原子吸收分光光度法测定植株中钙、镁的几种样品前处理方法的比较

本文比较了原子吸收分光光度法测定植株中钙、镁的三种样品前处理方法：干友化法、１ｍｏｌ／ＬＨＣｌ振荡提取法（振荡法）和１ｍｏｌ／ＬＨＣｌ静止浸泡提取法（浸泡法）．结果表明，振荡法和浸泡法对钙的测定结果平均分别为干灰化法的１０１％和９２．０％，对镁的测定结果平均分别为１０３％和９７．６％．振荡法和浸泡法与干灰化法之间不存在显著性差异（α＝０．０５），它们之间有极显著的正相关性（相关系数在０．９９以上）．因此，在大批量样品的常规分析中，１ｍｏｌ／ＬＨＣｌ提取法可代替干灰化法．     

农林复合经营研究──桉树人工林间种西瓜对林木和土壤的效应

本文调查研究了雷州林业局纪家、河头林场桉树人工林间种西瓜对林木和土壤的影响．结果表明，利用造林前空隙种一造西瓜或在桉树林地间种西瓜，均有利于桉树生长．单位面积林木蓄积量和年生长量均比对照林分显著增加，经济效益显著；土壤养分也有增加。作为农林复合经营的有益尝试，值得在有条件的地区推广。     

6—叠氮—6—脱氧—1,2：3,4—二—氧—异丙叉基—α—D—半乳糖的构象分析

在合成卡那霉类似物的核心结构时，发现６－叠氮－６脱氧１，２；３，４－二－氧－惜内叉基－α－Ｄ－半乳糖的核磁共振数据与普通六元环的船式或椅式构象大不相同，进一步通过分子力学模型ＭＭＰ２的计算，发现它具有扭船式的分子构象（Ｔｗｉｓｔ ｂｏａｔ）。     

酸性pH及铝对鲤鱼（Cyprinus carpio）吸收^45Ca的影响

本文用放射性核素~(45)Ca作为示踪剂,研究在酸性pH及加铝的条件下,鲤鱼(Cyprinus carpio)对钙离子的吸收分布情况.结果表明,在pH值为7.10时,~(45)Ca在鲤鱼体内各器官的96h放射仕比度为鳃13886 cpm·g~(-1),骨骼10811 cpm·g~(-1),肝脏3276cpm·g~(-2)·肌肉2865cpm·g~(-1);在酸性pH(4.30)条件下,鲤鱼对钙离子的吸收和积累受到明显抑制;加铝后,鲤鱼体内各器官~(45)Ca放射性比度与未加铝的对照组相比,下降百分比分别为鳃42、4%.骨骼18 5%,肝脏44、2% 并讨论了酸雨危害鱼体钙代谢的可能影响.     

发挥网络优势 搭建服务平台 大力推进电子废弃物回收处理产业发展

<正>1供销合作社系统具有比较健全的再生资源回收网络,有利于再生资源的有效集中和高效利用我国人口众多,人均资源占有量远低于世界平均水平,重要资源短缺已成为制约经济社会发展的重要因素。再生资源回收利用作为一个传统行业,在建设资源节约型与环境友好型社会的新的历史时期,越来越引起各级政府的高度重视和全社会的广泛支持。     

The adsorption characteristics of heavy metals by various particle sizes of MSWI bottom ash

The incineration rate of municipal solid waste (MSW) has been increased because of difficulty in securing a proper disposal site for MSW in Korea. The advantage of incineration is reduction of the volume of waste; however, significant amounts of bottom ash and fly ash were generated in the incineration process. Their treatment has attracted growing interest because of the potential toxicity of hazardous heavy metals. Generally, heavy metals are less released from bottom ash than from fly ash. In this study the adsorption characteristics of heavy metals were investigated using various particle sizes of MSWI bottom ash. Since bottom ash has a broad particle size distribution, it was sieved to size classes of +20, -20, -48, -80, -100 mesh. Cation exchange capacity (CEC) was analyzed by the ammonium acetate method to evaluate the potential as an adsorbent. The CEC values and surface areas increase as the range of particle size becomes finer. The adsorption experiment was conducted using synthetic (Cu and Ni) and plating rinse water as a function of reaction time (10-180 min), liquid/solid ratio (2-100) and particle size (+20 to -100 mesh), respectively. The adsorption rate increased with decreasing particle size and with increasing liquid/solid ratio; however, the removal efficiency of Cu was higher than that of Ni. In the case of plating rinse water, the adsorption rate decreased sharply at high liquid/solid ratio, and it showed over 80% of adsorption rates for Cu and Ni at an initial pH of 3.     

氯氧化锆生产中废碱液的回收利用

建立了以 CaO 为沉淀剂去除废碱液中 SiO2回收 NaOH 的工艺,研究了各工艺因素对siO2去除效果的影响,实验结果表明,CaO 沉淀除去废碱液中 SiO2的最佳工艺条件为:CaO 与废碱液中 SiO2摩尔比 3.0,反应温度80～95℃,反应时间 40～60 min,搅拌转速 200 r/min.在此条件下,S...     

北京地区15000年以来环境变迁中灾害性气候突变事件的讨论

通过高分辨率孢粉分析及烧失量、炭屑实验结果的统计分析，结合１４Ｃ、古地磁等，对北京房山东甘池１５０００ａ以来植被变化和环境变迁进行了较为深入的研究，特别强调气候变化的灾害性突变事件。初步得知约在１４１００～１４０００ａＢ．Ｐ．前后曾出现与哥得堡反转相对应的事件，在１００００ａＢ．Ｐ．左右出现类似与新仙女木事件相对应的事件，在大约５７７０ａＢ．Ｐ．和４５６０ａＢ．Ｐ．左右及２８５０～２６５０ａＢ．Ｐ．出现了大暖期的突然降温事件。     

城市空气质量达标规划编制中的关键技术及其案例应用

本文结合重庆市空气质量限期达标规划编制案例,介绍了城市空气质量达标规划编制中的几个关键技术及其具体应用,包括本地化污染源排放清单编制、污染物来源解析、污染物排放形势预测与减排潜力分析以及大气环境容量核算等。本地化污染源排放清单是城市空气质量达标规划编制的基础,针对现有污染源制定科学合理的减排方案是达标规划的核心内容。分析不同区域的污染物组分浓度特征、污染源贡献以及未来污染排放形势预测,有助于识别出制约未来空气质量达标的关键因素及污染源。基于污染源减排潜力和污染传输矩阵制定的污染源减排方案更具合理性和可行性,应用空气质量模型估算大气环境容量可为规划目标可达性提供依据。     

Community structure and biotic integrity of aquatic plants along the North Canal in Beijing北大核心CSCD

Aquatic plants along the North Canal in Beijing were studied to identify the community structure of aquatic plants and vegetation index of biotic integrity (VIBI), and to provide scientific basis for the management and protection of urban rivers. Aquatic plants from 49 sampling sites along the North Canal were investigated during June 2015. Based on the field data, distributing range analysis, discriminatory power analysis, and correlation analysis were used stepwise to select core metrics from candidate metrics to establish the VIBI assessment system. The VIBI value of each sampling site was calculated as the average of the scaled values of all core metrics. Thirty-six aquatic plant species, including 14 hygrophytes, 13 emergent species, 6 submergent species, 2 floating-leaved species, and 1 floating species were collected. Species diversity was low in the North Canal, and no aquatic plants were recorded in 28 sampling sites, of which 9 sampling sites were dried up. Five sites were in excellent condition (VIBI > 0.60), 5 were good (0.60 > VIBI > 0.38), 7 were fair (0.38 > VIBI > 0.23), and 4 were poor (VIBI < 0.23). Based on the distribution of VIBI, Shahe River and Wenyu River upstream, and Fenghe River located in suburbs had a higher VIBI. Downstream tributaries, such as Qinghe River, Bahe River, and Liangshui River, had a lower VIBI. Correlation analysis showed that habitat quality, habitat complexity, and vegetation diversity along riparian zones were the important factors affecting VIBI along the North Canal, Beijing. Aquatic plants along the North Canal showed low species diversity owing to human disturbance. VIBI along tributaries with limited disturbance from human activities was higher; however, VIBI along tributaries disturbed by frequent human activities was lower. © 2018 Science Press. All rights reserved.