Relative leaching and aquatic toxicity of pressure-treated wood products using batch leaching tests

Size-reduced samples of southern yellow pine dimensional lumber, each treated with one of five different waterborne chemical preservatives, were leached using 18-h batch leaching tests. The wood preservatives included chromated copper arsenate (CCA), alkaline copper quaternary, copper boron azole, copper citrate, and copper dimethyldithiocarbamate. An unpreserved wood sample was tested as well. The batch leaching tests followed methodology prescribed in the U.S. Environmental Protection Agency toxicity characteristic leaching procedure (TCLP). The wood samples were first size-reduced and then leached using four different leaching solutions (synthetic landfill leachate, synthetic rainwater, deionized water, and synthetic seawater). CCA-treated wood leached greater concentrations of arsenic and copper relative to chromium, with copper leaching more with the TCLP and synthetic seawater. Copper leached at greater concentrations from the arsenic-free preservatives relative to CCA. Arsenic leached from CCA-treated wood at concentrations above the U.S. federal toxicity characteristic limit (5 mg/L). All of the arsenic-free alternatives displayed a greater degree of aquatic toxicity compared to CCA. Invertebrate and algal assays were more sensitive than Microtox. Examination of the relative leaching of the preservative compounds indicated that the arsenic-free preservatives were advantageous over CCA with respect to waste disposal and soil contamination issues but potentially posed a greater risk to aquatic ecosystems.     

防腐木材胶合性能的基础研究

本试验使用两种水溶性防腐剂铜铬砷(CCA)和氨溶烷基胺铜(ACQ-3)对人工林落叶松和杨树木材进行处理,分析处理后木材表面的接触角的变化,利用差示扫描量热仪分析处理后的木材对胶粘剂固化的影响。试验结果表明:经过CCA处理后的木材表面的接触角变化相对较小;经过ACQ处理后的木材,更适合用异氢酸酯进行胶合;经过CCA处理后木材,较适合用酚醛树脂和间苯二酚胶合。     

Effect of simulated rainfall and weathering on release of preservative elements from CCA treated wood

The release of arsenic from wood pressure-treated with chromated copper arsenate (CCA) can be decreased by application of wood finishes, but little is known about the types of finishes that are best suited for this purpose. This study evaluated the effects of finish water repellent content and ultraviolet (UV) radiation on the release of arsenic, copper, and chromium from CCA-treated wood exposed to simulated rainfall. Deck boards treated with CCA were either left unfinished or dipped in a finish prepared with 1%, 3%, or 5% water repellent. All specimens were exposed to leaching from simulated rainfall, and a subset of specimens was also exposed to UV radiation. The rainfall was collected and analyzed for total elemental arsenic, copper, and chromium. The water repellent significantly decreased the amounts of these elements in the runoff, but for the short duration of this study there was no difference among the three water repellent concentrations. It is possible that water repellent content would have a greater effect over a longer exposure period. Exposure to UV radiation caused a significant increase in leaching from both finished and unfinished specimens. This effect may be a result of increased surface area during weathering as well as loss of fibers caused by UV-induced surface erosion.     

Resistance based moisture content measurements on native,modified and preservative treated wood

Resistance characteristics were determined for a total of 27 wood-based materials containing native soft- and hardwoods, differently modified timbers and preservative treated timbers. A functional relation between measured electrical resistance and gravimetrical wood moisture content (MC) was established in a range between 15 and 50 % MC. Most precise MC estimation was found for salt-treated timber (±2.5 %), followed by native timber (±3.5 %) and modified timber (±7 %) in the hygroscopic range. As expected, preciseness decreased above fiber saturation, but was still sufficient for native timber (±8 %) and preservative treated wood (±5 %) at approx. 50 % MC.     

Resistance of preservative treated rubber wood (Hevea brasiliensis) to marine borers

The susceptibility of rubber (Hevea brasiliensis) wood to marine borer attack limits its use for marine purposes. In the present study three types of biocides viz. copper creosote, arsenical creosote and a dual preservative treatment with copper- chrome- arsenic and creosote were selected for comparing their relative efficacy in preventing biodeterioration. The treated panels were exposed at the test site in Cochin harbour. The extent of internal damage through marine borer attack was assessed through visual observations, X-ray photographs and mechanical strength testing. The untreated test panels were destroyed within six months whereas it was found that preservative treatment prevented biodeterioration under marine conditions. This was confirmed by radiographic studies and comparison of compressive stress at maximum force. The service life of this cheaply and easily available timber can be increased to meet the growing demand of timber in the small-scale fisheries sector.

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Resistenz von behandeltem Gummibaumholz gegen Bohrmuscheln

Zusammenfassung Die Anfälligkeit von Gummibaumholz gegen den Angriff von Bohrmuscheln begrenzt seine Verwendung für die Seefahrt. In dieser Studie werden drei Typen von Bioziden ausgewählt, nämlich Kupfer-Kreosot, Arsen-Kreosot und eine zweifache Schutzbehandlung mit Kupfer-Chrom-Arsen und Kreosot. Die entsprechenden Schutzwirkungen gegen biologischen Abbau wurden ermittelt und verglichen. Die behandelten Platten wurden im Hafen von Conchin zur Prüfung ausgesetzt. Das Ausmaß der Schädigung durch Bohrmuscheln wurde visuell, mittels Röntgenaufnahmen sowie durch Prüfen der mechanischen Festigkeit bestimmt. Die unbehandelten Proben waren innerhalb von sechs Monaten zerstört, während die Schutzbehandlung den biologischen Abbau im Meer verhinderte. Das wurde bestätigt durch radiographische Untersuchungen und Drucktests bei maximaler Last. Die Lebensdauer dieses billigen und leicht erhältlichen Schnittholzes kann soweit erhöht werden, dass die Anforderungen des kleinen Wirtschaftssektors der Fischerei erfüllt werden.

     

Leachability and termite resistance of wood treated with a new preservative: ammonium borate oleate

Synthesis of a new chemical compound combining water-repellence of oleic acid and biocidal effect of boric acid linked by ammonia have been followed and validated by fourier transformed infra red (FTIR). This compound named ammonium borate oleate (ABO) has then been studied as a wood preservative. Different molar ratios of oleic acid have been involved in the synthesis of ABO and leachability of those mixes from wood observed according to Japanese industrial standard. The formulation one mole of boric acid and one of ammonia (1:1:4) for four moles of oleic acid has shown the best efficiency compared to formulations 1:1:1, 1:1:2 and 1:1:3 with about 52% of boron remaining after weathering when other formulations retained respectively 10%, 29% and 46% of boron in the case of an impregnation of Cryptomeria japonica. Seven solutions of 1:1:4 ABO in ethanol of different concentrations were then produced and sapwood blocks of C. japonica and Fagus crenata were impregnated. A toxicity threshold of around 2.0 kg/m³ for both species was determined in a termite resistance test to Coptotermes formosanus indicating the positive effect of combining water repellent and biocide. Termite mortality recording and microscopic observations complete this study indicating that the action mechanism of ABO is providing a water resistant inner coating.     

Extraction of hexavalent chromium from chromated copper arsenate treated wood under alkaline conditions

Information on chromium (Cr) oxidation states is essential for the assessment of environmental and health risks associated with the overall life-cycle of chromated copper arsenate (CCA) treated wood products because of differences in toxicity between trivalent [Cr(III)] and hexavalent [Cr(VI)] chromium compounds. Hypothetical Cr(VI) fixation products were investigated in CCA type C treated sawdust of aspen and red pine during or following preservative fixation by extraction with Cr(VI)-specific extractants. Cr(VI) was found only in alkaline extracts of treated wood. A major source of Cr(VI) was method-induced oxidation of fixed Cr(III) during alkaline extraction, as confirmed by demonstrated oxidation of Cr(III) from CrCl3 treated wood. Oxidation of nontoxic and immobile Cr(III) to toxic and mobile Cr(VI) was facilitated by the presence of wood at pH > 8.5. Thermodynamic equilibrium between Cr(III) and Cr(VI) is affected by pH, temperature, rates of dissolution of CrIII) compounds, and oxygen availability. Results of this study recommend against alkaline extraction protocols for determination of Cr(VI) in treated wood. This Cr oxidation mechanism can act as a previously unrecognized route for generation of hazardous Cr(VI) if CCA treated wood is exposed to alkaline conditions during its production, use, or waste management.     

糟辣椒复合防腐剂配方的优化

采用响应面的方法优化了复合防腐剂对糟辣椒中腐败菌的佳抑菌配方。采用微量释法测定出三种防腐剂对从糟辣椒中分离出的13种腐败菌的小抑菌浓度MIC值,得到X2和X9作为实验菌;采用响应面优化法设计,以抑菌圈直径为响应值,对复合防腐剂进行复配。经响应面分析后建立多元回归模型,确定佳配方的添加量为:脱氢醋酸钠0.1 mg/mL,苯甲酸钠0.22 mg/mL,山梨酸钾0.14 mg/mL。     

臭氧水在水产品保鲜中的应用研究

本文就臭氧水杀灭鱼体表细菌的条件及其对四种淡水鱼的杀菌效果进行了探讨,并对它在草鱼片保鲜中的应用进行了初步研究。结果表明,臭氧水杀灭鱼体表细菌的最佳条件为:处理方式,冲洗:处理时间,10 min;臭氧水浓度,5ppm;水量,5倍。还表明,臭氧水对鲫鱼、鳊鱼、鲢、鳙四种淡水鱼体表均具有良好的杀菌效果。臭氧水处理可改善草鱼片的感官及微生物质量,并将其保鲜期延长约1.5d。     

防腐剂和抗氧化剂在肉制品中的应用

肉制品已逐渐成为我国的主要食品之一，人们在生活中对它的要求，除了营养和良好的质地外，适当的保质期同样也很重要，特别是现代社会，生产相对集中，而销售又比较分散的情况下，肉制品的防腐保鲜尤为重要，科学地选择、规范化地使用防腐剂确实是很必要的。     

木材胶粘剂废水污染及治理

分析了当前木材胶粘剂废水污染的现状和原因;提出了治理废水污染的建议;综述了处理废水的方法和研究现状。     

Arsenic leaching from mulch made from recycled construction and demolition wood and impacts of iron-oxide colorants

Mulch made from recycled construction and demolition (C&D) wood has been reported to contain elevated levels of arsenic from inadvertent inclusion of chromated copper arsenate (CCA)-treated wood. Such mulch is also commonly colored with iron oxide, a compound known to bind arsenic. The objectives of this study were to quantify the releases of arsenic from mulch made from C&D wood, to evaluate the impacts of an iron-oxide colorant in potentially decreasing arsenic leaching rates, and to evaluate the relative significance of additional variables on leachate concentrations. Atotal of 3 sets of mulch samples (0%, 5%, or 100% CCA-treated wood) were prepared containing a sample either with or without colorant addition. Each sample was subjected to two tests: a field leaching test and the Synthetic Precipitation Leaching Procedure (SPLP). Results showed that arsenic concentrations in the field leachate from the 0% treated wood mulches were consistently low (<0.003-0.013 mg/L) whereas leachates from 5 and 100% treated wood mulches were characterized by higher arsenic concentrations (0.059-2.23 mg/L for 5%; 0.711-22.7 mg/L for 100%). The mass of arsenic leached from the field samples during the 1-year monitoring period was between 10 and 15% of the initial mass of arsenic. The colorant reduced the leaching of arsenic by more than 20% for the field leachate and 50% for the SPLP leachate, on average. However, the study showed that the effect may not last for long periods. Besides colorant addition other factors were observed to affect the amount of arsenic leached from contaminated mulch. These include the proportion of CCA-treated wood in the mulch, time, and pH of rainfall.     

肉制品的防腐措施与复合防腐剂

肉制品的防腐理论和方法最广泛、最被接受的是栅栏理论在防腐中的应用。肉制品防腐的栅栏因子的作用效果是相互协同叠加的，微生物的生长由于栅栏因子的设置足以使微生物被抑制时，就达到了我们防腐的目的，正确的栅栏因子设置可以达到事半功倍的效果。主要介绍了肉制品的防腐措施与复合防腐剂的应用。     

Effect of fixation time on leaching of copper-ethanolamine based wood preservatives

Fixation in copper-ethanolamine treated Norway spruce wood is finished in the first or in the second week after impregnation depending on the concentration of wood preservatives used. However, copper losses increased after four weeks of fixation again, presumably due to lignin depolymerisation caused by ethanolamine.     

Weathering characteristics of wood treated with water glass, siloxane or DMDHEU

Specimens of Scots pine sapwood (Pinus sylvestris) and beech wood (Fagus sylvatica) were treated with a sodium water glass solution, an amino-alkyl-functional oligomeric siloxane and 1,3-dimethylol-4,5-dihydroxyethylene urea (DMDHEU). The specimens were exposed outside without ground contact for 24 months. Colour measurements during outside exposure showed a discoloration of all wood specimen surfaces. FTIR spectroscopy displayed lignin degradation of all specimens during the initial exposure time. Chemical treatments decelerated fungal infestation of wood, while their effect on lignin degradation was not discernible. SEM studies revealed that fungal infestation was affected by the different treatments. The untreated specimens showed radial penetration of fungal hyphae through the pits. Only superficial infestation and no radial penetration were visible at water glass and siloxane treated specimens. A significantly reduced radial penetration of fungal hyphae was exhibited at DMDHEU treated specimens. Fungal infestation through the pits was not visible.     

Effect of fixation time on leaching of copper-ethanolamine based wood preservatives

Zusammenfassung Fixation in copper-ethanolamine treated Norway spruce wood is finished in the first or in the second week after impregnation depending on the concentration of wood preservatives used. However, copper losses increased after four weeks of fixation again, presumably due to lignin depolymerisation caused by ethanolamine.      

White rot and manganese deposition in TnBTO-AAC preservative treated pine stakes from field tests

A pine test stake prevlously impregnated in 1978 with 12.0 kg/m³ loading of a TnBTO-AAC formulation and set out under field test conditions in the south of Sweden failed in the summer of 1996 with decay rate of Class 4 according to EN 252. Visual and microscopic examination of the test stake showed the outer 1–2 mm to be degraded by soft rot cavity forming fungi whereas internal attack throughout the groundline region and below was by simultaneous white rot characterized by cell wall thinning, and pronounced bore hole formation. Observations showed the visual presence of very large numbers of characteristic brownish-black flecks associated with the white rotted wood. These flecks were characterized by transmission electron microscopy (TEM) in conjunction with x-ray microanalysis and were found comprised primarily of manganese possibly as MnO₂. Observations further showed gross manganese penetration into partially degraded tracheid wall layers and middle lamella regions and its association with extracellular fungal slime in the wood cell lumina.     

茶多酚对水产品的保鲜机理及其应用研究进展

水产品营养丰富,含有丰富的蛋白质和不饱和脂肪酸,并且水分含量又高,容易腐败变质,因此水产品的保鲜技术成为研究的热点,尤其是生物保鲜.茶多酚是茶叶中酚类物质的总称,具有良好的抗氧化、抑菌、抗肿瘤等保健功能.本文介绍了天然防腐剂茶多酚的组成、抗氧化机理及抑菌机理,综述了茶多酚在水产品保鲜中的应用,并展望了茶多酚的应用前景.