食用林产品中氨基甲酸酯类农药残留量测定

建立了分散固相萃取-高效液相色谱-串联质谱联用法测定食用林产品(香菇)中14种氨基甲酸酯类农药残留量的方法。样品经乙腈提取,PSA和少量GCB混合吸附剂分散固相萃取净化,然后采用HPLC-MS/MS测定,外标法定量。14种氨基甲酸酯类农药在0.005~0.100 0 mg/L范围内线性良好,相关系数均大于0.995 8。在0.01~0.05 mg/kg浓度范围内,14种目标物的平均加标回收率为70.0%~104.5%,相对标准偏差为3.2%~9.1%。该方法简单、快速、灵敏,可满足香菇中14种氨基甲酸酯类农药残留的检测需要。     

MAE在线GPC-GC-MS/MS法测定板栗中20种有机磷农药残留

先以乙腈为提取溶剂,采用微波辅助萃取技术(MAE)对板栗样品中20种有机磷农药进行萃取(前处理),然后将提取液经分散固相萃取净化,除去样品中大部分的脂肪和甾醇等干扰基质,再经在线GPC/GC—MS—MS在多反应监测模式(MRM)下进行检测和确证,建立了板栗中20种有机磷农药残留量的在线GPC—GC—MS/MS快速测定方法。测定结果表明:20种有机磷农药在0.01~0.20 mg/kg范围内的加标平均回收率为71.5%(104.0%,相对标准偏差为3.4%~9.4%。该方法准确、快速、净化效果好。     

杭州市雷竹林土壤与竹笋有机农药残留规律研究

经多点取样检测杭州市雷竹林土壤与竹笋有机农药残留,结果表明:雷竹林土壤与竹笋有机农药污染具有普遍性.土壤中检测到3类16种有机农药残留,HCH及其异构体、DDT及其同系物、五氯硝基苯有机氯农药(OCP)10种,HCH检出率100%,显著高于DDT.甲基对硫磷、对硫磷、甲胺磷、乐果有机磷农药(OPP)4种,甲基对硫磷检出率100%.氯氰菊酯和顺-氰戊菊酯拟除虫菊酯类农药(PYP)2种,检出率低于75%;土壤中有机农药残留量均低于100 μg·kg-1,低于有机农药土壤残留有关规定,其中,HCH、DDT低于20μg·kg-1,有机磷农药低于50喀·kg～.笋体检测到有机农药9种,均为有机氯农药,HCH、DDT检出率均达100%,DDT较HCH更趋于稳定,五氯硝基苯检出率88.24%.竹笋对HCH、DDT等有机氯农药有富集效应.笋体中有机氯农药残留量均值均低于50μg·kg-1,符合国家食品安全标准和浙江省优质竹笋标准. 检出率100%.氯氰菊酯和顺-氰戊菊酯拟除虫菊酯类农药(PYP)2种,检出率低于75%;土壤中有机农药残留量均低于100 μg·kg-1,低于有机农药土壤残留有关规定,其中,HCH、DDT低于20 g·kg-1,有机磷农药低于50μg·kg-1.笋体检测到有机农药9种,均为有机氯农药,HCH、DDT检出率均达100%,DDT较HCH更趋于稳定,五氯硝基苯检出率88.24%.竹笋对HCH、DDT等有机氯农药有富集效应.笋体中有机氯农药残留量均值均低于50μg·kg-1,符合国家食品安全标准和浙江省优质竹笋标准. 检出率100%.氯氰菊酯和顺-氰戊菊酯拟除虫菊酯     

顶空固相微萃取-气质联用检测梨中有机氯农药残留

该文应用顶空固相微萃取-气质联用（HS-SPME-GC/MS）技术建立了梨中艾氏剂、环氧七氯、对对-滴滴滴、对对-滴滴涕、邻对-滴滴涕和顺式九氯6种有机氯农药的快速测定方法。实验优化了HS-SPME萃取条件和GC-MS条件,结果表明：在0.002～1mg/L的质量浓度范围内,各组分线性相关系数R在0.993～0.999,RSD（n=5）在4.3%～7.1%,方法检出限在0.0017～0.0071mg/kg,回收率在95.38%～99.83%。该方法快速、灵敏、准确、试剂用量少,且各项方法学指标符合检测要求,是一种快速检测梨中有机氯农药残留的方法。     

液相色谱串联质谱法快速测定油茶籽中9种农药残留量

建立了高效液相色谱串联-质谱法同时检测油茶籽中吡虫啉、乐果、甲胺磷、马拉硫磷、三唑酮、对硫磷、毒死蜱、丁草胺、噻嗪酮9种农药的残留量。样品经乙腈提取后,取上清液直接过膜后进行液相色谱串联质谱分析。采用Agilent SB—C18色谱柱分离,用4 g/L甲酸铵水溶液-乙腈作为流动相进行梯度洗脱,电喷雾正离子(ESI+)模式电离,多反应监测(MRM)模式检测。结果表明:各物质峰面积与样品浓度在0.001~0.5 mg/L范围内呈良好的线性关系,线性回归系数大于0.999 0。在添加浓度0.01~1.0 mg/kg范围内,9种农药的平均添加回收率在64.2%~114.1%范围内,变异系数在1.2%~9.4%之间,该方法能满足油茶籽中9种农药残留量分析的要求。     

HPLC-ICP-MS联用测定猪场废水中的砷形态

建立了HPLC-ICP-MS联用测定猪场废水中5种砷形态化合物的检测方法。将HAMILTON PRP-X100与CNW C18-WP色谱柱进行对比,优化色谱条件,以(2.5mmol/L柠檬酸+2.5mmol/L己烷磺酸钠pH4.5)+甲醇(99:1v/v)为流动相,在6min同时分析检测5种砷形态化合物。添加2~80μg/L浓度水平时,5种砷形态化合物添加回收率在87.6%~92.6%之间,相对标准偏差(RSD)在3.9%~5.6%之间,方法检出限(S/N=3)在0.3~0.8μg/L之间。结果表明:该方法前处理简单,灵敏度高,可用于日常监督检测工作。对了解规模化养猪场废水重金属砷污染状况,进一步开展规模化养猪污水对人类生活用水的污染提供数据基础。     

分散固相萃取-气相色谱三重四极杆串联质谱法测定玫瑰花茶中13种菊酯类农药残留

建立了分散固相萃取-气相色谱三重四极杆串联质谱法测定玫瑰花茶中的13种菊酯类农药的分析方法。玫瑰花茶经乙腈和甲酸(99∶1_v/v)提取后,QuEChERs净化,MRM模式测定,外标法定量。以QuEChERs作为前处理方法,优化吸附剂组合和用量,以及碰撞能和驻留时间。结果表明:13种菊酯含量在10～200μg/L间呈良好的线性关系,相关系数r^2均大于0.995。以空白基质进行3个水平添加浓度0.02～0.20 mg/kg,平均回收率为75.4%～87.6%,相对标准偏差(RSD)为1.9%～7.7%,该方法的简单快速,灵敏度、准确度和精密度均符合菊酯类农药测定的技术要求。     

基质固相分散-气相色谱质谱联用法测定沉香中精油的化学成分

以海南生物结香的沉香木为原料,建立了沉香精油的基质固相分散-气相色谱/质谱联用(MSPD-GC/MS)分析方法.采用基质固相分散技术进行沉香精油的提取,采用单因素试验得到优化工艺条件为:吸附基质为硅酸镁,吸附基质与样品的质量比为4:1,分散溶剂为异丙醇,分散溶剂与样品的比例为4:1(mL:g),洗脱溶剂为体积比9:1的...     

超高效液相色谱-质谱法测定饮用水源水中邻苯二甲酸酯类化合物

利用液相色谱-三重四级杆质谱联用仪(LC-MS/MS),建立了饮用水源水中邻苯二甲酸二丁酯(DBP)和邻苯二甲酸二(2-乙基己基)酯的检测方法。水样经高速离心后取上清液进样,以C18色谱柱分离,甲醇-0.1%甲酸水为流动相梯度洗脱,正离子模式下质谱多反应监测(SRM)模式检测。实验中探索了使空白干扰得到有效控制的方法。结果表明:两种邻苯二甲酸酯类化合物(DBP和DEHP)分别在5~100μg/L范围内线性良好,相关系数R均大于0.9990,回收率为86.3%~102%,相对标准偏差为4.4%和5.2%,方法检出限分别为0.35μg/L和0.28μg/L,说明该方法适合水源水中两种痕量邻苯二甲酸酯的快速准确分析。     

超声辅助分散液液微萃取-高效液相色谱法检测水样中的西维因

采用超声辅助分散液液微萃取结合高效液相色谱法检测了环境水样中的西维因,考察了萃取剂种类及体积、超声时间、离心时间、溶液pH值和盐浓度等因素对萃取效率的影响。结果发现色谱检测条件为:以甲醇/水=65/35(v/v)作为流动相,流速为0.6mL/min,检测波长为220nm,柱温为23℃。在优化的条件下,西维因的线性范围为0.01~1.0μg/mL,检出限为0.9μg/L,相对标准偏差(n=5)为2.3%~8.0%,样品的加标回收率为80.1%~98.3%。本实验方法适合于环境水样中痕量西维因的分析。     

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.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

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.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

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。