云南玉龙山东南坡降雨因子与土壤流失关系的研究

水土流失做为破坏生态环境、阻碍工农业生产、限制自然资源优势发挥的重要因素之一,是我国大部分地区生态环境系统中所面临的突出问题。本文以1985年云南玉龙雪山东南坡水土流失定点观测的实测数据为依据,着重定量分析了水土流失与其主要影响因子一降雨之间的关系。通过对比研究,阐述了不同降雨特征值对流失土量的影响,提出了雨强递减系数这一新的降雨影响因子。     

关于区域地质调查中水土流失定量研究的初步探讨

根据水库自成封闭系统，自分水岭至水库内，被洪水或其它地质营力所搬运的泥砂沉积封存于水库内的基本原理．提出定量研究水土流失的基本方法。并以江西田坂街幅1：5万区域地质调查为例，按照这一思路和方法进行了定量研究。结果表明，不同岩类区与不同时期的泥沙流失量是不同的，与全新统比较．前震旦纪浅变质岩区水土保持较好，侵蚀速率下降；而白垩纪红层区则达中度侵蚀，并呈恶化趋势。     

Soil loss due to harvesting of various crop types in contrasting agro-ecological environments

Soil erosion studies on cropland usually only consider water, wind and tillage erosion. However, significant amounts of soil are also lost from the field during the harvest of crops such as sugar beet (Beta vulgaris L.), potato (Solanum tuberosum L.), chicory roots (Cichorium intybus L.), cassava (Manihot spp.) and sweet potato (Ipomoea batatas (L.) Lam). During the harvest soil adhering to the crop, loose soil or soil clods and rock fragments are exported from the field together with these crops.This soil erosion process is referred to as ‘soil losses due to crop harvesting’ (SLCH). Most of the studies investigated SLCH variability and its controlling factors for one crop type in similar agro-ecological environments and for comparable harvesting techniques. In this study, a compilation of SLCH studies was made in order to investigate the effect of crop type, agricultural systems, ecological conditions and harvesting technique on SLCH variability. SLCH rates ranged from few to tens of Mg ha⁻¹ harvest⁻¹ and SLCH was highly variable both in space and time. Comparison of four studies on SLCH for sugar beet revealed that harvesting technique and soil moisture content at harvesting time can be equally important for SLCH variability. The occurrence of soil clods harvested with the crop explained why SLCH was significantly larger for mechanically harvested potato in Belgium compared to manually harvested potato in China. SLCH values for manually harvested sugar beet, potato, cassava and sweet potato in China and Uganda were in general smaller than SLCH values for mechanically harvested sugar beet, potato and witloof chicory roots measured in Belgium and France. However, SLCH may also vary significantly within Europe due to differences in harvesting techniques. Soil moisture content at harvesting time was besides harvesting technique one of the key factors controlling SLCH variability. There were no systematic differences in SLCH between crop types, although the soil–crop contact area–crop mass ratio could explain more than 40% of the means from several SLCH studies.     

均质滤料过滤阻力的数学模型

以NaCl为示踪剂 ,测定滤层内水流电导率的变化 ,通过分析、计算可以得到滤层内絮体的体积比截留量 .不同条件下的试验结果表明 ,在过滤过程中 ,水头损失梯度的变化只与截留的絮体体积有关 ,与滤床厚度、加药量、滤速的改变几乎无关 .根据示踪剂实验结果 ,得出了滤层过滤阻力数学模型的具体表达式 ,并讨论了相关过滤阻力模型的适用性     

炼山对杉木人工幼林养分流失影响的定量研究

根据５ａ长期定位观察结果,本文应用两模型参数ｔ检验、弹性分析及边际分析法,探讨年时间序列对炼山与对照的杉木人工幼林养分流失的效应。ｔ检验表明,不同处理在年时间序列上的铵态氮、亚硝态氮、硝态氮、磷酸盐、钾、有机质流失模型的Ｂ、Ａ参数存在显著差异。弹性分析和边际分析表明,年时间对不同处理的上述养分效应呈负效应,在炼山条件下,上述养分流失的弹性系数分别为－１．２１５％、－１．２１４％、－１．２１５％、－１．２１５％、－１．２４１％、－１．２１４％,上述养分流失的边际量分别为－０．３９４ｋｇ、－０．０３３ｋｇ、－０．３６５ｋｇ、－０．０２３ｋｇ、－３０．０１０ｋｇ、－５９．４２１ｋｇ。在不炼山处理下,上述养分流失的弹性系数分别为－０．８４２％、－０．８５１％、－０．８４４％、－０．８５４％、－０．８４５％、－０．８４１％,上述养分流失边际量分别为－０．１５９ｋｇ、－０．０１０ｋｇ、－０．０８５ｋｇ、－０．００６ｋｇ、－１２．０２４ｋｇ、－１７．７６７ｋｇ。     

水污染造成的水资源价值损失分析——以福州市第二水源山仔水库为例

该文讨论了水资源的价值及价格，在回顾已有的水污染经济损失计算模型的基础上，应用L．D詹姆斯等模型，对山仔水库地区水污染趋势进行分疥，并估算其污染造成的价值损失。     

分析浮顶罐低液位控制对于蒸发损耗的影响

目前外浮顶及内浮顶罐在石油化工行业已被广泛地使用，其有效地控制了罐内储存油品的蒸发损耗．从而减少了对环境的污染。从减少蒸发损耗的角度出发，阐述了控制罐内低液位使得浮盘处于悬浮状态的重要性。     

Early amniocentesis: A clinical review

Early amniocentesis at less than 14 weeks gestation is becoming more common in prenatal diagnosis populations. Randomized studies are minimal and have not had the power to determine the accuracy and safety of the procedure compared to chorionic villus sampling or mid-trimester amniocentesis. Procedures at 11⁺⁰-12⁺⁶ weeks should be considered experimental. This clinical review considers the ethics, embryology, and clinical experience (cytogenetics, AFP, AChE, procedure and cytogenetic failures, spontaneous and therapeutic pregnancy losses, congenital anomalies) of early amniocentesis.     

基于分区制定水库富营养化管理标准的探讨

在总结水库的区域、流域特性,水动力学特征及功能用途等导致水库富营养化特征之差异性的基础上,讨论水库富营养化分区管理标准的制定方法。研究认为:我国水库富营养化分区管理标准的制定,一是选取合适的分区指标,将水库纳属相应的地理区域;二是选取相应的指标体系制定科学的标准。同时,分区选取的指标应以地理类的指标为主,而标准指标应以营养盐、水动力学及藻类为主。未来工作应主要集中于水库降雨、温度、土地利用、水质等数据的收集及积累。     

湿地资源开发利用及生态功能恢复

采用生态环境现状调查方法，查清了辽河三角洲资源种类、数量、分布、物种多样性组成、生境条件。分析了生态系统整体性特点、结构、环境服务功能、湿地资源动态变化对生态环境影响。为保护生态功能，提出了有效的恢复性措施。