Biology 5, Environmental Biology and Chemodynamics, RWTH Aachen University, D-52056 Aachen, Germany.
Environ Sci Technol. 2012 Aug 21;46(16):8843-50. doi: 10.1021/es3018732. Epub 2012 Aug 10.
The nature of the abiotic birnessite (δ-MnO(2))-catalyzed transformation products of phenolic compounds in the presence of soil organic matter is crucial for understanding the fate and stability of ubiquitous phenolic carbon in the environment. (14)C-radioactive and (13)C-stable-isotope tracers were used to study the mineralization and transformation by δ-MnO(2) of two typical humus and lignin phenolic monomers--catechol and p-coumaric acid--in the presence and absence of agricultural and forest soil humic acids (HAs) at pH 5-8. Mineralization decreased with increasing solution pH, and catechol was markedly more mineralized than p-coumaric acid. In the presence of HAs, the mineralization was strongly reduced, and considerable amounts of phenolic residues were bound to the HAs, independent of the solution pH. The HA-bound residues were homogeneously distributed within the humic molecules, and most still contained the unchanged aromatic ring as revealed by (13)C NMR analysis, indicating that the residues were probably bound via ester or ether bonds. The study provides important information on δ-MnO(2) stimulation of phenolic carbon binding to humic substances and the molecular distribution and chemical structure of the bound residues, which is essential for understanding the environmental fates of both naturally occurring and anthropogenic phenolic compounds.
无生命的水钠锰矿（δ-MnO₂）催化存在土壤有机质时酚类化合物转化产物的性质对于了解环境中普遍存在的酚类碳的归宿和稳定性至关重要。¹⁴C 放射性和¹³C 稳定同位素示踪剂被用于研究在 pH 值为 5-8 时，两种典型的腐殖质和木质素酚单体——儿茶酚和对香豆酸——在农业和森林土壤腐殖酸（HA）存在和不存在的情况下，被 δ-MnO₂矿化和转化的情况。矿化作用随溶液 pH 值的增加而降低，儿茶酚的矿化程度明显高于对香豆酸。在 HA 的存在下，矿化作用被强烈抑制，并且相当数量的酚类残留物与 HA 结合，而与溶液 pH 值无关。HA 结合的残留物均匀分布在腐殖质分子内，并且大多数仍含有未改变的芳环，如¹³C NMR 分析所示，这表明残留物可能通过酯或醚键结合。该研究提供了关于 δ-MnO₂刺激酚类碳与腐殖质结合以及结合残留物的分子分布和化学结构的重要信息，这对于理解天然存在和人为酚类化合物的环境归宿至关重要。
