我国高校贷款的现状、问题及对策研究

本文从高校、银行、政府三方面全面地分析了高校贷款的现状及高校贷款问题的成因, 并提出对策和建议。笔者认为, 由于高等教育的准公共性, 单由高校一方或政府一方还贷都是缺乏合理性的, 除了要采取加大财政投入力度、严格贷款审批程序、完善教育经费投入机制、扩充高校经费来源渠道等措施外, 笔者建议建立高校和政府合理分担的还款机制来解决我国目前存在的高校贷款问题, 旨在为高校贷款问题的解决提供一点思路。     

新疆柴窝堡湖湿地的植物群落组成及其类型

柴窝堡湖湿地是乌鲁木齐的重要水源地和生态屏障。本研究通过野外实地调查方法分析了柴窝堡湖湿地的植物群落组成、区系及其类型。结果表明,柴窝堡湖湿地共有维管束植物30科84属122种,其中,蕨类植物1科1属1种,双子叶植物23科62属90种,单子叶植物6科21属31种;种子植物区系成分较为简单,具有典型温带属性。生活型以草本植物为主,占总种数的94.2%;水分生态型中,中生植物种类最多,共42种,占总种数的34.4%;柴窝堡湖湿地共有20个植物群系,北岸主要为布顿大麦群系(Form.Hordeum bogdanii)、细叶沼柳群系(Form.Salix rosmarinifolia)、芦苇群系(Form.Phragmites australis)等,西岸主要为盐穗木群系(Form.Halostachys caspica)、盘花乳菀群系(Form.Galatella biflora)、盐角草群系(Form.Salicornia europaea)等,东岸和南岸只有多枝柽柳群系(Form.Tamarix ramosissima)。本研究结果不仅可以为柴窝堡湖湿地植被稳定性维持和生物多样性保护提供本底数据,而且可以为水源地生态保护提供基础资料。     

Factors affecting sulfate adsorption,organic sulfur formation,and mobilization in forest and grassland spodosols

Forest and grassland soils that contained varying amounts of Fe and Al were collected from England and Wales. Fractionation of free Fe and Al was accomplished to determine which components affected sulfate adsorption. Organic Fe and Al were the dominant fractions in most soil horizons and high amounts of these organically bound metals and, to some extent, crystalline Fe oxide were associated with high sulfate adsorption potentials. These adsorption potentials reflected naturally occurring amounts of absorbed sulfate and ester sulfate. Overall, the C content exhibited a positive relationship with sulfate adsorption potentials. Soils with a high C content also exhibited high rates of organic S formation. The rate of organic S mobilization was greater in soils with higher amounts of soluble sulfate. Organic S was the largest pool and, typically, sulfonate S was the most abundant constituent of the organic pool.     

A field experiment on the influence of the postulated global climatic change on coastal marshland soils

A climatic scenario postulates an increase of atmospheric CO₂, 55 cm water‐level rise combined with a 30 cm higher tidal amplitude for the North Sea. Further, more frequent and stronger west storms, a 2.5°C mean‐annual‐temperature increase together with 15% more rainfall during winter time are to be expected until 2050 due to recent human impact. The possible consequences of the postulated changes in temperature and flooding dynamics were studied for soil formation as well as for soil‐ecological attributes and processes of two sites at Hedwigenkoog foreshore in N Germany: a Hypersali‐tidalic Fluvisol (protothionic, calcaric) (1.5 m asl with >500 annual floods) and a Gleyi‐sali‐tidalic Fluvisol (calcaric) under a salt meadow (2.2 m asl with 70 annual floods). Temperature, water, redox, nutrient and gas dynamics were measured at different soil depths for a period of 2 y. The topsoil of the Gleyi‐sali‐tidalic Fluvisol was permanently heated over an area of 14 m² to simulate a temperature rise of 1.5–2.5°C. The results are discussed in relation to two realistic scenarios. If the ground level of the Gleyi‐sali‐tidalic Fluvisol is heaved up (due to sedimentation) as intensively as the sea level rises, it may be assumed that the soil unit including vegetation cover in principle will not noticeably change. Then, the temperature increase will intensify the activity of soil organisms, bioturbation, and formation of a crumb structure, however, there will be no further accumulation of soil humus. If there was no sedimentation during the next 50 y, the salt meadow itself together with the upper part of the Gleyi‐sali‐tidalic Fluvisol would be destroyed by erosion, and a Hypersali‐tidalic Fluvisol would be formed similar to the studied one.     

Ripening of clayey dredged sediments during temporary upland disposal a bioremediation technique

Background and Goal  In the Netherlands about 40 million m³ of sediment has to be dredged annually for both maintenance and environmental reasons. Temporary upland disposal is the most widely adopted alternative for dredged sediments worldwide. For good management of temporary disposal sites, knowledge is needed on the processes controlling the behavior of the sediments during disposal. Therefore, a review of the literature was made to get an integrated overview about processes that take place during temporary disposal. Ripening  After disposal of clayey sediments, the following spontaneous dewatering processes can be distinguished: sedimentation, consolidation, and ripening. Sedimentation and consolidation are relatively fast processes, whereas ripening can take up to several years. In a remediation perspective, the ripening of sediments is the most important dewatering process. Ripening, which may be subdivided into physical, chemical, and biological ripening, transforms sediment into soil. Physical ripening is the irteversible toss of water and results in the formation of soil prisms separated by shrinkage cracks. Continuing water loss causes a breaking up of the prisms into aggregates. The aggregates produced by this ongoing desiccation process usually remain quite large (>50 mm) and can only be further broken down by weathering processes like wetting and drying or by tillage. As a result of the aeration caused by physical ripening, also chemical and biological ripening take place. Chemical ripening can be defined as the changes in chemical composition due to oxidation reactions and leaching of soluble substances. Biological ripening is the result of the activity of all kinds of soil fauna and flora that develop as a result of aeration, including both the larger and the microscopic forms of life. Decomposition and mineralization of soil organic matter caused by micro-organisms can be seen as the most important aspect of biological ripening. Many interactions exist between the different ripening processes. Conclusions and Outlook  Oxygenation of the dredged sediment is improved as a result of the natural ripening processes: the air-filled porosity increases, the aggregate size decreases, and the initially high respiration rates caused by chemical and biological ripening decreases. Therefore, conditions in the disposal site become more favorable for aerobic biodegradation of organic pollutants like Polycyclic Aromatic Hydrocarbons (PAH) and mineral oil. It is concluded that the naturally occurring process of ripening can be used as a bioremediation technique. Ripening in an upland disposal site is an off-site technique, and therefore, the process could be enhanced by means of technological interference. However, it is concluded that the knowledge currently available about upland disposal is not sufficient to distinguish critical process steps during the ripening and bioremediation of PAH and mineral oil polluted sediments because of the complex relationships between the different ripening processes and bioremediation.     

新疆土壤次生盐化主要成因及对策

概述了新疆耕地次生盐化现状,分析了土壤次生盐化的4个主要成因,基于新疆特殊内陆干旱气候和地理环境特征,从加强渠道防渗、减少水库渗漏、推行高效节水、完善灌排工程等方面提出并分析了盐碱地治理的研究对策。     

生活垃圾堆肥过程中有机态氮形态的动态变化

利用接种不同外源微生物进行城市生活垃圾的堆肥试验,研究在堆肥过程中不同形态有机态氮组分的变化规律。结果表明,随着堆肥的进行,全氮与酸水解性氮含量均呈下降的趋势,其中外源微生物处理能加速全氮与酸水解性氮含量的降低,但至堆肥结束时,与不加外源微生物处理相比,并没有引起氮素的损失。氨基酸态氮含量则呈现先降低后增加的趋势,堆肥结束时,外源微生物处理氨基酸态氮含量明显高于不加微生物处理,表明外源微生物处理可促进氨基酸态的形成;酰胺态氮与氨基糖态氮含量有相同的变化趋势,各处理都是在堆肥的升温期、高温期增加,随着堆肥温度的下降而降低,在堆肥的腐熟阶段,则呈现较为平稳的走势。但相对于堆肥的不同时期,由于处理不同,酰胺态氮与氨基糖态氮含量有明显的差异,其中外源微生物处理酰胺态氮含量明显低于不加微生物处理,而氨基糖态氮则相反。     

自然降水量利用与旱地裸燕麦产量形成的关系

通过该项调查与分析表明：旱作区棵燕麦年平均降水量３００～４００ｍｍ，６～８月降水量占全年的６４～７４％，降水变率小，降水日数多，大于１０和２５ｍｍ降水次数多，１ｄ或１ｈ内降水强度小，全年超３００ｍｍ降水保证率达８０％，生长季内超２５Ｏｍｍ占７０％，７～８月超１００ｍｍ占６０％的降水资源，利于裸燕麦获得丰产。反之，则减产１３年中均出现丰、平、欠年规律；４、５、６月降水量大于１０、２５、５０ｍｍ，７和８月大于１００ｍｍ。或者有两次１０ｍｍ的保苗雨，４０～６０ｍｍ的抽穗雨，１００ｍｍ的灌浆雨，亩产达５１～７４ｋｇ。反之，仅２０～３０ｋｇ。通过蓄住天上水，保住地里墒，形成土壤小水库的耕作措施；合理调节播种期；搭配不同熟性品种，增强抗旱性和经济性状，达到持续丰产和稳产目的。     

限根条件下混配基质对甜樱桃生长发育的影响

以甜樱桃品种“抉择”/本溪山樱为试材,研究在限根条件下7种人工混配基质对植株生长发育的影响。结果表明:基质中添加草炭、炉渣后,容重变小,固、液、气三相比例适宜,甜樱桃生长发育好,植株成花比例高、产量高,易获得早期丰产;基质中添加炭化稻壳,植株生长量小,产量低,综合效果较差。     

棉花芦管育苗新技术研究Ⅳ.芦管育苗移栽对棉花产量形成影响研究初报

盆栽和小区试验结果表明,芦管育苗移栽棉的果枝、现蕾和铃数增长在早期显著低于营养钵育苗移栽棉,中后期则增长较快,逐渐赶上和接近对照;蕾、铃脱落则明显少于对照;单铃重及籽棉产量均无明显差异;芦管育苗移栽棉伏桃和早秋桃的铃壳重较低,棉铃经济系数较高,利于棉花经济高效形成.对芦管育苗移栽棉优质高产栽培实践具有重要指导意义.