沙漠生态旅游适宜度评价

生态旅游适宜度评价是旅游资源开发的前提,特别在沙漠旅游领域更应如此。本研究基于对沙漠旅游的影响因素——沙漠旅游资源、生态环境承载力的分析,构建了沙漠生态旅游适宜度评价指标体系,从而提出了一套沙漠生态旅游适宜度评价方法,并对中国8个典型沙漠旅游景区生态旅游适宜度进行评价。结果表明：沙漠旅游景区的生态旅游适宜度都比较低,大部分属于中适宜、低适宜2个水平。最后讨论了沙漠生态旅游适宜度的评价方法及沙漠旅游资源生态保护。     

基于数字图像的中国西北地区戈壁表面砾石形貌特征研究

中国戈壁面积约66.08万km²,超过了流动沙丘和半固定沙丘的面积之和,但目前对戈壁沉积特征的研究程度相对较低。本文采用ImageJ软件,对中国西北地区戈壁原位无干扰的表面数字图像进行量算,获取了砾石覆盖度、粒径、磨圆度和形状比率等形貌参数。结果表明：中国西北地区戈壁表面的砾石覆盖度介于31.5%～84.6%,以中覆盖度为主,70%的戈壁属于空气动力学稳定表面;90%以上的戈壁表面砾石平均粒径为细砾和中砾。不同区域戈壁表面砾石磨圆度的平均值介于0.50～0.76,形状比率变化范围在1.38～2.46。戈壁表面砾石形貌特征与其成因类型密切相关：以剥蚀（侵蚀）-洪积作用为主形成的戈壁,砾石粒径较粗、形态比率较大、磨圆度低、覆盖度较高;以冲洪积为主形成的戈壁,砾石粒径和形态比率变小,磨圆度变好而覆盖度降低。砾石形貌特征可为追溯戈壁物源区和反演沉积物的搬运堆积过程提供参考。     

Migration of barchan dunes in the western Quruq Desert,northwestern China

Barchan dunes are common on Earth, Mars and Titan. Previous studies have shown that their formation, migration and evolution are influenced by the wind regime and other factors, but details vary among regions. Understanding barchan morphology and migration will both improve our understanding of dune geomorphology and provide a basis for describing the environmental conditions that affect the formation and development of these dunes on Earth and other planets. Here, we provide detailed measurements of barchan dune migration in China's Quruq Desert, in the lower reaches of the Tarim River. We monitored their migration direction and rate, and their morphological changes during migration, by comparing Google Earth images acquired in 2003 and 2014. The dunes migrated west-southwest, close to the local resultant drift direction. The migration rate averaged 8.9 to 32.1 m year⁻¹, with obvious spatial variation. In addition to the wind regime, the migration rate depended on dune morphology, density and vegetation cover; the rate was negatively related to dune height, density and vegetation cover, but positively linearly related to the length/width ratio (L_U/W) and to the decrease in this ratio from 2003 to 2014. We found correlations among the dune morphometric parameters, but the relationships were weaker than in previous research. Due to the complexity of the factors that affect the processes that underlie sand dune development and migration, the morphological changes during dune migration were also complex. Our measurements suggest that the aeolian environment played a dominant role in dune migration and its spatial variation in the Quruq Desert. These results will support efforts to control dune migration in the western Quruq Desert and improve our understanding of dune morphodynamics. © 2019 John Wiley & Sons, Ltd.     

库姆塔格沙漠北部三垄沙地区风成沉积物粒度特征

对位于库姆塔格沙漠北部的三垄沙地区,迄今尚未开展详细的风沙地貌研究。对该区域地表沉积物样品进行粒度分析,旨在探讨不同区域、不同沙丘类型以及沙丘不同地貌部位的沉积物特征差异。结果表明:三垄沙地区地表沉积物以中沙和细沙为主,二者平均含量之和为63.20%,平均粒径为0.95~1.89Φ,分选系数为0.55~1.55,粗于库姆塔格沙漠和塔克拉玛干沙漠,与世界其他沙海沙物质相比属于偏粗粒径。三垄沙地区的主要沙丘类型为新月形沙丘或沙丘链,其北部发育有线形沙丘;这两种沙丘表层沉积物平均粒径均属于中沙范围,且从沙丘底部到丘顶平均粒径变大、分选变好,最粗的沙粒出现在沙丘顶部,平均粒径分别为1.64Φ和0.71Φ,不同于其他地区沙丘顶部沉积物最细的分布模式。从概率累积曲线来看,流动沙丘多为二段或三段式,风成沙砾浪和剥蚀残丘多为三段或四段式,表明后者经历的分选过程较短。本区地表沉积物的平均粒径沿主导风向有变小的趋势,其中,新月形沙丘和线形沙丘的这一特征最为明显。     

巴丹吉林沙漠边缘地区植被特征

通过在巴丹吉林沙漠野外植被调查,描述了植被的生活型和群落的空间分布特征,分析了植被多样性、优势度及均匀度指数,并探讨了历年来气候变化对植被分布的影响。结果表明：（1）巴丹吉林沙漠植物种类较少,可分为小乔木、灌木、小灌木、半灌木、多年生草本和一年生草本6类生活型。其中灌木种类最为丰富,小乔木最少。（2）巴丹吉林沙漠东南一带物种丰富度和多样性高于西北一带,南缘地区植被群落分布及植被群落多样性亦均高于北缘地区。（3）近53 a巴丹吉林沙漠气温发生显著变化,蒸发量增加。南缘地区增温而降水减少。这种变化对于以水分为主导因子的沙漠地区植被发育来说极为不利,有加剧沙漠南缘荒漠化的威胁。     

基于激光垂直照射沙床面的风成沙波纹二维形态特征分析

风成沙波纹因其规则的波浪形几何图案吸引着研究者的兴趣,但是对其发育过程的认识还比较薄弱.原因之一就是缺少高精度和高分辨率的沙波纹形态动态测量方法.传统的风成沙波纹形态动态测量方法采用的倾斜光源照射方式忽略了沙波纹脊线高度和走向的变化,会导致沙波纹高度测量错误和形态变形.本研究建立的激光片光源垂直照射沙波纹表面的方式纠正...     

Seasonal variations in Dustfall and its iron content over North China

Extensive dustfall collections were carried out from April 2001 to May 2002 in North China. The highest level of dustfall occurred in the Gobi deserts and at the margins of sandy deserts in the region. The iron content in dustfall in North China varied from 0.6% to 6.0% and there was significant seasonal variation, which indicates the dust sources differed during the year. Although the iron content in dustfall in North China is higher in the Loess Plateau and arable lands and lower in the Gobi and sandy deserts, the total iron deposition was higher in the Gobi desert regions. If the fine particles （PM10） in dustfall in North China are the major contributors of dust transport to eastern China and western parts of the North Pacific, then the annual deposition rates of iron may have been underestimated in previous studies. Our analysis indicates that iron deposition may reach 1.38 × 10^3 to 2.43 × 10^3 kg km^-2 and that most iron deposition occurs in spring and summer. If the more-coarse fractions （PM50） are considered, deposition rates may reach 2.75 × 10^3 and 6.80 × 10^3 kg km^-2, which would represent a large source of iron deposition in eastern China and the western North Pacific.     

拉萨河谷爬坡沙丘沉积物特征

分析了青藏高原拉萨河谷爬坡沙丘表层及不同深度沉积物的粒度和地球化学元素特征。结果表明：(1)爬坡沙丘表层沉积物以细沙为主,平均粒径为2.51Φ(细沙),分选中等,粒度分布曲线为正偏、窄峰。随海拔升高,表层沉积物逐渐变细;随深度增加,沉积物粒径逐渐变细。(2)爬坡沙丘沉积物常量元素中SiO₂含量最高,微量元素中Ba含量最高。常量元素含量多随深度增加而减少,且在0—10 cm深度内变化幅度最大。与上部陆壳平均化学组成相比,除Na₂O、MnO、Cr、Co、Mo、SiO₂外,其余元素均处于亏损状态。拉萨河谷爬坡沙丘经历了中等的化学风化,处于大陆风化的早期阶段。     

黄河源区玛多盆地沙漠化土地粒度特征

为探讨黄河源区玛多盆地风沙沉积物分异特征,采集玛多盆地不同沙漠化程度、不同地貌部位、不同动力条件的沉积物样品进行粒度分析。结果表明：（1）玛多盆地沉积物随沙漠化程度增加,平均粒径增大,粗颗粒组分增多,分选性变好,偏度向负偏靠拢,峰态逐渐转向平坦,频率分布曲线也由双峰态转变为单峰态。（2）流动沙丘以中沙和细沙组分为主,分选性好,偏度近对称,峰度为中等尖锐。各个沙丘不同地貌部位沉积物粒度参数分异受风向改变的影响,变化规律不明显。流动沙丘沉积物相较于流动沙地沉积物的粒径更粗,分选性更好,可能是沙丘形成过程中风对沉积物颗粒的再次分选所致。（3）河流阶地剖面沉积物的主要粒级为中沙和细沙,分选中等偏差,偏度为正偏,峰尖锐,河流阶地沉积物的粒度组成与周围风成作用形成的流动沙丘（地）的粒度组成高度相似,极有可能是当地风沙活动的主要物源。