Occurrence of manganese deposits in test stakes exposed in groung contact situations

IRG/WP 96-10182

G F Daniel, T Nilsson, J Volc

Dark spots and flecks were frequently recognized on the surface and within non-preservative treated hard- and softwood test stakes placed in soil contact. Energy dispersive X-ray microanalysis in conjunction with electron microscopy showed the flecks to be composed primarily of manganese dioxide. Detailed transmission electron microscopy observations indicated intrusion of manganese into the wood cell lumena and into areas of erosion, cavity formation and decayed middle lamella regions in wood cells attacked by fungi and/or bacteria. Distinct zones of apparent delignification were also noted in the secondary cell walls and middle lamella regions of attacked cells. Manganese is thought to play a major regulating role in both lignin depolymerization and minerialization in the presence of organic acids and has been reported previously in white rotted wood removed from standing trees. Present observations also suggest the uptake of manganese into wood stakes during microbial degradation results from biotic activity. Soil type appears to be of major significance.


Keywords: MANGANESE; STAKES; DECAY; ELECTRON MICROSCOPY; TEM; ANALYSIS; WHITE ROT; EDXA

Conference: 96-05-19/24 Guadeloupe, France


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