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首页> 外文学位 >Groundwater flow dynamics and contaminant transport to coastal waters under low recharge conditions: Regional-scale study of the aquifer system underlying southern Baldwin County, Alabama.
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Groundwater flow dynamics and contaminant transport to coastal waters under low recharge conditions: Regional-scale study of the aquifer system underlying southern Baldwin County, Alabama.

机译：低补给条件下地下水流动力学和污染物向沿海水域的迁移：阿拉巴马州南部鲍德温县地下含水层系统的区域规模研究。

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摘要

This study examined the influence of drought conditions and increased hydrological stresses on the groundwater system flow dynamics, submarine groundwater discharge, and nitrate transport and discharge to the Gulf of Mexico. The results of these studies demonstrate that current stresses on the aquifer have led to significant saltwater intrusion and or direct infiltration into fresh groundwater, especially within the upper aquifers of the region. The nitrate and chloride data analyses reveal the persistent presence of multiple nitrate impacted zones within the study area. Stable isotope data support the hypothesis that nitrate in the investigated aquifers originates from the nitrification of ammonium in soils from a mixture of sources ranging from fertilizer to sewer and/or manure and that denitrification, the breakdown of nitrates to nitrogen gas, is not significant in the investigated aquifer system. Furthermore, groundwater isotope data indicates that water in the aquifer system of the study area is most likely to have originated from precipitation and soil infiltration through relatively localized recharge and that the aquifer system in the study area is highly dynamic, experiencing mixing of recent recharged waters with older, ambient groundwaters. The presence of low residence times and the absence of denitrification reveal the oxic character of this system. As a proxy for a number of contaminant types, the groundwater flow and transport model was used to simulate nitrate transport in response to variable-density groundwater flow. The simulation results indicate that in the investigated aquifer system complexities arise because groundwater flow dynamics and contaminant transport are additionally influenced by density variations that can occur from the incursion of saltwater.;The model predicts that the Beach Sand and Gulf Shores Aquifers will be impacted by severe saltwater intrusion whereas the deeper 350 and 500-Foot Aquifers will experience no saltwater intrusion for the entire simulation period. Consequently, nitrate discharge to the Gulf of Mexico originates from the lower part of the aquifer system through submarine groundwater discharge. This research will serve as a tool which may be applied to other similar coastal systems for more effective management strategies.
机译：这项研究考察了干旱条件和水文压力的增加对地下水系统流动动力学，海底地下水排放以及硝酸盐向墨西哥湾的运输和排放的影响。这些研究的结果表明，当前对含水层的压力已导致大量海水入侵和/或直接渗入新鲜地下水，特别是在该地区上部含水层内。硝酸盐和氯化物数据分析揭示了研究区内多个硝酸盐影响区的持续存在。稳定的同位素数据支持以下假设：所研究的含水层中的硝酸盐源自土壤中铵的硝化作用，该混合物来自化肥，下水道和/或粪便等多种来源，而反硝化作用（硝酸盐分解为氮气）在土壤中并不重要。调查的含水层系统。此外，地下水同位素数据表明，研究区域含水层系统中的水最有可能来自相对局部补给的降水和土壤渗透，并且研究区域中的含水层系统是高度动态的，正在经历近期补给水的混合与较旧的周围地下水。低停留时间的存在和反硝化的缺乏揭示了该系统的氧化特性。作为多种污染物类型的替代，地下水流量和迁移模型用于模拟硝酸盐的迁移，以响应可变密度的地下水流量。仿真结果表明，在研究的含水层系统中，由于地下水流动力学和污染物运移还受到咸水入侵可能引起的密度变化的影响而产生了复杂性;该模型预测，沙滩和海湾海岸含水层将受到以下影响严重的咸水入侵，而较深的350和500英尺含水层在整个模拟期间都不会遭受咸水入侵。因此，硝酸盐排放到墨西哥湾的原因是来自地下含水层系统的海底地下水排放。这项研究将作为一种工具，可以应用于其他类似的沿海系统，以实现更有效的管理策略。

著录项

  • 作者

    Murgulet, Dorina.;

  • 作者单位

    The University of Alabama.;

  • 授予单位 The University of Alabama.;
  • 学科 Geology.;Geochemistry.;Environmental Geology.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 216 p.
  • 总页数 216
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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