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Inorganic wood preservative levels in soil near a noise barrier treated with different preservatives after 8 years in service
2005 - IRG/WP 05-50234
In March 1996 nine test sections of a noise barrier were installed near Stockholm Sweden. The test sections include untreated Scots pine, spruce and larch and Scots pine, treated with different wood preservatives. After 8 years in service, the untreated spruce, pine and larch boards in contact with the soil were significantly decayed, with an estimated service life of about 5-10 years, while the untreated wood above ground is stained but not visibly decayed. Some degradation was detected in wood in soil contact for some of the preserved pine sections treated to AB levels (i.e. use class 3, above ground). Soil samples were collected at three horizontal distances from the barriers (0, 7 and 14 cm) with the 7 cm sample representing the drip line under a protective wedge designed to keep water out of the joints. Samples were collected at two depths representing groundline and the depth of the barrier in the soil (7.5 – 13 cm) and directly under the barrier. Soil samples collected after 8 years showed highest contaminant levels close to the barrier and under the wedge dripline. Arsenic levels in some locations close to CCA treated panels exceeded Swedish and Canadian soil guidelines for agricultural use and copper levels were above residential/park guidelines for some locations near ACQ and Tanalith MCB treated panels.
P A Cooper, Y T Ung, M-L Edlund, J Jermer, O Söderström


Field Test Results after Nine Years for CCA and ACQ Preservative-treated Wood Fixed in Different Climates
2003 - IRG/WP 03-30303
During assessment of the ground contact stakes in the Norwegian test field, we have frequently found that the first visual rot attack is in the zone of the stakes, where the stakes have been in contact with each other during the fixation. These parts are usually light green, caused by the lack of light during fixation, compared to the rest of the stake surface, which has a darker colour. To investigate if light on the stakes during fixation can affect the durability of the treated wood, we started a test in 1993. CCA and ACQ treated stakes were tested according to EN 252. The stakes were treated with two retentions of each salt. One according to the Nordic Class A (for ground contact i.e. hazard class 4) and one lower retention (25 % of the class A retention. This is even lower than the Nordic class AB (HC 3) retention). Before exposure they were fixed in 7 different climates: 1) Normal fixation = 60 % RH and 25 °C, light days, dark nights for 7 days, 2) Dark fixation = normal fixation without light for 7 days, 3) UV-light fixation = normal fixation with UV-light 24 hours for 7 days, 4) Hot fixation = 95 % RH and 90 °C for 2 hours, 5) Cold fixation = 50 % RH and 10 °C for 30 days, 6) Dry fixation = 10 % RH and 50 °C, for 24 hours, 7) Wrapped fixation = each stake packed in black plastic foil, 50 °C and without light for 24 hours. The colour of the ACQ stakes varied from light green to black, depending on the fixation climates. These different colours and the durability results after 5 years were reported at the 30th IRG meeting in 1999. The different fixation procedures give only small differences in durability/rot index after 9 years in field test. Hot, dry and wrapped fixations give ACQ a better durability than CCA in the Nordic class A retention. None of the ACQ stakes were rejected in the first 9 years, while the CCA stakes had a few rejected stakes after 8 and 9 years caused by sot-rot. For the low retention, ACQ gives a better durability than CCA for all fixation procedure, but both preservatives had several rejected stakes.
F G Evans


Leaching of inorganic wood preservatives – Investigating the relationship between leachability, dissociation characteristics and long-term leaching potential
2003 - IRG/WP 03-50199
Estimation of the leaching properties of preservative components is greatly affected by the leaching test method applied since not all methods equally consider the physical components responsible for leaching. These include: wetting of the wood and penetration of water (affected by dimensions, amount of end grain, permeability, duration and nature of water exposure); solution of preservative components into available moisture (affected by component solubility, wood moisture content, temperature, etc.); diffusion of components out of wood (affected by product dimensions, permeability, direction of movement, moisture content, temperature, nature of the diffusing species, etc.); and re-drying of the wood between moisture exposures. Aggressive leaching of finely ground wood provides a measure of the ultimate amounts of preservative compounds available for leaching while analysis of the equilibrium dissociation or solubility of components in free water in the wood provides information on their effective concentration which drives the diffusion process. Combining this information with a simple diffusion test should allow the estimation of potential risk from leaching over a wide range of specified conditions. In this paper, the leaching of several inorganic wood preservatives is compared and related to dissociation of preservatives within the wood structure and diffusion out of wood.
L Waldron, Y T Ung, P A Cooper


Disposal of Pressure Treated Wood in Construction and Demolition Debris Landfill
2005 - IRG/WP 05-50235
Pressure treated wood is often disposed in landfills in the US, very frequently in construction and demolition (C&D) debris landfills. C&D debris disposal facilities in many states are not equipped with liner systems to protect underlying groundwater. In this paper, issues associated with the disposal of metal-containing treated wood in C&D debris landfills are discussed. C&D debris landfills can be biological active systems, dominated by the activity of sulfate reducing bacteria. The leachate is characterized by relatively low biodegradable organic compound concentrations, high salt concentrations, a neutral pH, and a moderately to strongly reducing environment. Simulated landfills containing CCA-treated wood often show relatively high concentrations of As and Cr, but only minimal concentrations of Cu. Cu-based preservatives such as alkaline copper quaternary (ACQ) also show minimal copper leaching, suggesting that disposal of Cu-based wood preservatives posees minimal impact to groundwater from Cu leaching.
T G Townsend, B Dubey, J Jambeck, H M Solo-Gabriele


Marine performance of preservative treated Southern pine panels. Part 2: Exposure at Mourilyan Harbour, Queensland, Australia
2000 - IRG/WP 00-10337
Southern yellow pine panels treated with ACQ type B, ACQ type A, CCA type C, creosote, and copper naphthenate have been exposed at Mourilyan Harbour, north Queensland, Australia for almost 6 years. These panels have been inspected and rated for fouling and attack by Teredinid, Limnoria, Martesia, and Sphaeroma during this exposure. After 70 months exposure, overall performance of ACQ type B was equivalent to CCA type C at similar loadings, while ACQ type A did not perform as well. CCA and ACQ at 40 and 20 kg/m3 are performing similar to creosote at 430 and 200 kg/m3, respectively. The copper naphthenate treated panels did not perform as well as the ACQ panels at similar total copper loadings. Fouling of panels treated with ACQ was less than that found on CCA and creosote treated panels, but similar to that found on copper naphthenate treated panels exhibiting the same level of performance.
A R Zahora, A F Preston, K J Archer, S Kleinschmidt


Effect of incising depth and density on treatment of Douglas fir, hem fir and spruce-pine-fir lumber with CCA, ACZA or ACQ
1997 - IRG/WP 97-40093
Incising markedly improves both the depth and uniformity of preservative treatment of refractory wood species, but there are few studies directly comparing the effects of incising depth and density on penetration and retention of commonly used waterborne preservatives in wood species from the western United States. The effects of two incision densities (7300 and 8900 incisions/square meter) at two depths (5 and 7 mm) were investigated using two strength classes of Douglas fir, hem fir and spruce-pine-fir lumber. In general, grade or strength class had no significant effect on treatability. Treatability markedly improved with increasing incision depth, while increased incision density produced less tangible results. Ammonia-based treatments were associated with deeper penetration reflecting the ability of the heat and/or ammonia to improve preservative penetration. Further studies are underway to evaluate the effects of incising and subsequent preservative treatment on strength properties.
M Anderson, J J Morrell, J E Winandy


Laboratory bioassay on the termiticidal efficacy of two ACQ formulations
1999 - IRG/WP 99-30199
The termiticidal efficacy of two ammoniacal copper quaternary ammonium formulations (ACQ) was evaluated in a laboratory bioassay using two species of subterranean termites, Mastotermes darwiniensis Froggatt and Coptotermes acinaciformis (Froggatt). Five retentions (1.0, 2.0, 4.0, 6.0 and 8.0 kg/m3 of active ingredient) of each ACQ formulation (MitrexACQ and ACQ97) were assessed in sapwood specimens of the softwood Pinus radiata D. Don and compared with the same retentions of the conventional benchmark preservative CCA (Tanalith C). All specimens (including controls) were subjected to an artificial weathering schedule prior to the bioassay. Under the conditions of the laboratory bioassay, both MitrexACQ and ACQ97 showed considerable potential as water-borne preservatives for preventing significant attack of P. radiata sapwood from two of Australia's most economically significant species of termite. At each of the retentions tested, MitrexACQ and ACQ97 performed comparably or better than equivalent retentions of CCA.
J W Creffield, A F Preston, N Chew


Bioprocessing preservative-treated waste wood
2000 - IRG/WP 00-50145
Disposal of preservative-treated waste wood is a growing problem worldwide. Bioprocessing the treated wood offers one approach to waste management under certain conditions. One goal is to use wood decay fungi to reduce the volume of waste with an easily managed system in a cost-effective manner. Wood decay fungi were obtained from culture collections in the Mycology Center and Biodeterioration research unit at the USDA-FS Forest Products Laboratory (FPL), Madison, Wisconsin, and from FPL field sites. The 95 isolates had originally been taken from at least 66 sites from around the United States. Isolates were screened in a bioassay (known as the 'choice test') for tolerance to CCA, ACQ, creosote and pentachlorophenol. A tolerant rating was based on fungal growth toward or on treated wood, with 17 tolerant to CCA, 21 to ACQ, 12 to creosote and 5 to pentachlorophenol. Decay capacity of the tolerant isolates was determined as percent weight loss by the ASTM D-1413-76 soil bottle method. We identified 8 isolates for experiments on preservative remediation. Isolates of Meruliporia incrassata and Antrodia radiculosa gave the highest percent degradation of ACQ and CCA-treated wood. Several A. radiculosa isolates and a Neolentinus lepideus isolate grew on creosote-treated wood, but had only a 4-5% weight loss. In this paper we discuss the potential use of decay fungi to degrade or remediate preservative-treated wood.
B Illman, V W Yang, L Ferge


International comparison of three field methods for assessing the in-ground termite resistance of materials - highlights after two years
1999 - IRG/WP 99-20157
First-year results of a comparative study, evaluating the in-ground termite resistance of a range of materials, including CCA and ACQ-treated timbers, using the below-ground exposure, ground contact and graveyard methods against diverse termite faunas were provided in IRG/WP/98-20132. Further annual inspections have confirmed early trends and identified notable differences between sites and methods. Termites have contacted specimens more frequently at tropical sites, irrespective of the method, and in below-ground exposure trials, irrespective of site. Overall, levels of fungal decay have been low. Fungal decay was more prevalent in specimens using the ground-contact and graveyard methods. Notable levels of termite attack have been recorded for some CCA- and ACQ-treated Pinus radiata specimens at the retention of 2kg/m3, after two years or only one year (Phuket, Thailand). Some specimens of the durable timber bald cypress (Taxodium distichum) have sustained significant levels of termite attack and fungal decay.
M Lenz, J W Creffield, A F Preston, B M Kard, C Vongkaluang, Y Sornnuwat


Field tests of preservative-treated radiata pine in Japan
1995 - IRG/WP 95-30083
Test stakes of radiata pine treated with various alkyl ammonium compound (AAC) formulations and with copper-chrome-arsenate (CCA) as reference preservative were installed in 3 test sites in Japan in 1981-82. When inspected in 1995, CCA-treated stakes showed less decay at all three sites than stakes treated with other formulations. Ammoniacal copper quaternary (ACQ)- treatment was only slightly less effective than CCA at two sites (Tsukuba and Fukiage-Hama), but more markedly less effective at the high decay hazard Uji site. Unamended AAC treatment was least effective, but there was little difference in performance between didecyl dimethyl ammonium chloride (DDAC) and benzalkonium chloride (BAC) formulations.
M E Hedley, K Tsunoda, K Suzuki


Comparison of three methods for assessing the in-ground termite resistance of treated timber, durable timber and plastics at sites in Australia, USA and Thailand - First results
1998 - IRG/WP 98-20132
The in-ground resistance of materials to attack by subterranean termites is most commonly assessed with one form or another of the conventional graveyard method, despite the significant shortcomings of this method. In Australia, an alternative method, in which all samples of test materials are placed below-ground, has been in use for more than 10 years. The method provides reliable exposure of samples to prolonged contact by termites and offers a number of other advantages, notably ease of removal and re-installation of specimens, and protection from fires or damage caused by animals and vandalism. We describe a study in which assessments of materials with the below-ground exposure method were compared with the graveyard procedure and a modification of the South African ground contact method. Sites encompassed a range of climatic conditions and termite faunas, subtropics with species of Reticulitermes in Mississippi, USA; humid tropics with a diverse termite fauna dominated by Macrotermitinae (fungus-culturing termites) in SW Thailand; wet and dry tropics with separate trials for the two economically important species, Mastotermes darwiniensis and the mound-building form of Coptotermes acinaciformis, in Northern Australia; and at a semi-arid inland site with a temperate climate in Eastern Australia where the tree-nesting form of Coptotermes acinaciformis is the dominant species. Materials included in the investigation were: CCA- and ACQ-treated Pinus radiata (each at two retentions), a durable timber (bald cypress, Taxodium distichum) and two plastic cable sheathings (nylon and low density polyethylene). This paper provides details of the trial and gives first observations from inspections at three sites after one year of exposure of the materials to termites.
M Lenz, A F Preston, J W Creffield, K J Archer, B M Kard, C Vongkaluang, Y Sornnuwat


Tendency of the preservative use for impregnation industries in Japan
1998 - IRG/WP 98-50101-05
In Japan, since 1997, the acceptable limit of the arsenic in the waste water become to 0,1 mg/l and the additional regional severer restriction can be established. In this reason, Japanese wood preservation industries intend to use other than CCA, like DDAC, ACQ, Tanalith CuAz, copper-naphthate and zinc-naphthenate, as replacing from CCA. In Jan-June 1997, the share of CCA preservatives was less than 30% in contradiction to over 90% in Jan-June 1996.
K Suzuki


IUFRO rating system compares favourably to weight loss for soil-bed testing
1990 - IRG/WP 2343
The soil-bed/small stake test is commonly used for rapidly evaluating the performance of new, more environmentally acceptable, preservatives. In a 1.5 year experiment with three copper-based waterborne preservatives, visual evaluation and probing using the IUFRO performance rating scale (0-4) gave very similar toxic thresholds to those derived from measurement of weight loss at the end of the experiment. Visual evaluation therefore appears to be a reliable indicator for comparing the performance of these copper-based waterborne preservatives. However, caution should be exercised in interpreting performance rating data as the stakes approach failure.
P I Morris


Effect of test site, preservative and wood species on decay type Glenbervie pastoral and radiata pine forest sites
2000 - IRG/WP 00-30248
Pinus radiata stakes were treated with 0.8, 1.2, 1.8, 2.7 and 4.1 kg/m3 of CCA and Fagus sylvatica with 2.7, 4.1 and 6.1 kg/m3 of CCA. Both wood species were also treated with equivalent retentions of a copper plus triazole preservative (CT) (0.89, 1.3, 2 and 3 kg/m3 of copper for pine & 2.5 and 4 for beech) and chlorothalonil plus chlorpyriphos in oil (CC) (1.4, 2.1, 3.2 and 4.8 kg/m3 of chlorothalonil for pine and 3.2 and 7.2 for beech). Furthermore, P. radiata was treated with ammoniacal copper plus a quaternary ammmonium compound (ACQ) (0.8, 1.1, 1.7 and 2.6 kg/m3 copper) and a 60/40 mixture of high temperature creosote plus oil (C) (18, 27, 41 and 61 kg/m3). Treated and untreated stakes were exposed in the ground at 13 sites in New Zealand and Australia for between 4 and 6 years. This paper reports the significance of site, timber species, preservative and its concentration and time of exposure, on extent and type of decay, at two sites in Northland, New Zealand. The two sites were adjacent (200 metres), appeared to have essentially similar clay loam soil and climate but one was pastoral and the other was situated within a radiata pine forest. Most types of decay reported in the literature, were observed in this study but other undescribed or only partially characterised types were also found. The decay types found differed between test sites, preservative and timber species. The significance of tunnelling hyphae, which often caused severe decay of wood treated with the higher retentions of various preservatives, appears much greater than the prior literature would suggest. For pine the highest retentions of CC, CT and ACQ gave at least equivalent performance to the reference standards creosote and CCA, after approximately 5 years, at both test sites. For beech CC and CT both gave superior protection to CCA, at both sites. All the preservatives tested exhibited some weaknesses in terms of resistance to the various decay types observed.
R N Wakeling


Performance of Paraserianthus falcataria treated with ACZA, ACQ, CC or CCA and exposed in Krishnapatnam harbour, India
2005 - IRG/WP 05-30382
Paraserianthus falcataria (=Albizia falcataria) treated to two retentions with ammoniacal copper zinc arsenate (ACZA), ammoniacal copper quaternary (ACQ), ammoniacal copper citrate (CC) and chromated copper arsenate (CCA) was assessed over 34 months in a tropical marine waters at Krishnapatnam harbour on the east coast of India. ACZA treatment showed comparatively better resistance than CCA, ACQ and CC, while CC provided the least resistance to marine borer attack. Eight species of borers i.e. Martesia striata, M. nairi, Teredo furcifera,T. parksi, Lyrodus pedicellatus, Nausitora hedleyi, Bankia campanellata and B. rochi were recorded on test panels. Of these, M. striata, L. pedicellatus, T. furcifera and B. campanellata were the dominant species, while other species settled sporadically. The results suggest that copper based preservatives are less likely to perform well under extreme tropical exposures without arsenic.
B Tarakanadha, K S Rao, J J Morrell


Leaching amount of wood preservatives from treated wood in different size during outdoor exposure for 6 months
2000 - IRG/WP 00-50160
Eighteen impregnated specimens with CCA, ACQ, and BAAC preservatives were subjected to a outdoor leaching test. Test specimens, 10 x 10 x 25 cm3, 5 x 10 x 25 cm3, 2 x 10 x 25 cm3 in size, were cut from Japanese cedar (Cryptomeria japonica). Both of end surfaces were sealed with a silicone sealer in the half number of specimens. Total leaching amounts of copper from the open-end ACQ specimens of 10 x 10 x 25 cm3, 5 x 10 x 25 cm3, 2 x 10 x 25 cm3 in size were 76.2 g/m3, 60.6 g/m3, 153.4 g/m3 respectively during 6 months exposure. Those from the end-sealed ACQ specimens were 40.9 g/m3, 50.9 g/m3, 92.7 g/m3 respectively. The ratio of surface area to volume influenced the leaching amount of preservatives. Sealing of end surface of samples reduced the loss of preservatives considerably.
K Yamamoto, S Motegi, A Inai


Diffusion modeling of inorganic wood preservative leaching in service
2005 - IRG/WP 05-50224-5
To evaluate the potential environmental and health implications of leaching of inorganic wood preservatives in service under different conditions, there is a need for a predictive model that provides estimates of the rate and extent of leaching over a wide range of product dimensions and exposure conditions. In this paper, we show that the leaching behavior of inorganic preservative components from wood in continuous water contact can be characterized by three easily measured parameters: total leachable component (Le) based on intensive leaching of fine ground material; amount of dissolved or dissociated component (Di) in water saturated wood; preservative component diffusion coefficients (Dt,l) in the transverse and longitudinal directions. Use of the applicable D and Di or Le in a diffusion model allows the prediction of total amount leached and emission rate at different times of exposure. Both D and Di increase somewhat with increasing ambient temperature. Laboratory determined parameters for alkaline copper quaternary (ACQ), copper azole (CA), chromated copper arsenate (CCA) and borate (DOT) wood preservatives are used to predict leaching rates from larger lumber samples. Preliminary comparisons of predicted leaching with measured leaching of larger samples in laboratory and natural rain exposure indicate that the approach is surprisingly effective at predicting leaching performance but some model refinements are needed for some components such as copper in CCA to account for the slow dissolving of a component of the preservative available for leaching.
L Waldron, P A Cooper, Y T Ung


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


Effect of a water repellent additive on the performance of ACQ treated decks
2000 - IRG/WP 00-40168
The performance of a water repellent (WR) additive formulated for use with ACQ has been evaluated. The water repellency of wood treated with this formulation was studied in laboratory and field tests. The change in moisture content of ACQ/WR treated boards under field exposure conditions is compared with that of CCA/WR treated boards. Although the water repellency of the ACQ/WR system is lower than that of the CCA/WR system in laboratory tests, the field performance of both systems are equal after more than two years of natural weathering. The use of water repellent additives is clearly one of the options for optimizing the overall performance of copper based preservative systems.
F Cui, A R Zahora


Alternatives to CCA-treated Pinus radiata as vineyard posts
2004 - IRG/WP 04-50212
An estimated 10 million trellis posts per year are used in Australian vineyards and about 75% of these are CCA-treated Pinus radiata. CCA-treated Pinus radiata posts are brittle and at times in short supply. Use of some products containing CCA is being restricted in Australia. Recently, plantation forestry has expanded rapidly for disposal of industrial and irrigation wastewater. Thinnings from these plantations are used as firewood, mulch or simply dumped. Thinnings could be treated and used as vineyard posts. Consequently, our research was conducted to investigate the alternatives to CCA and the suitability of plantation thinnings as vineyard posts. Results have shown a moderate, but not statistically significant, difference in bending strength between CCA and ACQ-treated debarked Pinus radiata posts, in favour of CCA. On average there was no significant difference in bending strength between PEC and ACQ-treated debarked posts of hardwood species (P = 0.54), although two species showed borderline significant differences in favour of ACQ. However, some hardwood species treated with ACQ had more posts rejected due to splitting compared with the same species treated with PEC. No ACQ or CCA-treated Pinus radiata posts were rejected because of splitting.
M Mollah, J Smith, K McCarthy, L J Cookson


Fouling organisms as indicators of the environmental impact of marine preservative-treated wood
1995 - IRG/WP 95-50063
This study evaluates the use of fouling organisms (epibiota) to assess the environmental impact of preservative treated wood. This paper presents initial findings from treated panels exposed for 6 months at Sagres, Algarve, Portugal. Panels were treated with CCA, two copper-containing quaternary ammonium (ACQ) formulations and creosote, with nominal retentions from 10 to 40 kg/m³ (creosote 25 pcf). The presence of an abundant, diverse and healthy epibiotic community growing on treated wood was used as an indication that the preservative treatment had a relatively low impact on its immediate environment. Algae and mussels (Mytilus galloprovincialis) were the dominant members of the fouling community which developed on all preservative treated wood panels. The biomass (dry weight of organisms) and species diversity of epibiota scraped from the surface of preservative treated wood panels showed the following order CCA > Creosote > ACQ 1:1 > ACQ 2:1. No difference was detected concerning the shell dimension of mussels between treatments, but mussel biomass was much lower on ACQ-treated test samples, indicating that mussel settlement was affected by ACQ treatment, but growth was not. Algal biomass was highest on creosotetreated panels, with biomass on other panels fitting the following sequence: Creosote > CCA > ACQ 1:1 > ACQ 2:1. Copper, chromium and arsenic contents of algae were determined by atomic absorption spectroscopy (AAS). Elevated levels of Cu, Cr and As were found in the macroalgal mat from CCA-treated panels. These levels showed significant positive linear regressions with panel preservative retention levels. Higher levels of copper were found in macroalgal mats from ACQ-treated wood, but showed no linear relationship to panel preservative loadings. Copper levels did not exceed 9 ppm in algal tissue, chromium and arsenic levels were below 1 ppm.
R M Albuquerque, S M Cragg


Marine performance of preservative treated Southern pine panels. - Part 1: Exposure in Newport, Oregon
2000 - IRG/WP 00-10368
The ability of selected wood preservative to protect southern pine sapwood against marine borer attack was evaluated over a 6 year period in Yaquina Bay, Oregon. The site exposed the wood to potential attack by both Teredo navalis and Limnoria spp. Both creosote and CCA provided excellent protection at moderate retentions, while ACQ produced slight differences in performance depending on the copper to quat ratio. Copper naphthenate provided poor protection, while ACZA was intermediate in its ability to resist attack at lower retention levels. A wood/plastic composite provided good protection for the first 5 years, but has now begun to experience Limnoria attack.
R G Rhatigan, J J Morrell, A R Zahora


Comparison of Temporal Changes in Metal Leaching and Aquatic Toxicity from Wood Treated with CCA and Alternative Preservatives
2005 - IRG/WP 05-50236
This study compares the temporal variation of chemical leaching and aquatic toxicity of wood treated with chromated copper arsenate (CCA) and other copper-based wood preservatives (alkaline copper quaternary (ACQ), copper boron azole (CBA), copper citrate (CC) and copper dimethyldithiocarbamate (CDDC)). Treated wood blocks were leached for 21 days and the leachate collected was analyzed for preservative chemicals and aquatic toxicity. The measured rate of copper leaching was fit using the recently proposed diffusion model for predicting preservative leaching rates. An unpreserved wood sample was tested as a negative control. In general the predicted values for flux rate were on the same order of magnitude as calculated using the experimental data. In natural water, several physical and chemical factors may affect the bio-availability and toxicity of chemicals. Copper concentrations and resulting aquatic toxicity obtained using two natural waters as leaching solutions were found to be lower compared with data obtained using de-ionized water as the leaching fluid.
B Dubey, T G Townsend, G Bitton, H M Solo-Gabriele


Development of software to automate the quantification of checking occurring in preservative treated wood exposed to weathering
2001 - IRG/WP 01-20228
Surface checking often disfigures the appearance of wood treated with water-borne preservatives and treatments designed to reduce such checking have been receiving increasing attention. Progress in this area has however been slowed by the lack of a method of rapidly and accurately quantifying checking at treated wood surfaces. A software package has therefore been developed which identifies, measures and records the dimensions and numbers of surface checks in scanned images of preservative treated wood specimens. The program uses grey-scale 600 dpi TIFF images of wood specimens and operates within the data acquisition, analysis and presentation software IgorPro (Wavemetrics). Procedures within the program analyse images sequentially pixel by pixel and one row at a time searching for brightness minima (dark areas) which satisfy criteria that are characteristic of checks. A black and white (b/w) image is then produced in which probable checks are shown black on a white background. Further procedures reduce noise in the b/w image eliminating artifacts (specks of dirt) and small checks that cannot be discerned by the naked eye. The final stage of the analysis rasters through the cleaned b/w image establishing which black pixels connect to each other and identifying and labeling checks and quantifying check positions, sizes and shape. These data are then presented in a spreadsheet. Using this package it has been possible to successfully quantify checking in a range of preservative treated wood specimens that have been subjected to natural weathering. This paper describes the principal features of the software package and presents preliminary data from analysis of treated and weathered specimens. The advantages of the system for quantifying checking in preservative treated wood as well as its limitations are discussed.
A G Christy, P D Evans


Working plan: Second international collaborative field trial
1995 - IRG/WP 95-20056
This paper describes the scope, objectives, and approaches to be used in the second international collaborative field trial approved by the Scientific Programme Committee for partial funding in 1994. The trial is designed to develop a broad data base on causal mechanisms, interactions, and factor affecting the performance of treated wood in ground contact. The trial encompasses 12 different field test sites representing all continents except Antarctica. Preservatives were chosen to represent new technologies and include oilborne, waterborne copper-organic, and water-dispersible systems. CCA is used as the reference system. Task forces to research the following areas are described: accelerated soilbed testing, decay types/modes of failure, preservative depletion, abiotic factors, and copper tolerance.
H M Barnes, T L Amburgey


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