Studied Wood Species Research Articles

Exploring visible spectrum wavelengths in light transmission through wood material

Wood is a multiscale heterogeneous natural composite material with properties depending on its growing conditions and its genetic heritage. This variability is challenging for industries that work to perform homogeneous and reliable products. In industry, different non-destructive testing methods are in use to classify, grade, and select wood products to optimize their usage. Among them, the use of lasers to detect fiber orientation with different wavelengths. This orientation significantly influences the mechanical behavior of wood, including stress limits and stiffness. According to our knowledge, the use of laser diffusion still is limited to grain angle measurement. Our objective in this paper is to realize transmission light scattering maps for wood samples from several wood species (poplar, oak, Douglas fir, beech), and then identify the most suitable wavelength to study light diffusion in wood, depending on the property that will be measured. A supercontinuum laser is used over a wavelength range from 500 to 800 nm, allowing precise adjustment of the wavelengths. It was found that near-infrared light better scatters in the studied wood species than lower wavelength. However, the wavelength that gives the best contrast between earlywood and latewood depends on the sample studied and is not necessarily in the near infrared rays.

Application of the 2D diamond scheme to predict the macroscopic thermal conductivity of a three-phase composite with local anisotropy directions

In this contribution, we are interested in the prediction of the macroscopic thermal conductivity of three-phasic composite materials such as wood fibers. The main idea is to make use of up-scaling such as homogenization to link the pore scale and the sample scale. The studied wood species incorporates three phases: the air, the lumen or matrix and the fibers. Image processing is preformed on a tomographic acquisition with high resolution of some micrometers. It serves to identify the present phases and generates the morphology mesh. The 2D diamond scheme is employed to discretize Fourier's model posed on the segmented morphology. The resulting algorithm is validated using an exact solution. Optimal numerical convergence rates of second order are recorded. The thermal conductivity is therefore estimated following the 2D orthotropic directions. An emphasis is set on the impact of the orientation of fibers on this thermal property.

Chemical Composition and Mechanical Properties of Wood after Thermal Modification in Closed Process under Pressure in Nitrogen.

In this study, silver birch (Betula pendula) and Scots pine (Pinus sylvestris) wood planks (1000 × 100 × 25 mm) were thermally modified in pilot-scale equipment. Research extended our knowledge of the thermal modification (TM) process in a closed system under nitrogen pressure, as well as how process parameters affect the chemical composition and mechanical strength of wood. Various TM regimes were selected-maximum temperature (150-180 °C), modification time (30-180 min), and initial nitrogen pressure (3-6 bar). Chemical analyses were performed to assess the amount of extractives, lignin, polysaccharides and acetyl group content following the TM process. The mechanical properties of TM wood were characterized using the modulus of rupture (MOR), modulus of elasticity (MOE), and Brinell hardness. The MOR of both studied wood species following TM in nitrogen was reduced, but MOE changes were insignificant. The Brinell hardness of TM birch wood's tangential surface was much higher than that of the radial surface, although Scots pine wood showed the opposite pattern. TM birch and pine wood specimens with the highest mass loss, acetone soluble extractive amount, and the lowest xylan and acetyl group content had the lowest MOR and Brinell hardness.

Usporedba reakcijskoga i normalnog drva nekih komercijalnih vrsta drva

This study aims to analyze the reaction wood samples for some industrial tree species naturally grown in Kastamonu province in Turkey and compare them with the relevant standards. Some anatomical, chemical, fiber morphological, optical properties, and color changes before and after drying were analyzed for the reaction wood (RW) samples. While the holocellulose content of fir and pine compression wood (CW) was found to be lesser (~3-4 %), the lignin content was higher than those of the opposite wood (OW) (~34 % for pine and 12 % for fir). On the contrary, the amount of holocellulose was found to be higher (~1-4 %), and the lignin was lower (at about 6-15 %) in the tension wood (TW) samples. It was observed that average lengths are more extended in TW(~50-54 %) and shorter in CW (~13-17 %) than those of OW. Significant differences were observed between the anatomical structures of the coniferous and deciduous species studied. Although, the greatest color differences in wet and oven-dried samples of coniferous trees were measured in CW (~15-17 %), it has been found as about 0.7-3 % in TW for deciduous species. Some differences were observed in the anatomical, optical, fiber morphological, and chemical properties of the RW for the studied wood species. Due to its higher lignin content and better physical properties, CW can be used for producing small households and hand tools, ornaments, toys, etc. It will also be appropriate for use in milling and turning work. It is recommended that, because of the lower lignin content and higher polysaccharide ratio, TW should be primarily used for the cellulose, pulp, and paper industries, where high mechanical resistance values are required. Consequently, RW formation causes some physical, chemical, mechanical, anatomical, and optical differences compared to OW in deciduous and coniferous species.

Теоретическое и экспериментальное обоснование характера взаимодействия модифицированных связующих с древесиной

There are numerous methods for analyzing surface phenomena when bonding wood materials, mutual arrangement of pores in the wood substrate, and depth of liquid adhesive penetration into wood. Electron microscopic methods such as atomic force and scanning tunneling microscopy are used along with optical methods. They allow evaluating the influence of factors describing the interaction between the liquid adhesive molecules and the porous wood surface. Phenol formaldehyde resin modified with pectol and urea formaldehyde resin modified with lignosulfonates were used for substantiation of the interaction mechanism between modified adhesives and wood. Electron microscopy was used to study the depth of adhesive penetration into veneer. The plywood was produced using modified urea and phenol formaldehyde adhesives. After conditioning, samples with a thickness of 0.025 mm were cut out and examined with a scanning electron microscope. The article shows that the interaction between liquid phenol formaldehyde adhesive modified with pectol and wood results in a sequential increase in the molecular weight of the substances and, consequently, in the penetration degree (depth). The studied wood species (birch, pine and larch) and modified thermosetting urea and phenol formaldehyde adhesives are polar materials (adhesive interacts with wood molecules with the formation of intermolecular bonds, including hydrogen bonds). The molecular weight growth and the freely joined nature of the main chain (liquid modified adhesive macromolecules), which contains a large number of polar functional groups (adhesive and wood), promote intermolecular association. The formation of an adhesive bond between urea formaldehyde adhesive modified with lignosulfonates and wood occurs due to chemical interaction between hydroxyl groups of cellulose macromolecules and methoxyl groups of urea resin with the formation of esters (hydrogen atoms of hydroxyl groups OH are substituted with hydrocarbon radicals R). The formation of a bond between the adhesive and the wood surface is the result of molecular interaction forces at the liquid adhesive – wood interface, when the distance between molecules of the same polarity (adhesive and wood) is less than 0.5 nm. Then, adsorption equilibrium sets in. For citation: Rusakov D.S., Varankina G.S., Chubinsky A.N. Theoretical and Experimental Substantiation of the Nature of Interaction between Modified Binders and Wood. Lesnoy Zhurnal = Russian Forestry Journal, 2022, no. 6, pp. 153–163. (In Russ.). https://doi.org/10.37482/0536-1036-2022-6-153-163

Гигроскопические свойства древесины лиственных пород

Hygroscopic properties of nine hardwoods from Hungary were studied by moisture sorption isotherms, methods of thermogravimetry (TG) and differential scanning calorimetry (DSC). The studied wood species included oak, beech, hornbeam, black locust, lime, ash, maple, alder, and aspen. The parameters of the wood — water sorption system were calculated using the equations of Brunauer — Emmett — Teller (BET), Guggenheim — Anderson — de Boer (GAB), Frenkel — Halsey — Hill (FHH), Zimm — Lundberg (ZL), and the theory of the volume filling of micropores (TVFM). Within the frameworks of these models, the monolayer capacity, the apparent specific surface area, the parameters of clustering of water in wood, the characteristic energy of adsorption, and other parameters were calculated. Based on the data of TG and the fourth derivative of the mass loss rate contour during drying, the «fractional composition» of hygroscopic moisture was established. According to the Ozawa — Flynn — Wall isoconversion method, the dependence of the activation energy of moisture thermal desorption on the degree of drying was calculated. The enthalpy of vaporization of hygroscopic moisture ΔНvap was measured using DSC. The complex of measured and calculated parameters of the wood — water system made it possible to differentiate the studied hardwoods regarding the hygroscopic properties of wood. According to the value of the apparent specific surface area (BET, GAB) the wood species found to be in the following order: lime < black locust < beech < oak < hornbeam < ash < alder < maple < aspen. Hardwoods were ranked as follows by the value of the characteristic energy of adsorption Ec (TVFM): lime < beech < hornbeam < ash < black locust < oak < maple < alder < aspen. The intrinsic stresses in wood change in the same row as Ec. An increase in Ec indicates an increase in intrinsic mechanical stresses. Analysis of the enthalpy of vaporization of hygroscopic moisture during non-isothermal drying of wood revealed three sub-ranges of moisture content (0 — ~0,04; 0,04 — ~0,08 and > 0,08 g H2O/g dry weight). This, on the one hand, «unites» the wood species, on the other, differentiates them by the bonding energy of water in wood.

The Effects of Iron Rust on the Ageing of Woods and Their Derived Pulp Paper.

The accelerated ageing of wood in terms of heating or iron rusting has a potential effect on the physio-mechanical, chemical and biological properties of wood. The effects of accelerated ageing on the mechanical, physical and fungal activity properties of some wood materials (Schinus terebinthifolius, Erythrina humeana, Tectona grandis, Pinus rigida and Juglans nigra) were studied after several cycles of heating and iron rusting. The fungal activity was assayed against the growth of Aspergillus terreus, Aspergillus niger, Fusarium culmorum and Stemphylium solani. In addition, the mechanical and optical properties of paper sheets produced from those wood pulps by means of Kraft cooking were evaluated. The mechanical and chemical properties of the studied wood species were affected significantly (p < 0.05) by the accelerated ageing, compared to control woods. With Fourier transform infrared (FTIR) spectroscopy, we detected an increase in the intensity of the spectra of the functional groups of cellulose in the heated samples, which indicates an increase in cellulose content and decrease in lignin content, compared to other chemical compounds. For pulp properties, woods treated by heating showed a decrease in the pulp yield. The highest significant values of tensile strength were observed in pulp paper produced from untreated, heated and iron-rusted P. rigida wood and they were 69.66, 65.66 and 68.33 N·m/g, respectively; we calculated the tear resistance from pulp paper of untreated P. rigida (8.68 mN·m2/g) and T. grandis (7.83 mN·m2/g) and rusted P. rigida (7.56 mN·m2/g) wood; we obtained the values of the burst strength of the pulp paper of untreated woods of P. rigida (8.19 kPa·m2/g) and T. grandis (7.49 kPa·m2/g), as well as the fold number of the pulp paper of untreated, heated and rusted woods from P. rigida, with values of 195.66, 186.33 and 185.66, respectively. After 14 days from the incubation, no fungal inhibition zones were observed. Accelerated ageing (heated or iron-rusted) produced significant effects on the mechanical and chemical properties of the studied wood species and affected the properties of the produced pulp paper.

Impact of annual growth pattern on swelling of selected wood species

Impact of annual growth pattern on swelling of selected wood species. Unit swelling was investigated in radial and tangential directions as well as in the intermediate directions for wood of density ranging from 300÷500 kg/m3 and 500÷700 kg/m3 and above 700 kg/m3. Species selected included pine – PNSY (Pinus sylvestris L.), oak – QCXE (Quercus. robur L.) and bangkirai – SHBL (Shorea spp.), teak – TEGR (Tectona grandis), merbau – INXX (Intsia bijuga), jatoba – HYCB (Hymenaea courbaril L). For all the studied wood species, the lowest swelling in the radial direction (0°) was found after both 2 h and 24 h of wetting in water, which increased with the angle of inclination of the annual growth and, after reaching 90°, corresponded to the maximum swelling in the tangential direction. For pine (PNSY) sapwood and heartwood and for oak (QCXE), a high swelling unit was obtained after a wetting time of 2 h, with little change after 24 h of wetting. Swelling increments for the other wood species were lower, ranging from 1% to over 2% after a wetting time of 2 h, showing slight differences between radial and tangential directions. For these wood species, after 24 h of wetting the swelling was higher and varied from more than 2% to nearly 5% in the radial direction and from more than 4% to 10% in the tangential direction. The study showed that, for high-density wood species, it becomes necessary to extend the wetting time in order to determine the actual maximum swelling per unit. The swelling anisotropy coefficients ε of the studied wood species corresponded to the values found in the literature. Higher coefficients were found for oak (QCXE) and teak (TEGR), bangkirai (SHBL) and jatoba (INXX), and were related to the characteristic features of the density structure and anatomical structure. The unit swelling values calculated with the Krzysik (1974) and Vorreiter (1949) equations may be used to assess changes in the dimensions of elements in intermediate directions. The discrepancies between the experimental and theoretical values are smaller for the unit swelling values calculated with the Vorreiter (1949) equation compared to the Krzysik (1974) equation.

Mass loss kinetics of thermally modified wood species as a time–temperature function

The mass loss kinetics of thermally modified wood species was analyzed as a time–temperature function. European beech (Fagus sylvatica L.), English oak (Quercus robur L.), Norwegian spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.) wood specimens of dimensions 20 × 20 × 10 mm3 were thermally modified at 140 °C, 160 °C, 180 °C, 200 °C and 220 °C for 1–6 h using atmospheric pressure and superheated steam environment. The process intensity was determined by mass loss (ML), based on oven-dry mass before and after the thermal modification. Furthermore, the equilibrium moisture content (EMC) was determined before and after thermal modification to analyze the effect of mass loss on the sorption properties. Measured mass loss data were compared with the three-dimensional analytical function and its applicability to mass loss prediction was verified. For the studied wood species, the ML was found to be less than 1–1.5% when temperature of 140 °C and 160 °C was applied. Differences between studied species were more significant at temperatures higher than 160 °C. With the highest tested temperature (220 °C), mass loss reached 13.5% (beech), 18.8% (oak), 6.7% (spruce) and 13.5% (pine). According to the results, hardwoods have been shown to be more sensitive to the thermal degradation than softwoods as demonstrated by the higher mass loss recorded for the same modification time and temperature. The three-dimensional analytical function was confirmed as valid for all the species studied (R2 = 0.89–0.99) and relevant for the mass loss prediction using fitted parameters. The EMC was reduced after thermal modification within the range of 4–48%, 0.4–47%, 1–32% and 0.7–40% for beech, oak, spruce and pine, respectively. Further, the EMC correlates exponentially (R2 = 0.91–0.95) with the decrease in the specimens’ mass depending on the wood species used and modification temperature applied. However, the EMC seems to be almost stabilized beyond a limit value of approximately 10–12% of mass loss. The results provide a better insight into the mass loss and EMC kinetics of thermally modified wood species and can be used as a tool for prediction of mass loss values and required material properties (EMC) for designed wooden products.

Fluence of age factor on main strength and deformative properties of timber

The analysis of literature sources on this topic is carried out. It was found that the influence of age on the main strength and deformation parameters has not been studied. The method of experimental researches of coniferous and deciduous species of solid wood of different age at one-time short-term loading along fibers is resulted. To solve the problems, a series of samples of 1 sort of solid wood in the form of prisms with a cross section of 30x30x120 mm were made. The following species of wood were tested: coniferous species - larch, pine, spruce; deciduous - birch, alder, ash. The age of wood was 20, 40, 60 years. At the time of testing, the moisture was 12%. The humidity of the wood was controlled using a moisture meter MD-814. Experimental studies were performed on a servo-hydraulic test machine STM-100 under a rigid load regime (by increasing the displacements of the press plate of the test machine). Based on the obtained results, complete diagrams of deformation of deciduous (birch, alder, ash) and coniferous (larch, pine, spruce) species of solid wood at different ages (60, 40, 20 years) were constructed. The number of twin samples that were tested was 126 pieces. The main strength and deformation parameters were determined experimentally, in particular the average critical deformations of all studied wood species and the corresponding average maximum stresses. It is established that in the case of a rigid test regime, the deformation diagram of solid wood necessarily has two branches - ascending and descending. That is, the samples work in the so-called supercritical stage of work. It was found that the age of wood directly affects the strength and deformability of solid wood. In particular, with increasing age from 20 to 60 years, the strength and deformability of deciduous and coniferous species of solid wood increases significantly. Based on the test results, conclusions were drawn. Further research on this topic is highlighted.

Time of exposure at 60 °C service temperature: Influence on strength and modulus of elasticity in compression parallel to the grain of hardwood species

The aim of this research was to determine the influence of exposure time at 60 °C in the compression strength parallel to the grain (fc0) and modulus of elasticity in compression parallel to the grain (Ec0) for cupiúba (Goupia glabra), eucalypt (Eucalyptus saligna), garapeira (Apuleia leiocarpa) and jatobá tamarindo (Hymeneae sp.) wood species. The factor investigated in this research was the residence time in kiln (exposure at controlled temperature 60 °C) of specimens: 0 (wood tested at room temperature and moisture content around to 12%), 168, 456, 720, and 2160 hours, simulating the reaction of the material in confined roof structures. Compression parallel to the grain tests were conducted according to the methods of the Brazilian Standard Code ABNT NBR 7190 (1997). ANOVA results indicated that the temperature (60 °C) had a significant influence in the five exposure times. All studied wood species showed an increase in the fc0 value with increasing time of exposure at 60 °C. For Ec0, this phenomenon occurred only for the jatobá tamarindo and cupiúba wood species.

Using a parametric study to analyse the performance of wood solar dryers with glazed walls

Parameters characterizing wood and air were studied in order to analyze the performance of a wood solar dryer functioning under Moroccan climate. A mathematical model based on the climate data of Rabat city was used to investigate theoretically the wood drying process. Two wood speciesthuya(Tetraclinis articulate) and pine (Pinus pinaster)-were examined in the present study. The results obtained by computer simulations are in good agreement with the experimental values. Furthermore, our findings indicate that the use of a global mass transfer coefficient for low temperature convectiveand homogenous drying conditions allows the influence of the principal operating parameters (wood thickness, wood density, air temperature, air velocity and ventilation mode) on the drying time to be estimated with great accuracy. Analyses pertaining to the two studied wood species revealed that(1)pine dries more quickly than thuya, (2) the drying process is faster in the summer relative to other seasons, (3) increasing the air velocity by 100% results in a 20% reduction in the drying time, and (4) continued ventilation reduces the drying time by 43%.

An investigation of accelerated temperature-induced ageing of four wood species: colour and FTIR

The study investigated and compared the behaviour of four wood species, originating from Europe and China, in terms of temperature-induced artificial ageing. It was conducted at 100 °C for a total period of 288 h. Ageing effects were evaluated by colour measurements in the CIE Lab system and by FTIR analysis. Colour changes were then related to chemical changes in the wood. The investigated wood species were European ash (Fraxinus excelsior), European walnut (Juglans regia), Chinese ash (Fraxinus mandshurica) and Chinese walnut (Juglans mandshurica). Colour changes were maximum for European ash and minimum for Chinese ash, while European walnut and Chinese walnut evolved quite similarly. Main chemical changes due to temperature ageing were reduction of hydroxyl groups, increase of the unconjugated carbonyl groups and an apparent slight increase of lignin, more evident for European ash and delayed for European walnut. Formation of aromatic carbonyl conjugated groups as quinoid structures as a result of oxidative reactions was revealed especially for European ash. The different behaviour of the studied wood species may be explained by their different chemical composition, especially hemicelluloses, lignin and extractives content.

Chemical Study of Wood Chip Drying: Biodegradation of Organic Pollutants in Condensate Waters from the Drying Process

In 2008, the European Union Commission put forward a proposal for a new directive on renewable forms of energy. Each of the member states should increase its share of renewable energies in an effort to boost the total share of the EU from the current 8.5% to 20% by 2020. The level of renewable energy in Finland was 28.5% in 2005, and the national target share of renewable energy by 2020 is 38%. To assist in reaching this goal, one solution is to further develop drying techniques of biomasses and utilization of untapped biomasses, because in Finland, up to 20 million tons of waste wood biomass per year are left unused during forestry operations. In this study the drying of biomasses and the condensate, including biodegradation of organic pollutants, is examined. The cost-efficiency and energy-efficiency of wood chips combustion can be increased by drying the wood to optimize moisture content before being utilized in different applications. However, the removal of moisture is the most expensive unit process in combustion. Studied wood species were pine (Pinus sylvestris), spruce (Picea abies), aspen (Populus tremula) and two birch species (Betula pendula and Betula pubescens). The biodegradation degrees of studied organic pollutants in condensing waters were between 25% and 61%. Furthermore, the biodegradation of organic compounds in condensing waters showed that at least the studied condensates can be safely disposed via municipal wastewater treatment plant (WWTP).

Analysis of the pore-size distribution and fiber saturation point of native and thermally modified wood using differential scanning calorimetry

The aim of this paper was to investigate pore-size distributions in the nano-diameter range of wood and their alteration due to thermal modification of wood using thermoporosimetry, and to find out what consequences can be derived regarding the biological durability. Thermoporosimetry is a technique that is based on the measurement using differential scanning calorimetry (DSC). The method is based on the fact that frozen water contained within small pores is at elevated pressure and therefore has a depressed melting temperature as a function of the appropriate pore diameter. In addition, the fiber saturation points (FSP) were determined by DSC. The former were performed in an isothermal-step method and the latter using the continuous heating-up method. Native and thermally modified twin samples of Norway spruce (Picea abies (L.) Karst.), Sycamore maple (Acer pseudoplatanus L.) and European ash (Fraxinus excelsior L.) were analyzed. The results clearly show that the pore shares of wood for the measurable diameter range between 4 and 400 nm decrease considerably in all studied wood species due to thermal modification of the wood. Furthermore, thermal modification of wood leads to a decreased FSP for all studied wood species. For evaluation as well as reproducibility of the results of pore-size distribution and FSP, the consideration of sensible heat and specific heat of fusion plays an important role. If this is not done, it can lead to misinterpretations.

Aromatic potential of Castanea sativa Mill. compared to Quercus species to be used in cooperage

The composition of volatile and semi-volatile compounds of chestnut (Castanea sativa Mill.) was studied and compared to oak wood species frequently used in cooperage (Quercus alba, Quercus petraea, Quercus robur and Quercus pyrenaica) to evaluate its aromatic potential. Chestnut was found to be a suitable wood for use in ageing processes, based on the large, diverse number of detected compounds (e.g., lactones, furanic compounds, terpenes, lignin derivatives and triterpenic compounds). Chestnut wood possessed high levels of volatile phenols and phenolic aldehydes, specifically vanillin and its derivatives. Each wood species exhibited a characteristic, quantifiable composition of volatile compounds, and therefore, the sensorial profile of each wood species is expected to be different. The levels of certain volatile compounds were also useful for discriminating among the studied wood species.

Comparative natural durability of five wood species from Mozambique

The objective of this study was to evaluate the natural durability of five lesser-utilized wood species from Mozambique. Both laboratory methods and field tests were applied for assessing wood decay of muanga ( Pericopsis angolensis), metil ( Sterculia appendiculata), namuno ( Acacia nigrescens), ncurri ( Icuria dunensis), and ntholo ( Pseudolachnostylis maprounaefolia). Laboratory tests involved soft-, brown-, and white-rot fungi and termites. Heart- and sapwood of ncurri and ntholo were exposed in above-ground field tests; additionally, all species were exposed to in-ground contact tests. The results indicated that namuno, muanga, ncurri, and ntholo are resistant to soft-, brown- and white-rot fungi and the termite species Reticulitermes grassea and Mastotermes darwiniensis. Comparatively, soft-rot caused more severe decay on the studied wood species than did basidiomycete fungi. The brown-rot fungi Coniophora puteana, Gloeophiyllum trabeum, and Postia placenta caused less decay on the tested species than did the white-rot Trametes versicolor. Metil was not resistant to any of the mentioned hazards. Therefore, this species is not recommendable for exterior use if untreated.

Thermogravimetry/mass spectrometry analysis of energy crops

The aim of this work was to study the thermal decomposition of different plant species obtained from energy plantations. Thermogravimetry/mass spectrometry (TG/MS) experiments have been performed with two herbaceous crops (Miscanthus sinensis, pelletized energy grass) and two wood samples (willow, water locust) in inert and oxidative atmospheres. Owing to the large number of data obtained in the experiments, a chemometric tool, principal component analysis (PCA) has been used to help the interpretation of the results. It has been found that the thermal decomposition of the studied wood species is similar, whereas that of the studied herbaceous samples exhibits significant differences. PCA has been found to be useful for finding correlations between the various experimental data.

Phenolics in selected European hardwood species by liquid chromatography-electrospray ionisation mass spectrometry.

The phenols in beech (Fagus sylvatica), birch (Betula pendula) and ash (Fraxinus excelsior) wood dusts were compared using a mass spectrometer fitted with an electrospray ionisation interface with liquid chromatographic separation. Hardwood dust is a carcinogen, and an analysis of the polyphenol profile is a useful method for identifying the dust source in workplace air. The mass spectrometer was operated in both the negative and positive ion modes. Phenolic compounds were identified by comparing mass spectra and retention times from liquid chromatography with those for standard compounds and data in the literature. The phenol contents of the studied wood species varied considerably, and only a few common compounds were found in them.

The effect of wood species composition on the toxicity of simulated mechanical pulping effluents

AbstractA series of simulated mechanical pulping (SMP) effluents, prepared from wood species commonly employed in Canada, were analyzed for wood extractives and tested for acute toxicity to fathead minnows (Pimephales promelas) and acute/chronic toxicity to Ceriodaphnia affinis. The acute and chronic toxicities of the SMP effluents were found to vary substantially for the studied wood species. According to wood species, the acute lethal toxicity of the SMP effluents to both fathead minnows and Ceriodaphnia was found to follow the order white pine &gt; balsam fir &gt; hemlock &gt; black spruce &gt; aspen. The chronic effects of the various SMP effluents on Ceriodaphnia reproduction followed the order balsam fir &gt; hemlock &gt; white pine ˜ black spruce ˜ aspen. The effluent prepared from balsam fir exhibited the lowest chronic toxicity threshold, affecting Ceriodaphnia reproduction at concentrations as low as 0.005%. The compound primarily responsible for this effect was identified as dehydrojuvabione, a naturally occurring sesquiterpenoid ester known to be present in balsam fir. Dehydrojuvabione was found to affect Ceriodaphnia reproduction adversely at concentrations as low as 0.5 μg/L.