Ravikrishna Raghunathan, Valsaraj Kalliat T, Thibodeaux Louis J, Price Cynthia B, Brannon James M, Yost Sally
Gordon A. and Mary Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge 70803, USA.
J Air Waste Manag Assoc. 2002 Oct;52(10):1214-29. doi: 10.1080/10473289.2002.10470852.
Remedial dredging of contaminated bed sediments in rivers and lakes results in the suspension of sediment solids in the water column, which can potentially be a source for evaporation of hydrophobic organic compounds (HOCs) associated with the sediment solids. Laboratory experiments were conducted in an oscillating grid chamber to simulate the suspension of contaminated sediments and flux to air from the surface of the water column. A contaminated field sediment from Indiana Harbor Canal (IHC) and a laboratory-inoculated University Lake (UL) sediment, Baton Rouge, LA, were used in the experiments, where water and solids concentration and particle size distribution were measured in addition to contaminant fluxes to air. A transient model that takes into account contaminant desorption from sediment to water and evaporation from the water column was used to simulate water and sediment concentrations and air fluxes from the solids suspension. In experiments with both sediments, the total suspended solids (TSS) concentration and the average particle diameter of the suspended solids decreased with time. As expected, the evaporative losses were higher for compounds with higher vapor pressure and lower hydrophobicity. For the laboratory-inoculated sediment (UL), the water concentrations and air fluxes were high initially and decreased steadily implying that contaminant release to the water column from the suspended solids was rapid, followed by evaporative decay. For the field sediments (IHC), the fluxes and water concentrations increased initially and subsequently decreased steadily. This implied that the initial desorption to water was slow and that perhaps the presence of oil and grease and aging influenced the contaminant release. Comparison of the model and experimental data suggested that a realistic determination of the TSS concentration that can be input into the model was the most critical parameter for predicting air emission rates.
对河流和湖泊中受污染的河床沉积物进行修复性疏浚会导致沉积物固体在水柱中悬浮，这可能成为与沉积物固体相关的疏水性有机化合物（HOCs）蒸发的一个来源。在一个振荡格栅室中进行了实验室实验，以模拟受污染沉积物的悬浮以及从水柱表面向空气的通量。实验中使用了来自印第安纳港运河（IHC）的受污染现场沉积物以及路易斯安那州巴吞鲁日的实验室接种的大学湖（UL）沉积物，除了测量向空气的污染物通量外，还测量了水和固体的浓度以及粒度分布。一个考虑了污染物从沉积物解吸到水以及从水柱蒸发的瞬态模型被用于模拟水和沉积物浓度以及来自固体悬浮体的空气通量。在两种沉积物的实验中，总悬浮固体（TSS）浓度和悬浮固体的平均粒径随时间下降。正如预期的那样，对于蒸气压较高且疏水性较低的化合物，蒸发损失更高。对于实验室接种的沉积物（UL），水浓度和空气通量最初较高并稳步下降，这意味着从悬浮固体向水柱的污染物释放很快，随后是蒸发衰减。对于现场沉积物（IHC），通量和水浓度最初增加，随后稳步下降。这意味着最初向水的解吸很慢，也许油和油脂的存在以及老化影响了污染物的释放。模型与实验数据的比较表明，能够输入模型的TSS浓度的实际测定是预测空气排放速率的最关键参数。
