Ecological problems and ecological restoration zoning of the Aral Sea

The Aral Sea was the fourth largest lake in the world but it has shrunk dramatically as a result of irrational human activities, triggering the "Aral Sea ecological crisis". The ecological problems of the Aral Sea have attracted widespread attention, and the alleviation of the Aral Sea ecological crisis has reached a consensus among the five Central Asian countries(Kazakhstan, Uzbekistan, Tajikistan, Kyrgyzstan, and Turkmenistan). In the past decades, many ecological management measures have been implemented for the ecological restoration of the Aral Sea. However, due to the lack of regional planning and zoning, the results are not ideal. In this study, we mapped the ecological zoning of the Aral Sea from the perspective of ecological restoration based on soil type, soil salinity, surface water, groundwater table, Normalized Difference Vegetation Index(NDVI), land cover, and aerosol optical depth(AOD) data. Soil salinization and salt dust are the most prominent ecological problems in the Aral Sea. We divided the Aral Sea into 7 first-level ecological restoration subregions(North Aral Sea catchment area in the downstream of the Syr Darya River(Subregion Ⅰ);artificial flood overflow area in the downstream of the Aral Sea(Subregion Ⅱ);physical/chemical remediation area of the salt dust source area in the eastern part of the South Aral Sea(Subregion Ⅲ);physical/chemical remediation area of severe salinization in the central part of the South Aral Sea(Subregion Ⅳ);existing water surface and potential restoration area of the South Aral Sea(Subregion Ⅴ);Aral Sea vegetation natural recovery area(Subregion Ⅵ);and vegetation planting area with slight salinization in the South Aral Sea(Subregion Ⅶ)) and 14 second-level ecological restoration subregions according to the ecological zoning principles. Implementable measures are proposed for each ecological restoration subregion. For Subregion Ⅰ and Subregion Ⅱ with lower elevations, artificial flooding should be carried out to restore the surface of the Aral Sea. Subregion Ⅲ and Subregion Ⅳ have severe salinization, making it difficult for vegetation to grow. In these subregions, it is recommended to cover and pave the areas with green biomatrix coverings and environmentally sustainable bonding materials. In Subregion Ⅴ located in the central and western parts of the South Aral Sea, surface water recharge should be increased to ensure that this subregion can maintain normal water levels. In Subregion Ⅵ and Subregion Ⅶ where natural conditions are suitable for vegetation growth, measures such as afforestation and buffer zones should be implemented to protect vegetation. This study could provide a reference basis for future comprehensive ecological management and restoration of the Aral Sea.

新疆2018年冬季雨雪风沙强降尘事件

2018年11月30—12月3日中国西北新疆地区发生了罕见的冬季雨雪风沙强降尘天气事件,基于气象观测记录、环境监测和大气降尘连续观测数据,分析研究了此次异常天气过程的大气污染物的时空变化特点及其环境影响。结果显示:该天气过程造成新疆90%以上的绿洲城市遭受大气颗粒物污染,污染组分主要以粗颗粒污染物为主,环境PM_(10)(空气动力学直径≤10μm的颗粒物)最大浓度高达4745μg·m^(-3);大风天气与PM_(10)浓度以及空气质量指数(Air Quality Index,AQI)高度正相关;首府乌鲁木齐市大气颗粒物总沉降量约90×10^(4)~152×10^(4)t,大气降尘强度均值为85 g·m^(-2),超过城市年均值的60%。此次冬季异常雨雪风沙天气过程导致环境空气重污染和高降尘量,风蚀沙尘颗粒物在大气环流场急流作用下传输到绿洲区域,对城市大气环境质量的恶化影响显著,塔克拉玛干沙漠是造成此次西北新疆地区大范围强降尘事件的主要源地。

北非埃及地区风蚀沙尘时空变化研究

通过分析1990—2020年北非埃及气象观测数据和卫星遥感资料,研究风蚀沙尘的时空变化特点,并阐明主要影响因素。结果显示:埃及近30 a沙尘天气发生频次在20~65 d·a^(-1)之间变化,整体呈现出逐渐降低的变化趋势,总悬浮颗粒物(Total Suspended Particulates,TSP)年均浓度在400~1200μg·mg^(-3)之间波动,在全球干旱区处于较高强度水平;扬沙天气发生频率最高,其次是浮尘、沙尘暴和强沙尘暴天气,其中春、夏两季扬沙天气日数占全年沙尘天气总日数的60%以上,环境TSP浓度与沙尘天气发生频次高度相关;近30 a埃及地面风速呈现减小趋势,风力侵蚀作用是影响地区空气质量的关键因素;沙尘天气频率与大西洋多年代际振荡(Atlantic Multidecadal Oscillation,AMO)指数显著负相关,相关系数约为-0.67。本研究为全面了解北非埃及地区风蚀沙尘的时空变化特征和预防沙尘暴灾害提供理论依据和数据支持。

1961-2019年中国北方沙漠沙地极端气候变化特征及其影响因素

本文利用1961—2019年中国北方沙漠沙地腹地和周边地区61个气象站点逐日最高温度、最低温度、降水量等观测数据,选取了通用的24种极端气候指数,分析了中国北方沙漠沙地极端气候的时空变化特征及其影响因素。结果表明:①1961—2019年,中国北方沙漠沙地增温趋势明显,不同的极端气温指数变化趋势显著,并且空间差异较小。其中,气温极值指数显著上升,并且年极端低温的上升幅度最大。霜冻日数、冷昼日数等极端冷事件显著减少,夏日日数、暖昼日数等极端暖事件显著增加。②中国北方沙漠沙地极端降水指数的年际波动较大,并且在空间上呈现出“西增东减”的区域差异性特征。其中,西部沙漠的年降水量以5.11 mm/10a的速率显著增加,一日最大降水量、强降水量等其他极端降水指数也显著增加。而东部沙地的极端降水显著减少,呈现出明显的干旱化趋势。③中国北方沙漠沙地极端气温指数的变化特征与中国其他地区具有较好的一致性,且变化幅度大多超过了北美、南非、澳大利亚以及全球陆地极端气温指数的变化幅度。④北极涛动(AO)对东部沙地极端低温和极端冷事件的变化有显著影响。近几十年来东亚夏季风的减弱是导致东部沙地极端降水减少的主要原因,而西部沙漠极端降水的增加可能受到北大西洋年代际振荡(AMO)和太平洋年代际振荡(PDO)等多重因素的共同影响。

塔克拉玛干沙漠南缘近4年沙尘天气下的气象要素相关性分析

利用2010年9月1日至2014年7月31日塔克拉玛干沙漠南缘策勒流沙地的风沙气象站观测的风速、大气相对湿度、气温和太阳辐射能同步观测数据,运用回归分析、统计法、相关分析等研究方法分析了起沙风出现的时间段、起沙风持续时间以及与平均风、温、湿、太阳辐射能之间的相关性,探讨沙尘天气下气象要素相互影响机制,为沙尘天气的预测提供理论依据。结果表明,一天中超过0.5 h的起沙风在12:00(北京时,下同)13:00时间段出现的频率最高,占总频率的8.78%,10:00 18:00的频率占总频率的57.94%,从早上到晚上呈现先上升后下降的趋势,与气温的日变化趋势基本一致。起沙风持续时间在2~2.5 h时间段的频率最高,占13.62%。流沙前缘的月平均风速与月平均气温呈显著线性同向变化关系,月平均湿度和月平均气温呈反向变化。平均垂直风速差、垂向温度差、垂向湿度差在0.01水平上呈显著相关性,平均风速与起沙风持续时间在0.01水平上呈显著正相关性,平均风速、平均湿度与平均垂向湿差均呈显著负相关性,平均气温与平均相对湿度在0.01水平上呈极显著负相关性。平均垂直温度差与垂直风速差之间呈极显著负相关,平均垂直温度差与垂直湿度差之间呈极显著正相关性。除了0.5 m高度平均风速外,太阳辐射能均与其余气象要素之间呈极显著相关性。策勒流沙前缘的沙尘天气主要发生在春夏季,起沙风主风向以WNW、W风向为主,应加强绿洲外围WNW、W方位的防沙措施。

新疆荒漠类型特征及其保护利用

新疆荒漠具有分布广泛、成因复杂、类型多样等特点。利用新疆数字地貌图结合Landsat卫星TM数据与GIS制图技术,通过长期野外调查结合有关资料编制荒漠类型图,获得荒漠类型面积数据,据此探讨荒漠分布规律、结构特征、形成演变,并提出利用和保护荒漠的建议。结果显示:(1)新疆荒漠具有水平地带性分布与垂直地带性分布的规律及非地带性分布特点,荒漠多分布于干旱程度较高的南疆和东部吐鲁番及哈密地区,东部荒漠占新疆面积的45. 86%,占东部区域面积的91. 77%。(2)荒漠分布广,面积大,总面积达1. 31×106km2,占新疆面积的80. 55%。荒漠类型面积最大的是沙漠为42. 7×104km2,占荒漠面积32. 49%,泥漠面积仅1. 06×104km2,占0. 81%。(3)荒漠类型复杂多样,成因各异,有沙漠、砾漠、盐漠等11种类型,分别主要由气候、地貌、地表物质组成、人为作用等因素单独或共同作用所形成。(4)受自然环境变化与人为作用,荒漠类型之间、荒漠类型与其他地物之间可发生演变。(5)各种荒漠类型的要素特征不同,宜合理利用荒漠资源,划分荒漠环境退化敏感区,保护荒漠环境,针对不同荒漠类型采取适应保护措施,以保障区域可持续发展。

南疆塔中-38团沙漠公路沿线风沙输移规律与防沙体系研究

在建塔中-38团沙漠公路由塔克拉玛干沙漠腹地延伸至其东南缘,全程皆分布不同程度的风沙危害形式,对沙漠公路的建设、服役、养护等造成严重威胁。基于该地区的遥感影像解译及风况数据分析,揭示了沙漠公路沿线不同区段内的风沙环境特征和沙丘移动规律,在此基础上提出了相应的沙害防治体系框架。通过研究发现:(1)沙漠公路沿线区段盛行起沙风向为NE、ENE、E,起沙风频率由21.7%增长至33.8%,风向特征由锐双峰态势发展为钝双峰态势,风沙环境逐步恶劣;(2)沿线区段输沙势介于178.23~309.43 VU,风能环境为低至中等,合成输沙方向介于SW-WSW,风向变率为中等;(3)区段沙丘年平均移动速度在3.16~6.26 m·a^(-1)之间,沙丘移动速度和方向存在明显空间差异,且部分区段沙丘移动方向与合成输沙方向一致性较差。基于以上沙漠公路区段环境特征,提出阻-固结合的沙漠公路防沙体系,对沙漠公路沙害的发展变化规律与公路的可持续研究具有实际应用价值。

近20a蒙古国土壤风蚀变化特征及主要影响因素分析

蒙古国风蚀沙漠化严重,成为世界主要的沙尘源地之一,为了深入了解蒙古国全域风蚀时空变化特征,利用蒙古国境内的GLDAS、OLM、MOD13Q1、NASA-SRTM等气象和遥感数据,基于GEE(Google Earth Engine)云计算平台,利用RWEQ模型计算了蒙古国土壤风蚀量和时空变化规律,分析了土壤风蚀的主要影响因素及作用机制。结果表明:(1)自2001-2020年,蒙古国土壤风蚀呈北部低、南部高的空间分布格局;土壤风蚀主要发生在春季,风蚀量占全年的45%;近20 a土壤风蚀量总体上呈显著增加趋势,风蚀模数以0.06 t·hm^(-2)·a^(-1)的速度增长。(2)蒙古国土壤风蚀变化整体上与气候因子及由其引起的植被盖度变化有关,与放牧、耕地开垦等人为活动增强有密切关系。研究结果可为蒙古国风蚀沙漠化防治提供重要的科学参考。

基于CiteSpace的沙产业研究进展

[目的]分析沙产业的发展现状、研究热点及其发展趋势,揭示目前沙产业的研究态势,为未来沙产业的研究提供新思路。[方法]以Web of Science核心合集中1984—2021年沙产业领域的文献作为数据源绘制科学知识图谱。[结果]①沙产业研究经历了由缓慢增长到快速增长的发展过程。②沙产业的主要研究力量为中国、美国、德国、意大利等国。③沙产业发文机构间的合作较为紧密,科研交流互动频繁,形成了几个相对稳定的合作类团,其研究者也较多,但研究人员的研究方向、研究领域比较宽泛,目前尚未形成固定的研究主题和研究范式。④研究热点主要从“修复与平衡”视角出发,通过构建可持续发展框架,完善生态系统服务,发展生态工程,建立沙漠公园,开展工厂化养殖等多种途径来践行沙漠治理与开发。[结论]在新时代生态文明建设背景下,沙产业作为战略新兴产业,需在理论探析的基础上更加关注多元化的实践探索。

平行智能风沙防护治理决策支持系统——塔克拉玛干沙漠公路及其防沙体系

针对风沙防护治理系统难以建模、难以解析预测等问题,以塔克拉玛干沙漠公路及其防沙体系为研究对象,提出平行智能风沙防护治理决策支持系统。基于防沙专家常年积累的经验知识,结合实际系统风沙环境信息,模拟风沙防护治理过程,构建沙漠公路防沙体系人工系统;基于计算实验,评估防沙体系人工系统的防沙效果,通过与实际系统进行比较与学习,对系统进行评估与校准;基于平行智能理论,分析风沙防护治理决策支持系统,实现人工系统与实际系统的相互学习、相互借鉴,为风沙防护治理提供决策支持,促进风沙环境可持续化发展。

Damage by wind-blown sand and its control measures along the Taklimakan Desert Highway in China

Desertification is one of the most serious environmental problems in the world,especially in the arid desert regions.Combating desertification,therefore,is an urgent task on a regional or even global scale.The Taklimakan Desert in China is the second largest mobile desert in the world and has been called the''Dead Sea''due to few organisms can exist in such a harsh environment.The Taklimakan Desert Highway,the longest desert highway(a total length of 446 km)across the mobile desert in the world,was built in the 1990s within the Taklimakan Desert.It has an important strategic significance regarding oil and gas resources exploration and plays a vital role in the socio-economic development of southern Xinjiang,China.However,wind-blow sand seriously damages the smoothness of the desert highway and,in this case,mechanical sand control system(including sand barrier fences and straw checkerboards)was used early in the life of the desert highway to protect the road.Unfortunately,more than 70%of the sand barrier fences and straw checkerboards have lost their functions,and the desert highway has often been buried and frequently blocked since 1999.To solve this problem,a long artificial shelterbelt with the length of 437 km was built along the desert highway since 2000.However,some potential problems still exist for the sustainable development of the desert highway,such as water shortage,strong sandstorms,extreme environmental characteristics and large maintenance costs.The study aims to provide an overview of the damages caused by wind-blown sand and the effects of sand control measures along the Taklimakan Desert Highway.Ultimately,we provide some suggestions for the biological sand control system to ensure the sustainable development of the Taklimakan Desert Highway,such as screening drought-resistant species to reduce the irrigation requirement and ensure the sound development of groundwater,screening halophytes to restore vegetation in the case of soil salinization,and planting cash crops,such as Cistanche,Wolfberry,Apocynum and other cash crops to decrease the high cost of maintenance on highways and shelterbelts.

Ecological environment quality evaluation of the Sahel region in Africa based on remote sensing ecological index

Long-term monitoring of the ecological environment changes is helpful for the protection of the ecological environment.Based on the ecological environment of the Sahel region in Africa,we established a remote sensing ecological index(RSEI)model for this region by combining dryness,moisture,greenness,and desertification indicators.Using the Moderate-resolution Imaging Spectroradiometer(MODIS)data in Google Earth Engine(GEE)platform,this study analyzed the ecological environment quality of the Sahel region during the period of 2001-2020.We used liner regression and fluctuation analysis methods to study the trend and fluctuation of RSEI,and utilized the stepwise regression approach to analyze the contribution of each indicator to the RSEI.Further,the correlation analysis was used to analyze the correlation between RSEI and precipitation,and Hurst index was applied to evaluate the change trend of RSEI in the future.The results show that RSEI of the Sahel region exhibited spatial heterogeneity.Specifically,it exhibited a decrease in gradient from south to north of the Sahel region.Moreover,RSEI in parts of the Sahel region presented non-zonal features.Different land-cover types demonstrated different RSEI values and changing trends.We found that RSEI and precipitation were positively correlated,suggesting that precipitation is the controlling factor of RSEI.The areas where RSEI values presented an increasing trend were slightly less than the areas where RSEI values presented a decreasing trend.In the Sahel region,the areas with the ecological environment characterized by continuous deterioration and continuous improvement accounted for 44.02%and 28.29%of the total study area,respectively,and the areas in which the ecological environment was changing from improvement to deterioration and from deterioration to improvement accounted for 12.42%and 15.26%of the whole area,respectively.In the face of the current ecological environment and future change trends of RSEI in the Sahel region,the research results provide a reference for the construction of the"Green Great Wall"(GGW)ecological environment project in Africa.

Characteristics of Wind Erosion and Deposition in Oasis-desert Ecotone in Southern Margin of Tarim Basin,China

The oasis-desert ecotone is a fragile ecological zone that is affected both by oasis and desert conditions. To understand the impact of the differences in wind power, and the influence of wind erosion and deposition on the ecotone, meteorological data and contemporaneous wind erosion and deposition data were collected on the southern margin of Tarim Basin with serious sand-blown hazards. The wind velocity, average wind velocity, sand drift potential(DP), resultant sand drift potential(RDP), and sand transportation rate decrease significantly and successively across four landscape types with increasing vegetation coverage(VC). Flat surfaces and areas of shifting sandy ground experience intense wind erosion with fast movement of mobile sand dunes; semi-fixed sand areas experience extensive wind deposition but only slight wind erosion; and fixed sand areas experience only slight wind erosion and deposition. Volume of wind erosion on bare newly reclaimed farmland is up to 6.96 times that of bare shifting sandy ground. Wind erosion volume per unit area and VC follow an exponential function relationship in natural conditions, while wind deposition volume per unit area does not conform to any functions which has close relationship with vary topography and arrangement patterns of vegetation besides for VC. The results indicate that the volume of wind erosion has a close correlation with VC, and different types and distribution patterns of topography and vegetation also profoundly influence the wind deposition volume in the field, and underground water tables in different landscape types control the plant community distribution.

Stable oxygen-hydrogen isotopes reveal water use strategies of Tamarix taklamakanensis in the Taklimakan Desert, China

Tamarix taklamakanensis,a dominant species in the Taklimakan Desert of China,plays a crucial role in stabilizing sand dunes and maintaining regional ecosystem stability.This study aimed to determine the water use strategies of T.taklamakanensis in the Taklimakan Desert under a falling groundwater depth.Four typical T.taklamakanensis nabkha habitats(sandy desert of Tazhong site,saline desert-alluvial plain of Qiemo site,desert-oasis ecotone of Qira site and desert-oasis ecotone of Aral site)were selected with different climate,soil,groundwater and plant cover conditions.Stable isotope values of hydrogen and oxygen were measured for plant xylem water,soil water(soil depths within 0–500 cm),snowmelt water and groundwater in the different habitats.Four potential water sources for T.taklamakanensis,defined as shallow,middle and deep soil water,as well as groundwater,were investigated using a Bayesian isotope mixing model.It was found that groundwater in the Taklimakan Desert was not completely recharged by precipitation,but through the river runoff from snowmelt water in the nearby mountain ranges.The surface soil water content was quickly depleted by strong evaporation,groundwater depth was relatively shallow and the height of T.taklamakanensis nabkha was relatively low,thus T.taklamakanensis primarily utilized the middle(23%±1%)and deep(31%±5%)soil water and groundwater(36%±2%)within the sandy desert habitat.T.taklamakanensis mainly used the deep soil water(55%±4%)and a small amount of groundwater(25%±2%)within the saline desert-alluvial plain habitat,where the soil water content was relatively high and the groundwater depth was shallow.In contrast,within the desert-oasis ecotone in the Qira and Aral sites,T.taklamakanensis primarily utilized the deep soil water(35%±1%and 38%±2%,respectively)and may also use groundwater because the height of T.taklamakanensis nabkha was relatively high in these habitats and the soil water content was relatively low,which is associated with the reduced groundwater depth due to excessive water resource exploitation and utilization by surrounding cities.Consequently,T.taklamakanensis showed distinct water use strategies among the different habitats and primarily depended on the relatively stable water sources(deep soil water and groundwater),reflecting its adaptations to the different habitats in the arid desert environment.These findings improve our understanding on determining the water sources and water use strategies of T.taklamakanensis in the Taklimakan Desert.

An over review of desertification in Xinjiang,Northwest China

Desertification research in arid and semi-arid regions has always been actively pursued.In China,the problem of desertification in Xinjiang has also received extensive attention.Due to its unique geography,many scholars have conducted corresponding research on the desertification status of Xinjiang.In this paper,we comprehensively reviewed desertification in Xinjiang,and compared the underlying mechanisms of desertification and the status of desertification conditions after the implementation of ecological control projects.On a larger scale,desertification in Xinjiang can be divided into soil salinization inside oases and sandy desertification on the edges of oases.Human activities are considered the main cause of desertification,but natural factors also contribute to varying degrees.Research on the mechanisms of desertification has effectively curbed the development of desertification,but unreasonable use of land resources accelerates the risk of desertification.For desertification control,there are several key points.First,desertification monitoring and the early warning of desertification expansion should be strengthened.Second,monitoring and reversing soil salinization also play an important role in the interruption of desertification process.It is very effective to control soil salinization through biological and chemical methods.Third,the management of water resources is also essential,because unreasonable utilization of water resources is one of the main reasons for the expansion of desertification in Xinjiang.Due to the unreasonable utilization of water resources,the lower reaches of the Tarim River are cut off,which leads to a series of vicious cycles,such as the deterioration of ecological environment on both sides of the river and the worsening of desertification.However,in recent years,various desertification control projects implemented in Xinjiang according to the conditions of different regions have achieved remarkable results.For future studies,research on the stability of desert-oasis transition zone is also significantly essential,because such investigations can help to assess the risk of degradation and control desertification on a relatively large scale.

Effect of the W-beam central guardrails on wind-blown sand deposition on desert expressways in sandy regions

Many desert expressways are affected by the deposition of the wind-blown sand,which might block the movement of vehicles or cause accidents.W-beam central guardrails,which are used to improve the safety of desert expressways,are thought to influence the deposition of the wind-blown sand,but this has yet not to be studied adequately.To address this issue,we conducted a wind tunnel test to simulate and explore how the W-beam central guardrails affect the airflow,the wind-blown sand flux and the deposition of the wind-blown sand on desert expressways in sandy regions.The subgrade model is 3.5 cm high and 80.0 cm wide,with a bank slope ratio of 1:3.The W-beam central guardrails model is 3.7 cm high,which included a 1.4-cm-high W-beam and a 2.3-cm-high stand column.The wind velocity was measured by using pitot-static tubes placed at nine different heights(1,2,3,5,7,10,15,30 and 50 cm)above the floor of the chamber.The vertical distribution of the wind-blown sand flux in the wind tunnel was measured by using the sand sampler,which was sectioned into 20 intervals.In addition,we measured the wind-blown sand flux in the field at K50 of the Bachu-Shache desert expressway in the Taklimakan Desert on 11 May 2016,by using a customized 78-cm-high gradient sand sampler for the sand flux structure test.Obstruction by the subgrade leads to the formation of two weak wind zones located at the foot of the windward slope and at the leeward slope of the subgrade,and the wind velocity on the leeward side weakens significantly.The W-beam central guardrails decrease the leeward wind velocity,whereas the velocity increases through the bottom gaps and over the top of the W-beam central guardrails.The vertical distribution of the wind-blown sand flux measured by wind tunnel follows neither a power-law nor an exponential function when affected by either the subgrade or the W-beam central guardrails.At 0.0H and 0.5H(where H=3.5 cm,which is the height of the subgrade),the sand transport is less at the 3 cm height from the subgrade surface than at the 1 and 5 cm heights as a result of obstruction by the W-beam central guardrails,and the maximum sand transportation occurs at the 5 cm height affected by the subgrade surface.The average saltation height in the presence of the W-beam central guardrails is greater than the subgrade height.The field test shows that the sand deposits on the overtaking lane leeward of the W-beam central guardrails and that the thickness of the deposited sand is determined by the difference in the sand mass transported between the inlet and outlet points,which is consistent with the position of the minimum wind velocity in the wind tunnel test.The results of this study could help us to understand the hazards of the wind-blown sand onto subgrade with the W-beam central guardrails.

Re-evaluating the vertical mass-flux profiles of aeolian sediment at the southern fringe of the Taklimakan Desert, China

Reliable estimation of the mass-flux profiles of aeolian sediment is essential for predicting sediment transport rates accurately and designing measures to cope with wind-erosion. Vertical mass-flux profiles from seventeen wind-erosion events were re-evaluated using five typical models based on observed data obtained from a smooth bare field at the southern fringe of the Taklimakan Desert, China. The results showed that the exponential-function model and the logarithmic-function model exhibited the poorest fit between observed and predicted mass-flux profiles. The power-function model and the modified power-function model improved the fit to field data to an equivalent extent, while the five-parameter combined-function model with a scale constant（σ） of 0.00001 m（different from the σ value proposed by Fryear, which represented the height above which 50% of the total mass flux occurred） was verified as the best for describing the vertical aeolian sediment mass-flux profiles using goodness of fit（R2） and the Akaike Information Criterion（AIC） values to evaluate model performance. According to relationships among model parameters, the modified power model played a prominent explanatory role in describing the vertical profiles of the observed data, whereas the exponential model played a coordinating role. In addition, it was found that the vertical profiles could not be extrapolated using the five selected models or easily estimated using an efficient model without field observations by a near-surface sampler at 0 to 0.05 m.

风蚀沙尘对新疆绿洲城市大气环境的影响研究

通过分析2020年新疆16个绿洲城市的环境监测记录和气象观测数据,研究沙尘天气频率、大气降尘强度和PM_(10)(空气动力直径≤10μm的颗粒物)浓度的变化特征以及风蚀沙尘对绿洲城市大气环境的影响.统计分析结果显示:2020年南疆沙尘天气日数为180 d,是北疆和东疆沙尘天气总日数的4倍以上;新疆地区春夏两季浮尘天气日数占全年沙尘天气总日数的50%以上;北疆、东疆和南疆城市沙尘天气PM_(10)浓度较非沙尘天气分别增加14%~253%、20%~422%和24%~804%.风蚀沙尘造成75%的绿洲城市年均PM_(10)浓度高于国家环境空气质量标准的二级浓度限制,且呈现出由北向南递增的变化趋势;南疆城市风蚀沙尘中PM_(10)贡献率高达67%,其次是东疆和北疆城市,分别为22%和11%.新疆绿洲城市降尘强度和PM_(10)浓度呈显著正相关,南疆最大月均降尘强度为143 t·km^(-2),是北疆和东疆的14倍和8倍;风蚀沙尘造成南疆城市空气质量污染比重均在80%以上,大气能见度显著低于北疆和东疆.总之,风蚀沙尘对新疆绿洲城市大气环境的影响显著,其影响程度与沙尘天气发生频率和地处沙源区密切相关.

河西走廊—塔克拉玛干沙漠边缘阻击战:风沙形势与防治任务

为落实习近平总书记在加强荒漠化综合防治和推进“三北”等重点生态工程建设座谈会上的重要讲话精神,文章以打好河西走廊—塔克拉玛干沙漠边缘阻击战为主要目标,深入开展了河西走廊—塔克拉玛干沙漠边缘风沙形势与防治任务研究工作。依据河西走廊—塔克拉玛干沙漠边缘沙化土地特征和风沙活动形势,以“流沙不再漫延,尘源有效防控”为目标指向,以“防风、阻沙、控尘”为核心课题,确定河西走廊—塔克拉玛干沙漠边缘阻击战的思路。通过系统梳理“风、沙、尘”的源区和路径,瞄准沙漠边缘防沙治沙关键带和突出沙害治理重点,提出了河西走廊—塔克拉玛干沙漠边缘防沙治沙重点任务区和重点任务,以期为打好、打赢河西走廊—塔克拉玛干沙漠边缘阻击战提供科技支撑。

大国治理:中国荒漠化防治的战略选择与未来愿景

中国70余年来持续开展的荒漠化防治取得了巨大成就。当前中国荒漠化防治进入新阶段,仍面临沙化土地基数大、治理难度高等问题,需要全方位满足生态建设、乡村振兴和沙戈荒地区风电光伏开发利用等国家战略需求。新时期中国荒漠化防治的战略选择是整体提升、重点突破,战略核心是全域治理、创新驱动、技术集成,分类施策的制度安排是全面实施“一荒四制”(养、防、治、用),全力打好打赢“三北”攻坚战的“三大标志性战役”,优先布局一批重点示范工程,加快政策更新,打造科技新引擎,助力荒漠化防治提质增效、擘画“三生”融合、人沙和谐的中国式现代化美好愿景,推进荒漠化防治的“中国方案”走向世界、惠益全球。