Key Laboratory of Low-Carbon Green Agriculture in Northwestern China, Ministry of Agriculture and Rural Affairs, College of Nature Resources and Environment, Northwest A & F University, Yangling 712100, PR China.
Program for Environment and Sustainability, Department of Environment and Occupational Health, School of Public Health, Texas A&M University, College Station, TX 77843, United States.
Sci Total Environ. 2023 Apr 15;869:161747. doi: 10.1016/j.scitotenv.2023.161747. Epub 2023 Jan 21.
The formation of toxic by-products, such as environmentally persistent free radicals (EPFRs), is one of the causes for concern by polycyclic aromatic hydrocarbons (PAHs) in soils. However, the distribution of EPFRs in different soil fractions and their relative contribution to the oxidation potential (OP) have not been investigated. In the present paper, contaminated samples were obtained from the former gasworks sites and were fractionated into different size particles, which were analyzed for EPFRs, reactive oxygen species (ROS), and OP-assayed by dithiothreitol (DTT) (OP). The results showed the highest concentration of EPFRs in the soil particle size with diameters <0.15 mm due to co-existence of PAHs and transition metals. ROS generation is in accordance with the size-specific distribution of EPFRs. Using the DTT assays, the redox activity of various size soil particles was examined, and found it was approximately 4- to 8-folds higher than that of un-contaminated samples and strongly associated with EPFRs, ROS, and PAHs. The obtained results advanced our knowledge on the EPFRs distribution in soil fractions at former MGP sites and emphasized the significance of PAH-EPFRs as a class of compounds to be considered in risk assessment of contaminated sites.
有毒副产物的形成，如环境持久性自由基（EPFRs），是土壤中多环芳烃（PAHs）引起关注的原因之一。然而，EPFRs 在不同土壤组分中的分布及其对氧化电位（OP）的相对贡献尚未得到研究。在本文中，从以前的煤气厂遗址获得了受污染的样品，并将其分为不同粒径的颗粒，对 EPFRs、活性氧物种（ROS）和用二硫苏糖醇（DTT）测定的氧化电位（OP）进行了分析。结果表明，由于 PAHs 和过渡金属的共存，直径<0.15mm 的土壤颗粒中 EPFRs 的浓度最高。ROS 的生成与 EPFRs 的尺寸特异性分布一致。使用 DTT 测定法，检查了各种粒径土壤颗粒的氧化还原活性，发现其活性比未受污染的样品高约 4-8 倍，并且与 EPFRs、ROS 和 PAHs 密切相关。所得结果提高了我们对前 MGP 遗址土壤组分中 EPFRs 分布的认识，并强调了 PAH-EPFRs 作为一类化合物在污染场地风险评估中需要考虑的重要性。
