McInnis Daniel P, Bolster Diogo, Maurice Patricia A
Department of Civil & Environmental Engineering & Earth Sciences, University of Notre Dame , Notre Dame, Indiana.
Environ Eng Sci. 2015 Jan 1;32(1):4-13. doi: 10.1089/ees.2014.0253.
Transport of dissolved organic matter (DOM) from the Suwannee River and of synthetic polystyrene sulfonates (PSSs) was investigated in columns packed with naturally Fe/Al-oxide-coated sands from Oyster, Virginia. Surface-water samples were collected in May 2012 and processed by XAD-8 (humic substances; HPOA), XAD-4 (transphilic acids [TPIAs]), and reverse osmosis (broad range of components; NOM). Median transport time ( ) of PSSs increased with molecular weight (MW) from 1,000 to 8,000 Da but decreased for the largest PSS (18,000 Da), which is consistent with previous observations of MW effects on DOM adsorption and transport. Breakthrough curves (BTCs) of HPOAs and NOM were similar whereas TPIA transport was distinct; although all DOM samples had similar values, BTC asymmetry and dispersivity were greater for TPIAs. All samples exhibited power-law tailing that is characteristic of heterogeneous sorbent/sorbate interactions, potentially including kinetic effects. The one-dimensional advection-dispersion equation was unable to capture the tailing but it was captured well using a continuous-time random walk (CTRW) model. CTRW parameters were similar for the NOM and HPOA samples but distinctly different for TPIAs, which had more pronounced tailing. While retardation of organics generally tends to increase with MW, the lower average MW of TPIAs did not result in decreased overall retardation, which suggests the importance of compositional differences. Results suggest that while TPIAs tend to be a relatively minor component of DOM, their transport behavior differs from that of the predominant HPOA fraction, and they might thus have different impacts on pollutant transport.
在填充有弗吉尼亚州牡蛎市天然铁/铝氧化物包覆砂的柱体中，研究了来自苏万尼河的溶解有机物（DOM）和合成聚苯乙烯磺酸盐（PSSs）的迁移情况。2012年5月采集了地表水样本，并通过XAD - 8（腐殖物质；HPOA）、XAD - 4（亲水性酸[TPIAs]）和反渗透（广泛的成分；NOM）进行处理。PSSs的中位迁移时间（ ）随着分子量（MW）从1000 Da增加到8000 Da而增加，但对于最大的PSS（18000 Da）则下降，这与先前关于分子量对DOM吸附和迁移影响的观察结果一致。HPOA和NOM的突破曲线（BTCs）相似，而TPIA的迁移则不同；尽管所有DOM样本具有相似的 值，但TPIA的BTC不对称性和分散性更大。所有样本均表现出幂律拖尾，这是异质吸附剂/吸附质相互作用的特征，可能包括动力学效应。一维对流扩散方程无法捕捉到拖尾现象，但使用连续时间随机游走（CTRW）模型能很好地捕捉到。NOM和HPOA样本的CTRW参数相似，但TPIA的参数明显不同，TPIA有更明显的拖尾现象。虽然有机物的滞留通常倾向于随着分子量增加而增加，但TPIA较低的平均分子量并未导致总体滞留减少，这表明成分差异的重要性。结果表明，虽然TPIA往往是DOM中相对较小的成分，但其迁移行为与主要的HPOA部分不同，因此它们可能对污染物迁移有不同的影响。
