Suchana Shamsunnahar, Edwards Elizabeth, Mack E Erin, Lomheim Line, Melo Natanna, Gavazza Sávia, Passeport Elodie
Department of Civil & Mineral Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario M5S 1A4, Canada.
Department of Chemical Engineering & Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada.
Sci Total Environ. 2024 Jan 1;906:167628. doi: 10.1016/j.scitotenv.2023.167628. Epub 2023 Oct 6.
Compound specific isotope analysis (CSIA) is a powerful technique to demonstrate in situ degradation of traditional groundwater contaminants when concentrations are typically in the mg/L range. Currently, an efficient preconcentration method is lacking to expand CSIA to low aqueous concentration environmental samples. Specially for the H- and N-CSIA of heteroatom-bearing non-traditional compounds, the CSIA analytical detection limits are significantly higher than that of the C-CSIA. This work demonstrates the compatibility of polar organic chemical integrative sampler (POCIS) with C-, H-, and N-CSIA using four nitro- and amino-substituted chlorobenzenes that are common industrial feedstocks for numerous applications and are commonly detected in the environment at mg/L to μg/L range. Using lab experiments, we showed isotopic equilibrium in POCIS was achieved after 30 days with either a negligible (<0.5 ‰) or a constant shift for C (<1 ‰) and N (<2 ‰). Similar negligible (<5 ‰) or constant shift (<20 ‰) was evident for H isotope except for 3,4-dichloroaniline. The method quantification limits for the combined sorbent and membrane of one POCIS were comparable to that of the solid phase extraction (SPE) using 10 L water. Next, we demonstrated the field applicability of POCIS for C- and N-CSIA after a 60-day deployment in a pilot constructed wetland by showing <1 ‰ difference between the δC and δN obtained from POCIS and SPE. Finally, we evaluated whether the biofilm development on POCIS membrane could affect the isotope signature of the sampled compounds during field deployment. Although a diverse microbial community was identified on the membrane after a 60-day deployment, we did not observe significant isotope fractionation. This was likely due to either slower diffusion in the biofilm or microbial degradation of the sampled compounds. This work demonstrates the potential of using POCIS-CSIA as a simple, fast, and sensitive method for low-concentration contaminants, such as pesticides, pharmaceuticals, and flame-retardants.
化合物特异性同位素分析（CSIA）是一种强大的技术，可用于证明传统地下水污染物在浓度通常处于毫克/升范围内时的原位降解情况。目前，缺乏一种有效的预浓缩方法来将CSIA扩展至低水相浓度的环境样品。特别是对于含杂原子的非传统化合物的氢和氮CSIA，其分析检测限显著高于碳CSIA。本研究使用四种硝基和氨基取代的氯苯，证明了极性有机化学综合采样器（POCIS）与碳、氢和氮CSIA的兼容性，这四种氯苯是众多应用中常见的工业原料，在环境中通常以毫克/升至微克/升的浓度被检测到。通过实验室实验，我们发现POCIS在30天后实现了同位素平衡，碳（<0.5‰）和氮（<1‰）的变化可忽略不计或呈恒定偏移，氢同位素除3,4 - 二氯苯胺外也有类似的可忽略不计（<5‰）或恒定偏移（<20‰）。一个POCIS的吸附剂和膜组合的方法定量限与使用10升水的固相萃取（SPE）相当。接下来，我们通过展示POCIS和SPE获得的δC和δN之间的差异<1‰，证明了POCIS在中试人工湿地中部署60天后对碳和氮CSIA的现场适用性。最后，我们评估了POCIS膜上生物膜的形成是否会在现场部署期间影响采样化合物的同位素特征。尽管在部署60天后在膜上鉴定出了多样化的微生物群落，但我们未观察到明显的同位素分馏现象。这可能是由于生物膜中扩散较慢或采样化合物被微生物降解所致。本研究证明了使用POCIS - CSIA作为一种用于低浓度污染物（如农药、药物和阻燃剂）的简单、快速且灵敏方法的潜力。
