一些国家停止修建大型水坝

目前,包括苏联在内的许多国家,已认识到修建大型水坝将给人类带来不利影响,都在重新考虑,有的甚至取消或缩减划时代的兴建水坝的计划。巴西已经把原计划在亚马逊河上修建而尚未动工的所有25座水坝全部搁置起来;在马来西亚,全国普遍反对在沙捞越修建巴昆大坝的计划;另外,在印度,在澳大利亚,也由于群众反对而停止和取消。     

苏联对盐渍土壤的研究

在地球各大陆的某些地区里都分布有盐渍土壤。而分布最广的是在宽广无边的干旱无水地区和沙漠地带。然而我们常常见到的是散布在其他土壤中间的个别地段或面积不大的小块。根据当代最伟大的土壤学家Л.И.普拉索洛夫院士的调查,在苏联,盐渍土壤及与盐渍土壤在发生上有关系的碱土,共占全国面积约10%。而在中亚的一些共和国国家里,在外高加索的东部,在里海沿岸的低地以及在西伯利亚的一些     

东北黑土区水土流失综合防治试点工程项目概况

1　东北黑土区概况1.1　自然概况目前地球上共分布着三大块宝贵的黑土区 :一块在欧洲 ,主要分布在东欧的乌克兰大平原 ,面积大约190万km2 ;一块在北美洲 ,主要分布在美国的密西西比河流域 ,面积大约 12 0万km2 ;一块在亚洲 ,主要分布在我国东北的松辽流域 ,号称中国东北黑土区     

钙镁磷肥在江苏省主要土壤上的肥效初步研究

近几年来,钙镁磷肥的使用,在国内外受到了广泛的注意,随着农业丰产对于肥料的需要,这种磷肥在江苏省很多地区都先后进行了生产试制与使用,为了进一步确定钙镁磷肥在全省范围内使用的肥效,我们在本省选用了几种主要的土壤类型,在田间与温室进行了肥效试验,现将结果报告如下。     

~(137)Cs在卧龙自然保护区土壤中的分布特征

对137Cs在卧龙自然保护区内不同生态系统土壤中的分布特征进行测量分析的结果表明:137Cs在耕地土壤中均匀分布,在其余6种非耕地土壤中呈明显的指数递减分布;非耕地土壤在0~10 cm土层内存在一个137Cs富集层,富集层以下137Cs含量有一个骤降的过程;137Cs在耕地土壤中的分布深度大于耕层厚度20 cm,在非耕地土壤中的分布深度在24 cm左右;137Cs的面积浓度在高山草甸土壤中最大,在适温灌丛土壤中最小,前者是后者的2.6倍。     

谈数值预报产品在天气预报业务中的应用浅析

近些年,国内外的数值天气预报的水平不断提升,这主要得益于科技水平的发展,在这种环境下数值预报产品的数量在不断增多,产品的精度也在不断提升。越来越多的产品得到了广大的气象业务研究人员和相关部门的使用,在这种背景下有很多的数值产品都在不断产生,其在天气预报业务中获得了良好的效果。基于此,分析数值预报产品在天气预报业务中应用的相关情况,希望所得内容能够为相关领域提供有价值参考。     

广西降雨亏缺型骤旱的演变过程及时空分布特征

为研究降雨亏缺型骤旱在湿润地区的特性,以广西为研究区,在分析降雨亏缺型骤旱演变过程的基础上采用Mann-kendall,Hurst,BG分割算法、EEMD等分析了该型骤旱在广西的时空分布特征。结果表明:(1)该型骤旱在发生前期土壤湿度已明显偏低,在发生过程中,蒸散发、太阳辐射、气温等要素的变化特征显著相关,在发生后,土壤湿度会持续偏低1～5候;(2)在广西地区发生频率为1.0%～2.0%,发生面积主要集中在10%以下,持续时间主要集中在1～2候,在夏季多发且历时长;(3)在1979—2015年呈现出显著下降趋势,频次序列存在3.45 a的周期,且在1999年存在突变;(4)骤旱频次在桂南较高,历时在桂西南等地较长;而桂中地区,频次和历时呈现出显著下降趋势;(5)与季节性干旱同时发生的骤旱约有6%～15%,其中桂中及桂西南地区较高。该成果可为完善广西地区旱灾预警机制提供参考。     

覆盖作物减少耕地氮流失能力的研究

在北欧地区对覆盖作物减少氮素(N))流失的研究结果表明:所有覆盖作物平均降低氮淋溶43%,黑麦草的覆盖作物长势最好,平均吸氮量为7~38kg/hm^2。在斯堪纳维亚南部和芬兰,覆盖作物以不同方式进入农业环境方案。在丹麦是强制性执行的,在挪威、瑞典和芬兰是通过补贴进行的。在丹麦沙土上的实验研究表明,削减氮淋溶值最多达51kg/hm^2。在瑞典站点,10a间覆盖作物减少冬小麦地氮淋溶约为43%。在不同国家,不同试验点覆盖作物减少氮淋溶最大差值不同,在丹麦为63kg/hm^2,在挪威为29kg/hm^2,在瑞典和芬兰分别为18kg/hm^2和15kg/hm^2。各国覆盖作物减少氮淋溶平均值也不同,在丹麦为33kg/hm^2,在挪威为16kg/hm^2,在瑞典为11kg/hm^2,在芬兰为6.5kg/hm^2。     

欢庆新中国成立40周年略述水土保持各项研究工作的进展与成效

欢庆新中国成立40周年之际,中国科学院、水利部西北水土保持研究所仅就建所30多年来,在土壤侵蚀规律及其预测预报的研究中,在土壤和土地资源的评价与合理利用的研究中,在植被恢复的理论与技术的研究中,在旱作农业增产体系及依据的研究中,在水土流失综合治理以及在其它方面的研究中,取得的较大进展和显著成效,分六个部分概述与回顾。     

果树在园林绿化中的作用和应用分析

为了更有效地加快园林实现绿化,为生态营造出良好的环境,通常在园林栽种一些果树。基于此,介绍果园在园林绿化中的作用,分析了果树在园林绿化中的应用现状,并在此基础上提出了果树在园林绿化应用的措施,探讨了果树在园林绿化中的应用前景,希望以此进一步提高人们对果树作用和实际应用的了解,从而更好地促进园林绿化的发展,形成良好的园林生态环境。     

Climate and soil salinity in the deserts of Central Asia

A comparative analysis of climatic and soil salinity characteristics of the deserts of Central Asia, including deserts of the Turan Depression, the Gobi Desert, and deserts of the Dzungar and Tarim depressions was performed. The climatic characteristics—the degree of aridity, the degree of continentality, and the amount and regime of precipitation—are different in these deserts. No direct relationships between the areas occupied by the automorphic salt-affected soils and the aridity of the climate are observed in the studied regions. In the automorphic landscapes of Asian deserts, the degree and chemistry of the soil salinization and the distribution of salt-affected soils are controlled by the history of the particular territories rather than by their modern climatic conditions. The presence and properties of the salt-bearing rocks and the eolian migration of salts play the most significant role. The deficit of moisture in the modern climate favors the preservation of salt accumulations in places of their origin. The specific features of the climate, including the regime of precipitation, affect the redistribution of salts in the profiles of automorphic salt-affected soils. An increase in the degree of climatic continentality is accompanied by the decrease in the intensity of weathering and initial accumulation of salts. A different situation is observed in the soils of hydromorphic desert landscapes, in which the degree of salinity of the surface horizons and the area occupied by salt-affected soils are directly influenced by the modern climatic conditions.     

自由活塞发动机进气及压缩终了缸内气体流动特性分析

为组织好自由活塞发动机缸内气体流动,以提高可燃混合气混合质量,进而改善发动机燃烧质量,依据自由活塞运动特点,建立自由活塞发动机系统仿真模型,采用数值模拟方法对进气冲程和压缩冲程缸内流场进行仿真研究。分析结果表明,在进气冲程和压缩冲程时间之和一定情况下,进气冲程活塞运动快慢对进气终了缸内工质运动强度影响不大;快速压缩可提高压缩终了缸内工质运动强度,压缩终了单位质量湍动能在压缩冲程时间占进气冲程时间与压缩冲程时间总和45%时高达4.883 m2/(s2·kg),比压缩冲程时间占进气冲程时间与压缩冲程时间总和55%时高40%。采用慢进气快压缩的活塞运动规律,增大了压缩终了缸内流场运动强度,有利于火焰传播。该研究为组织缸内气体流动提供参考,对提高发动机性能具有重要意义。     

Assessment of the postagrogenic transformation of soddy-podzolic soils: Cartographic and analytic support

The results of experimental studies of the postagrogenic transformation of loamy soddy-podzolic soils on the southern slope of the Klin-Dmitrov Moraine Ridge are discussed. A chronosequence of soils (arable soils (cropland)-soils under fallow with meadow vegetation-soils under secondary forests of different ages-soils under a conventionally initial native forest) was examined, and the stages of the postagrogenic transformation of the automorphic soddy-podzolic soils were identified. The differentiation of the former plow horizon into the A1 and A1A2 horizons (according to the differences in the humus content, texture, and acidity) served as the major criterion of the soil transformation. A stage of textural differentiation with clay depletion from the uppermost layer was identified in the soils of the 20- to 60-year-old fallows. The specificity of the postagrogenic transformation of the soils on the slopes was demonstrated. From the methodological point of view, it was important to differentiate between the chronosequences of automorphic and semihydromorphic soils of the leveled interfluves and the soils of the slopes. For this purpose, a series of maps reflecting the history of the land use and the soil cover pattern was analyzed. The cartographic model included the attribute data of the soil surveys, the cartographic sources (a series of historical maps of the land use, topographic maps, remote sensing data, and a digital elevation model), and two base maps: (a) the integral map of the land use and (b) the map of the soil combinations with the separation of the zonal automorphic, semihydromorphic, and erosional soil combinations. This scheme served as a matrix for the organization and analysis of the already available and new materials.     

The use of algae-cyanobacterial communities for the assessment of lead pollution of gray forest soils

The effect of lead acetate on the characteristics of the algae-cyanobacterial communities of a gray forest soil was studied in a model experiment. The investigation was carried out using the method of water-soil cultures. The advantages and disadvantages of the application of this method for the ecotoxicological experiments are considered. The species of cyanobacteria and algae tolerant and sensitive to heavy metals were revealed. The addition of lead acetate at doses of 750 and 1500 mg/kg to soil caused a decrease in the species diversity and abundance of the cyanobacteria and algae, a reduction of the total content of chlorophyll, and changes in the morphology of individuals, whereas a dose of 300 mg/kg stimulated the development of the algae-cyanobacterial communities. The effect observed is suggested to be due to the double action of the salt: the adverse influence of the lead cations, and the positive influence of the acetate anions and the protective function of the soil. The use of a complex of different parameters of the biological organization of the communities at the cell, organism, and community levels results in the objective and complete assessment of the toxicant effects on the algae-cyanobacterial community of the gray forest soil.     

基于灌溉制度优化和种植结构调整的用水总量控制

该文以农业耗水总量及灌溉取水总量为约束条件,采用优化灌溉制度和种植结构调整措施下京郊农业发展面积阈值。结果表明:1)采用优化灌溉制度措施能显著降低研究区农业耗水量与灌溉量,使区域农业耗水总量低于耗水总量控制指标及其使农业灌溉量取水总量低于其多年实际平均水平,但是农业灌溉取水总量仍超过其控制指标;2)在北京市大兴区减少耗水量高的露地蔬菜与冬小麦的种植面积,增加灌溉量少且耗水较低的夏玉米种植面积,同时进一步发展农业用水效率较高的设施农业面积,能够满足农业灌溉取水总量与耗水量总量控制指标,且符合国家规划稳定粮食产量与提高蔬菜产量的要求;3)满足灌溉取水总量控制下农业发展面积阈值为4.60?104~7.42?104 hm2,而满足耗水总量控制下农业发展面积阈值为6.72?104~9.48?104 hm2,而同时满足2种约束条件下农业发展面积阈值为7.42?104 hm2;4)在维持用水总量不变情况下,随着设施农业发展面积扩大,传统农业发展面积相应减少,但因用水总量约束值差异设施农业与传统农业的发展阈值并不完全一致。可见,为维持区域水资源持续高效利用,确保区域农业健康发展,势必采用优化灌溉制度与种植结构调整等节水措施,控制农业发展阈值在合理范围内,才能使区域农业用水总量不能突破灌溉取水总量与耗水总量的控制指标。研究对类似京郊资源性缺水地区农业健康发展具有重要参考价值。     

The genesis of vertisols with gilgai microtopography: A review

Different hypotheses about the genesis of gilgai microtopography and corresponding soil complexes with clayey swelling soils are considered in this review. Their diversity is stipulated by specificities of the objects themselves and by the history of studies of the composition, properties, regimes, and landscape conditions of the areas with Vertisols in different countries. Most of the hypotheses about the genesis of Vertisols with the gilgai microtopography suggest that strong swelling–shrinking processes take place in these soils in the course of moistening–drying cycles; the origin of shear stress in the soils, its spatial patterns, and the particular ways of translocation of the soil material are discussed. At the early stage of Vertisol studies, a hypothesis about the leading role of the process of “self-swallowing” of the soils as a result of filling of open cracks with the material from the upper soil horizons was popular. However, numerous facts suggest that the intensity of this process is relatively low, so that it cannot play the major role in the gilgai formation and cyclic changes in the thickness and properties of the soil horizons in Vertisols. Another important mechanism is the uneven moistening and drying of the whole soil volume resulting in the irregular distribution of inner tensions in the soil with the development of shear stress and plastic deformation of the soil mass. The hypotheses suggested in the recent decades are based on the models of soil mechanics. A number of hypotheses consider possible alternation and duration of evolutionary stages of the development of Vertisols with the gilgai microtopography.     

锥形改流体下部孔径对筒仓卸料流态的影响

为了获取锥形改流体（cone-in-cone）下部孔径对筒仓内卸料流态和仓壁压力的影响,实现中心流筒仓内物料流态从中心流到整体流的转变,改善筒仓内物料流动环境,建立模型,用试验验证模型是正确的,该文采用离散元法对三维筒仓中ABS球卸料过程进行了数值模拟。数值模拟结果表明：筒仓卸料口尺寸不变时,减小锥形改流体下部孔径,整体流系数增大,筒仓内物料流态能够从中心流转变为整体流,筒仓壁峰值压力减小且峰值压力位置上移。改流体倾角为120°、135°时,当锥形改流体距筒仓锥形壁面的距离与锥形改流体下部孔径的比值大于等于1时,能实现从中心流到整体流的转变。该研究基于数值模拟结果提出了锥形改流体的设计标准,可为工程上确定改流体结构、位置参数提供参考。     

Digitized version of the state soil map on a scale of 1 : 1 M: Problems and solutions

Problems of the creation of a high-quality digitized version of the State Soil Map (SSM) on a scale of 1 : 1 M for the European part of Russia are discussed. Sheets of the SSM have been compiled for the entire territory of Russia. For the European part of Russia, they have been digitized, and a corresponding geographic information system has been created. At present, the attribute database to the map is being developed. In the course of the digitization of separate sheets of the map and the creation of a general legend, certain drawbacks of the map have been revealed. They are related to the insufficient completeness of information on the genesis of soil-forming rocks shown on different sheets; to the inconsistency in the names of some soils; and to the use of the same conventional signs for describing the soil texture in the upper horizons and in the parent material, which is incorrect in the case of texture-differentiated soils. The reasons for these drawbacks of the original map are explained. It is stressed that the SSM is a highly informative map that has played a crucial role in the development of pedology and soil cartography in Russia. A digitized version of this map makes it possible to introduce certain corrections to the original map sheets. The essence of the first stage of the work on the correction of the SSM in the digitized version and the methods applied for this purpose are characterized. Problems related to the creation of the database for the digitized version of this map are also discussed.     

水轮机调速器功率调节模式下负荷调节过渡过程稳定性研究

作为电力系统中调峰调频的骨干电源,水电机组负荷调节过渡过程稳定性对电网安全运行及源网协调意义重大。该文采用理论分析及数值仿真的方法对水轮机调速器功率模式下负荷调节过渡过程的稳定性进行了深入分析,得出了以调速器参数为变量的机组运行稳定域,并推导出满足稳定性的判别式。分析了水流惯性、接力器响应特性以及水轮机特性对稳定域的影响,得出水流惯性不利于系统的稳定,而接力器响应特性对系统稳定性有利,及水轮机特性最不利工况为水轮机综合特性系数与水轮机传递系数ey乘积值最大处。该文的研究成果能够准确地找到负荷调节稳定性的最不利工况,有效的指导水轮机调速器功率模式下参数整定,保障水电机组的稳定运行。     

湿干循环下膨胀土渠道边坡的破坏模式及稳定性

针对北疆地区膨胀土渠道因季节性通水导致的边坡失稳破坏问题,通过建立简化地质条件的离心模型试验,得到了湿干循环下膨胀土渠道边坡的变形及破坏特征,提出了由渠道通水、停水引起的湿干循环下膨胀土渠道边坡的破坏模式;在此基础上,利用GeoStudio软件分析了不同裂隙分布形式对膨胀土渠道边坡渗流特性及稳定性的影响。结果表明:运行过程中渠基膨胀土开裂是引起渠道边坡发生浅层失稳破坏的决定性因素;渠道因季节性通水造成的湿干循环作用下膨胀土渠道边坡破坏模式主要由“子土块”剥落破坏及“后缘张拉裂隙的扩展”2种破坏相互混合叠加构成。对比数值模型中不同后缘裂隙深度下渠坡的安全系数可知,当裂隙贯穿区深度为0.5 m时(工况1),对应的安全系数下降幅度约为60%,但此时的安全系数仍较大,渠坡可视为稳定;而当裂隙贯穿区深度继续增加至1 m时,渠道的安全系数下降幅度达到约74%,此刻的安全系数接近一级安全等级阈值(1.25),渠坡虽仍为稳定,但已经具备了失稳的可能。边坡的浅层破坏主要由“子土块”剥落模式决定,而后缘张拉裂隙的扩展对渠坡的失稳起到促进作用。此外,数值模拟结果还显示裂隙的存在加剧了坡面表层土体的孔压波动,易造成表层“子土块”的剥落。研究成果为进一步揭示季节性通水诱发的膨胀土渠道灾变提供了参考依据。