the sandstone. Not all wells with relative U enrichment in the sandstone produced water with U above the MCL, indicating that the effect of U enrichment in the sandstone may be modified by other hydrogeochemical factors. Well water had high redox, indicating U is in its highly soluble VI) valence. Equilibrium modeling indicated that aqueous U is complexed with carbonates. In general, wells with elevated U concentrations had low 234U/238 U activity ratios. However, in some areas U concentrations and 234U/238U activity ratios were simultaneously high, possibly indicating differences in rock-water interactions. Limited groundwater age dating suggested that residence time may also help explain variations in well water U concentrations. Low levels of U enrichment 4 to 30 ppm) in the Jacobsville sandstone may make wells in its oxidized aquifers at risk for U concentrations above the MCL. On average, U concentrations were highest in heavy mineral and clay layers and rip up conglomerates. Uranium concentrations above 4 ppm also occurred in siltstones, sandstones and conglomerates. Uranium enrichment was likely controlled by deposition processes, sorption to clays, and groundwater flow, which was controlled by permeability variations in the sandstone. Low levels of U enrichment were found at deltaic, lacustrine and alluvial fan deposits and were not isolated to specific depositional environments.* *This dissertation is a compound document contains both a paper copy and a CD as part of the dissertation). The CD requires the following system requirements: Adobe Acrobat； Microsoft Office. Groundwater ; Geochemical prospecting Jacobsville, Mich. ; Jacobsville, Mich. Electronic dissertations. aeBook. aCN bNGL http://pqdt.bjzhongke.com.cn/Detail.aspx?pid=akx95%2fDASDs%3d NGL Bs1501 rCNY371.35 ; h1 bs1204