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The use of a physical field model to study the effects of remedially treated timber on the growth of perennial ryegrass (Lolium perenne) and rye (Secale cereale), and the accumulation of toxic preservative constituents in Lolium perenne
1995 - IRG/WP 95-50040-02
Low cost laboratory model systems can be used to give relatively rapid indications of the environmental effects of preservative treated timber in soil contact. This paper details the effects of remedially treated timber on the growth of crops of Lolium perenne and Secale cereale seeded on soilbeds of different texture in close proximity to remedially treated creosoted pole sections. Lolium perenne sward samples were subjected to chemical analysis for fluoride and chromium content to identify bio-accumulation of these toxic preservative components. Significant but variable reductions in the dry weight yields of Lolium perenne samples were found in conjunction with increased fluoride and chromium contents, together with significant reductions in the density of Lolium perenne swards. The difference in soil texture however was found to be a more significant influence on the growth of Secale cereale than the presence of treated timber. Secale cereale plants within a crop canopy established on the lighter textured soil were characteristically larger and more numerous than plants from canopies on heavier soils. Results are discussed as part of an overall environmental assessment of the remedial treatment and in terms of the suitability of the physical field model as a testbed for such plant studies.
D C R Sinclair, G M Smith, A Bruce, H J Staines

Oxalate production and calcium oxalate accumulation by Gloeophyllum trabeum in buffered cultures
1994 - IRG/WP 94-10075
Most basidiomycetous fungi produce oxalic acid as a result of their metabolic activities and nutrient procurement. There is currently a renewed interest in the role that oxalic acid may play in the decomposition of wood by basidiomycete fungi. It has been observed that although most wood degrading fungi have the capacity to produce oxalic acid, not all of these organisms express this capacity equally in the wood environment. In addition, not all of the fungi which produce oxalic acid will accumulate this metabolite. Very often the production of oxalic acid is coincident with the precipitation of oxalate salts such as calcium oxalate. At this time it is unclear as to what controls the differential production and accumulation of oxalate by wood degrading fungi. An investigative series of experiments was established using the brown rot fungus Gloeophyllum trabeum to examine the conditions which favor oxalate production and accumulation as manifested through the production of metastable calcium oxalate dihydrate crystals. Batch cultures which were buffered by base cation exchange sites of mineral amendments stimulated the production of calcium oxalate crystals. The results of these buffering experiments indicate that at pH values below approximately 6.0 there is a diminution of oxalate accumulation, and that a pH environment of approximately 3.0 is consistently attained in weakly buffered cultures inoculated with this fungus. These pH values correspond to the pH optima for oxaloacetase (EC and oxalate decarboxylase (EC respectively, and thereby suggest a mechanism for both pH control and oxalate production and accumulation.
J H Connolly, J Jellison

Determination of absorption, accumulation and transport of copper in mycelium of some wood decay fungi
1999 - IRG/WP 99-10323
Copper compounds are common wood preservatives. However, tolerance of some wood decay fungi to copper compounds has been observed recently. Therefore, we tried to elucidate possible causes of this phenomenon. We investigated uptake, accumulation and secretion of copper in the mycelium of potentially copper tolerant fungi (Antrodia sp.) and non tolerant fungus Trametes versicolor. We observed that potentially tolerant fungi have lower uptake of copper to the mycelium than non tolerant species. They also do not transport copper into the medium. That means that copper tolerance of fungi is probably based on low uptake of copper to the mycelium and not on the active transport from the mycelium to the medium.
F Pohleven, S Breznikar, P Kalan, M Petric

Surface accumulation of copper on CCA-impregnated Pinus patula stakes during marine preservative trials in the southern hemisphere
1992 - IRG/WP 92-4181
Pinus patula stakes treated with CCA to target retentions of 30 kg/m³ salts were exposed to sea water in marine and estuarine ecosystems off the coast of Southern Africa for two years. Samples were then analysed for copper and arsenic. Analysis of samples from the marine ecosystem showed (IRG/WP/4167) that arsenic was longitudinally and transversely leached from the wood, whereas the copper was redistributed to the surfaces of the wood. Recent analyses have now confirmed that similar trends of copper mobility occurred in Pinus patula exposed to the estuarine ecosystem, i.e., copper levels within the wood decreased while the levels of the exterior zones of the wood increased correspondingly.
G D Shelver, C D McQuaid, M Tarin, A A W Baecker

Relationship between degradation of wood, cellulose or lignin-related compounds and production of hydroxyl radical or accumulation of oxalic acid in cultures of brown-rot fungi
1994 - IRG/WP 94-10062
The degradation activities of brown rot fungi against wood, cellulose, and lignin-related compounds were measured in cultures containing glucose or wood as a carbon source. Also the activities of one-electron oxidation and hydroxyl radical production and the amount of oxalic acid present in the cultures were measured. The degradation activities of the fungi against wood, crystalline cellulose and the lignin model compounds were in direct proportion to the activities of one-electron oxidaton and hydroxyl radical production. The amount of oxalic acid win the cultures was inversely proportional to those activities and oxalic acid was almost not detectable in the cultures in which wood was actively degraded. On the basis of these results it is concluded that one-electron systems including hydroxyl radicals play important roles in the initial stage of wood decay by brown rot fungi and degrade oxalic acid produced by the fungi to trace amounts.
S Itakura, T Hirano, H Tanaka, A Enoki

Biological Safety Evaluation of Animal Contact of Preservative-Treated Wood
2003 - IRG/WP 03-50196
Biological safety of preservative-treated woods that could be contacted to human and animal was evaluated for rat and rabbit exposed to CCA-, ACQ- and CCFZ-treated woods. The accumulation of preservatives ingredient in the rat’s plasma and viscera, and the transforming function of replacing preservatives were examined in this study. The result indicated that preservative-treated wood did not bring changes for the enzyme related with replacing function of preservative components in the plasma. The accumulated amount of chrome from the CCA-treated wood was detected to be very small quantity, which was less than the measurement range. However, the presence of arsenic was detected in lung, liver, and heart of rats. Furthermore, the amount of accumulated arsenic in rat's viscera was greater than that of the untreated control. Copper, a common as ingredient of all CCA-, CCFZ- and ACQ-treated woods was detected in the liver of rat exposed to the CCA-treated sample. And the copper was also detected in the lung and liver of rat exposed to the ACQ-treated samples, while it was also present in the both liver and heart of rats exposed to the CCFZ-treated sample. To evaluate dermal safety of preservative-treated wood, clinical formulations were prepared by dissolving ACQ, CCA, and CCFZ in saline solution at five times concentration of normal treatment. Dermal irritation test was repeated for nine rabbits using the prepared solution. No changes were detected for rabbits exposed to daily dermal irritation using the solution for 14 days. And cumulative dermal irritation (CDI) score using the solution for 14 days was equal to zero. This result demonstrated that the local irritation of the preservatives tested to the intact skin was negligible. Histopathological examination revealed no hemorrhage and edematous change of the subcutaneous tissue in the rabbits treated with ACQ, CCA and CCFZ.
Dong-heub Lee, Dong-won Son, Myung Jae Lee, Chang Ho Kang, Cheon Ho Kim, Eui-Bai Jeung

Accumulation of copper in parenchyma cells in southern pine wood treated with micronized and amine-copper preservatives
2019 - IRG/WP 19-20657
Our previous research used X-ray micro-computed tomography to examine the micro-distribution of copper in southern pine wood treated with a micronized wood preservative (MCA) and an amine-copper preservative (ACQ). We found that copper in wood treated with MCA was mainly concentrated in fusiform rays (rays containing resin canals), and in vertical (axial) resin canals. A similar, although not identical distribution of copper was found in wood treated with ACQ. Hitherto we assumed that copper was located in the radial and axial resin canal voids. Our latest research shows that this is not the case. Instead, copper appears to be mainly located in parenchyma cells adjacent to resin canal voids. It is possible that these parenchyma cells are important flow paths for aqueous preservatives in southern pine, and further research, possibly using 4-D X-ray micro-CT, is needed to answer this question.
D Feng, M L Turner, A Limaye, M A Knackstedt, P D Evans

Premature adhesion failure of exterior wood coatings – The influence of substrate temperature at coating application and moisture accumulation during storage
2022 - IRG/WP 22-40937
The present study aimed at extending the knowledge about premature coating failures of industrially finished wood cladding. Two potential factors were studied: the influence of substrate temperature at coating application and moisture accumulation during storage on the adhesion of waterborne coating systems. In the first experiment, 4 batches of wood specimens were submitted to 4 different temperatures (-25°C, 0°C, 10°C, 20°C) before coating. In the second experiment, coated wood specimens were divided into two batches. One batch was conditioned to 12% moisture content, the other one to 27%. Both batches were then exposed to IR- and UV-radaition in a chamber, simulating intense solar radiation causing intense warming of the cladding boards after being installed on a façade. None of the two studied factors were found to affect coating adhesion. The results suggest that the risk of adhesion defects due to sub-zero substrate temperatures and moisture accumulation during storage is low and that other parameters, especially drying conditions, are of significantly greater importance in quality control of industrially finished cladding.
U Hundhausen