Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing, China.
Environ Toxicol Chem. 2012 Jul;31(7):1431-7. doi: 10.1002/etc.1844. Epub 2012 May 9.
The organic matter-mineral complex plays an important role in regulating the fate of hydrophobic organic compounds (HOCs) in the environment. In the present study, the authors investigated the microbial bioavailability of phenanthrene (PHE) sorbed on the original and demineralized humic acids (HAs) and humin (HM) that were sequentially extracted from a peat soil. Demineralization treatment dramatically decreased the 720-h mineralized percentage of HM-sorbed PHE from 42.5 ± 2.6% to 3.4 ± 1.3%, whereas the influence of this treatment on the biodegradability of HA-associated PHE was much lower. Degradation kinetics of HA- and HM-sorbed PHE showed that its initial degradation rate was negatively correlated with the aromatic carbon content of humic substances (p<0.05). This was attributed to the strong interactions between PHE and the aromatic components of humic substances, which hampered its release and subsequent biodegradation. The 720-h mineralized percentage of PHE was inversely correlated with the estimated thickness of the organic matter layer at the surfaces of HAs and HMs. Therefore, in a relatively long term, diffusion of PHE within the organic matter layer could be an important factor that may limit the bioavailability of PHE to bacteria. Results of the present study highlight the molecular-scaled mechanisms governing bioavailability of PHE sorbed on humic substances.
有机-矿物复合体在调节环境中疏水性有机化合物（HOCs）的命运方面起着重要作用。在本研究中，作者研究了从泥炭土壤中依次提取的原始腐殖酸（HA）和腐殖质（HM）吸附的菲（PHE）的微生物生物可利用性。脱矿物质处理使 HM 吸附的 PHE 在 720 小时内的矿化百分比从 42.5±2.6%急剧下降至 3.4±1.3%，而这种处理对 HA 相关 PHE 的生物降解性的影响要低得多。HA 和 HM 吸附的 PHE 的降解动力学表明，其初始降解速率与腐殖质中芳香碳含量呈负相关（p<0.05）。这归因于 PHE 与腐殖质的芳香成分之间的强相互作用，这阻碍了其释放和随后的生物降解。PHE 的 720 小时矿化百分比与 HA 和 HM 表面估计的有机物层厚度呈反比。因此，在较长的时间内，PHE 在有机物层内的扩散可能是限制 PHE 对细菌生物可利用性的一个重要因素。本研究的结果突出了控制腐殖质吸附的 PHE 生物可利用性的分子尺度机制。
