微波消解塞曼石墨炉原子吸收法测定大米中微量镍

利用微波消解技术处理样品,用塞曼石墨炉原子吸收法测定了大米中的镍,该方法具有简便、快速、结果准确可靠的优点。测定结果表明:镍的浓度在0~25μg/L范围线性良好,相关系数0.9991,镍的加标回收率为97.3%~104.2%;测定结果的相对标准偏差为1.9%,检出限为0.152μg/L。     

球磨仪-微波消解石墨炉原子吸收法测定土壤中的铅元素

采用行星式球磨仪制样、微波消解、石墨炉原子吸收法测定了土壤样品中的铅含量,球磨仪制样颗粒超细且均匀,干净卫生,不存在扬尘污染;微波消解仪操作简便快速,消耗试剂少,密闭消解,酸污染少。结果表明:测定土壤标准样品GSS-22的相对误差为1%,GSS-26相对误差为1.2%,测定实际试样相对标准偏差均值为1.6%,均满足试验要求。     

原子吸收石墨炉法测定固体废物中钡

采用醋酸缓冲溶液对固体废物样品进行了浸提,经微波消解后,用原子吸收石墨炉法测定了消解液中的钡。此方法检出限为4．15μg／L ,测定下限为16．6μg／L。相对标准偏差为2．93％,实际样品加标回收率在87．5％～107．0％之间,具有检出限低、灵敏度高、精确度和准确度高等优点,适用于固体废物中钡浸出毒性的测定。     

石墨炉原子吸收标准加入校正法测定土壤中痕量镉

选用硝酸-氢氟酸-高氯酸、硝酸-盐酸-氢氟酸-高氯酸2种消解体系,建立了石墨炉原子吸收标准加入校正法测定土壤中镉的方法,能够实现对土壤镉的准确测定.以硝酸钯为基体改进剂,优化灰化温度为550℃,原子化温度为1600℃.分别取土壤标准样品GBW07452、GBW07388经微波消解或全自动消解后,定量加入到标准溶液系列中...     

石墨炉原子吸收光谱法测定2,3,4,4'-四羟基二苯甲酮中痕量铁

建立了用石墨炉原子吸收光谱法测定2,3,4,4′-四羟基二苯甲酮中痕量铁的方法,用Zeeman/200型原子吸收分光光度计,在干燥温度120℃、灰化温度700℃、原子化温度2400℃、空心阴极灯电流3mA时,测定其铁的含量.铁质量浓度在2.5～10.0μg/L范围内与吸光度呈良好的线性关系,重复性(RSD)为1.99%,测定方法的回收率为94.2%,本方法精密度好,重现性好,可满足2,3,4,4′-四羟基二苯甲酮中痕量铁的原子吸收测定要求.     

不同品种核桃仁中钙、铁、锌微量元素的检测分析

以云南、陕西、山西等6个核桃主产区40个核桃仁试样为原料,采用微波消解-火焰/石墨炉原子吸收光谱仪测定样中铁、锌和钙。结果表明,核桃仁中Fe含量在0.010-0.193mg/g之间,平均含量0.072mg/g;Zn含量在0.005-0.070mg/g之间,平均含量0.036mg/g;Ca含量在0.255-0.660mg/g之间,平均含量0.491mg/g。所测试样中铁元素含量差异较大,其次是钙元素,锌元素含量差异较小。     

桑叶茶元素分析及其保健功能分析

用微波消解技术对样品进行消解,用火焰原子吸收法测定了浙江桐乡桑叶茶中8种矿物元素的含量,结果表明,桑叶茶中的矿物元素含量较高,其中含量最高的是K、Ca、Mg,比茶叶高出3 ～ 6倍,且其比例有利于人体吸收,有较高的营养保健价值,适合各类人群饮用.     

石墨炉原子吸收光谱法测定2,3,4,4'-四羟基二苯甲酮中痕量铁

建立了用石墨炉原子吸收光谱法测定2,3,4,4′-四羟基二苯甲酮中痕量铁的方法,用Zeeman/200型原子吸收分光光度计,在干燥温度120℃、灰化温度700℃、原子化温度2400℃、空心阴极灯电流3mA时,测定其铁的含量。铁质量浓度在2.5~10.0μg/L范围内与吸光度呈良好的线性关系,重复性(RSD)为1.99%,测定方法的回收率为94.2%,本方法精密度好,重现性好,可满足2,3,4,4′-四羟基二苯甲酮中痕量铁的原子吸收测定要求。     

土壤样品中重金属消解方法的探讨

为探讨适用于重金属分析的土壤样品前处理方法。利用原子吸收光谱法测定了土壤中铜锌铅铬镍5种金属元素的含量,并对电热板、石墨和微波3种消解方法进行了比较,结果表明：3种样品前处理方法均能将土壤样品完全消解,方法的检出限、准确度和精密度均能满足实际分析检测的要求。其中,电热板消解为敞开式消解,同时需要人员不定时根据实际情况加酸,所用试剂、时间和人力等资源消耗多,且消解过程中产生的大量酸雾会危害人身健康并污染环境;石墨消解法为半封闭式消解,试剂用量比电热板消解要少,可操作性强,适合大批量的样品前处理;微波消解为密闭式消解,实现了消解过程的无人自动化,所用样品和试剂用量少,消解时间短且彻底,安全环保,但成本较高。     

正交试验在石墨炉原子吸收法测定食用菌中铅的应用

通过正交试验优选出了较满意的测定食用菌中铅的石墨炉原子吸收法检测条件,并采用该方法测定了34个食用菌样品中的Pb含量。结果表明:Pb含量测定的最适条件为磷酸二氢铵+硝酸镁混合基体改进剂,加入量10μL,灰化温度600℃,原子化温度1900℃;铅的检出限为0.24ng/mL,回收率为95.5%～100.3%;34个食用菌样品中97%的食用菌铅含量小于2.0mg/kg。     

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.