Institute of Organic Contaminant Control and Soil Remediation , College of Resource and Environmental Sciences, Nanjing Agricultural University , Nanjing 210095 , PR China.
Department of Plant, Soil and Microbial Sciences, and Environmental Science and Policy Program , Michigan State University , East Lansing , Michigan 48824 , United States.
Environ Sci Technol. 2018 Mar 6;52(5):2694-2703. doi: 10.1021/acs.est.7b05174. Epub 2018 Feb 21.
The sorption of polycyclic aromatic hydrocarbons (PAHs) to montmorillonites is largely influenced by their interactions with dissolved organic matter (DOM). However, the role of DOM rather than humic and fulvic acids (e.g., extracellular DNA) in the PAH sorption to soil clays is little known. Here, we demonstrate that extracellular double-stranded salmon testes DNA substantially increased the sorption of phenanthrene and pyrene to Na-, Ca-, and Fe-modified montmorillonites. All PAH sorption isotherms fitted the linear and Freundlich models reasonably well ( R = 0.918-0.999). Distribution coefficients were increased from 0.0458-0.103 and 0.0493-0.141 L/g at 0 mg/L DNA to 0.413-0.589 and 0.385-0.560 L/g at 10 mg/L DNA for phenanthrene and pyrene, respectively. Spectroscopic and computational chemistry analyses confirmed that PAHs were first inserted into DNA by binding with the nucleobases via van der Waals and π-π electron donor-acceptor interactions. Compared to PAHs, the DNA-PAH complex can be more easily sorbed to cation-modified montmorillonites by complexation between DNA phosphate and exchangeable cations in addition to intercalation into clay interlayers. This work highlights the importance of understanding the control on contaminant sorption by many organic compounds that are ubiquitous in soils but not represented by humic and fulvic acids.
多环芳烃（PAHs）与蒙脱石的吸附在很大程度上受到其与溶解有机质（DOM）相互作用的影响。然而，DOM 而非腐殖酸和富里酸（如胞外 DNA）在 PAH 吸附到土壤黏土中的作用知之甚少。在这里，我们证明了胞外双链鲑鱼精 DNA 大大增加了菲和芘在 Na-、Ca-和 Fe 改性蒙脱石上的吸附。所有 PAH 吸附等温线都很好地符合线性和 Freundlich 模型（R = 0.918-0.999）。分配系数从 0 毫克/升 DNA 时的 0.0458-0.103 和 0.0493-0.141 L/g 增加到 10 毫克/升 DNA 时的 0.413-0.589 和 0.385-0.560 L/g，分别用于菲和芘。光谱和计算化学分析证实，PAHs 首先通过范德华力和π-π电子供体-受体相互作用与碱基结合插入 DNA 中。与 PAHs 相比，DNA-PAH 复合物可以通过 DNA 磷酸盐与可交换阳离子之间的络合以及插入黏土夹层来更容易地被阳离子改性蒙脱石吸附，除了插层进入黏土夹层之外。这项工作强调了理解许多在土壤中普遍存在但未被腐殖酸和富里酸代表的有机化合物对污染物吸附的控制的重要性。
