西藏自治区的土地、粮食和人口

本文讨论了西藏自治区土地系统、农业发展、人口增长和它们之间的相互关系。指出西藏土地类型复杂多样,极少土地能用于种植业,单位产量亦不高。人均占有粮食不足300kg,若干牧区不足50kg。粮食生产不能满足人口增长的需求。这种趋势在今后30年内仍将继续下去。 为了解决土地—粮食—人口三者之间关系的不协调,需采取若干切实措施。文中亦强调人口控制的必要。     

关于黄土高原空间范围的讨论

长期以来,黄土高原的空间范围缺乏明确的定论。争论的焦点反映出不同学者对自然地理现象空间分布过渡性的认识和处理的差异。本文从黄土、黄土分布区、黄土高原及其毗邻的黄土分布区、黄土高原、典型黄土地貌区等几个不同层次的概念出发,探讨了划分黄土高原的客观标准,并根据野外考察和航卫片判读确定了黄土高原的空间范围。     

环境与生态系统资本价值评估的若干问题

近年来,环境与生态系统资本价值评估中的概念界定、系统价值认定及评价模式选择等之类的问题成为相关研究中有争议的议题.鉴于此,对环境与生态系统资本价值评估中的一些问题进行了探讨.①在肯定环境与生态系统资本价值评估意义的基础上,指出对于环境与生态系统的整体价值要予以充分估价;②针对目前评价模式单一的现状,提出了整合类型与区域评估的新模式;③在分析了环境与生态系统的资本价值在空间上流动之后,认为应对价值的积累和流动过程给予充分关注;最后,提出了几条具体的建议.     

生活饮用水中六六六、滴滴涕、六氯苯测定方法的优化

文章综合现有国标中关于六六六(BHC)、滴滴涕(DDT)和六氯苯(HCB)测定方法,在此基础上,通过改变取样量、萃取剂量、分离程序等进行方法优化和验证,采用时间定性,外标法定量。实验结果表明,利用InertCap 5石英毛细管柱、电子捕获检测器进行测定,在0.025～0.5μg/L添加水平下,六六六、滴滴涕、六氯苯9种物质的平均回收率为92.5%～104.3%,相对标准偏差为0.9%～4.5%,方法检出限为0.01～0.04μg/L。优化后的方法具有试剂用量少,操作简单、快速,灵敏度、回收率、精密度和准确度高等优点,具有实用价值。     

黄土高原主要农作物水分盈亏与雨养农业问题

黄土高原在气候上属亚湿润向半干旱的过渡地区。水分缺乏是农业生产的重要限制因素。本文围绕降水和蒸发,主要作物的需水和降水间的相互关系,农田干湿状况和水分盈亏额进行了分析讨论。认为,发展雨养农业应该是黄土高原农业生产的一条基本方针;在雨养农业作物的选择上,除谷子可以在全区种植外,其他作物受地区局限性很大;发挥雨养农业生产潜力的基本途径应该是增加土壤水分含量和提高土壤有效水分的利用系数,为达到这一目的宜采用平整土地、增施肥料等一系列农业措施。     

Removal of Methylene Blue from Water by Peach Gum Based Composite Aerogels

Journal of Polymers and the Environment - In this study, novel composite aerogels of peach gum/activated carbon (PGAC) and peach gum/graphene oxide (PGGO) were synthesized by freeze-drying method...     

Dike Breach Risks of Different Flood Conditions in the Lower Yellow River

Based on the analysis of hanging rivers' actuality in the lower Yellow River and researches related to the evaluation of dike breach risks, it is put forward that the influencing factors of dike beach risks in the lower Yellow River should involve four aspects, the flow and sediment movement, the regional crustal stability, the variation of river regime and the stability of river dikes. With this, the evaluation indexes system of dike breach risks is established, and with the support of geographic information systems technology, the model of multi-hierarchical fuzzy comprehensive judgment is applied to estimate the dike beach risks of the hanging rivers in the lower Yellow River under different flood conditions. The evaluation results of dike breach risks show the following distributing regularities of dike breach risks in the lower Yellow River: (1) Dike breach risks increase with the increase of the flood. (2) Dike breach risks decrease with the changes of river patterns along the channel. (3) There are great risks of dike breach in the wandering reaches, and it is relatively higher in the south bank than in the north in wandering reaches. (4) There is a higher dike breach risk in the north bank than in the south in winding reaches. Simultaneously, the evaluation results manifest that the evaluation indexes system established from the flow and sediment movement, the regional crustal stability, the variation of river regime and the stability of river dikes can represent the actual situation of the lower Yellow River more comprehensively. The application of multi-hierarchical fuzzy comprehensive judgment can preferably resolve the problem of hanging river dike breach, which has numerous influencing factors and complicated functionary mechanisms. The applications of geographic information systems technology with powerful spatial analysis functions make dike beach risks quantificationally displayed in different spatial positions, and reflect the differences of dike beach risks in different spatial positions of the channel in the lower Yellow River.     

罗丹明6G共振散射光谱法测定水中痕量六价铬

在 0 .0 4mol/L H2 SO4 和 8.0× 10 - 4mol/L KI介质中 ,罗丹明 6G ( Rh G)在 5 80 nm处有 1个同步荧光峰。当有 Cr( )存在时 ,Cr( )与过量的 I-反应生成 I- 3,I- 3与 Rh G形成缔合微粒 ,在 32 0、40 0、5 95 nm处产生 3个共振散射 ( RS)峰 ;而在 5 80nm处荧光峰猝灭。六价铬浓度在 1.0× 10 - 7～ 2 0× 10 - 7mol/L范围内与 40 0 nm波长处的共振散射光强度成线性关系。据此建立了测定水中六价铬的共振散射光谱分析法。光谱研究结果表明 ,( Rh G-I3) n缔合微粒和界面的形成是导致体系 RS增强的根本原因。