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首页> 外文学位 >Exchange of DDE and DDE associated fine suspended sediments between streams and streambeds.
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Exchange of DDE and DDE associated fine suspended sediments between streams and streambeds.

机译：DDE和DDE相关的细小悬浮沉积物在溪流和河床之间的交换。

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摘要

Stream-subsurface exchange has important implications for contaminant transport in streams because it can cause the retention of contaminants in the streambed and also has the potential to enhance the release of contaminants from the streambed. Hydrophobic organic contaminants (HOCs), such as dichloro-diphenyl-dichloroethane (DDE) have the potential to strongly adsorb onto sediment particles and their release from contaminated sediment can be influenced by factors such as changes in water chemistry, and by the presence of high molecular weight organic substances known as dissolved organic carbon (DOC). Thus, to accurately determine the fate and transport of HOCs and the ecological risks involved, it is essential to understand their fluxes between sediments and overlaying water under varying stream conditions.;In this study, laboratory batch and flume experiments were conducted to demonstrate the DDE transport behavior under varying stream conditions including pH, ionic strength, and in the presence of DOC. DDE transport from stream water to streambed and DDE transport from streambed into stream water were examined under a defined physical (the presence of streambed topography) condition. Fundamental process-based multiphase stream-subsurface exchange models were applied to interpret the flume experimental results.;Results showed that changes in water chemistry influenced the release of p,p'- DDE from contaminated sediment and associations between p,p'-DDE and DOC. Decreasing pH decreased p,p'-DDE -DOC associations and enhanced the release of p,p' -DDE from contaminated sediment in the batch experiments; however the effect of pH was undistinguishable in the flume experiments. Increases in ionic strength increased p,p'-DDE -DOC associations and led to a decrease in p,p'-DDE release from the contaminated sediment, which was observed in both the batch and flume experiments. The observed p,p'-DDE exchange was successfully predicted by the process-based models, thus indicating that these models were able to properly represent the physical and chemical processes controlling the transport of p,p'-DDE in stream systems. This study contributes to the mechanistic understanding of HOC transport and the factors governing HOC transport in river systems, and to the development of reliable, predictive models for the assessment of impacted streams.
机译：河流-地下交换对污染物在河流中的运输具有重要意义，因为它可以导致污染物保留在河流中，并且还具有增强污染物从河流中释放的潜力。疏水性有机污染物（HOC），例如二氯-二苯基-二氯乙烷（DDE），可能会强烈吸附到沉积物颗粒上，它们从受污染的沉积物中的释放可能受到诸如水化学变化和高浓度有机物等因素的影响。分子量有机物质称为溶解有机碳（DOC）。因此，要准确确定HOC的命运和运输以及所涉及的生态风险，必须了解它们在不同的水流条件下在沉积物和上覆水之间的通量。在各种流条件下（包括pH值，离子强度和DOC）的迁移行为。在确定的物理条件（存在河床地形）下检查了DDE从河水到河床的运输和DDE从河床到河水的运输。应用基于基本过程的多相流-地下交换模型解释了水槽的实验结果。结果表明，水化学的变化影响了污染沉积物中p，p'-DDE的释放以及p，p'-DDE与水之间的联系。 DOC。在分批实验中，降低pH值可降低p，p'-DDE -DOC缔合，并增加p，p'-DDE从受污染沉积物中的释放；但是在水槽实验中，pH值的影响是无法区分的。离子强度的增加增加了p，p'-DDE -DOC的缔合，并导致受污染的沉积物中p，p'-DDE的释放减少，这在分批和水槽实验中都可以观察到。通过基于过程的模型成功预测了观察到的p，p'-DDE交换，因此表明这些模型能够正确表示控制p，p'-DDE在流系统中传输的物理和化学过程。这项研究有助于对HOC输送的机理的理解以及控制河流系统HOC输送的因素，并有助于开发可靠的预测模型来评估受影响的河流。

著录项

  • 作者

    Camarena, Celina Ines.;

  • 作者单位

    Texas A&M University - Kingsville.;

  • 授予单位 Texas A&M University - Kingsville.;
  • 学科 Engineering Environmental.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 185 p.
  • 总页数 185
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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