重视和加强中国东部地区土地退化整治研究

根据《２１世纪议程》土地荒漠化定义，从全球环境研究角度，论述了中国东部湿润、半湿润地区土地退化及其危害和开展中国东部地区土地退化研究的必要性和可行性，并提出了点面结合的初步研究设想。     

云南元谋干热河谷土地退化及其防治对策*

本文探讨了云南元谋干热河谷土地退化的特点、分布及其危害,提出了加强基础教育、控制人口增长、改革耕作制度、继续农业基础设施建设、因地制宜发展林业和农业等于热河谷土地退化防治对策。     

黄土高原晋陕蒙毗邻地区土地退化遥感分析

本文利用遥感技术通过典型区的分析,对黄土高原土地退化现状及其成因过程进行了深入研究。结果表明,黄土高原地区由于特殊的自然条件,加以长期人类活动影响,土地退化十分严重,并处于不断发展之中,主要表现为水土流失和土地沙化等。     

Chemical structural units of macromolecular coal components

Chemical degradations of coal resins, coal asphaltenes and coal residues have been performed with selective, non-oxidative reagents. The coal comprise samples a rank interval 0.30–1.21 %R_m. Degraded low-molecular-weight compounds were analyzed by GC-MS. The distributions of pentacyclic terpanes, isoprenoids, n-alkanes, acids and alcohols obtained as degradation products illustrate a considerable variability between the macromolecular coal fractions. A structural study on the molecular level of the degraded compounds from coal resins and coal asphaltenes show their potential to generate hydrocarbons during coalification process.     

澜沧江上游德钦县亚高山、高山草地群落类型及其特点

摘要：采用样方调查方法获得94个草地群落样方,对澜沧江上游德钦县亚高山、高山草地群落类型及其特点进行了初步分析。结果表明,该县亚高山、高山草地群落类型存在20个类型。在放牧干扰下,大多数群落类型处于退化状态,相互之间存在明显的群落替代关系;调查发现群落中每平方米内平均含8种草本植物,平均盖度62．4％,地上平均生物量是4859kg／hm^2,平均可食率为61．5％;鸢尾群落、牛旁群落和小狼毒群落是草地严重退化后形成的典型有毒害群落类型;长期的高强度放牧虽然增加了群落类型多样性,但减少了群落内物种多样性。总体而言,长期的放牧干扰降低了德钦草地的生物多样性的质量及其生态服务功能,导致草地生态系统的非持续发展。     

Pastoralists’ perceptions and realities of vegetation change and browse consumption in the northern Kalahari, Namibia

Pastoral production around artificial watering points in semi-arid environments affects the density and composition of plant communities. In the Kalahari desert of southwestern Africa, bush encroachment is often regarded as the major form of land degradation resulting from pastoral production around watering points. We investigated the OvaHerero pastoralists’ perceptions of the extent of vegetation change since the establishment of artificial watering points in the northern Kalahari desert of Namibia, and related this to ecological data on vegetation change. We determined the utility of woody vegetation to pastoralists’ livelihoods in terms of provision of construction material, fuel wood and browse. We quantified local knowledge of cattle browse consumption and correlated this with field data. We also assessed the purposes for which major livestock types were used. Our results showed that: (1) pastoral knowledge of bush encroachment and browse consumption was consistent with concurrently collected field data, (2) the current level of bush encroachment was perceived to be beneficial for pastoral production, and (3) cattle played an important role in the production of milk and milk by-products for domestic use, and served as a source of cash income, while sheep and goats were primarily kept for meat consumption. This result contrasts with historical studies that mainly portray cattle as a symbol of social status among OvaHerero pastoralists.     

干酪根化学降解产物的碳同位素组成研究

采用一系列温和的化学降解法对松辽盆地南部嫩江组烃源岩的干酪根进行连续的选择性化学降解，并对不同降解产物进行色谱—同位素比值质谱分析。研究表明碱性水解和脱硫产物以一元脂肪酸和正构烷烃为主，其中正构烷烃碳同位素分布曲线呈现一定的“负倾”（即随碳数增加呈现逐渐贫13C）趋势；一元脂肪酸以C16和C18为主，具有明显的偶碳优势，与同碳数的正构烷烃具有相似的碳同位素组成。氧化产物则以一元脂肪酸和α,ω 二元脂肪酸为主，一元脂肪酸低碳数部分呈现“负倾”趋势，高碳数部分则呈现“正倾”的趋势；α,ω 二元脂肪酸与低碳数的一元脂肪酸具有相似的分布，表明它们可能具有相同的母源。对比研究表明JL 30抽提物中正构烷烃可能存在混源的影响，其碳同位素组成是多源混合的结果。     

Spatial pattern of Karst rock desertification in the Middle of Guizhou Province,Southwestern China

Karst rocky desertification is a typical type of land degradation in the Southwestern China. It has great ecological and economical implications for the local people. Landsat images from the middle of Guizhou Province collected in 1974, 1993 and 2001 were used for change detection of the pattern of Karst rocky desertification. The results show the following findings: (1) Desertification area expanded drastically in 27 years, at an increasing rate about 116.2 km²/year. (2) High areas (900–1,500 m) are the most affected. (3) Areas with the slope <5° or >25° are also easily tend to be Karst rocky deserted. (4) The process of Karst rocky desertification is nearly irreversible. Few areas of Karst rocky desertification could be meliorated to non-desertification land. (5) Most of the degraded lands are located in the south and the central of the study region, and the meliorated land areas are sparsely located in the east and the west part of the region. All these findings would provide bases for the decision-making of the local government to improve the Karst rocky desertification     

枯草芽孢杆菌(Bacillus subtilis)降解萘的动力学研究

枯草芽孢杆菌(Bacillus subtilis)HBS-4是从油田中分离出来的一株能高效降解有机物萘的菌株。当萘的初始浓度为100mg时,该菌株在pH为8.0,温度为40℃下具有较好的降解效果,作用69h能降解50%以上的萘。通过HBS-4菌株降解萘的动力学研究,在Williams结构模型的基础上建立了HBS-4作用萘的四组分动力学模型,并用此模型解释菌株HBS-4在降解萘的过程中,葡萄糖含量、菌液浓度、pH、Eh随时间的变化特征。     

气候影响下的荒漠下的荒漠化监测

根据揭示沙漠化扩张内在规律的相关气候驱动因子的假说,气候作用影响之下的沙漠化是在具反射率-降水正、负反馈特点的气候系统之中的区域干旱化过程与干旱土壤退化过程相互作用的结果。在辐射调节下的地表下垫面温度占主导的条件下,气候成因的沙漠化是由区域气候系统反馈所形成。正反馈的外部调节因子是降水量的变化和极端降水事件(特别是旱灾)的出现频率,降水量减少以及降水频率的降低直接影响沙漠化的程度。20世纪下半叶,人类因素导致的干旱土地退化作为另外的正反馈调节因子,其重要性正在增加。通常正反馈的扩大趋势会被通过蒸腾而进行的地表温度调节的负反馈所抑制。由正反馈到负反馈的转换是通过地球表面与大气层之间的热量交换的调节所确定的,其中非潜热因子处于增加状态。上述情况在反射率和地表温度同时增加的条件下发生。在超出绿色植物生物量及其NDVI指数阈值的条件下,负反馈向正反馈的转换就会发生。人为作用导致的植被退化加快了向绿色植物生物量阈值逼近的进程,从而引起气候因素驱动的沙漠化扩大。一个主要由气候因素影响的荒漠化区域,在大多数情况下,其绿色生物量均在季节变化和年际变化中达到了阈值。在中度的人为影响的植被退化条件下,这些地域一般都包括部分干旱与半干旱土地。然而有时,人类活动也会导致干旱的半湿润土地退化。本文运用Turan和Sahel地区1982-2001年NDVI指数的监测结果,分析了全球变暖和人为作用导致的土地退化。