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Fungal degradation of wood treated with metal-based preservatives. Part 2: Redox states of chromium
1996 - IRG/WP 96-10164
Concerns have arisen about the leaching of heavy metals from wood treated with metal-based preservatives, such as chromated copper arsenate (CCA). Of particular concern is the toxic redox state of chromium and arsenic in aging and decayed CCA-treated wood. Generally, hexavalent chromium is more toxic than trivalent chromium and trivalent arsenic is more toxic than pentavalent arsenic. The desired outcome from treating wood with CCA is total change of Cr(VI) to Cr(III) and As(III) to As(V). As part of an on-going study to determine the fate of copper, chromium and arsenic during aging and decay of CCA-treated wood, we detected Cr(III) and Cr(VI) in situ in CCA-treated southern yellow pine lumber. The redox states of Cr were determined using synchrotron X-ray fluorescence spectroscopy (SXRF). An SXRF microprobe was used to to detect Cr redox states by measuring X-ray absorption near-edge structure (XANES). The ratio of Cr(III) to Cr(VI) was determined (1) on the surface and interior of lumber two years after CCA treatment and (2) in lumber during decay by a CCA-tolerant fungus, Meruliporia incrassata TFFH-294. The XANES spectrum for Cr(VI) has a strong pre-edge feature that is not present in the spectrum for Cr(III). Only the Cr(III) XANES spectrum was detected on the surface and in the interior of the wood, indicating total reduction of Cr(VI). The XANES spectrum for Cr(III) was detected in wood after 12 week decay by Meruliporia incrassata TFFH-294, indicating that the fungus does not oxidize Cr(III) to Cr(VI) during the decay process. We are currently using XANES spectroscopy to detect and map in situ redox states of As in CCA-treated wood.
B Illman, S Bajt, T L Highley


Studies of the mechanism of chromated-copper preservative. Fixation using electron spin resonance
1992 - IRG/WP 92-3701
Two softwoods and one hardwood species were treated with chromium trioxide, copper sulphate, chromated-copper wood preservative (CCA). The treated wood samples were analyzed during fixation by electron spin resonance (ESR). ESR spectra indicated that more than one Cr(V) species was generated from Cr(VI) soon after CCA treatment. The Cr(V) signal became strong within increased several hours followed by the gradual decay of Cr(V) accompanying with generation of single broad Cr(III) species. Cr(V) signal still remained at least up to six months after the treatment. ESR spectral parameters from Cu(II) signal consisted of a quadruplet at lower field with a unresolved absorption of higher field, suggesting a evidence of a dX²-Y² ground state of Cu2+ ions bound in inner-sphare complexes with "O4" ("O6") ligands arranged in square planar cordination (distorted octahedral) cordination. Cu(II) signal did not change significantly during fixation.
K Yamamoto, J N R Ruddick


A quantitative weathering study of wood surfaces modified by chromium VI and iron III compounds
1989 - IRG/WP 2330
Thin veneers of Pinus radiata were treated with dilute aqueous solutions of chromium VI and iron III compounds and exposed to natural weathering for 35 days. Zero-span tensile strength and weight losses of treated veneers were compared with losses observed in untreated specimens In a study designed to demonstrate the applicability of strength and weight loss measurements to the rapid quantitative assessment of wood surface protective treatments. The application of the recognised surface protective agent chromium trioxide restricted weight loss after weathering, although at the rate applied of 0.4 mg chromium per cm², strength loss was similar to that observed in untreated weathered specimens. The application of ferric nitrate to veneers at 0.43 mg iron per cm² slightly reduced weight loss, but increased strength loss compared to untreated controls. Ferric chloride at the same application rate increased both weight and strength loss compared to untreated controls. This was unexpected as previously ferric chloride was reported to have a photoprotective effect. It is suggested that while both zero-span tensile strength and weight loss of treated wood veneers during weathering are caused by radical induced oxidative processes, the former results from depolymerization of cellulose whereas the latter results from degradation and loss of lignin. The strength and weight loss criteria may therefore be used as a quantitative means of assessing the ability of chemical treatments to protect respectively, the cellulose, or the lignin components of wood during weathering.
P D Evans, K J Schmalzl


Minutes of the meetings of WG III
1985 - IRG/WP 3355
IRG Secretariat


Minutes of the meetings of WG III
1980 - IRG/WP 3161
IRG Secretariat


Minutes of the meetings of WG III
1977 - IRG/WP 3103
IRG Secretariat


Physical properties of ß-1,4-Xylanase produced by Postia (=Poria) placenta: Implications for the control of brown rot
1987 - IRG/WP 1318
The degradation of hemicelluloses is an early event in wood decay by brown-rot fungi. An understanding of the physical properties of hemicellulases may suggest target mechanisms for the development of new control agents. Endo-b-1,4-xylanase was partially purified by column chromatography from wood decayed by Postia (= Poria) placenta. The enzyme was extremely resistant to denaturing conditions; no loss of activity was detected after 2 h in 9 M urea or 6 M guanidine-HCl. Boiling the enzyme for 5 min in 2.5% SDS + 0.5% b-mercaptoethanol reduced its activity by 65%, as measured by the production of reducing sugars. The activity of a-D-galactosidase, another enzyme detected in large quantities in the decayed wood, was reduced by 98% under these conditions. Optimum pH and temperature ranges were pH 2-6 and 50-60°C, respectively. The enzyme appears to be a glycoprotein containing 50-60% carbohydrate (w/w); the carbohydrate moiety may protect the enzyme from adverse environmental conditions. The control of brown rot by in situ inactivation of xylanase may not be feasible because of the enzyme's extreme stability.
J A Micales, F Green III, C A Clausen, T L Highley


Agenda WG III
1972 - IRG/WP 306
IRG Secretariat


Agenda WG III
1985 - IRG/WP 3350
IRG Secretariat


Collaborative soft rot tests: PRL tests of Cu/Cr/As preservative using method of Document No: IRG/WP/208
1973 - IRG/WP 223
These tests were undertaken as a preliminary to the next series of collaborative soft rot tests. An interim report has already been presented at Berlin in 1972 as Document No: IRG/WP/211
J K Carey, J G Savory


Minutes of the meetings of WG III
1981 - IRG/WP 3181
IRG Secretariat


Agenda WG III
1990 - IRG/WP 3621
IRG Secretariat


Agenda WG III
1989 - IRG/WP 3549
IRG Secretariat


Cu, Cr and As distribution in soils adjacent to CCA treated utility poles in Eastern Black Sea Region of Turkey
2004 - IRG/WP 04-50214
In this study, the main objective was to asses the distribution of Cu, Cr, and As in soils adjacent to CCA treated utility poles in Eastern Blacksea Region of Turkey (Trabzon, Rize and Artvin ) and determine the influence of soil composition. Surface (0-5cm), subsurface soil samples (30-40cm) were collected near CCA-treated utility poles and control soil samples away from CCA-treated utility poles were also collected. Water holding capacity, pH, mechanical properties of soil samples were determined for both depth levels. Results showed that Cu, Cr and As concentration in soil samples taken from all three cities in 0-5cm depth was higher than soil samples taken from 30-40cm depth. Cu, Cr and As concentrations were much higher in soil samples taken from city of Rize.
E D Gezer, Ü C Yildiz, A Temiz, S Yildiz, E Dizman


Trials on the field control of the Formosan subterranean termite with Amdro® bait
1982 - IRG/WP 1163
Amdro® - treated paper towels were introduced into two field colonies of the Formosan subterranean termite in Hawaii. At the concentration of 180 ppm, the toxicant bait was ineffective one month after the introduction. At higher concentrations (> 6,400 ppm), the baits were eaten initially; however, one week after introduction, termites avoided or covered the baits. The 15,000 ppm baits supressed the activity of one colony but did not affect the other.
N-Y Su, M Tamashiro, J R Yates III


Report of Section 1 2003
2003 - IRG/WP 03-10502
F Green III


Agenda WG III
1987 - IRG/WP 3457
IRG Secretariat


Agenda WG III
1988 - IRG/WP 3491
IRG Secretariat


Minutes of the meetings of WG III
1986 - IRG/WP 3397
IRG Secretariat


Minutes of the meetings of WG III
1989 - IRG/WP 3558
IRG Secretariat


Agenda WG III
1976 - IRG/WP 362
IRG Secretariat


Minutes of the Meeting of WG III 1971
1971 - IRG/WP 301
IRG Secretariat


Minutes of the meetings of WG III
1983 - IRG/WP 3267
IRG Secretariat


Agenda WG III
1991 - IRG/WP 3674
IRG Secretariat


Minutes of the Meeting of WG III 1969
1969 - IRG/WP III 2
IRG Secretariat


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