河北省苹果中农药残留含量分析

为了解苹果生产过程中农药的残留污染,用气相色谱法对河北省6个市苹果果实中的5种不同农药残留含量进行了测定,结果表明:苹果中甲氰菊酯含量最高的是衡水,其值为0.033mg/kg;氯氟氰菊酯残留含量最高的是张家口,其值为0.096mg/kg;氯氰菊酯残留含量最高的是邯郸,其值为0.036mg/kg;氰戊菊酯残留含量最高的是张家口,其值为0.052mg/kg;毒死蜱残留含量最高的是张家口,其值为0.069mg/kg。将河北省不同城市苹果中检测的5种农药残留量按等距离方法分为3级,其中大多数城市在Ⅰ级范围内,农药残留含量较小。     

河北省桃中氯氟氰菊酯残留量分析

氯氟氰菊酯属拟除虫菊酯类仿生物农药,具有杀虫谱广、高效、速度快、持效期长等特点。随着在生产中大量使用,其残留污染引起了人们的重视。为了解决桃生产过程中氯氟氰菊酯的残留污染,笔者用气相色谱法对河北省6个城市桃中氯氟氰菊酯残留量进行了测定。研究结果表明,衡水市桃中氯氟氰菊酯残留量最高,为0.065 5 mg/kg,远低于国家标准规定氯氟氰菊酯农药残留最大限量的0.2 mg/kg,故其残留对桃的质量安全不会造成负面影响。     

4种有机磷注射剂在苹果、梨果中残留量的测定

经高效液相色谱仪检测树干注射 4种有机磷农药后第 13d分析表明 ,梨和苹果果实中原药残留分别为氧化乐果 1 9,2 4mg/kg ,久效磷 1 3,1 8mg/kg,水胺硫磷 1 8,3 0mg/kg ,甲胺磷 1 2 ,0 8mg/kg ;第 2 5d果实中原药残留仅在苹果中测到水胺硫磷 0 0 0 1× 10 -6～ 0 0 0 5× 10 -6,其余 3种均未检测出。根据美国、日本对上述 4种农药在苹果、梨果中最高残留限量 :甲胺磷、久效磷、水胺硫磷均为 1 0mg/kg ,氧化乐果为 2 0mg/kg的标准 ,建议采前安全施药间隔期以 30d为宜     

QuEChERS-GC/MS法测板栗中10种有机磷农药残留

用QuEChERS方法对板栗样品中10种有机磷农药进行前处理优化,建立了板栗有机磷残留量的快速前处理方法,并进行验证。通过对比不同的提取溶剂、取样量、除水剂用量、净化剂用量确定板栗QuEChERS前处理的最佳组合,净化完成后用GC/MS检测。10种有机磷农药的线性相关系数均0.998,最低检出限为0.010~34 mg/kg,平均回收率为80.1%~105.4%,相对标准偏差值为3.5%~8.9%。该方法准确、快速、净化效果好,适用于板栗中多种有机磷农药残留的快速检测。     

林源中药饮片二氧化硫残留量检测

为了掌握市场上林源中药饮片中二氧化硫的残留情况,从而为林业资源的利用、林药资源加工技术规范的制定与执行以及林产品的安全监测提供参考依据,采用在国家标准的基础上自行改进的检测方法,对从市场上收集到的31种林源中药饮片中二氧化硫的残留量进行了检测。结果表明:未检出二氧化硫的有3种;二氧化硫含量30 mg/kg的有20种;其含量为30~150 mg/kg的有3种;其含量为151~400 mg/kg的有3种;其含量400 mg/kg的有2种。根据《中华人民共和国药典》中对中药饮片残留量的限制规定和文中的检测结果,黄柏、牡丹皮、合欢皮、陈皮、八角茴香等中药饮片的二氧化硫残留量超标,建议在林产品利用和监管时要特别加以注意。     

6种无公害农药防治北五味子白粉病农药残留分析

选用6种无公害农药对北五味子白粉病进行防治,对农药残留情况进行测定和分析,结果表明,三唑酮20%乳油在3、6、9、20、40d后,叶片内的农药残留量最高,40d时农药残留量为19.5mg/kg,而其余几种农药残留量相对较低。据此,在防治北五味子白粉病时,应选择除三唑酮20%乳油之外的农特安32.5%可湿性粉剂、天音12.5%乳油、粉锈醇20%可湿性粉剂、良美可湿性粉剂。     

桔梗药材质量分析

分析桔梗药材中有效成分含量、重金属和农药残留,为桔梗的质量控制和标准制定提供依据。方法:采用原子吸收光谱法测定铅、砷、镉,ICPMS法测定汞的含量,气相色谱法测定有机氯农药残留量。结果:桔梗总皂苷10.18%,铅(0.05mg/kg,汞(0.01mg/kg,砷(0.14mg/kg,镉(0.09mg/kg,BHC(8ug/kg,DDT(4ug/kg,PCNB未检出。结论:桔梗药材中含一定量重金属。     

山东省主产区板栗农药残留分析

为了解山东省主产区毛板栗中农药残留分布特征及其潜在的生态风险,对40个板栗产区的63份板栗抽样分析。研究结果显示:山东省主产区板栗中六六六和滴滴涕呈正态分布,其中ΣHCH0.005mg/kg和ΣDDT0.032mg/kg,所有测定值基本低于国家食品质量背景值标准,而除虫菊酯和有机磷农药均未检出,板栗中农药残留均处于国家食品质量背景值标准规定的安全水平。     

异菌脲在梨和土壤中的残留降解动态研究

采用乙腈提取、氟罗里硅土层析柱净化、GC-ECD 测定法,研究了异菌脲在梨和土壤中的降解动态和最终残留量.结果表明:异菌脲在梨上的半衰期为12d,施药后45d 的消解率在90豫以上;在土壤中的半衰期为7.8耀7.9d,施药后45d 的消解率在90豫以上.药后7、14、21d 采集的梨中最高残留量为0.37mg/kg,未超过我国国家标准规定5mg/kg 的 MRL值,在梨上的安全间隔期为7d     

罗汉果有机磷农药残留量分析及限量标准的制定

为给科学制定罗汉果产品质量标准提供依据,采用随机取样法,从我国广西罗汉果主产区永福县龙江乡、临桂县茶洞乡、龙胜县三门乡和融安县雅瑶乡的罗汉果中取样,然后用日本岛津GC-14B气相色谱仪对其敌敌畏、甲胺磷农药残留量进行了检测,结果未检测出两种农药的残留量;并参照我国其它中药材有机磷农药残留量的相关标准,制定了我国罗汉果有机磷农药残留的限量标准.     

Armillaria ostoyae in managed coniferous forests in Kastamonu in Turkey

Although several Armillaria species have been reported in Turkey, there is little information about their ecology in Turkish forests. In this study, we investigated five forest stands, approximately 5–74 ha in size, in Kastamonu province in the Black Sea Region of Turkey for the presence of Armillaria species in stumps and logs. The stands were mixed Abies nordmanniana ssp. bornmülleriana and Pinus sylvestris forests managed using a selective cuttings system; the proportion of fir in the total number of stems and stumps ranged from 36 to 98%. Based on sequence analysis of the internal transcribed spacer and intergenic spacer regions of the rDNA, all rhizomorphs sampled from the stumps and logs were of Armillaria ostoyae. The size of the genets was estimated with random amplified microsatellites analysis of the isolates and ranged from single stumps to approximately 450 m². One to seven genets were found in each stand. These results indicate that the genets had arisen from spores and vegetative spread was limited on most sites.     

上海中央公园特大银杏树白蚁防治探讨

通过对上海松江中央公园内65株特大银杏树白蚁为害情况的调查,发现该公园银杏受害率为100%,其中存在活白蚁的银杏占总量的56.9%,采用毒土处理、粉剂疗法、建立白蚁监测点等措施,经过两次灭杀,活白蚁的灭杀率达到92.3%和93.3%,从而使存在活白蚁银杏树的比例从56.9%下降到2.7%,白蚁发生情况明显降低。       

我国食品中农药残留研究进展

随着人们安全健康意识提高,食品中农药残留问题更加受到重视,本文综述了样品预处理研究进展及农药残留快速检测技术研究进展,并简单分析介绍各种方法的优缺点。     

建平半干旱地区石质山地造林技术研究

研究了不同植物在石质山地的造林成活率、土壤化学性质随造林年限的变化和造林措施对土壤化学性质和植物胸径、树高年净生长量的影响。结果表明：不同植物在石质山地的成活率在21%～85%之间,其中白榆和沙打旺的成活率分别为81%和85%,而小叶杨、刺槐、栾树的成活率均在70%左右;植被能明显提高石质山地不同土层的有机质、全N、P2O5含量,但提高程度随土层深度、养分种类和造林年限的不同而不同;在同一土层,生物复合肥料、菌剂和保水剂均显著提高土壤有机质含量（p〈0.01）并显著降低土壤P2O5含量（p〈0.01）;只有保水剂可引起土壤全K含量的明显升高;生物复合肥料、菌剂和保水剂均显著提高白榆、小叶杨、刺槐、栾树树高和胸径的年净生长量,但保水剂的提高程度最高。     

植物DNA甲基化研究进展

植物经常暴露在各种生物和非生物的胁迫之下,这些胁迫会影响植物的生长发育和繁殖并最终导致植物死亡。为了抵御不利的环境条件,植物已经进化出复杂而精细的网络来感知胁迫并激活防御系统。为此,植物激活许多信号转导通路,这些信号转导通路可以改变一些胁迫响应基因的表达,从而引起植物形态、生理和生化的改变以适应逆境。DNA胞嘧啶甲基化是高等真核生物的主要表观遗传机制之一,在维持基因组稳定性和调节基因表达方面起着关键作用。表观遗传变异比遗传变异更为灵活。一旦环境条件发生变化,为了适应新的环境植物都会发生表观遗传的改变。许多研究表明DNA甲基化参与植物的发育和应激反应。基于相关研究对DNA甲基化进行了综述,对植物逆境胁迫有重要意义。     

木材碳封存研究进展

碳封存可以分工业封存和生物封存, 工业封存包括地质封存、海洋封存、矿石碳化以及工业循环利用, 这些方法能快速回收CO₂, 但工艺流程技术复杂, 成本较高。木材碳封存是生物碳封存的一种类型, 树木光合作用吸收的碳主要存贮在木材中。运用木材密度、微密度等检测仪器, 通过确定木材密度变化, 结合其含碳率来计量木材的碳封存过程以及封存过程中碳的分配格局, 同时研究其与环境因子的相关性, 可以为研究森林的碳吸收动态提供便捷的方法和科学的依据。     

Natural regeneration in patch clear-cutting in Picea abies stands in Southern Finland

Abstract

The success of natural regeneration on patch clear-cuts in Norway spruce stands in Southern Finland was examined in terms of stocking and tree height. The experiment was established in mature spruce stands in the submesic Myrtillus (MT) site type. In each of the eight study sites, three plots were treated with clear-cutting and planting, clear-cutting with partial tree retention and planting, and patch clear-cutting without site preparation, respectively. In three of the study sites, one plot with patch clear-cutting and site preparation was established. Each plot was 1 ha, out of which three patches of 40×40 m were clear-cut in the patch treatments. 10–11 years after cutting, the patches had on average 1316 crop trees ha^–1, of which 91% were spruces. Some 27% of the stands were up to the target stocking level (≥1600 ha^?1), and 36% were at least satisfactory (≥1300 ha^?1). Site preparation did not yield greater stocking levels on patches, but that result is ambiguous due to a difference in initial stocking. The average spruce tree height in the patches (0.76 m) was much smaller than in the case of clear-cutting and planting (2.42 m). In conclusion, the patches had been restocked tolerably well with spruce and birch for practical purposes during the 10- to 11-year period, but the regeneration process had been very slow compared to clear-cutting and planting.     

Tree regeneration in patch cutting in Norway spruce stands in northern Finland

The study focused on the success of regeneration on patch cuts in spruce-dominated stands in terms of stocking and tree height. It was based on an experiment in the Kainuu region in northern Finland. The experimental design included 8 stands with 58 clearcut patches of variable size (0.09–0.37?ha), on which either natural regeneration without site preparation or site preparation and planting of Scots pine was applied. A regeneration survey was conducted 13–15 growing seasons after treatments. Patches without site preparation had been restocked quite well from natural seed sources. The average number of trees was about 11,000?ha^?1, of which 1700?ha^?1 crop trees. With site preparation and planting, the stocking levels were also very high, 25,000 and 2100?ha^?1, respectively. One hundred percent of the planted patches and 75% of the naturally regenerated patches had an acceptable density. Restocking was equally good across the range of patch sizes. Tree growth had been somewhat slower in the smallest patches than in the largest ones in the range. Natural regeneration was capable of yielding good regeneration results in most patches, especially when site preparation was applied. Stocking levels and height development were higher yet in the planted patches.     

Changes in micropores in dry wood with elapsed time in the environment

To investigate the changes in microstructures of wood with elapsed time in the environment, CO₂ adsorption onto dry wood was measured at ice-water temperature (273 K) for samples aged from 0.1 years to over 1000 years. The micropore size distribution was obtained using the Horvath-Kawazoe method. Micropores smaller than 0.6 nm in wood decreased in number with elapsed time in the environment, and a negative correlation was found between cumulative pore volume for pores smaller than 0.6 nm and elapsed time in the environment. Cumulative pore volume in the 1000-year sample was almost half of that in the 0.1- year sample. Micropores smaller than 0.6 nm in wood with a few decades or more of elapsed time increased in number after rewetting and drying. Consequently, microstructures of wood with longer time elapsed in the environment were considered to be more stable, because of longer-term thermal motion and possibly more repeated moisture adsorption and desorption and/or temperature variation in the environment.