Preliminary Electron Paramagnetic Resonance (EPR) studies of copper/chromium (CC) treated spruce wood, subjected to laboratory soil decay test showed increased intensities of Mn(II) EPR signal in partially decayed specimens. Several reasons might be responsible for this phenomenon: Mn(II) could originate from the wood after being released from the typical ligand binding, from reduction of other Mn species in the wood into Mn(II), or because of translocation of Mn by wood decay fungi. To elucidate this question, we performed several extensive laboratory investigations. Untreated and copper treated spruce wood samples were exposed in petri dishes to fungal cultures of Antrodia vaillantii, Gloeophyllum trabeum and Trametes versicolor for two to twelve weeks. Some samples were not exposed to fungi but treated only with aqueous solutions of oxalic or sulphuric acid. After exposure to fungi or acid solutions, pH values and EPR spectra of wood specimens were measured. In addition, Mn content in decayed wood samples was determined by AAS. Increased intensities of Mn(II) EPR signal were detected in wood, treated with the acid solutions. Similar observation was noticed also at partially decayed specimens. AAS revealed that the concentration of Mn in wood, exposed to A. vaillantii and T. versicolor did not increase during decay. On the basis of these findings we believe that the increase of Mn(II) EPR signal is the result of chemical changes (reduction) of intrinsically present Mn in wood due to acidifying by wood rotting fungi and not caused by translocation via fungal mycelium from the substrate into wood samples. The exception was G. trabeum, for which important contribution of translocation process was observed.

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