竹砧板中甲醛释放量测定方法及限量值的确定

以市场上购买的不同产地的碳化与未碳化竹砧板为材料,通过水浸提法和40 L干燥器法检测其游离甲醛的含量和甲醛释放量,并采用40 L干燥器法抽样检测不同产地样品的甲醛释放量。结果表明:国家标准GB 18580—2001中甲醛释放量指标采用40 L干燥器法检测,限量值定为≤1.5 mg/L是较为科学合理的。     

干燥器法测定木制品甲醛释放量的研究

通过对干燥器法甲醛释放模型的分析 ,探讨并验证影响木制品甲醛释放量的因素 ,分析比较 10L与 4 0L干燥器法测定值的关系。结果表明 :该甲醛释放模型较好地表述了干燥器法中影响甲醛释放的因素 ,甲醛浓度与水体积成反比 ;随水表面积增加 ,甲醛浓度逐渐增加。对于边部面积与表面面积之比相同的试样 ,4 0L与 10L干燥器法甲醛测定值之间存在很好的一元线性关系 ,4 0L干燥器值约为 10L的 3 5～ 3 9倍 ;但对于表面甲醛释放速率不同的试样 ,如果不封边或边部面积与表面积之比不同 ,则 10L与 4 0L干燥器法没有可比性。试样边部释放甲醛的速率明显高于试样表面。对于刨花板和中密度纤维板 (MDF) ,边部释放速率约为表面的 2倍 ;对饰面MDF ,87%以上的甲醛从边部释放 ;对于胶合板 ,约 4 0 %的甲醛从边部释放     

基于改良干燥器法的甲醛快速测试研究

为更加方便快捷测试人造板中的游离甲醛,提出一种改良的干燥器法游离甲醛测试装置,采用同一传感器及同型号不同传感器对板材的游离甲醛进行测试。结果表明:试验所选用的甲醛传感器具有较好的灵敏性和可重复性,通过进一步对比气候箱法游离甲醛的测试结果,初步认定研究所提出的改良干燥器法与国家标准中的气候箱法的测试结果有一定的相关性。研究结论可为利用传感器法测试人造板中的游离甲醛提供依据。     

干燥器法与穿孔萃取法测定中密度纤维板甲醛释放量的相关性研究

分别采用GB 18580标准中的干燥器法和穿孔萃取法检测中密度纤维板的甲醛释放量，并根据两种方法检测出的结果分析其相关性。结果表明，两种检测方法呈显著线性相关。     

人造板甲醛检测方法的相关性研究

在阐明人造板甲醛含量/释放量测定原理的基础上,系统总结以往研究成果,通过对板材甲醛释放过程的分析,从理论上推导板材甲醛含量与空气中甲醛浓度的函数关系。根据标准测试参数及板材甲醛释放规律,对该函数关系进行适当简化,得到气候箱法甲醛检测值与穿孔萃取法、干燥器法甲醛检测值的线性计算方程,为建立人造板甲醛检测方法之间的相关性提供理论支撑,亦为线性计算方程的推广应用提供理论依据。     

中密度纤维板中氨释放量测定方法研究

企业在生产中使用氨处理来降低中密度纤维板中甲醛释放量的行为,引发了中密度纤维板的氨释放。氨对人体健康有很大的危害,而我国尚无中密度纤维板中的氨释放量检测方法。笔者采用气候箱法、干燥器法、气体分析法对中密度纤维板中氨释放量进行测定,分析不同氨释放量检测方法之间的相关性。结果表明,采用气候箱法、干燥器法、气体分析法能较好地检测出中密度纤维板中氨释放量,并且部分中密度纤维板中的氨释放量较高,同时不同方法测定的氨释放量之间存在一定的换算关系。     

气候箱法和干燥器法测试甲醛释放量的比较分析

分别采用1m~3气候箱法和9～11L干燥器法测试强化木地板和实木复合地板的甲醛释放量,并对两种测试方法进行比较分析。结果表明,两种测试方法检测的两种地板甲醛释放量测定值之间,均具有较显著的一元线性关系。在企业内部质量控制时,可采用9～11 L干燥器法替代1 m~3气候箱法监控和测定产品的甲醛释放量;但当产品批次、结构和生产工艺参数发生变化时,线性回归方程尚需调整。     

人造板甲醛穿孔萃取法与气体分析法的比较与相关性

甲醛释放量是人造板安全性的重要指标。GB18580—2012《室内装饰装修材料人造板及其制品中甲醛释放限量》中规定了4种甲醛测试方法:气候箱法、干燥器法、气体分析法和穿孔萃取法。其中气体分析法和穿孔萃取法是欧洲国家广泛采用的测定方法。气体分析法和穿孔萃取法的检测原理不同,标准规定限量水平也不同。目前,尚未有文献报道两者测定结果之间的对应关系。笔者以中密度纤维板为材料,分别应用穿孔萃取法和气体分析法测定其甲醛释放量,并建立两种测定方法结果之间的相关性和换算关系,     

干燥器法测定木家具中有害物质限量（甲醛）不确定度评定

立足于干燥器法检测木家具中有害物质限量（甲醛）试验过程,确定显著影响试验结果各个测量步骤,系统地分析检测过程中不确定度来源,确定了测量结果不确定度,提高测量结果置信度和准确性。试验表明：试验条件下干燥器法测定木家具中有害物质限量（甲醛）测量结果的相对扩展不确定度为：0.03 mg/L(k=2)。     

新旧版GB/T17657干燥器法检测人造板甲醛释放量的对比

为促进新版GB/T 17657-2013《人造板及饰面人造板理化性能试验方法》的实施,对比了新、旧版标准中甲醛释放量检测干燥器法的差异,并分别用于细木工板、胶合板和成品木门木板的甲醛释放量检测。结果表明:新版标准的检测方法更系统、全面,对试件数量、平衡处理、空白试验、甲醛吸收液的储存条件及显色反应条件等均有了明确要求,且标线的甲醛浓度范围更小,检测精度更高,易于实现标准化。     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.