Validation of a hybrid "two-site gamma" model for naphthalene desorption kinetics
Validation of a hybrid "two-site gamma" model for naphthalene desorption kinetics
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DOI：
10.1021/es971104l
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发表时间：
1999-09-15
影响因子：
11.4
通讯作者：
Shuler, ML
中科院分区：
文献类型：
--
作者：
Ahn, IS;Lion, LW;Shuler, ML
比较了土壤中多环芳烃（PAH）污染物的三种吸附/解吸模型：“伽玛”模型、“两个位点/两个区域”非平衡模型和“混合”模型对PAH在土壤中迁移的预测能力。在“混合”模型中，土壤有机质在概念上分为两个区室；具有快速吸附/脱附动力学的部分和具有传质有限动力学的隔室。假定污染物吸附在快速隔室中与水相处于瞬时平衡状态，而污染物从慢速隔室中的释放受速率系数的伽马分布控制。“混合”模型成功地描述了模型多环芳烃污染物萘从中等有机含量（等于2.3%）的过筛土壤样品中最初的快速释放，以及在批量解吸实验中观察到的25天以上的缓慢释放。其他必要的模型参数，如萘的水动力分散系数和大孔孔隙率，在单独的实验中进行了评估。一个包含萘吸附/解吸“混合”模型的输运模型在无参数可调的独立土壤柱实验中成功地预测了萘的洗脱剖面。混合模型的成功表明，多种速率控制控制着多环芳烃的解吸。这一结论与土壤是由不同吸附成分和异构物理约束组成的观点是一致的。
Three models for sorption/desorption of polycyclic aromatic hydrocarbon (PAH) contaminants from soil were compared for their ability to predict the transport of PAH in soil: a "gamma" model, a "two-site/two-region" nonequilibrium model, and a "hybrid" model. In the "hybrid" model, soil organic matter was conceptually divided into two compartments; a fraction with rapid sorption/desorption kinetics and a compartment with mass-transfer-limited kinetics. Contaminant sorbed in the rapid compartment was assumed to be in instantaneous equilibrium with the aqueous phase, while the release of contaminant from the slow fraction was assumed to be governed by a gamma distribution of rate coefficients. The "hybrid" model successfully described the initial rapid release of a model PAH contaminant, naphthalene, from a sieved soil sample of moderate organic content (congruent to 2.3%) as well as the following slow release observed over 25 days in batch desorption experiments. Other necessary model parameters, such as the hydrodynamic dispersion coefficient of naphthalene and the macropore porosity, were evaluated in separate experiments. A transport model incorporating the "hybrid" model for naphthalene sorption/desorption successfully predicted the elution profile of naphthalene in independent soil-column experiments with no adjustable parameters. The success of the hybrid model suggests that a wide array of rate controls govern PAH desorption. This conclusion is consistent with the view of soils as consisting of a mix of different sorptive constituents and heterogeneous physical constraints on PAH release.