Subsurface Transport Potential of Perfluoroalkyl Acids at Aqueous Film-Forming Foam (AFFF)-Impacted Sites
Subsurface Transport Potential of Perfluoroalkyl Acids at Aqueous Film-Forming Foam (AFFF)-Impacted Sites
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DOI：
10.1021/es3048043
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发表时间：
2013-05-07
影响因子：
11.4
通讯作者：
Higgins, Christopher P.
中科院分区：
文献类型：
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作者：
Guelfo, Jennifer L.;Higgins, Christopher P.
在与水成膜泡沫 (AFFF) 影响位点相关的共污染物存在的情况下，通过各种土壤的批量吸附实验研究了一系列全氟烷基酸 (PFAA) 的地下传输潜力。具体来说，研究了在非水相液体 (NAPL) 和非氟化 AFFF 表面活性剂存在下，PFAA 对多种土壤的吸附情况。这项研究首次报告了全氟丁酸 (PFBA) 和全氟戊酸 (PFPeA) 的吸附（log K-oc = 1.88 和 1.37，分别），并发现这些化合物的吸附并不遵循较长链长 PFAA 观察到的链长依赖性趋势。 PFBA 的吸附与全氟辛酸盐相似（PFOA，log K-oc = 1.89）。 NAPL 和非氟化 AFFF 表面活性剂对长链（> 6 CF2 基团）PFAA 的吸附都有不同的影响。 NAPL 的主要影响是在低 f(oc) 土壤（土壤 A）中观察到的，当 NAPL 存在时，Freundlich n 值会增加。非氟化水成膜水成膜表面活性剂的影响随表面活性剂和土壤的不同而变化。阴离子表面活性剂癸基硫酸钠 (SDS) 对两种具有不同 f(oc) 的带负电荷的土壤产生非法的 PFAA 链长依赖性影响。在土壤 A 中，使用 SDS 后，全氟庚酸 (PFHpA) 的 K-d 值增加了 91%，而全氟癸酸 (PFDA) 的值仅增加了 28%。两性表面活性剂 n,n-二甲基十二胺 n-氧化物 (AO) 对带正电荷的土壤（土壤 C）上的 PFAA 吸附具有最显着的影响。在这种土壤中，AO 氧化物显着增加了对长链 PFAA 的吸附（即 PFDA 的 K-d 增加了 528%）。 SDS 和 AO 引起的吸附变化可能是由于混合半胶束的形成、竞争性吸附或 PFA 溶解度的变化。 NAPL、SDS 和 AO 存在下的短链 PFAA 行为再次值得注意。共污染物通常会增加这些化合物对所有土壤的吸附。在 NAPL、SDS 和 AO 存在下，土壤 A 中 PFBA 的 Log K-d 值分别增加了 85%、372% 和 32%。使用 K-d 值计算 PFAA 的延迟因子 (R-f)，证明了共污染物对 PFAA 迁移影响的可变性。尽管 NAPL 和非氟化表面活性剂在较低 PFOS 浓度（1 μg/L）下降低了全氟辛烷磺酸（PFOS）的吸附，但它们导致在较高 PFOS 浓度（500 μg/L）下吸附增加。这些结果表明，PFAA 地下水迁移取决于固相特性以及 PFAA 浓度和链长。可能需要详细的特定地点信息来准确预测受 AFFF 影响的地点的 PFAA 迁移。
Subsurface transport potential of a suite of perfluoroalkyl acids (PFAAs) was studied in batch sorption experiments with various soils and in the presence of co-contaminants relevant to aqueous film-forming foam (AFFF)-impacted sites. Specifically, PFAA sorption to multiple soils in the presence of nonaqueous phase liquid (NAPL) and nonfluorinated AFFF surfactants was examined. This study is the first to report on sorption of perfluorobutanoate (PFBA) and perfluoropentanoate (PFPeA) (log K-oc = 1.88 and 1.37, respectively) and found that sorption of these compounds does not follow the chain-length dependent trend observed for longer chain-length PFAAs. Sorption of PFBA was similar to that of perfluorooctanoate (PFOA, log K-oc = 1.89). NAPL and nonfluorinated AFFF surfactants all had varying impacts on sorption of longer chain (>6 CF2 groups) PFAAs. The primary impact of NAPL was observed in low f(oc) soil (soil A) where Freundlich n-values increased when NAPL was present. Impacts of nonfluorinated AFFF surfactants varied with surfactant and soil. The anionic surfactant sodium decyl sulfate (SDS) illicited PFAA chain-length dependent impacts in two negatively charged soils with varying f(oc). In soil A, K-d values for perfluoroheptanoate (PFHpA) increased 91% with SDS, whereas values for perfluorodecanoate (PFDA) increased only 28%. An amphoteric surfactant, n,n-dimethyldodecylamine n-oxide (AO), had the most notable impact on PFAA sorption to a positively charged soil (soil C). In this soil, AO oxide significantly increased sorption for the longer chain PFAAs (i.e., 528% increase in K-d for PFDA). Changes in sorption caused by SDS and AO may be due to mixed hemimicelle formation, competitive sorption, or changes to PFAA solubility. Short-chain PFAA behavior in the presence of NAPL, SDS, and AO was again notable. Co-contaminants generally increased the sorption of these compounds to all soils. Log K-d values of PFBA in soil A increased 85%, 372%, and 32% in the presence of NAPL, SDS, and AO, respectively. Use of K-d values to calculate retardation factors (R-f) of PFAAs demonstrates the variability of co-contaminant impacts on PFAA transport. Whereas NAPL and nonfluorinated surfactants decreased the sorption of perfluorooctanesulfonate (PFOS) at lower PFOS concentrations (1 mu g/L), they led to increases in sorption at higher PFOS concentrations (500 mu g/L). These results demonstrate that PFAA groundwater transport will depend on the solid phase characteristics as well as PFAA concentration and chain length. Detailed site-specific information will likely be needed to accurately predict PFAA transport at AFFF-impacted sites.