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首页> 外文期刊>Journal of Hazardous Materials >An environmental screening model to assess the consequences to soil and groundwater from railroad-tank-car spills of light non-aqueous phase liquids
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An environmental screening model to assess the consequences to soil and groundwater from railroad-tank-car spills of light non-aqueous phase liquids

机译：一种环境筛选模型，用于评估轻型非水相液体对铁路罐车泄漏产生的土壤和地下水的影响

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摘要

North American railroads transport a wide variety of chemicals, chemical mixtures and solutions in railroad tank cars. In the event of an accident, these materials may be spilled and impact the environment. Among the chemicals commonly transported are a number of light non-aqueous phase liquids (LNAPLs). If these are spilled they can contaminate soil and groundwater and result in costly cleanups. Railroads need a means of objectively assessing the relative risk to the environment due to spills of these different materials. Environmental models are often used to determine the extent of contamination, and the associated environmental risks. For LNAPL spills, these models must account for NAPL infiltration and redistribution, NAPL dissolution and volatilization, and remediation systems such as pump and treat. This study presents the development and application of an environmental screening model to assess NAPL infiltration and redistribution in soils and groundwater, and to assess groundwater cleanup time using a pumping system. Model simulations use parameters and conditions representing LNAPL releases from railroad tank cars. To take into account unique features of railroad-tank-car spill sites, the hydrocarbon spill screening model (HSSM), which assumes a circular surface spill area and a circular NAPL lens, was modified to account for a rectangular spill area and corresponding lens shape at the groundwater table, as well as the effects of excavation and NAPL evaporation to the atmosphere. The modified HSSM was first used to simulate NAPL infiltration and redistribution. A NAPL dissolution and groundwater transport module, and a pumping system module were then implemented and used to simulate the effects of chemical properties, excavation, and free NAPL removal on NAPL redistribution and cleanup time. The amount of NAPL that reached the groundwater table was greater in coarse sand with high permeability than in fine sand or silt with lower permeabilities. Excavation can reduce the amount of NAPL that reaches the groundwater more effectively in lower permeability soils. The effect of chemical properties including vapor pressure and the ratio of density to viscosity become more important in fine sand and silt soil due to slow NAPL movement in the vadose zone. As expected, a pumping system was effective for high solubility chemicals, but it was not effective for low solubility chemicals due to rate-limited mass transfer by transverse dispersion and flow bypassing. Free NAPL removal can improve the removal efficiency for moderately low solubility chemicals like benzene, but cleanup times even after free NAPL removal can be prolonged for very low solubility chemicals like cyclohexane and styrene.
机译：北美铁路在铁路罐车中运输各种化学品，化学混合物和解决方案。发生事故时，这些材料可能会溢出并影响环境。在通常运输的化学品中，有许多轻质非水相液体（LNAPL）。如果这些溅出，它们会污染土壤和地下水，并导致昂贵的清理工作。铁路需要一种客观地评估由于这些不同材料的溢出而对环境造成的相对风险的方法。通常使用环境模型来确定污染程度以及相关的环境风险。对于LNAPL泄漏，这些模型必须考虑NAPL的渗透和再分配，NAPL的溶解和挥发以及诸如泵送和处理的修复系统。这项研究提出了一种环境筛选模型的开发和应用，以评估NAPL在土壤和地下水中的渗透和再分布，并使用抽水系统评估地下水的净化时间。模型仿真使用代表铁路罐车LNAPL释放的参数和条件。考虑到铁路油罐车泄漏场的独特特征，对碳氢化合物泄漏筛查模型（HSSM）进行了修改，该模型假定圆形表面泄漏区域和圆形NAPL透镜，以考虑矩形泄漏区域和相应的透镜形状地下水位，开挖和NAPL蒸发对大气的影响。修改后的HSSM首先用于模拟NAPL的渗透和再分布。然后实施了NAPL溶解和地下水输送模块以及一个抽水系统模块，并将其用于模拟化学性质，开挖和自由NAPL去除对NAPL重新分配和清理时间的影响。在渗透率高的粗砂中，到达地下水位的NAPL量大于渗透率低的细砂或粉砂中。在较低渗透率的土壤中，开挖可以更有效地减少到达地下水的NAPL量。化学性质的影响，包括蒸气压和密度与粘度之比，在细砂和粉砂土中，由于渗流区中NAPL的缓慢移动而变得更加重要。不出所料，泵送系统对高溶解度化学品有效，但对低溶解度化学品无效，这是由于通过横向分散和绕过流量进行速率限制的传质所致。游离NAPL的去除可以提高中等溶解度较低的化学品（如苯）的去除效率，但是对于溶解度非常低的化学物质（如环己烷和苯乙烯），即使游离NAPL去除后的清除时间也可以延长。

著录项

  • 来源
    《Journal of Hazardous Materials》 |2009年第3期|332-344|共13页
  • 作者

    Hongkyu Yoon; Charles J. Werth; Christopher P.L. Barkan; David J. Schaeffer; Pooja Anand;

  • 作者单位

    Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205N Mathews Ave., Urbana, IL, United States;

    Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205N Mathews Ave., Urbana, IL, United States;

    Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205N Mathews Ave., Urbana, IL, United States;

    Department of Veterinary Biosciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States;

    Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205N Mathews Ave., Urbana, IL, United States;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    NAPL; HSSM; railroad-tank-car accident; environmental consequence; screening model; hazardous materials transportation risk;

    机译：NAPL;HSSM;铁路罐车事故;环境后果;筛选模型;危险品运输风险;

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