...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Reactive transport of trace elements and isotopes in the Eutaw coastal plain aquifer, Alabama
【24h】

Reactive transport of trace elements and isotopes in the Eutaw coastal plain aquifer, Alabama

机译：阿拉巴马州Eutaw沿海平原含水层中微量元素和同位素的反应性运输

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

We integrate groundwater geochemistry, mineralogy, and numerical modeling techniques to study the reactive transport of heavy metals and isotopes in the Eutaw coastal plain aquifer, Alabama. Geochemical data show that the elevated concentrations of Fe, Mn, and Sr can be correlated with high pH and alkalinity. These geochemical correlations suggest that that elevated metal concentrations may be derived from bacterial iron and manganese reduction. Geochemical modeling of bacterial Fe(III) and Mn(IV) reduction shows that the biotransformation of iron and manganese minerals could control mobility and concentrations of Fe and Mn in coastal plain aquifers. Petrographic, SEM, and EDAX studies of sediments show the formation of biogenic siderite, rhodochrosite, and pyrite in sediments associated with Fe- and Mn-rich groundwater. Rhodochrosite and siderite occur together as spheroids (≈1.0 mm) in which rhodochrosite forms the center and siderite forms an outer rind, which is consistent with the redox sequence of mineral precipitation predicted by the geochemical modeling. The low δ 13C ratios of siderite and rhodochrosite (?14.4 to ?15.4‰, PDB) and groundwater DIC (?20.6 to ?14.1‰, PDB) imply carbon of biogenic origin. Higher DIC-δ 13C levels are found to be correlated with elevated Fe and Mn concentrations and high pH values of groundwater. This unexpected result implies novel carbon isotopic fractionation processes associated with bacterial Fe(III) reduction. We used 36Cl/Cl ratios of groundwater and isotope transport modeling to calculate the residence time of regional groundwater in the Eutaw aquifer. The calculation considering the natural decay only would yield 36Cl levels that are significantly higher than field data, suggesting that a significant mixing with Cl-rich, older groundwater at depth is an important reason for substantial 36Cl depletion along flow path.
机译：我们整合了地下水地球化学，矿物学和数值模拟技术，以研究阿拉巴马州尤塔（Eutaw）沿海平原含水层中重金属和同位素的反应性迁移。地球化学数据表明，Fe，Mn和Sr浓度升高与高pH和碱度有关。这些地球化学相关性表明，升高的金属浓度可能来自细菌铁和锰的还原。细菌Fe（III）和Mn（IV）还原的地球化学模型表明，铁和锰矿物质的生物转化可以控制沿海平原含水层的迁移率以及Fe和Mn的浓度。沉积物的岩石学，SEM和EDAX研究表明，与富含铁和锰的地下水相关的沉积物中形成了生物型菱铁矿，菱锰矿和黄铁矿。菱铁矿和菱铁矿作为球体（≈1.0毫米）一起出现，其中菱铁矿形成中心，菱铁矿形成外皮，这与通过地球化学模型预测的矿物沉淀的氧化还原序列一致。菱铁矿和菱锰矿的δ13C比值低（PDB约为14.4至15.4‰）和地下水DIC（PDB约为20.6至14.1‰）意味着存在生物成因碳。发现更高的DIC-δ13C水平与铁和锰浓度升高以及地下水的高pH值相关。这一出乎意料的结果暗示了与细菌Fe（III）还原相关的新型碳同位素分馏过程。我们使用36Cl / Cl的地下水比例和同位素迁移模型来计算Eutaw含水层中区域地下水的停留时间。仅考虑自然衰减的计算将得出的36Cl水平明显高于现场数据，这表明在深处与富含Cl的较旧地下水进行大量混合是沿流路大量消耗36Cl的重要原因。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号