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首页> 外文期刊>Journal of Hazardous Materials >Air emissions from exposed, contaminated sediments and dredged materials 1. Experimental data in laboratory microcosms and mathematical modelling
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Air emissions from exposed, contaminated sediments and dredged materials 1. Experimental data in laboratory microcosms and mathematical modelling

机译：来自暴露，受污染的沉积物和疏materials材料的空气排放1.实验室缩影和数学模型中的实验数据

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The air emissions of two polycyclic aromatic hydrocarbons (pyrene and phenanthrene) and one heterocyclic compound (dibenzofuran) from an 'aged' contaminated sediment (Rouge River, Michigan) were studied in an experimental microcosm. The sediment-to-air flux of the above semivolatile organic compounds (SOCs) was obtained from an initially water-saturated sediment. The magnitude of flux varied as dibenzofuran > phenanthrene > pyrene. At a low air flow rate (10 ml min~(-1)) the flux was low and stable and air-phase resistance controlled. At a larger flow rate (100 ml min~(-1)) the flux was high initially and then declined, indicating the effects of sediment-side diffusion on mass transfer to air. The flux was also sensitive to the relative humidity (RH) of the air flowing above the sediment. It was observed that the flux, though high initially, declined rapidly as dry air (0% RH) was passed over the wet sediment. Loss of sediment moisture which increased the sorptive capacity of the sediment for the contaminants was also noted. Subsequent exposure of the dry sediment to humid air increased the flux. The steady state flux was consistently high when humid air was passed over dry sediment. The experimental data were analyzed using a mathematical model which estimated the air emission from an exposed sediment layer under both sediment-side and air-side resistance controlled conditions. The model incorporated an advancing 'drying front' in the direction of airflow for water evaporation in accordance with our observations. The sharp decrease in contaminant flux was attributed to the drying-out of the sediment and a consequent increase in its sorptive capacity for the contaminant. The framework of the theory underlying the air emission modelling from exposed sediment, dredged and placed in a confined disposal facility (CDF) is summarized.
机译：在实验微观世界中研究了来自“老化的”受污染沉积物（密歇根州罗格河）的两种多环芳烃（py和菲）和一种杂环化合物（二苯并呋喃）的空气排放。上述半挥发性有机化合物（SOC）的沉积物-空气通量是从最初的水饱和沉积物中获得的。通量的大小随二苯并呋喃>菲> pyr而变化。在低空气流量（10 ml min〜（-1））下，通量低且稳定，并且可控制气相电阻。在较大的流速下（100 ml min〜（-1）），通量开始时较高，然后下降，这表明了沉积物侧扩散对传质到空气的影响。通量还对沉积物上方流动的空气的相对湿度（RH）敏感。可以看到，通量虽然开始时很高，但随着干燥空气（0％RH）通过湿的沉积物而迅速下降。还注意到了沉积物水分的损失，这增加了沉积物对污染物的吸附能力。随后将干燥的沉积物暴露于潮湿的空气中会增加通量。当湿空气通过干燥的沉积物时，稳态通量始终很高。使用数学模型分析了实验数据，该数学模型估计了在沉积物侧和空气侧阻力受控条件下暴露的沉积物层的空气排放。根据我们的观察，该模型在气流蒸发方向上纳入了一个先进的“干燥前沿”。污染物通量的急剧下降归因于沉积物的干and以及随之而来的对污染物的吸附能力的提高。总结了从裸露的沉积物，疏and并放置在密闭处理设施（CDF）中进行空气排放建模的理论框架。

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