School of Agriculture, Food and Wine, The University of Adelaide, PMB 1, Waite Campus, Glen Osmond, SA 5064, Australia.
ALS, Life Sciences Division, 277 Woodpark Road Smithfield, NSW 2164, Australia.
Sci Total Environ. 2021 Apr 20;766:144857. doi: 10.1016/j.scitotenv.2020.144857. Epub 2021 Jan 2.
The global problem of groundwater being contaminated with per- and polyfluoroalkyl substances (PFASs) originating from highly contaminated soils has created a need to remediate these locations. In situ immobilisation of PFASs in soil by applying sorbents is often a preferred low-cost technique to reduce their mobility and leaching to groundwater, but the long-term efficacy of sorbents has not yet been investigated. In this study, the longevity of remediation of two different soils by two common sorbents (RemBind®, and pulverized activated carbon, Filtrasorb™ 400) was assessed. Regulatory agencies often rely on standardised leaching procedures to assess the risk of contaminant mobility in soils. Hence, the Australian Standard Leaching Procedure and the U.S. EPA Leaching Environmental Assessment Framework were applied to quantify the desorption/leaching of a wide range of PFASs from unremediated and remediated soils under a range of pH conditions (pH 2 to 12). Ease of desorption and subsequent leaching from the unremediated soils was related to C-chain length; while short-chain PFASs were easily desorbed and leached, long-chain PFASs were more difficult to desorb. Desorption of long-chain PFASs was also pH dependent in unremediated soils, with desorption being greater at high pH. Both sorbents retained PFASs strongly in the remediated soils (> 99% for most PFASs) across a broad range of pH conditions, with only small differences between the sorbents in terms of efficacy. Both sorbents showed better retention of PFASs under low pH conditions. Remediation of PFAS-contaminated soils with these sorbents could be considered robust and durable in terms of changes in soil pH, with little risk of subsequent PFASs desorption under normal environmental pH conditions. Ultimately, to give regulators and site owners the greatest level of confidence that immobilisation is stable for the longer term, it should also be tested under repeated cycles of leaching and under different conditions.
地下水受到源自高度污染土壤的全氟和多氟烷基物质 (PFASs) 污染是一个全球性问题，因此需要修复这些地点。通过施用吸附剂将 PFASs 在土壤中就地固定化，通常是一种降低其流动性和向地下水淋滤的低成本技术，但吸附剂的长期效果尚未得到研究。在这项研究中，评估了两种常见吸附剂（RemBind®和粉碎的活性炭 Filtrasorb™ 400）对两种不同土壤的修复持久性。监管机构通常依赖标准化浸出程序来评估土壤中污染物迁移的风险。因此，应用澳大利亚标准浸出程序和美国环保署浸出环境评估框架来量化未修复和修复土壤中各种 PFASs 在一系列 pH 值条件下（pH 2 至 12）的解吸/浸出。未修复土壤中解吸和随后浸出的容易程度与 C 链长度有关；虽然短链 PFASs 容易解吸和浸出，但长链 PFASs 则更难解吸。未修复土壤中长链 PFASs 的解吸也依赖于 pH 值，在高 pH 值下解吸更大。在广泛的 pH 值条件下，两种吸附剂都能强烈保留修复土壤中的 PFASs（大多数 PFASs 的保留率超过 99%），在功效方面两者之间只有很小的差异。在低 pH 值条件下，两种吸附剂对 PFASs 的保留效果更好。考虑到土壤 pH 值变化时，这些吸附剂修复 PFAS 污染土壤的效果可以被认为是稳健和持久的，在正常环境 pH 值条件下，几乎没有随后 PFASs 解吸的风险。最终，为了让监管机构和场地所有者对固定化在更长时间内的稳定性有最大程度的信心，还应在重复浸出循环和不同条件下进行测试。
