Investigation of Boundary Layer Fine Structure in Arid Regions: Injection of Fine Dust into the Atmosphere

Fine structure of the atmospheric boundary layerin desert regions of Kalmykia and on dried bottom of theAral Sea and its relation to soil particle emission in theatmosphere are discussed. It was found that in a hot seasonin the absence of dust storms convective processes lift updust particles into the atmospheric boundary layer fromsandy landscapes of Kalmykia and Sub-Aral regions. Thisaerosol consists of aggregate particles and contains asignificant amount of long-living aerosol of size less than5 m (including fine-dispersion 0.01–0.1 maerosol). The increasing of fine aerosol concentration wasfound at air temperature above 25 °C, surfacetemperature above 50 °C, and relative humidityless than 40–50%. Some mechanisms influencing the particle emission rates are briefly considered.     

塔里木沙漠油田开发工程的环境影响评价

塔里木是一个内陆封闭盆地，是世界第二大流动沙漠，它具有丰富的油气资源，目前正在积极开发中。在油气田开发过程中必须做环境影响评价，文中介绍了沙漠环境及生态状况，在沙漠区域必须以水域和生态环境影响评价为重点，评价结果应提出固沙、防沙和保护自然生态等一系列防治措施和对策。     

Climatic and Environmental Changes in the Source Areas of Dust Storms in Xinjiang, China, during the Last 50 Years

The desert environmental changes in the source areas of dust storms occurring in Xinjiang are discussed based on the climate changes and the impacts of human activities in Xinjiang during the past 50 years. The results show that the climate in Xinjiang is changing from a warm-dry type to a warm-wet one. The warm-wet climate has been obvious since the mid-1970's, and especially the sensitivity of the regional climate change in this arid area is obviously revealed by many factors, such as the characteristics of the local climate change in south Xinjiang and north Xinjiang, the difference of climate change in the alpine zones and the basins, and the change of areas of the waters bodies. Furthermore, these factors also reveal the difference in the regional climate change between Xinjiang and central and eastern areas of China. The occurrence and development of dust storms are directly affected by the precipitation, air humidity, status of underlying surface, etc. in the arid areas. The frequency and intensity of dust storms are closely related to the natural conditions, changes of climate and desert environment, as well as the dynamic conditions (i.e., weather systems) in the source areas of dust storms. Therefore, global warming is one of the main causes resulting in the degradation of the ecological environment and the frequent occurrence of natural disasters, especially the disasters of sand drift and dust storms in the arid areas since the late-1980's, which reveals that the inland arid areas are sensitive regions to climate changes.     

Duststorms and Mesoscale Cloud Systems over The East Asian Deserts in Spring

Meteorological characteristics and morphology of duststorms and other dust weather phenomena in the arid regions of East Asia were described in order to investigate a possible role of mesoscale cloud disturbances that develop in synoptic-scale mid-latitude cyclones in intensifying dust weather. This study is a statistical examination of conventional surface observational data as well as satellite data obtained during April 2000–2003. In the deserts of Mongolia and northern China (e.g., the Gobi Desert) duststorms and other weaker dust weather (i.e., dust whirls, blowing dust) frequently occur under a strong influence of synoptic-scale cyclones; on the other hand in the Taklamakan Desert (northwestern China), dust weather phenomena occur in a less organized fashion and may be driven mainly by local meteorological and geographical effects. A significant signal was identified, revealing of the intensification of dust weather by the presence of convective cloud disturbances. Meteorological changes such as pressure rise and temperature drop, typically found during the passage of cold fronts, were frequently observed in the cases of duststorms occurring in the analysis region. However, no definite tendency was found for moisture change and wind speed in relation to cloud activity, probably because rainfall amount is generally too low to moisten the boundary-layer air.     

塔克拉玛干沙漠公路交通事故趋势预测分析

应用塔克拉玛干沙漠干线公路建成通车以来的交通事故统计数据,在分析交通事故主要指标发展变化特征和分布特征的基础上,建立了适用于沙漠公路交通事故特点的GM(1,1)预测模型,对未来几年内交通事故发展趋势进行了预测。预测结果表明,未来几年沙漠公路交通事故次数、死亡人数、受伤人数以及直接经济损失等4项指数将分别以15.9%,10%,4.5%和5%的年平均增长率快速增长。同时针对预测结果提出了相应的对策。     

沙尘天气多发区民勤县发现多例非职业性尘肺病

为了调查非职业性尘肺在我国沙尘天气多发区的发病情况,采用多阶段随机抽样方法随机抽取沙尘天气多发区甘肃省民勤县6个乡镇从未接触过职业性沙尘的1500名18岁以上的农民为调查对象,对其中自觉呼吸系统不适的480人进行了胸透,其中81人进行了X光拍片,分析非职业性尘肺病的发生.分析结果表明,有8例非职业性尘肺患者.如果假设在所调查的未进行X光拍片的农民中无人患有非职业性尘肺病(实际上漏检的可能性是存在的),其患病率也高达5.33‰,表明长期暴露于沙尘天气可引发非职业性尘肺,且发病率高,症状严重,对当地农民的健康影响很大.对此,应引起高度重视.由此结论:长年暴露于沙尘天气可导致非职业性尘肺病的发生.论文建议,将这种因常年暴露于沙尘天气而引起的非职业性尘肺病定名为"沙漠尘肺"(简称:沙漠肺)。     

不同封育年限荒漠草原土壤呼吸日、季动态变化及其影响因子

围封禁牧措施可以改善退化草地生态环境,是我国退化草地植被恢复的主要措施.为探讨干旱区荒漠草原不同围封禁牧年限的土壤呼吸作用特征及影响因子,在生长季连续观测围封禁牧11 a、7 a、放牧不封育(CK)荒漠草原土壤呼吸速率及环境因子,结果表明:1在日、季尺度上,封育11 a、7 a和CK荒漠草原土壤呼吸速率均具有明显的单峰曲线变化规律,在日尺度上,最大、最小值分别出现在12:00~16:00和00:00~06:00;在季节变化尺度上,最大值出现在降水较多温度适宜的8月,土壤呼吸均值表现为11 a[0.143 g·(m2·h)-1]7 a[0.138 g·(m2·h)-1]CK[0.106 g·(m2·h)-1].2封育与未封育荒漠草原的土壤呼吸速率与空气、土壤温度均呈极显著的指数关系(P0.001),相关性大小为:地表温度(R2:0.408~0.413)空气温度(R2:0.355~0.376)5~20 cm土壤温度(R2:0.263~0.394);温度敏感性系数Q10随着土层的加深逐渐变大,不同封育年限Q10表现为11 a(2.728)7 a(2.436)CK(2.086).3封育11 a、7 a和CK荒漠草原土壤呼吸速率与空气湿度、土壤含水量一元二次模型达到显著水平(P0.05),与空气二氧化碳呈极显著线性负相关(P0.01),与风速呈显著线性正相关(P0.05),与光照强度呈极显著线性正相关(P0.01).4干旱区荒漠草原土壤呼吸作用随着围封禁牧年限的增加而增加,温度敏感性系数亦随之增加,0~20 cm土壤温度和水分是其土壤呼吸的主要影响因子.     

Rheum palaestinum (desert rhubarb), a self-irrigating desert plant

The rare plant Rheum palaestinum (Polygonaceae) is a perennial hemicryptophyte that grows during the rainy winter in desert mountainous areas in Israel and Jordan that receive an average annual rainfall of ca. 75 mm. It produces between one and four large round leaves that are tightly attached to the ground and form large rosettes of up to 1 m². These leaves differ markedly from the typical small leaves of most desert plants. Moreover, they have a unique 3D morphology resembling a scaled-down mountainous area with well-developed steep drainage systems, raising the question which selective agents were involved in their evolution. We propose that the large leaves collect rainwater that then infiltrates the soil surrounding the root. We measured the seasonal course of leaf growth, examined the area of wet soil surrounding the root after actual and simulated rain, and modeled the water harvesting capacity using the plant leaf area and the weekly precipitation. We show that even in the slightest rains, water flows above the veins to the leaf’s base where it irrigates the vertical root. A typical plant harvests more than 4,100 cm³ of water per year, and enjoys a water regime of about 427 mm/year, equivalent to the water supply in a Mediterranean climate. This is the first example of self-irrigation by large leaves in a desert plant, creating a leaf-made mini oasis. All authors contributed equally to this paper.     

Adaptation of Nitraria sphaerocarpa to wind-blown sand environments at the edge of a desert oasis

This study addresses the adaptation of Nitraria sphaervcarpa to blown sand at the edge of a desert oasis with regard to the aspects of soil seed banks, seedlings, and population. Horizontally, the total number of seeds per unit area decreased from the shrub canopy center to intershrub areas, and most seeds were found under shrub canopies. Vertically, the highest proportion of seeds was found at depths of 5-10 cm. The emergence percentage, seedling mass, and seedling height, which were significantly affected by both burial depth and seed size, were highest at the optimal burial depth of 2 cm, and decreased with increasing burial depth in each seed size-class. Although seedling mass was usually greatest for large seeds and least for small seeds at each burial depth, little difference was observed in seedling height at shallow burial depths of 0-3 cm. The population shows a patchy and discontinuous distribution pattern. Population height increases with increasing sand depth. Also the density increases with increasing depth of sand in the desert; however, there is a steady decrease when the depth of sand is more than 100 cm. This result indicates that the depth of sand that is most suitable for the growth of Nitraria sphaervcarpa is 100 cm. The size of the population is significantly correlated with the sand depth, which increases with increasing depth in the desert.     

干旱沙区人工固沙植被演变过程中土壤有机碳氮储量及其分布特征

通过测定干旱沙区不同年代人工植被固沙区土壤剖面1 m深度容重和有机碳、全氮含量,估算了人工固沙植被演变过程中土壤有机碳和全氮储量特征及其垂直分布格局.研究表明,干旱沙区人工固沙植被演变过程中,0～100 cm深土壤有机碳和全氮储量均呈增加趋势;有机碳氮储量表现出了固沙初期的显著增加期(<16 a),随后的缓慢增加积累期(16～25 a),及后期的显著增加期(>25 a),该变化趋势主要体现在0～20 cm的表层.土壤有机碳氮储量增加程度随深度增加有降低趋势,并且表层土壤(0～20 cm)有机碳和全氮储量远大于深层土壤(20～100 cm);固沙初期土壤有机碳和全氮储量的增加体现在0～100 cm各个深度,而随后积累期主要体现在0～20 cm深度,固沙后期的增加也主要在0～20 cm深度,20 cm以下增加不明显;0～100 cm深土壤有机碳氮储量表聚性随固沙植被演变越来越明显.明确了降水<200 mm的沙区人工固沙过程中植被和土壤特征的改变对土壤有机碳氮储量及分布特征的影响,为更好地理解干旱人工植被区的碳循环特征和预测该生态系统与气候变化间的反馈关系奠定了基础.