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Our previous 4-week repeated dose toxicity study showed that wood preservative chromated copper arsenate (CCA) induced hepatocellular hypertrophy accompanied by biochemical hepatic dysfunction and an increase in oxidative stress marker, 8-hydroxydeoxyguanosine, in female rats. To further explore the molecular mechanisms of CCA hepatotoxicity, we analyzed 10%-buffered formalin-fixed liver samples from female rats for cell proliferation, apoptosis, and protein glutathionylation and conducted microarray analysis on frozen liver samples from female rats treated with 0 or 80 mg/kg/day of CCA. Chemical analysis revealed that dimethylated arsenical was the major metabolite in liver tissues of male and female rats. CCA increase labeling indices of proliferating cell nuclear antigen and decrease terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling accompanied with increased expression of protein glutathionylation, indicating a decrease in glutathione (GSH) in hepatocytes of female rats. Microarray analysis revealed that CCA altered gene expression of antioxidants, glutathione-S-transferase (GST), heat shock proteins and ubiquitin-proteasome pathway, cell proliferation, apoptosis, DNA methylation, cytochrome P450, and glucose and lipid metabolism in female rats. Increased expression of GSTs, including Gsta2, Gsta3, Mgstl, and Cdknlb (p27), and decreased expression of the antioxidant Mtl, and DNA methylation Dnmtl, Dnmt3a, and Ctcf were confirmed in the liver of female rats in a dose-dependent manner. Methylation status of the promoter region of the Mtl was not evidently changed between control and treatment groups. The results suggested that CCA decreased GSH and altered the expression of several genes, including antioxidants, GST, and DNA methylation, followed by impaired cell proliferation in the liver of female rats. [ABSTRACT FROM AUTHOR]

Plywood is a structural composite mainly applied in construction. For this purpose, some sort of preservative treatment is recommended to increase its durability. One option of the available treatments is heat treatment, which promotes the modification of the wood properties. This treatment is carried out on the final product (plywood), because it can reduce strength if applied to the veneers. However, no study has proven such a reduction. Therefore, the aim of this work was to evaluate three different temperatures (160 °C, 180 °C and 200 °C) of the heat treatment on the veneer surface and on the physical properties (specific gravity, moisture content and swelling in thickness) and mechanical properties (MOE and MOR in static bending) of Pinus taeda plywood. A reduction was observed in the roughness of the veneer's surfaces and the total extractives content changed, with a minimum value reached in the 160 °C treatment. The plywood specific gravity initially increased with the heat treatment and did not change at higher temperatures, moisture content reduced, and thickness swelling was not affected. There was no change in the mechanical properties of the plywood, evidencing that the veneer heat treatment does not prejudice mechanically the final product. [ABSTRACT FROM AUTHOR]

Preservative treatments increase the durability of wood, and one of the alternative treatments involves the use of chromated copper arsenate (CCA). Due to the toxicity of CCA, the disposal of CCA-treated wood residues is problematic, and burning is considered to provide a solution. The ecotoxicological potential of ash can be high when these components are toxic and mutagenic. The aim of this study was to evaluate the toxicity and genotoxicity of bottom ash leachates originating from CCA-treated wood burning. Physical-chemical analysis of the leachates revealed that in treated wood ashes leachate (CCA-TWBAL), the contents of arsenic and chromium were 59.45 mg.L−1 and 54.28 mg.L−1, respectively. In untreated wood ashes leachate (UWBAL), these contents were 0.70 mg.L−1 and 0.30 mg.L−1, respectively. CCA-TWBAL caused significant toxicity in Lactuca sativa, Allium cepa, and microcrustacean Artemia spp. (LC50 = 12.12 mg.mL−1). Comet assay analyses using NIH3T3 cells revealed that concentrations ranging from 1.0 and 2.5 mg.mL−1 increase the damage frequency (DF) and damage index (DI). According to MTT assay results, CCA-TWBAL at concentrations as low as 1 mg.mL−1 caused a significant decrease in cellular viability. Hemolysis assay analyses suggest that the arsenic and chromium leachate contents are important for the ecotoxic, cytotoxic, and genotoxic effects of CCA-TWBAL. [ABSTRACT FROM AUTHOR]

Wood is extensively used in Brazil and other countries to produce paper, building materials, and furniture, and a large amount of wood waste is produced. Chromated copper arsenate (CCA) is a preservative used in wood treatment because it can inhibit the action on biodeteriorating agents, therefore increasing the durability of the wood. As a result, environmental problems will arise due to the large amount of wood waste treated with CCA. The wasted CCA-treated wood is used as a fuel, resulting in the emission of toxic chemical compounds. Therefore, the aim of this work was to determine the toxicological effects of fly ash from the combustion of wood treated with CCA compared to the fly ash from untreated wood. Commercial samples of treated and untreated wood were subjected to controlled combustion. The particulate material, fly ash, was precipitated in water and in an acidic medium. The effluent from the HNO3 medium was submitted to analysis of metals (As, Cr, Cu) and polycyclic aromatic hydrocarbons (PAHs), and that collected in water was used for analysis of toxicity. The analysis of metals showed the presence of As and Cr in the effluent, main components of the chromated copper arsenate (CCA) salt. The toxicity analysis showed, in most cases, a significant increase in toxicity of the effluent from the combustion of the treated wood. However, there was some toxic effect on the effluent from the fly ashes of the untreated wood due to the presence of PAHs in them.

The remediation of wood preservative–contaminated sites is an important issue due to the carcinogenic nature of some contaminants derived from wood preservatives (e.g., Cr+6, arsenate, and pentachlorophenol). This study evaluated the effects of fertilizer application on remediation potential of co-plantings of Salix interior Rowlee. (Salix) and Festuca arundinacea Schreb. (Festuca) in a wood preservative–spiked technosol while considering the potential contaminant and nutrient leaching. Two levels of nitrogen (N) and phosphorus (P) fertilizers, NaNO3 and NaH2PO4 (25 and 75 mg L−1), were applied to achieve three N:P ratios, i.e., 3:1 (75:25), 1:3 (25:75), and 1:1 (25:25), that were compared with a control treatment (0:0 N:P) in a mesocosm experiment. Roots of the plant supplied with 1:1 and 1:3 N:P had more than double arsenic (As) and copper (Cu) amounts (i.e., biomass × concentration) compared to the control ones. Highest As and Cu amounts in shoots were found for Salix stems and Festuca leaves in the 1:3 and 1:1 N:P treatments, respectively. Arsenic and P leaching was high in mesocosms supplied with 1:3 N:P. Contamination and nutrient leaching in the 1:1 N:P treatment did not differ from the control, except for Cu. In conclusion, 1:1 N:P treatment yielded the best results in terms of metal(loid) uptake and contaminant and nutrient leaching. In 1:1 N:P treatment, the maximum values of percent As, Cr, and Cu in Salix and Festuca aboveground were 0.18%, 0.024%, and 1.20% and 0.89%, 0.08%, and 1.78%, respectively. [ABSTRACT FROM AUTHOR]

Technosols are a major component of urban areas with little to no value, but many benefits can be gained by the use of native plants for their ecological reclamation. The aim of this study is to examine the capacity of North American native woody species to establish in and remediate a wood preservative‐contaminated technosol. Nine species are planted in mesocosms containing highly contaminated or non‐contaminated synthetic technosols. Remediation potential and plant physiology parameters (survival, photosynthesis and root growth) are monitored during one growing season. Results show an inverse relation between species performance ranking in the non‐contaminated technosol compared to ranking in contaminated soil. Overall, Salix bebbiana and Sambucus canadensis show good potential for phytomanagement of heterogenous contaminated technosols, offering the best compromise between performance in non‐contaminated and contaminated soils. Most species are able to phytoextract copper (Cu), with Rhus typhina, Alnus crispa, and S. bebbiana showing the highest Cu concentrations in stems. The use of multiple native species for technosol reclamation can be beneficial due to the heterogeneous nature of soil contaminants. [ABSTRACT FROM AUTHOR]

Fast-growing species are gradually being used more in the Brazilian timber market. Such species are more susceptible to deterioration and require conservative treatment to prolong their service life. This work analyzed the influence of the chromated copper arsenate oxide (CCA-A) treatment on the physical-mechanical properties of the tropical woods Simarouba amara (C20), Cedrelinga catenaeformis (C30), and Erisma uncinatum (C40), which were chosen to cover the three lower strength classes, as prescribed by Brazilian Standard Norm. The CCA-A was applied to the wood with the vacuum-pressure process, which could increase the amount of surface defects and weaken the wood properties. To investigate the influence of this process, complete characterization of the species with and without CCA-A was performed, and a Tukey's multiple comparisons test (5% significance level) was applied. Also, scanning electron microscopy (SEM) images and energy dispersive spectra (EDS) were obtained to investigate the behavior of the preservative at the cellular level. Through the obtained results, it was concluded that the CCA did not affect the physical-mechanical properties of the studied species. [ABSTRACT FROM AUTHOR]

Abstract The physico-chemical factors affecting the distribution, behavior and speciation of chromium (Cr), copper (Cu) and arsenic (As) was investigated at a former wood impregnation site (Fredensborg, Denmark). Forty soil samples were collected and extracted using a sequential extraction technique known as the Chemometric Identification of Substrates and Element Distributions (CISED) and a multivariate statistical tool (redundancy analysis) was applied. CISED data was linked to water-extractable Cr, Cu and As and bioavailable Cu as determined by a whole-cell bacterial bioreporter assay. Results showed that soil pH significantly affected the solid phase distribution of all three elements on site. Additionally, elements competing for binding sites, Ca, Mg and Mn in the case of Cu, and P, in the case of As, played a major role in the distribution of these elements in soil. Element-specific distributions were observed amongst the six identified soil phases including residual pore salts, exchangeable, carbonates (tentative designation), Mn-Al oxide, amorphous Fe oxide, and crystalline Fe oxide. While Cr was strongly bound to non-extractable crystalline Fe oxide in the oxic top soil, Cu and notably, As were associated with readily extractable phases, suggesting that Cu and As, and not Cr, constitute the highest risk to environmental and human health. However, bioavailable Cu did not significantly correlate with CISED identified soil phases, suggesting that sequential extraction schemes such as CISED may not be ideally suited for inferring bioavailability to microorganisms in soil and supports the integration of receptor-specific bioavailability tests into risk assessments as a complement to chemical methods. Graphical abstract Unlabelled Image Highlights • CISED and redundancy analysis was used to assess factors affecting the solid phase distribution of Cr, Cu and As. • pH is the key parameter affecting all three elements. • P with As and Ca, Mg and Mn with Cu could compete for binding sites. • As and Cu were associated with readily extractable phases while Cr was not. • Cu bioavailability to microbes cannot be inferred solely using CISED. [ABSTRACT FROM AUTHOR]

This manuscript provides a brief review about chemical and biological agents used to bioremediate treated wood waste. Wood preservatives have been used to increase wood's useful life, because any species is subject to decay. Studies indicate that the disposal of treated wood after its service has drawn concern and scrutiny. Practices have included disposal in landfills or construction sites as well as destruction by burning, so it is apparent that more environmentally friendly options are needed. To mitigate these problems, acidic agents, fungi, and bacteria can be used as alternatives to remove heavy metals. At optimum temperature and concentration, acids play a major role in the removal process. The process is enhanced when a bioremediation technique is used after chemical extraction. In fact, bioremediation has been shown to be a remarkable technique for recovering copper, arsenic, creosote, and other compounds. The major drawback is the extensive duration of fungal activity for release of heavy metals. [ABSTRACT FROM AUTHOR]

Abstract There is increasing concern about the use of chromated copper arsenate (CCA) treated timber due to the possible leaching of toxic metals or metalloids. CCA-treated timber waste are currently stockpiled across Australia with limited information about their risks to the environment or human health. In this study, the treatment and utilisation of CCA-treated timber waste as garden mulch, garden retaining walls, and soil additive were investigated. Iron materials were used as immobilising agents. The bioavailability of Cr, Cu and As to Spinacia oleracea from CCA-treated timber, before and after treatment, was determined in the context of human health risk assessment. The results showed that the iron-based treatments resulted in significant decreases in the concentrations of Cu and As in spinach grown in CCA-treated timber in soil. Analyses of CCA derived Cu and As in spinach showed that they accumulated in the roots rather than in the leaves. The risks of toxicity to humans varied for different utilisation scenarios and the immobilisation amendments were shown to reduce carcinogenic and non-carcinogenic risks. The information obtained in this study can inform development of utilisation options for CCA-treated timber wastes. Graphical abstract Image 1 Highlights • Iron materials reduced leachability, bioavailability and risks for CCA metal(loid). • As, Cr mainly accumulated in root of spinach rather than leaves. • Most As and Cr present in leaves are As(V) (50–90%) and Cr (III) (50–100%). • Treated mulch showed acceptable low carcinogenic and non-carcinogenic risks. [ABSTRACT FROM AUTHOR]

Pentachlorophenol and chromated copper arsenate (CCA) have been used worldwide as wood preservatives, but these compounds can toxify ecosystems when they leach into the soil and water. This study aimed to evaluate the capacity of four treatment wetland macrophytes, Phalaris arundinacea, Typha angustifolia, and two subspecies of Phragmites australis, to tolerate and treat leachates containing wood preservatives. The experiment was conducted using 96 plant pots in 12 tanks filled with three leachate concentrations compared to uncontaminated water. Biomass production and bioaccumulation were measured after 35 and 70 days of exposure. There were no significant effects of leachate contamination concentration on plant biomass for any species. No contaminants were detected in aboveground parts of the macrophytes, precluding their use for phytoextraction within the tested contamination levels. However, all species accumulated As and chlorinated phenols in belowground parts, and this accumulation was more prevalent under a more concentrated leachate. Up to 0.5 mg pentachlorophenol/kg (from 81 µg/L in the leachate) and 50 mg As/kg (from 330 µg/L in the leachate) were accumulated in the belowground biomass. Given their high productivity and tolerance to the contaminants, the tested macrophytes showed phytostabilization potential and could enhance the degradation of phenols from leachates contaminated with wood preservatives in treatment wetlands.

Abstract A limitation to recycling wood from construction and demolition (C&D) waste is contamination of metals from the inadvertent inclusion of preservative treated wood, in particular wood treated with chromated copper arsenate (CCA) and newer copper-based formulations. To minimize contamination many regions have developed best management practices (BMPs) for separating treated from untreated wood. The objective of this study was to evaluate the fraction of preservative treated wood in recycled C&D wood after the implementation of BMPs, using Florida as a case study. Methods involved collecting recycled C&D wood samples from throughout the state, measuring metals concentrations (As, Cu, and Cr) in the samples to compute the fraction of recycled wood treated with waterborne wood preservatives, and comparing measurements with those taken prior to the formalization of BMPs. Metals concentrations were measured using two methods, one based on traditional laboratory digestion methods and another using a more rapid hand-held X-ray Fluorescence (XRF) device in the field. The proportion of waterborne preservative-treated wood in recycled wood products has reduced significantly in the intervening 20 years (from 6% to 2.9%), and the fraction of CCA-treated wood has been reduced even further, to 1.4%. The remaining fraction of waterborne preservative-treated wood is comprised of new formulations of copper-based preservatives. This suggests that restrictions from the wood preservation industry and best management practices implemented at recycling facilities have been effective in reducing heavy metal contamination from pressure treated lumber in recycled wood products. Graphical abstract Image 1 Highlights • In previous work, 6% of recycled wood was treated with chromated copper arsenate. • Since then, industry-led changes have influenced the recycled wood market. • Copper-based wood preservatives are replacing CCA in the market. • This study found that 1.4% of recycled wood was treated with CCA, 1.5% with copper. • In 20 years, waterborne preservatives in recycled wood has decreased by 50%, CCA by 75%. Best management practices and changes to the preservative wood industry have resulted in a reduction in arsenic-treated wood within recycled C&D wood by a factor of 4. [ABSTRACT FROM AUTHOR]

The genera Eucalyptus and Corymbia are widely used in Brazil. Although they present remarkable applicability, they manifest substantial endsplitting and surface checks, which allows wood decay organisms to penetrate the wood. Thereby, the resistance of Eucalyptus grandis x Eucalyptus urophylla (EU) and Corymbia citriodora (CT) treated with chromated copper arsenate type-C (CCA-C) against fungi decay was evaluated. Seventy-two fence posts were assessed; for each species, there were 18 posts treated with CCA-C and 18 non-treated posts. The posts were 2.20 m long and classified into three classes of diameter. The 2% active ingredient was used with a vacuum-pressure cycle. On each fence, disks measuring 2.0 cm thick were cut at the outcrop zone. Two sets of depths were analyzed: the edge at 0 cm to 1.5 cm as well as the inner part at 1.5 cm to 3.0 cm. The samples were subjected to Postia placenta, Gloeophyllum trabeum, and Trametes versicolor attack. The treatment was effective against all fungi, but for CT, the diameter range of 8 cm to 12 cm was optimal. The treated wood from EU samples reached the lowest weight loss for all fungi. Heartwood-sapwood ratio played a major role. By comparing the non-treated woods, EU yielded the highest mass loss. [ABSTRACT FROM AUTHOR]

Chromated copper arsenate (CCA) is used as a wood preservative worldwide. Exposure to it may adversely affect human health. Some events have increased human exposure to CCA, including the Great East Japan Earthquake, which generated a large amount of lumber debris from CCA-treated woods. We elucidated the toxicity due to daily exposure to CCA over a 4-week period at doses of 0,8,40, and 80 mg/kg/day in Wistar Hannover rats. Chromium (Cr) and arsenic (As), but not copper, were detected in the plasma samples of rats treated with various doses of CCA. Males and females showed sedation, and males had poor body weight gain. The clinical pathologies observed in both sexes included hypochromic and microcytic anemia, hepatic and renal dysfunction, and changes in lipid and glucose levels. Histopathologically, males and females showed forestomach hyperkeratosis, mucosal epithelial hyperplasia in the small intestine, rectal goblet cell hypertrophy, and lipofuscin deposition in the proximal renal tubule. Females showed diffuse hepatocellular hypertrophy with increased 8-hydroxydeoxyguanosine levels. These results indicated that oral administration of CCA mainly affected hematopoietic, gastrointestinal, hepatic, and renal systems owing to the toxic effects of As and/or Cr. Major toxic effects were observed in both sexes receiving 40 and 80 mg/kg/day. [ABSTRACT FROM AUTHOR]

Purpose: The present study investigates the possible use and effectiveness of starch-stabilized Fe/Cu nanoparticles for in situ immobilization of arsenic in contaminated soils.Materials and methods: For this purpose, 0.04 wt.% starch-stabilized Fe/Cu nanoparticles were synthesized and tested through batch and column tests for the immobilization of arsenic in a loamy soil contaminated by chromated copper arsenate (CCA).Results and discussion: When the CCA-contaminated loamy soil was treated with 0.4 g/L of starch-stabilized Fe/Cu nanoparticles (0.04 wt.%) at a soil-to-liquid ratio of 0.1, water-leachable arsenic was reduced by 92% and the toxicity characteristic leaching procedure (TCLP) leachability was reduced by 98%. Column elution experiments showed that through application of starch-stabilized Fe/Cu nanoparticles to CCA-contaminated soil, nearly all water-soluble arsenic was transferred to the nanoparticle phase. The TCLP leachability of arsenic remaining in the soil column was reduced by 70% due to the immobilization of arsenic by nanoparticles.Conclusions: In addition to an extremely high arsenic sorption capacity, starch-stabilized Fe/Cu nanoparticles exhibited excellent mobility in the soil environment. Both the high sorption capacity and the excellent mobility in the soil environment suggest potential for application of these nanoparticles to the contaminated soil for potential in situ arsenic immobilization. [ABSTRACT FROM AUTHOR]

Plywood can be used in the furniture industry and in civil construction due to its structural strength. However, for long useful life in construction, especially in tropical countries, it needs to undergo treatments against xylophagous organisms. The most common preservative treatment is the chemical chromated copper arsenate (CCA); there are alternatives, such as heat treatment, that do not use chemicals. The objective of this work was to evaluate the mechanical resistance of CCA and heat-treated plywood prepared at three different temperatures (160 °C, 180 °C, and 200 °C). Pinus taeda plywood with seven veneers and phenol-formaldehyde adhesive was produced and subjected to the preservative treatments. The results showed that the CCA treatment reduced the mechanical strength of the panels, while the heat treatment did not. Heat treatment also decreased panel hygroscopicity, indicating a better dimensional stability. [ABSTRACT FROM AUTHOR]

The disposal of eucalyptus poles used in the electricity network distribution is considered a potential contamination to the environment due to the chromated copper arsenate (CCA) used as a wood preservative. The thermochemical process can be an alternative to this toxic waste disposal. In this work, the slow pyrolysis of CCA-treated wood followed by the production and application of activated carbon was proposed. Metal retention (ICP-OES), concentration of non-condensable gases produced in the pyrolysis process (via GC), as well as the capacity of activated carbon on CO 2 adsorption (via TGA) were investigated. The highest formation rate of non-condensable gases was observed at 500 °C, while the maximum H 2 concentration was at 700 °C. The char obtained in the pyrolysis was chemically treated with H 3 PO 4 and activated in CO 2 flow. The pore size distribution of activated carbons showed pore sizes lower than 1 nm. The activated carbons showed a CO 2 adsorption capacity of 70–83 mg/g. The presence of chromium and copper may have influenced the CO 2 adsorption. The fast adsorption and desorption showed by the activated carbon produced from CCA-treated wood is interesting to systems that operate in short-time cycles, as pressure swing adsorption (PSA). The reuse of CCA-treated wood for activated carbon production and its application in the CO 2 adsorption could be a solution to minimize the environmental damage caused by this waste. [ABSTRACT FROM AUTHOR]

The importance of a circular economy is today widely accepted and advocated, but among the challenges in achieving this, we find difficulties in the implementation of legislation and policies designed to control various waste streams from society. The example used in this article is wood that has been treated with chromated copper arsenate (CCA), which, in Sweden, has been covered by the rules for hazardous waste since 2002. One year later, in 2003, a survey showed that only 42% to 50% of the expected amount of CCA waste could be traced to the public waste management system. An updated material flow analysis for 2010 revealed that the figure had increased to 73%, whereas the fraction of correctly treated CCA wood waste had increased from 11% to 35%. However, almost one third of the expected volume was still not tracable, and half of the amount that was correctly submitted was incinerated together with nontoxic waste fractions. This results in, for example, arsenic contamination of slag and fly ashes that prevents the further use of these residue products. So, despite legislative instruments, there is still an urgent need for an improved collection of hazardous wood waste, as well as better routines for identifying hazardous flows and separating them from nonhazardous ones. For a circular economy to be achievable, a key priority should be to reduce the gap between intended directions and legislation, on one hand, and activities in practice on the other. [ABSTRACT FROM AUTHOR]

Effects of natural weathering were studied relative to the adhesion strength, surface hardness, and color change of coated heat-treated and untreated Turkish fir and Scots pine wood. For this study, water-based coatings (varnish and paint) were applied on heat-treated samples. The coated heat-treated, and untreated samples were naturally weathered for one year. The difference between several properties such as adhesion strength, hardness, and color were measured before and after weathering. The test results showed that varnished heat-treated samples had good performance as compared to those of the untreated samples. [ABSTRACT FROM AUTHOR]

The paper discusses the potential of different waste biomaterials for biosorption. Waste biomaterials after citric acid fermentation and chitosan extraction using Aspergillus niger were evaluated for biosorption of toxic metals (Cu, Cr and As) from leachates of chromated copper arsenate woods. The different waste BMs, such as fungal biomass (living and dead), alkali insoluble material and acid and alkali insoluble material were used in this study. The effect of different parameters, such as biosorbent concentration, metal concentration and contact time were investigated. The fitness of biosorption data for Freundlich and Langmuir adsorption models was investigated through batch adsorption technique. Among the adsorption isotherm tested, Langmuir isotherm gave the best fit with correlation coefficients (R 2 ) value ranging from 0.89 to 0.97; 0.96–0.99 and 0.76–0.95 for As, Cr and Cu, respectively using solid state fermented biomass. Similarly, the significant removal of metals (>60% in leachate 2) from waste CCA wood leachate was achieved with the different BMs. Therefore, this study demonstrates the potential of CA fermentation derived waste BMs for biosorption of toxic metals from waste waters. [ABSTRACT FROM AUTHOR]

In addition to the combustion of vegetation, fires at the wildland-urban interface (WUI) burn structural materials, including chromated copper arsenate (CCA)-treated wood. This study identifies, quantifies, and characterizes Cr-, Cu-, and As-bearing incidental nanomaterials (INMs) in WUI fire ashes collected from three residential structures suspected to have originated from the combustion of CCA-treated wood. The total elemental concentrations were determined by inductively coupled plasma-time of flight-mass spectrometry (ICP-TOF-MS) following acid digestion. The crystalline phases were determined using transmission electron microscopy (TEM), specifically using electron diffraction and high-resolution imaging. The multi-element single particle composition and size distribution were determined by single particle (SP)-ICP-TOF-MS coupled with agglomerative hierarchical clustering analysis. Chromium, Cu, and As are the dominant elements in the ashes and together account for 93%, 83%, and 24% of the total mass of measured elements in the ash samples. Chromium, Cu, and As phases, analyzed by TEM, most closely match CrO 3 , CrO 2 , eskolaite (Cr 2 O 3), CuCrO 2 , CuCr 2 O 4 , CrAs 2 O 6 , As 2 O 5 , AsO 2 , claudetite (As 2 O 3 , monoclinic), or arsenolite (As 2 O 3 , cubic), although a bona fide phase identification for each particle was not always possible. These phases occur predominantly as heteroaggregates. Multi-element single particle analyses demonstrate that Cr occurs as a pure phase (i.e., Cr oxides) as well as in association with other elements (e.g., Cu and As); Cu occurs predominantly in association with Cr and As; and As occurs as As oxides and in association with Cu and Cr. Several Cr, Cu, and As clusters were identified and the molar ratios of Cr/Cu and Cr/As within these clusters are consistent with the crystalline phases identified by TEM as well as their heteroaggregates. These results indicate that WUI fires can lead to significant release of CCA constituents and their combustion-transformed by-products into the surrounding environment. This study also provides a method to identify and track CCA constituents in environmental systems based on multi-element analysis using SP-ICP-TOF-MS. [Display omitted] • Chromium, copper, and arsenic concentrations in WUI fire ash were determined. • The composition of Cr, Cu, and As INMs in WUI fire ash were determined. • Original and transformed Cr, Cu, and As-bearing INMs were detected in WUI fire ash. • The source of Cr, Cu, and As-bearing INMs in WUI fire ashes is treated wood. [ABSTRACT FROM AUTHOR]

Background: We investigated the particles released due to abrasion of wood surfaces pressure-treated with micronized copper azole (MCA) wood preservative and we gathered preliminary data on its in vitro cytotoxicity for lung cells. The data were compared with particles released after abrasion of untreated, water (0% MCA)-pressure-treated, chromated copper (CC)-pressure-treated wood, and varnished wood. Size, morphology, and composition of the released particles were analyzed. Results: Our results indicate that the abrasion of MCA-pressure-treated wood does not cause an additional release of nanoparticles from the unreacted copper (Cu) carbonate nanoparticles from of the MCA formulation. However, a small amount of released Cu was detected in the nanosized fraction of wood dust, which could penetrate the deep lungs. The acute cytotoxicity studies were performed on a human lung epithelial cell line and human macrophages derived from a monocytic cell line. These cell types are likely to encounter the released wood particles after inhalation. Conclusions: Our findings indicate that under the experimental conditions chosen, MCA does not pose a specific additional nano-risk, i.e. there is no additional release of nanoparticles and no specific nano-toxicity for lung epithelial cells and macrophages. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the dimensional stability, mechanical and biological performance and thermal degradation of wood–plastic composites made from high-density polyethylene and recycled wood treated with chromated copper arsenate (CCA), a commonly used wood preservative chemical. Virgin pine wood samples were also prepared with and without a coupling agent and used as the control group. Samples of CCA-treated Scots pine (Pinus sylvestris L.) with varying wood content were produced by adding different ratios of the coupling agent. The recycled CCA-treated wood-filled composites exhibited better flexural and tensile strength properties and dimensional stability than the control group, whilst their impact strength was less. Biological test values showed improved durability against termites and fungus with the recycled CCA-treated wood-filled composites. In addition, the leaching of heavy metals was significantly diminished when the coupling agent was utilized at a level of 5% (w/w), thus presenting a much lower impact on the environment. [ABSTRACT FROM AUTHOR]

The behavior of arsenic in chromated copper arsenate containing wood during gasification was modeled using thermodynamic equilibrium calculations. The results of the model were validated using bench-scale gasification tests. It is shown that over 99.6% of arsenic can be removed from the product gas by a hot filter when the gas is cooled below the predicted condensation temperature. [ABSTRACT FROM AUTHOR]

Animal enclosures are often constructed from wood treated with the pesticide chromated copper arsenate (CCA), which leaches arsenic (As) into adjacent soil during normal weathering. This study evaluated potential pathways of As exposure in 25 species of zoo animals living in CCA-wood enclosures. We analyzed As speciation in complete animal foods, dislodgeable As from CCA-wood, and As levels in enclosure soils, as well as As levels in biomarkers of 9 species of crocodilians (eggs), 4 species of birds (feathers), 1 primate species (hair), and 1 porcupine species (quills). Elevated soil As in samples from 17 enclosures was observed at 1.0–110 mg/kg, and enclosures housing threatened and endangered species had As levels higher than USEPA's risk-based Eco-SSL for birds and mammals of 43 and 46 mg/kg. Wipe samples of CCA-wood on which primates sit had dislodgeable As residues of 4.6–111 μg/100 cm 2 , typical of unsealed CCA-wood. Inorganic As doses from animal foods were estimated at 0.22–7.8 μg/kg bw/d. Some As levels in bird feathers and crocodilian eggs were higher than prior studies on wild species. However, hair from marmosets had 6.37 mg/kg As, 30-fold greater than the reference value, possibly due to their inability to methylate inorganic As. Our data suggested that elevated As in soils and dislodgeable As from CCA-wood could be important sources of As exposure for zoo animals. [ABSTRACT FROM AUTHOR]

Preservatives such as chromated copper arsenate (CCA) are used to increase the resistance of wood to deterioration. The components of CCA are highly toxic, resulting in growing concern over the disposal of the waste generated. The aim of this study was to investigate the removal of Cu, Cr and As present in CCA-treated eucalyptus wood from utility poles removed from service in southern Brazil, in order to render them non-hazardous waste. The removal was carried out by acid leaching in bench-scale and applying optimal extractor concentration, total solid content, reactor volume, temperature and reaction time obtained by factorial experiments. The best working conditions were achieved using three extraction steps with 0.1 mol L −1 H 2 SO 4 at 75 °C for 2 h each (total solid content of 15%), and 3 additional 1 h-long washing steps using water at ambient temperature. Under these conditions, removal of 97%, 85% and 98% were obtained for Cu, Cr and As, respectively, rendering the decontaminated wood non-hazardous waste. The wastewater produced by extraction showed acid pH, high organic loading as well as high concentrations of the elements, needing prior treatment to be discarded. However, rinsing water can be recycled in the extraction process without compromising its efficiency. The acid extraction is a promising alternative for CCA removal from eucalyptus wood waste in industrial scale. [ABSTRACT FROM AUTHOR]

The aim of this work was to increase the amount of recycled waste wood in the wood-processing industry. Contaminations such as plastics and wood preservatives therefore have to be identified and removed. A promising technique to detect this foreign matter is near-infrared (NIR) spectroscopy. For several organic and inorganic active compounds for wood preservation, the NIR reflectance spectra acquired with sensors with the capability of on-line measurements were characterized. Some of them were significantly different from those of previously published spectra. Moreover, untreated wood was distinguishable from wood treated with preservatives. Confounding factors, such as the water content, wood species and solvent of the preservative, were examined which had so far massively interfered the NIR detection and classification. Chemometric-based solutions are presented in this work to cope with analytical challenges arisen from the complexity of waste wood samples. This formed the basis for a sorting trial in which treated wood chips were detected in real time with an NIR spectrometer and automatically separated by pneumatic nozzles, showing that the laboratory experiments can be transferred into small industrial scale. Additionally, the experiments showed that wood-plastic composites (WPC) of different plastic types were distinguishable with NIR spectroscopy and can be sorted by ejection based on this information. Unmixed material is a major prerequisite for a high-quality recycling of WPC and has never been demonstrated on a technical scale. Furthermore, three different NIR devices (hyperspectral imaging camera, miniaturized spectrometer and sorting plant) were evaluated regarding their applicability in the waste wood recycling process. [ABSTRACT FROM AUTHOR]

Se realizó un análisis comparativo de la precisión de los resultados en la determinación de la retención de óxidos de cobre, cromo y arsénico en madera impregnada con arseniato de cobre cromatado entre fluorescencia de rayos X y espectrometría de reflectancia difusa de infrarrojos cercanos. Los resultados de la calidad de las predicciones fueron comparados entre sí y con valores de retención obtenidos experimentalmente por método gravimétrico, absorción atómica y por cenizas resultantes de su calcinación. Los resultados del coeficiente de determinación del análisis de regresión entre la intensidad de fluorescencia de rayos X de las líneas K-Alpha y entre el espectro de reflectancia difusa de infrarrojos con respecto a la retención medida por métodos convencionales se encontraron en un rango de 0,909 a 0,986. Los resultados obtenidos pueden ser considerados aceptables para fines predictivos o incluso adecuados para propósitos de control de calidad. A su vez, al ser comparados por sus niveles de error de estimación, estos resultados fueron mejores que los obtenidos por otros estudios similares. Abstract This paper evaluated the precision of predictions for chromated copper arsenate preservative retention in wood using X-ray fluorescence and near infrared diffuse reflectance. The quality of the predictions were compared with each other and with retention values obtained experimentally by gravimetric method, atomic absorption and total ash content. Coefficients of determination between the K-Alpha fluorescence intensities and near infrared diffuse reflectance with regard to conventional methods were between 0,909 and 0,986. The results can be considered acceptable for predictive purposes or even good for quality control purposes. In turn, the prediction errors were better than obtained by several studies.

In this study, we investigated the optical properties of CCA films prepared with poly[styrene-co-sodium 1-allyloxy-2-hydroxypropane sulphonate] particles via soap-free emulsion polymerisation. Experiments were performed by adjusting the several reaction factors such as styrene concentration, sodium 1-allyloxy-2-hydroxypropane sulphonate concentration, polymerisation temperature, initiator and divinylbenzene concentration. All latexes showed uniform spherical particles and they showed a size range of 160-550 nm. All CCA films prepared with self-assembled array showed the respective shiny structural colours from their photonic crystals. It is found that the changes in such polymerisation factors greatly affect the number of particles and particle diameter and refractive indices. Refractive indices and the reflectivity increased with sodium 1-allyloxy-2-hydroxypropane sulphonate concentration, on the other hand, and decreased with divinylbenzene concentration. [ABSTRACT FROM AUTHOR]

Effects of chromated copper arsenate (CCA) on fixation and leaching characteristics of eight Malaysian commercial hardwood, namely, acacia (Acacia mangium), bintangor (Calophyllum sp.), geronggang (Cratoxylum arborescens), medang (Litsea sp.), meranti rambai daun (Shorea acuminata), putat (Planchonia sp.), ramin (Gonystylus sp.) and simpuh (Dillenia sp.) were studied. CCA-fixation rate in wood was evaluated by monitoring the reduction of hexavalent to trivalent chromium in expressates. The amounts of copper, chromium and arsenic remaining in the unfixed state after 14 days were also determined. Acacia was the most suitable species for treatment with CCA. In comparison with radiata pine, leaching of CCA components from treated timbers was high and varied between species owing to their chemical composition especially lignin content. An additional study was conducted with geronggang and ramin to determine the effect of pre-extraction on fixation. Results indicated that differences in fixation and leaching characteristics of CCA-treated timbers (especially geronggang and ramin) were influenced by the extractive content of the wood. [ABSTRACT FROM AUTHOR]

Concern about children's exposure to arsenic (As) from wood treated with chromated-copper-arsenate (CCA) led to its withdrawal from residential use in 2004. However, due to its effectiveness, millions of American homes still have CCA-wood decks on which children play. This study evaluated the effects of three deck-cleaning methods on formation of dislodgeable As and hexavalent chromium (CrVI) on CCA-wood surfaces and in leachate. Initial wipes from CCA-wood wetted with water showed 3–4 times more dislodgeable As than on dry wood. After cleaning with a bleach solution, 9.8–40.3 μg/100 cm 2 of CrVI was found on the wood surface, with up to 170 μg/L CrVI in the leachate. Depending on the cleaning method, 699–2473 mg of As would be released into the environment from cleaning a 18.6-m 2 -deck. Estimated As doses in children aged 1–6 after 1 h of playing on a wet CCA-wood deck were 0.25–0.41 μg/kg. This is the first study to identify increased dislodgeable As on wet CCA-wood and to evaluate dislodgeable CrVI after bleach application. Our data suggest that As and CrVI in 25-year old CCA-wood still show exposure risks for children and potential for soil contamination. [ABSTRACT FROM AUTHOR]

In this study, As-, Pb-, and Cu-contaminated soil was stabilized using calcined oyster shells (COS) and steel slag (SS). The As-contaminated soil was obtained from a timber mill site where chromate copper arsenate (CCA) was used as a preservative. On the other hand, Pb- and Cu-contaminated soil was obtained from a firing range. These two soils were thoroughly mixed to represent As-, Pb-, and Cu-contaminated soil. Calcined oyster shells were obtained by treating waste oyster shells at a high temperature using the calcination process. The effectiveness of stabilization was evaluated by 1-N HCl extraction for As and 0.1-N HCl extraction for Pb and Cu. The treatment results showed that As, Pb, and Cu leachability were significantly reduced upon the combination treatment of COS and SS. The sole treatment of SS (10 wt%) did not show effective stabilization. However, the combination treatment of COS and SS showed a significant reduction in As, Pb, and Cu leachability. The best stabilization results were obtained from the combination treatment of 15 wt% COS and 10 wt% SS. The SEM-EDX results suggested that the effective stabilization of As was most probably achieved by the formation of Ca-As and Fe-As precipitates. In the case of Pb and Cu, stabilization was most probably associated with the formation of pozzolanic reaction products such as CSHs and CAHs. [ABSTRACT FROM AUTHOR]

Effects of microwave pre-treatment on impregnation properties in fir wood (Abies alba L.) with acid copper chromate (ACC) were studied here. Flat-sawn specimen boards were prepared with moisture content (MC) of 40 ± 5% and were exposed to microwave radiation with 2450 MHz frequency for 10, 12, 14, and 16 minutes at four different radiation treatments. Microwave-treated specimens, along with the control specimens, were conditioned to the final MC of 12% and then impregnated with 5%-ACC solution, using an empty-cell process. The impregnation properties were then measured, including retention, maximum and minimum depths of penetration, impregnated area in the cross-section, and ACC-leaching. Image J software was used to determine depths of penetration. Results showed that microwave pre-treatment significantly improved all the impregnation properties, with the exception of leaching. Clear direct relation was found between the duration of microwave radiation with the properties. It can be concluded that microwave pre-treatment can be used to significantly improve impregnation properties in fir wood. [ABSTRACT FROM AUTHOR]

The potential for pollution from arsenic, chromium and copper in chromated copper arsenate (CCA) treated wood waste was assessed using two lysimeter studies. The first utilised lysimeters containing soil and CCA wood waste mulch exposed to natural conditions over a five month period. The second study used the same lysimeter setup in a regulated greenhouse setting with a manual watering regime. Woodchip, soil and leachate samples were evaluated for arsenic, chromium and copper concentrations. Resultant concentration data were used to produce mass balances, an approach thus far unused in such studies. This novel analysis revealed new patterns of mobility and distribution of the elements in the system. The results suggest that CCA wood waste tends to leach on initial exposure to a leachant and during weathering of the wood. When in contact with soil, metal(loid) transport is reduced due to complexation reactions. With higher water application or where the adsorption capacity of the soil is exceeded, the metal(loid)s are transported through the soil column as leachate. Overall, there was an unexplained loss of metal(loid)s from the system that might be attributed to volatilisation of arsenic and plant uptake. This suggests a hitherto unidentified risk to both the environment and human health. [ABSTRACT FROM AUTHOR]

Arsenic exposure from wood treated with chromated copper arsenate (CCA) remains a concern due to its presence around homes. This study evaluated children's exposure to As from CCA-treated staircases through determination of bioaccessible soil As and measurements of dislodgeable As on hand railings, steps and surfaces of household objects impacted by CCA–wood leachate. Total As concentrations in 84 soil samples from 4 apartment complexes were elevated at 1.2–66.6mg/kg with bioaccessible As at 17–84%. Deterministic risk equations were used to estimate daily doses of As in children with estimates ranging from 0.41–54.9μg/day from ingestion of dislodgeable As. Lifetime average daily doses from ingestion of dislodgeable As and soil ranged from 8.1×10−6 to 3.0×10−5 mg/kg/day, with estimated cancer risks being 1.2–4.5×10−5. Collectively, these results highlight potential health risks in children who have near-daily exposure to As from CCA-wood and are consistent with estimates generated by USEPA's SHEDS-Wood probabilistic exposure model. [ABSTRACT FROM AUTHOR]

Chromated copper arsenate (CCA) is a common wood preservative that has been used worldwide. Studies have shown that there are leaching risks of the preservative components arsenic, chromium and copper. These risks include contamination of soil and water, resulting in toxic effects to humans, animals, plants and ecosystems. This study investigates leaching of the preservative components following exposure of the wood waste as mulch to soil and water. Diffusive gradient in thin films (DGTs) were used to quantify leaching of potentially bioavailable/dissolved forms of the elements along the soil profile. Speciation of chromium was also carried out. All elements were found to leach out of the wood. The containers that included CCA-treated wood waste as a mulch leached higher levels of arsenic, chromium and copper than the controls. The distribution was highest in the top 5 cm of the soil profile and decreased with depth. DGTs proved to be a useful, novel technique for measuring in situ leaching and speciation from waste materials into the environment. [ABSTRACT FROM AUTHOR]

In recent years, an efficient and economically attractive leaching process has been developed to remove metals from copper-based treated wood wastes. This study explored the applicability of this leaching process using chromated copper arsenate (CCA) treated wood samples with different initial metal loading and elapsed time between wood preservation treatment and remediation. The sulfuric acid leaching process resulted in the solubilization of more than 87% of the As, 70% of the Cr, and 76% of the Cu from CCA-chips and in the solubilization of more than 96% of the As, 78% of the Cr and 91% of the Cu from CCA-sawdust. The results showed that the performance of this leaching process might be influenced by the initial metal loading of the treated wood wastes and the elapsed time between preservation treatment and remediation. The effluents generated during the leaching steps were treated by precipitation–coagulation to satisfy the regulations for effluent discharge in municipal sewers. Precipitation using ferric chloride and sodium hydroxide was highly efficient, removing more than 99% of the As, Cr, and Cu. It appears that this leaching process can be successfully applied to remove metals from different CCA-treated wood samples and then from the effluents. [Copyright &y& Elsevier]

Concentrations of Cu, Cr, and As in soils surrounding 26 Douglas Fir Chromated Copper Arsenate (CCA) treated utility poles and in rainwater runoff from a new CCA treated utility pole segment (log) suspended outside in a cylinder were studied. The age of the utility poles, distances from the poles, rainfall amounts, and characteristics of soil samples including cation exchange capacity (CEC), pH, and total organic carbon (TOC) were considered. Heavier rainfall, damp conditions, and more weathered poles contributed to the greatest leaching of Cu, Cr, and As. The maximum measured soil concentrations of Cu, Cr, and As were 37.5, 65.5, and 38.9mmol/kg and maximumCu, Cr, and As concentrations in rainwater run-off were 14, 77.7 and 55.8 μmol/L. Metal concentrations decreased with distance fromthe poles and, except at one utility pole location, Cu was the most leached of the three elements. The As appeared to have greatermobility in the soil than the Cr. Along the transmission line nearest the coast and from which the greatest amount of samples was collected, soil CEC and TOC values were the highest and the CEC and TOC were directly and strongly correlated. [ABSTRACT FROM AUTHOR]

Firms play a key role in pollution abatement and control by engaging in beyond-compliance actions without the force of law in voluntary programs. This study examines the effectiveness of a bilateral voluntary agreement, one type of voluntary programs, negotiated between the U.S. Environmental Protection Agency (EPA) and the pressure-treated wood industry to phase-out the use of chromated copper arsenate (CCA), a poisonous arsenic compound. Arsenic is ranked number one on the EPA's priority list of hazardous substances. Unlike a majority of earlier studies on voluntary programs, dynamic panel estimation and structural break analysis show that while a technological innovation in semiconductors is associated with arsenic use increases, the CCA voluntary agreement is associated with a reduction in arsenic use to levels not seen since the 1920s. A voluntary ban in arsenic acid by pesticide manufacturers in the agriculture sector has also contributed to arsenic reductions. Furthermore, the results suggest that environmental activism has played a role in curbing arsenic use. Increasing stakeholder pressures, as measured by membership in the Sierra Club, improves voluntary agreement effectiveness. [Copyright &y& Elsevier]

Chromated copper arsenate (CCA) has been one of the most widely used since the 1933's as a wood preservative to protect wood against decay and insects for exterior applications such as decks, housing, utility poles, play equipment and fences. Although its major use for consumer lumber products was replaced with chromium- and arsenic-free preservatives in the USA, Canada and European Countries by the end of 2003, large volumes of CCA-treated wood has been still coming out-of-service each year. Therefore, at present, the potential loss of heavy metals from CCA-treated wood waste after disposal has become an important problem. The disposal of out-of service CCA treated wood materials at the end of its useful life remains a concern, despite the reduction in CCA-treated wood production. Waste management options for out-of service CCA-treat wood are limited and include minor amounts of recycling and incineration with the remainder going to landfill disposal. Because of new regulations and the concerns about environmental contamination, there is a need in developing methods for recycling out-of-service CCA-treated wood products. Acid extraction, with or without bioremediation, has been extensively studied for removal of copper, chromium and arsenic from out-of service CCA-treated wood. However, none of the researchers addressed the problem about the effects of wood species and retention levels on remediation efficiency. The objectives of this study were to investigate the effects of wood species and retention levels on removal of copper, chromium and arsenic from CCA-treated wood samples using calcium hypochlorite. The results showed that Ca(ClO)2 was very effective to remove copper, chromium and arsenic from CCA-C treated milled wood samples for all three species used in this study. Ca(ClO)2 may be very good option to remediate out-of- service CCA treated wood not only because of its high and relatively fast extraction efficiency but also because the chemical is relatively inexpensive. However, the results showed that wood species and initial retention levels of CCA-treated wood products played very important role in terms of removal of Cu, Cr and As. Therefore, whichever the remediation methods and chemicals are used for the removal of Cu, Cr and As, initial retention levels of the CCA treated wood products should be taken into account and CCA-treated wood products should be sorted according to their initial retention levels and wood species (if possible) before remediation process. [ABSTRACT FROM AUTHOR]

Search for effective, ecosystem-friendly wood preservative-chemicals, as safe-alternatives to the conventional inorganic types (e.g. CCA), has currently been extensive. Bio-potency of inestimable tropical plants has assumed folkloric dimensions. Thus, the influence of cold water-soluble extracts from potrodom ( Erythrophluem suaveolens) bark, moringa ( Moringa oleifera) and milk bush ( Thevetia peruviana) roots on the durability of pressure-treated ceiba ( Ceiba pentandra) stakes (500 × 50 × 10 mm) was examined under graveyard conditions (EN 252). Their field performance was compared with their CCA-impregnated counterparts. Control stakes were untreated. T. peruviana root extract and CCA were retained most (2.08 and 2.06 × 10 g/mm respectively) then E. suaveolens and M. oleifera root extracts (1.84 and 1.74 × 10 g/mm respectively). Thevetia peruviana extract-treated stakes recorded 19.4 % hardness loss, 41.5 % mass loss and visual durability rating of 3. Similarly, E. suaveolens impregnated stakes recorded 34.6, 28.8 % and 2; M. oleifera root extract 41.2, 98.9 % and 4; CCA-treated stakes 12.7, 19.4 % and 1, and the control 100, 100 % and 4 respectively. Biocides from the plant parts (especially E. suaveolens bark) were as effective as CCA. To broaden the preservative-chemical base for the wood treatment industry, chemicals from organic sources including vegetable-based types, which act as a pool for unlimited source of innocuous biocides, need be increasingly discovered and utilized as alternatives to the efficacious but noxious inorganic types, which pose regulatory, health and environmental fretfulness. Synergy of botanic extracts with the synthetic preservative-chemicals could likewise be explored industrially. [ABSTRACT FROM AUTHOR]

Abstract: The literature on the presence of heavy metals in contaminated wastes is reviewed. Various categories of materials produced from domestic and industrial activities are included, but municipal solid waste, which is a more complex material, is excluded. This review considers among the most abundant the following materials – wood waste including demolition wood, phytoremediation scavengers and chromated copper arsenate (CCA) timber, sludges including de-inking sludge and sewage sludge, chicken litter and spent pot liner. The partitioning of the metals in the ashes after combustion or gasification follows conventional behaviour, with most metals retained, and higher concentrations in the finer sizes due to vaporisation and recondensation. The alkali metals have been shown to catalyse the biomass conversion, particularly lithium and potassium, although other metals are active to a lesser extent. The most prevalent in biomass is potassium, which is not only inherently active, but volatilises to become finely distributed throughout the char mass. Because the metals are predominantly found in the ash, the effectiveness of their removal depends on the efficiency of the collection of particulates. The potential for disposal into soil depends on the initial concentration in the feed material. [Copyright &y& Elsevier]