CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai Shandong, 264003, PR China; Yantai Research Institute, Harbin Engineering University, Yantai, 264006, PR China.
State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China.
Water Res. 2024 Oct 15;264:122203. doi: 10.1016/j.watres.2024.122203. Epub 2024 Aug 2.
The passive sampling technique of diffusive gradients in thin-films (DGT) is promising for monitoring emerging contaminants such as per- and polyfluoroalkyl substances (PFAS). It is urgent to evaluate the impacts of salinity and exposure time on DGT sampling before it can be set as a standard method. Herein, DGT sampler based on the binding gel of weak anion exchanger (WAX) resin was deployed in a representative water system of the Xiaoqing river-estuary-sea for representative sampling windows (<1 day to 28 days) with high pH (8.18 ± 0.04 to 8.51 ± 0.17) and wide ranges of salinity (0.95 ± 0.07‰ to 14.37 ± 3.92‰), total dissolved solids (1.20 ± 0.09 g/L to 15.29 ± 3.91 g/L) and dissolved organic matter (2.8-32 mg/L). The results showed that the WAX-DGT sampler exhibited good performance for most target PFAS except for short-chain perfluorocarboxylates (C ≤ 5) in 14 days. When the exposure time was over 14 days, biofouling of the sampler may deflect the mass accumulation of the PFAS in the sampler. Salinity played an important role in the mass binding of PFAS by DGT. The shorter the carbon chain of the compound, the greater the influence of the salinity. PFAS with carboxyl groups had greater affinities for the biofouled membrane filter than those with sulfonic groups. In the river-estuary-sea system, where PFAS concentrations changed dynamically, the temporal resolution of the monitoring strategy has been demonstrated to be more important than spatial resolution. DGT provided a better integral of PFAS exposure than grab sampling in the dynamic water system and offered equivalent sensitivity of grab sampling with exposure time <10 d and greater sensitivity with exposure time ≥10 d. Thus, DGT has the advantage of providing high temporal resolution monitoring. This study provided support for the standardization of the DGT technique.
薄膜扩散梯度技术（DGT）是一种有前途的被动采样技术，可用于监测新兴污染物，如全氟和多氟烷基物质（PFAS）。在将其作为标准方法之前，迫切需要评估盐度和暴露时间对 DGT 采样的影响。在此，基于弱阴离子交换树脂（WAX）结合凝胶的 DGT 采样器被部署在一个具有代表性的小清河河口-海域系统中，用于具有高 pH 值（8.18±0.04 至 8.51±0.17）和宽盐度范围（0.95±0.07‰至 14.37±3.92‰）、总溶解固体（1.20±0.09 g/L 至 15.29±3.91 g/L）和溶解有机物（2.8-32 mg/L）的代表性采样窗口（<1 天至 28 天）进行代表性采样。结果表明，WAX-DGT 采样器对大多数目标 PFAS 表现良好，除了在 14 天内的短链全氟羧酸（C≤5）外。当暴露时间超过 14 天时，采样器的生物污垢可能会改变采样器中 PFAS 的质量积累。盐度对 DGT 中 PFAS 的质量结合起着重要作用。化合物的碳链越短，盐度的影响就越大。具有羧基的 PFAS 比具有磺酸基的 PFAS 对生物污染膜过滤器具有更大的亲和力。在 PFAS 浓度动态变化的河口水域系统中，监测策略的时间分辨率比空间分辨率更为重要。在动态水系统中，DGT 提供了对 PFAS 暴露的更好综合，与暴露时间<10 d 的抓样具有等效灵敏度，而暴露时间≥10 d 的抓样具有更高的灵敏度。因此，DGT 具有提供高时间分辨率监测的优势。本研究为 DGT 技术的标准化提供了支持。
