School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, PMB1, Glen Osmond, South Australia 5064, Australia.
School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, PMB1, Glen Osmond, South Australia 5064, Australia.
Environ Pollut. 2024 Sep 1;356:124234. doi: 10.1016/j.envpol.2024.124234. Epub 2024 May 28.
Per- and poly-fluoroalkyl substances (PFASs) are contaminants of emerging concern, yet the understanding of factors that control their leaching and release from contaminated soils remains limited. This study aimed to investigate the impact of dissolved organic carbon (DOC) on the release of PFASs-specifically, perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonate (PFOS), and perfluorooctanoic acid (PFOA)from soils contaminated by aqueous film forming foam (AFFF). Batch aqueous leaching experiments were conducted on AFFF-contaminated soils under alkaline solution conditions (pH 9.5, 10.5, and 12) as it enhances leaching of both PFAS and DOC. Leaching of PFOS was significantly increased under alkaline conditions. Although the leaching of PFAS generally increased with pH, PFOS appeared to be more retained under the very alkaline pH conditions used in this study. At the same solution pH, leaching of PFOS and DOC was less in Ca(OH) than in NaOH. The retention of PFOS under these conditions may be attributable to the shielding of the negative charge of the soil components and colloids (e.g., DOC and clay minerals) in the leachates and/or the screening of negative charges on head groups of PFOS due to the high concentration of divalent cations. Solution chemistry affected desorption of PFOS more than PFHxS and PFOA. The study highlights that the influence of DOC on PFAS leaching and transport can be very complex, and depends on leachate chemistry (e.g., pH and cation type), PFAS chemistry, the magnitude of PFAS contamination and factors that influence the solid:liquid partitioning of organic carbon in soil.
全氟和多氟烷基物质（PFAS）是新兴的关注污染物，但控制其从污染土壤中浸出和释放的因素仍知之甚少。本研究旨在探讨溶解有机碳（DOC）对 PFAS 释放的影响，特别是全氟己烷磺酸（PFHxS）、全氟辛烷磺酸（PFOS）和全氟辛酸（PFOA）从水性成膜泡沫（AFFF）污染土壤中的释放。在碱性溶液条件（pH 值 9.5、10.5 和 12）下进行了 AFFF 污染土壤的批处理水浸出实验，因为这会增强 PFAS 和 DOC 的浸出。在碱性条件下，PFOS 的浸出明显增加。尽管 PFAS 的浸出通常随 pH 值的增加而增加，但在本研究中使用的非常碱性 pH 值条件下，PFOS 似乎被保留得更多。在相同的溶液 pH 值下，在 Ca(OH)2 中 PFOS 和 DOC 的浸出量小于在 NaOH 中。在这些条件下 PFOS 的保留可能归因于土壤成分和胶体（例如，DOC 和粘土矿物）的负电荷在浸出液中的屏蔽和/或由于二价阳离子的高浓度，PFOS 头基上的负电荷的屏蔽。溶液化学对 PFOS 的解吸影响大于 PFHxS 和 PFOA。该研究强调，DOC 对 PFAS 浸出和迁移的影响可能非常复杂，取决于浸出液化学性质（例如，pH 值和阳离子类型）、PFAS 化学性质、PFAS 污染程度以及影响土壤中有机碳固液分配的因素。
