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首页> 外文学位 >Model simulations of upwelling of Persistent Bioaccumulative Toxic (PBT) organic pollutants from contaminated bed sediments for base flow events.
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Model simulations of upwelling of Persistent Bioaccumulative Toxic (PBT) organic pollutants from contaminated bed sediments for base flow events.

机译：来自基床事件的受污染床沉积物中持久性生物累积有毒（PBT）有机污染物上升流的模型模拟。

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摘要

In river systems, streambed sediments have been recognized as an important factor in the transport of contaminants since they have a strong capacity to adsorb contaminants such as pesticides, nutrients, toxic hydrocarbons and heavy metals. A thorough understanding of the contaminant transport processes occurring between the streambed and stream water is very important in predicting the fate of pollutants in rivers. The focus of this study was the release of Persistent Bioaccumulative Toxic (PBT) organic pollutants from contaminated streambed sediments into clean waters, i.e., upwelling, under low-flow stream conditions and the corresponding biological effects. A multi-phase reactive transport model which accounts for the physical exchange process occurring between the streams and streambeds and physicochemical processes like sorption/desorption was developed. This model simulates the release of PBT organic pollutants from contaminated streambed sediment and the biouptake of PBT organic pollutants by benthic organisms in the stream and streambed sediments under low flow rates. The advective pumping theory was used to model the physical exchange process. PBT organic pollutant's sorption/desorption was modeled using a two-site nonlinear equilibrium/kinetic model and a two-stage desorption model. A bioconcentration factor (BCF) equation was used to model biouptake of PBT organic pollutants by benthic organisms. Due to the small amount of organism used, it is assumed that the biouptake in the system will not affect significantly the contaminant concentration distributions during transport. Simulation results indicate an increase in the stream water contaminant concentration due to the release of contaminant from streambed and a decrease of the stream water contaminant concentration due to the adsorption of contaminant to the streambed sediments. Stream water contaminant concentration increases rapidly due to a high desorption of contaminants from the streambed and low or no re-adsorption. Meanwhile, a high re-adsorption results in reduced release of contaminant from the streambed into the stream even when a high desorption is used. Therefore, desorption and re-adsorption processes are both controlling the release of contaminant from the streambed. This study contributes to the understanding and predicting the transport and biouptake of PBT organic pollutants present in streambed sediments of natural streams.
机译：在河流系统中，河床沉积物具有很强的吸附能力，可以吸收污染物，例如农药，养分，有毒碳氢化合物和重金属，因此被认为是污染物运输的重要因素。全面了解河床和河水之间的污染物迁移过程对于预测河流中污染物的命运非常重要。这项研究的重点是在低流量条件下，从受污染的河床沉积物向净化水（即上升流）中释放持久性生物累积有毒（PBT）有机污染物。建立了一个多相反应性输运模型，该模型考虑了在流和流床之间发生的物理交换过程以及诸如吸附/解吸的物理化学过程。该模型模拟了低流速下河床和河床底泥中底栖生物对污染的河床底泥中PBT有机污染物的释放以及底栖生物对PBT有机污染物的生物吸收。平流抽水理论被用来模拟物理交换过程。使用两点非线性平衡/动力学模型和两阶段解吸模型对PBT有机污染物的吸附/解吸进行建模。生物浓缩因子（BCF）方程用于模拟底栖生物对PBT有机污染物的生物吸收。由于使用的生物量很少，因此可以假设系统中的生物吸收不会在运输过程中显着影响污染物的浓度分布。模拟结果表明，由于河床中污染物的释放，导致了河水中污染物浓度的增加；由于污染物对河床沉积物的吸附，导致了河水中污染物浓度的降低。由于污染物从河床中的高度解吸和再吸收低或没有，因此溪流水污染物浓度迅速增加。同时，即使当使用高解吸量时，高的重吸附量也导致减少了从流化床到流中的污染物的释放。因此，解吸和再吸附过程都控制着污染物从流化床中的释放。这项研究有助于理解和预测天然流的河床沉积物中存在的PBT有机污染物的运输和生物吸收。

著录项

  • 作者

    Otero Luna, Doris Diana.;

  • 作者单位

    Texas A&M University - Kingsville.;

  • 授予单位 Texas A&M University - Kingsville.;
  • 学科 Hydrology.Engineering Environmental.
  • 学位 M.S.
  • 年度 2009
  • 页码 60 p.
  • 总页数 60
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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