We compared the chemical composition of wood fibres and fibre surfaces of several eucalypt species and hybrids originating from various growth sites in South Africa. The objective was to test for differences in chemical surface composition due to genetics or site with the ultimate aim to facilitate a tailor-made supply of wood for pulping that results in an optimal blend of fibres that can be pulped together with similar yields. This, however, requires a sound knowledge of the fibre properties. The surface functionality on the single fibre level is a key property, because it determines how good inter-fibre bonding will be when paper is formed, which depends amongst other fibre properties on the amount of free hydroxyl groups that are available and therefore on the cellulose content on the fibre surface. The cellulose and lignin content on the fibre surface were determined with chemical force microscopy, a variation of atomic force microscopy. Since the general bulk composition of the fibre and the surface composition might differ, both parameters were determined. We found significant differences in the cellulose and lignin content on fibre surfaces, with regard to genotype and site, respectively. In some, but not all, cases, the surface composition of wood fibres followed the bulk composition, and differences were generally more pronounced. Differences due to genotype were significant, especially with regard to the surface lignin content-but variation due to site was also distinctly recognisable. This variation in surface functionality could be the reason why some pulpwood blends result in a lower pulp yield and different quality.
Some imported guitars and others made in Zambia exhibit poor sound quality and properties. Zambia grown timbers were evaluated for their suitability as tonewoods. Pinus kesiya was suitable for soundboard as it had brighter appearance and best radiation coefficient 7.3 m 4 s −1 kg. Its lower impedance 2733 Nmm 2 s m 3 gives better sustain. Pterocarpus angolensis was used for the back and sides as it was very stable, volumetric shrinkage 5.4%, and low impedance, 2,298 Nmm 2 s m 3 which reduced loudness. This species was also used for the neck. Baikiaea plurijuga was employed in fretboard and bridge construction as it was appreciably hard with Brinell hardness rating of 6.05 kN. A guitar made using the selected timbers was tested qualitatively. The Reference and the Experimental guitar attained the same score demonstrating improvements attributable to systematic wood selection. The study established that the quality of locally made guitars could be improved significantly if luthiers adopt appropriate wood selection criteria.
The bulk of exotic forest plantations and sawmills in Zambia are within the reach of air pollutants from mines on the Copperbelt province. Up to 60% of every cubic meter of the timber processed is waste, of which 0,12 m 3 is sawdust. Sawdust is largely used for various surface amendments and as a source of energy, but the dangers it poses to users are not known. Heavy metals assimilated by trees or adsorbed by sawdust from the environment may be a health hazard at certain levels. The amount of heavy metals in Eucalyptus and Pinus sawdust was evaluated on samples from Kitwe and Ndola to establish if the use of sawdust for energy and surface amendments was safe. Composite samples for each wood type were collected from each site and digested. The ensuing solution was filtered and analyzed by flame emission Atomic Absorption Spectroscopy for heavy metals. Smoke from a burning test was trapped on Whateman 41 filter paper and the particulate matter that was trapped was extracted. The extract mixture was centrifuged to obtain a clear solution which was then analyzed for heavy metals by AAS. The heavy metal concentrations in Eucalyptus sawdust were 11,5-61,1 mg Pb/kg; 3,3-7,9 mg Cd/kg; 4,9-56,9 mg Cr/kg and 20,2-43,4 mg Ni/kg while that in Pinus sawdust were 17,1-32,8 mg Pb/kg; 5,1-8,6 mg Cd/kg; 9,9-28,2 mg Cr/kg and 18,7-67,4 mg Ni/kg. The concentrations of chromium and cadmium in both wood types from Kitwe exceeded the limit, and so the sawdust was deemed unsuitable for surface applications. This was the same for nickel in Pinus sawdust. The study showed that sawdust from both wood types was not safe for mulching, composting and animal bedding. The annual exposure limits of 0,2 μg Cr/m 3 , 180 μg Ni/m 3 and 0,2 μg Cd/m 3 set by the World Health Organization were not exceeded by the smoke from both wood types. This suggested that heavy metals embedded on particulate matter from Eucalyptus and Pinus sawdust which has been in storage for about two years in conditions found in Kitwe is unlikely to have adverse short-term health effects associated with heavy metals.
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