PAH sorption mechanism and partitioning behavior in lampblack-impacted soils from former oil-gas plant sites
PAH sorption mechanism and partitioning behavior in lampblack-impacted soils from former oil-gas plant sites
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DOI：
10.1021/es0262683
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发表时间：
2003-08-15
影响因子：
11.4
通讯作者：
Luthy, RG
中科院分区：
文献类型：
--
作者：
Hong, L;Ghosh, U;Luthy, RG
本研究评估了加州五个油田油烟污染土壤中多环芳烃（PAH）的结合和水相分配。油烟是在制气过程中原油在高温下分解产生的固体残渣，并被石油气化副产物包裹或浸渍，其中多环芳烃是监管部门最关注的化合物。一套补充测量研究了油烟颗粒的特征和多环芳烃的位置，以及对油烟和水之间多环芳烃分配的相关影响。整体样品和密度分离组分的多环芳烃分析表明，油烟影响土壤中81 ~ 100%的多环芳烃与油烟颗粒有关。FTIR， C-13 NMR和SEM分析表明，油气油烟固体主要由具有煤烟状结构的芳香碳组成。在一些含有高浓度多环芳烃的油烟土中可能存在游离相芳香油。用气桥技术和离心/明矾絮凝程序获得了可比的长期水分配测量结果。固体/水分配系数（K-d）值在含有较低多环芳烃和油的样品中观察到，而Kd值在含有较高多环芳烃的油烟样品中测量到。前者与油烟配分模型一致，后者与煤焦油-水配分模型一致。含有高多环芳烃水平的油烟似乎耗尽了烟灰碳的吸收能力，产生了一种自由的芳香油相，其表现出与煤焦油中多环芳烃相似的分配行为。本研究提高了对前油气场地陈旧油烟残留物中多环芳烃吸附机理的认识，并为此类场地材料的多环芳烃浸出潜力和风险的机理评估提供了框架。
This study assessed polycyclic aromatic hydrocarbon (PAH) association and aqueous partitioning in lampblack-impacted field soils from five sites in California that formerly housed oil-gas process operations. Lampblack is the solid residue resulting from the decomposition of crude oil at high temperatures in the gas-making operation and is coated or impregnated with oil gasification byproducts, among which PAHs are the compounds of the greatest regulatory concern. A suite of complementary measurements investigated the character of lampblack particles and PAH location and the associated effects on PAH partitioning between lampblack and water. PAH analyses on both whole samples and density-separated components demonstrated that 81-100% of PAHs in the lampblack-impacted soils was associated with lampblack particles. FTIR, C-13 NMR, and SEM analyses showed that oil-gas lampblack solids comprise primarily aromatic carbon with soot-like structures. A free-phase aromatic oil may be present in some of the lampblack soils containing high PAH concentrations. Comparable long-term aqueous partitioning measurements were obtained with an air-bridge technique and with a centrifugation/alum flocculation procedure. Large solid/water partition coefficient (K-d) values were observed in samples exhibiting lower PAH and oil levels, whereas smaller Kd values were measured in lampblack samples containing high PAH levels. The former result is in agreement with an oil-soot partitioning model, and the latter is in agreement with a coal tar-water partitioning model. Lampblack containing high PAH levels appears to exhaust the sorption capacity of the soot-carbon, creating a free aromatic oil phase that exhibits partitioning behavior similar to PAHs in coal tar. This study improves mechanistic understanding of PAH sorption on aged lampblack residuals at former oil-gas sites and provides a framework for mechanistic assessment of PAH leaching potential and risk from such site materials.