摘要：

The nature of the abiotic birnessite (δ-MnO2)-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-MnO2 of two typical humus and ligninphenolic monomers--catechol and p-coumaric acid--in the presence andabsence 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 theresidues were probably bound via ester or ether bonds. The study provides important information on δ-MnO2 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.

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