Article

Modern dust storms in China: An overview

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Abstract

This paper discusses the sources, spatial distribution, frequency and trend of dust storms in China. Most dust storms in China originate from one of three geographic areas: the Hexi (River West) Corridor and western Inner Mongolia Plateau, the Taklimakan Desert, and the central Inner Mongolia Plateau. Dust is most likely from deteriorated grasslands, Gobi, alluvial, lacustrine sediments and wadis at the outer edge of deserts. But deserts themselves contribute only slightly to the dust storm directly. Two geographic areas frequently have dust storms: one is in the western Tarim Basin, a ground surface of deteriorated land and wadi, but it only affects its neighboring areas, and the other one is in the western Inner Mongolia Plateau, a ground surface of Gobi, alluvial and lacustrine sediments, but it causes most of the dust storms in north China. Generally speaking, dust storms have reduced in most regions of China from the 1950 to 2000. Dust storms are highly correlated with human activities and climate changes.

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... The selected locations surround the Inner Mongolian plateau, Taklimakan desert, and Hexi corridor, which are known sources of dust particles, especially in the spring season when dust storms are frequent (Qian et al. 2002;Wang et al. 2004). Another major source of aerosols is pollutants from the rapidly developing industrial regions in the eastern parts of China. ...
... It is also important to know the possible sources of these aerosols, whether natural or anthropogenic, to examine the implications on climate. The observed variations are discussed below based on the present understanding of the major sources and types over the study area (Chueinta et al. 2000;Lelieveld et al. 2001;Sun et al. 2001;Qian et al. 2002;Kim et al. 2004Kim et al. , 2007Wang et al. 2004;Lin et al. 2005;Lin et al. 2011;Reid et al. 2013). ...
... It has been reported that dust storms occur frequently over the Inner Mongolian plateau, Taklimakan desert and Hexi corridor (Sun et al. 2001;Wang et al. 2004). Several investigations have shown the influence of dust particles on the aerosol loading over the region Kim et al. 2005Kim et al. , 2014Lin et al. 2005;Mukai et al. 2006;Lee et al. 2007;He et al. 2012), especially in the February -May months. ...
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This paper investigates the aerosol properties over the major East Asian stations of Beijing, Gosan, Osaka, Taipei, Muk-dahan, and Bac-Giang, during the years 2002-2008. Aerosol optical thickness (AOT) product from the moderate resolution imaging spectroradiometers (MODIS) onboard the Aqua and Terra satellites are used for this study. The aerosol robotic network (AERONET) ground observations are used to validate the satellite AOT. The daily, monthly, seasonal, and inter-annual AOT variations over the selected locations are described along with meteorological parameters from National Center for Environmental Prediction, National Center for Atmospheric Research (NCEP-NCAR) reanalysis data and Global Precipitation Climatology Center (GPCC) data. Angstrom exponent (AE), and fine mode fraction (FMF) from MODIS and AERONET are used to discuss the size, type and possible particle sources. Seasonal wind patterns from NCEP-NCAR reanalysis data are used to confirm particle transport from the source regions around the study area to the chosen stations. The results suggest that the maximum aerosol loading occurs over Beijing with the daily mean AOT reaching above 2.0. Gosan and Taipei are among the stations having the smallest AOT in most seasons with values below 0.5. Dust influence appears to be significant over Beijing, Osaka, and Gosan and to a lesser extent over Bac-Giang in the spring. Pollution, bio-mass burning, etc. contribute in the summer and spring over all stations. The detailed AOT characteristic over Mukdahan and Bac-Giang are reported for the first time.
... Xinjiang Uyghur Autonomous Region, located in the western part of China (hereafter western China) (Fig. S1), accounts for about 1/5th of the total land area in China. Vast arid lands in Xinjiang (e.g., Taklimakan Desert) are key dust sources in the Northern Hemisphere (Wang et al. 2004) and dust storms are a frequent phenomenon in the desert atmosphere, which are sensitive to environmental changes. Dust storms contribute directly to air pollution by increasing particulate matter concentrations (Middleton 2017), often by orders of magnitude. ...
... The Taklimakan Desert (330,000 km 2 ) is the second-largest shifting sand desert in the world and the largest desert in China (Fig. S1). The Taklimakan Desert is characterized by dust weather in the dust storm season (March to August) and has an extremely dry climate (annual precipitation is < 25 mm) (Wang et al. 2004). The Tazhong (hereafter TZ) Station (38° 58′ N, 83° 39′ E, 1099 m a.s.l.) situated in the central part of the Taklimakan Desert (Fig. S1), which was the first meteorological station established in the Chinese desert region. ...
... Moreover, dust weather is a unique weather phenomenon in desert areas worldwide (Middleton 2017). In the Taklimakan Desert, dust storms mainly occur from March to August and the weather during this period is the driest of the year (Wang et al. 2004). Prior studies have demonstrated that the concentration of dust particulate during the dust storm period was several times higher than that during the non-dust storm period . ...
Article
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Arid lands such as deserts cover more than 35% of the Earth’s land surface. Concerns regarding ground-level O3 pollution have been widely addressed in many regions in China, but the behavior of the O3 cycles in the desert atmosphere remains poorly understood. An 8-year observation was conducted to investigate the long-term temporal O3 variations in the atmosphere of the Taklimakan Desert, western China. The results showed that the diurnal and seasonal variations of O3 were mainly influenced by natural processes such as temperature, leading to a different temporal pattern compared with other Chinese regions under the intensive influence of anthropogenic activities. Moreover, the long-term pattern indicates that there exists decoupling trends of O3 variations between our study site (i.e., decreasing trend) and the developed regions in China (i.e., increasing trend). Knowledge of the temporal O3 patterns could therefore provide crucial insights for future effective O3 control strategies in China.
... The Taklimakan Desert is one of the key dust sources in the Northern Hemisphere (Zhang et al., 1997;Huang et al., 2014a). Although dusty weather (e.g., duststorm, floating dust and blowing dust) occurs in most of the year over the Taklimakan Desert, frequent dust outbreaks is a common phenomenon during spring and summer (from March to August) (Wang et al., 2004;Zhang et al., 2018). The Taklimakan Desert is characterized by strong windy days during duststorm season (Wang et al., 2004). ...
... Although dusty weather (e.g., duststorm, floating dust and blowing dust) occurs in most of the year over the Taklimakan Desert, frequent dust outbreaks is a common phenomenon during spring and summer (from March to August) (Wang et al., 2004;Zhang et al., 2018). The Taklimakan Desert is characterized by strong windy days during duststorm season (Wang et al., 2004). ...
... When we divide into two seasons (i.e., duststorm season and non-duststorm season) to consider this pattern, we found that the volume-based Hg P from KS, MF and TZ stations (Fig. 3a, c, 3e) were significantly positively correlated with dust particulates (TSP) during duststorm season. In the Taklimakan Desert, duststorms mostly occur during spring and summer seasons (MarcheAugust) (Wang et al., 2004) when the synoptic Table 1 Averages of volume-based Hg P concentrations (pg m À3 ) and mass-based Hg P concentration (mg kg À1 ) and the estimates of annual amount of Hg associated with dust from the Taklimakan Desert. Dust emission flux was taken from Chen et al. (2017). ...
Article
The atmospheric circulation plays a critical role in the global transport and deposition of atmospheric pollutants such as mercury (Hg). Desert dust emissions contribute to nearly 60e95% of the global dust budget and thus, desert dust may facilitate atmospheric Hg transport and deposition to the downwind regions worldwide. The role of desert dust in biogeochemical cycling of Hg, however, has not been well recognized by the Hg research community. In this study, we measured the concentration of particulate bound Hg (Hg P) in total suspended particulate (TSP) collected from China's largest desert, Taklimakan Desert, between 2013 and 2017. The results show that Hg P concentrations over the Taklimakan Desert atmosphere are remarkably higher than those observed from background sites in China and are even comparable to those measured in most of the Chinese metropolitan cities. Moreover, Hg P concentrations in the Taklimakan Desert exhibit a distinct seasonal pattern peaking during dust storm outbreak periods in spring and summer (March to August). A preliminary estimation demonstrates that export of total Hg associated with atmospheric dust from the Taklimakan Desert could be 59.7 ± 60.3 (1SD) Mg yr À1. The unexpectedly high Hg P concentrations during duststorms, together with consistent seasonal pattern of Hg revealed from the snow/ice, clearly demonstrate that Asian desert dust could act as a significant carrier of atmospheric Hg to the cryosphere of Western China and even can have further global reach.
... Low precipitation, high atmospheric evaporative demand and high intensity of human activities contribute to the fragility of the desert ecosystem (Wang et al., 2017), and the ecological equilibrium may be disturbed by changes in the nutrient contents of topsoil. The Otindag Desert is presently regarded as both a potential dust source area and a deposition area of dust from the upwind Gobi deserts of the Mongolian Plateau (Wang et al., 2000(Wang et al., , 2004Zhang et al., 2003;Cheng et al., 2005). Previous studies focused mainly on dust emission and the resulting topsoil loss and the degradation of grassland, and the findings emphasized the role of this region as a dust source area. ...
... However, the positive feedback of plants on nutrient inputs by dust deposition is important and has been extensively reported. For example, nutrient inputs by dry deposition greatly affect population density and aboveground biomass of plant communities, and improve vegetation productivity and carbon sequestration in arid and semiarid areas of China (Fu and Zhuo, 1994;Wang et al., 2004;Su et al., 2013). Dust inputs in semi-arid ecosystems can change and diversify P speciation, influencing the acquisition strategies of plants for nutrients and the coupling to C and N cycles (Ceulemans et al., 2017;Gu et al., 2019). ...
Article
Quantification of fine fraction and nutrient inputs by dust deposition is vital to understand the biogeochemical cycling and its effect on vegetation succession in arid and semiarid regions. The Otindag Desert of China is usually regarded as a dust source area, and little is known about its sink function by dust deposition. Dust and topsoil sampling and nutrient analyses were conducted to determine the contributions of dust deposition (fractions <50 μm in diameter) on topsoil heterogeneity across the Otindag Desert. Mean dust deposition intensity from field investigation was 19.69 ± 7.77 g/m² from August 2018 to July 2019. There were significant spatial differences in dust deposition, and the Otindag Desert received more dust deposition from external sources. Inputs of available phosphorus, total phosphorus, total nitrogen and soil organic carbon were 0.45 ± 0.083 mg/m², 0.011 ± 0.007 g/m², 0.027 ± 0.018 g/m², and 0.331 ± 0.224 g/m², respectively. The nutrient contents within dust deposition fractions were higher on average by 104% than topsoil, and the cooccurrence of dust emission and deposition contributes to the heterogeneity of topsoil. The results of this study are essential for taking efficient measures to restore degraded land in the Otindag Desert and other similar regions.
... Most of the studies focused on assessing the spatial-temporal distribution of SDS and atmospheric monitoring [17,18]. They used national observed SDS records or satellite images [19][20][21][22][23], and identified the relationship between surface features, such as land cover types, vegetation states, soil types, etc. and climate conditions, such as precipitation, land surface temperature, etc. [24][25][26]. The occurrence of SDS was concentrated in spring and early summer [25,26], mainly in Taklamakan Desert and Gobi Desert, and recently, it has been on the decline. ...
... They used national observed SDS records or satellite images [19][20][21][22][23], and identified the relationship between surface features, such as land cover types, vegetation states, soil types, etc. and climate conditions, such as precipitation, land surface temperature, etc. [24][25][26]. The occurrence of SDS was concentrated in spring and early summer [25,26], mainly in Taklamakan Desert and Gobi Desert, and recently, it has been on the decline. Sun et al. [27] assessed spatial and temporal characteristics of SDS in China using the past 40 years of SDS records, and mentioned that Gobi Desert and Taklimakan Desert are major sources of East Asia. ...
Article
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Central Asian countries, which are included the Mid-Latitude Region (MLR), need to develop regional adaptive strategies for reducing Sand and Dust Storm (SDS)-induced negative damages based on adequate information and data. To overcome current limitation about data and assessment approaches in this region, the macroscale verified methodologies were required. Therefore, this study analyzed environmental conditions based on the SDS impacts and regional differences of SDS sources and receptors to support regional SDS adaptation plans. This study aims to identify environmental conditions based on the phased SDS impact and regional differences of SDS source and receptor to support regional adaptation plans in MLR. The Normalized Difference Vegetation Index (NDVI), Aridity Index (AI), and SDS frequency were calculated based on satellite images and observed meteorological data. The relationship among SDS frequency, vegetation, and dryness was determined by performing statistical analysis. In order to reflect phased SDS impact and regional differences, SDS frequency was classified into five classes, and representative study areas were selected by dividing source and receptor in Central Asia and East Asia. The spatial analysis was performed to characterize the effect of phased SDS impact and regional distribution differences pattern of NDVI and AI. The result revealed that vegetation condition was negatively correlated with the SDS frequency, while dryness and the SDS frequency were positively correlated. In particular, the range of dryness and vegetation was related to the SDS frequency class and regional difference based on spatial analysis. Overall, the Aral Sea and the Caspian Sea can be considered as an active source of SDS in Central Asia, and the regions were likely to expand into potential SDS risk areas compared to East Asia. This study presents the possibility of potential SDS risk area using continuously monitored vegetation and dryness index, and aids in decision-making which prioritizes vegetation restoration to prevent SDS damages with the macrolevel approach in the MLR perspective.
... Many studies showed a negative correlation between vegetation coverage and occurrence of dust storms by the analysis of long-term spatiotemporal variation of vegetation index Lee and Sohn, 2011; https://doi.org/10.1016/j.atmosres.2020.105031 Received 15 February 2020; Received in revised form 19 April 2020 Liu et al., 2004;Piao et al., 2005;Tan and Li, 2015;Zou and Zhai, 2004). Vegetation on grassland can absorb wind energy, increase land surface roughness, and effectively protect soils from wind erosion (Dong et al., 1999;Lancaster and Baas, 1998;Roels et al., 2001;Siddoway, 1963;Stockton and Gillette, 1990). ...
... Among these land surface types, forest land with higher vegetation coverage, water body of lakes and swamp, bare rock, and built-up area, can hardly contribute to sand and dust, thus could be excluded as possible sand and dust source areas. Cultivated land, grassland, sand desert, Gobi desert, and salt crust, on which aeolian process periodically dominates, are generally assumed as major source areas of dust storms (Cook et al., 2009;Liu et al., 2013;Singer et al., 2003;Wang et al., 2004). These five land surface types cover more than 80% of the arid and semiarid regions in northern China. ...
Article
Dust storm originates from arid and semiarid areas and could cause worldwide lasting effects along varying trajectories. As an extreme weather hazard, dust storm is usually induced by strong winds. In this paper, an aerodynamic parameter, defined as the ratio between dust storm frequency (DSF) and strong wind frequency (SWF), was calculated for quantifying dust storm susceptibility (DSS). The characteristic value and temporal change of DSS in five typical land surface areas, including cultivated land, grassland, sand desert, Gobi desert, and salt crust, were analyzed with dust storm and strong wind records at 15 weather stations. The spatial distribution of DSS in the arid and semiarid regions of northern China was described using dust storm and strong windrecords at 102 meteorological stations. There are positive correlations between SWF and DSF for any identical land surface type. Land surface conditions have a great influence on dust storm susceptibility. According to DSS value, the five land surface types can be divided into two categories: (1) Cultivated land and sand desert, with DSS between 0.64 and 0.53, about 2.6–10 times higher than that of the other three land surfaces, are prone to forming dust storm under strong wind conditions; (2) Gobi desert, grassland and salt crust, with average DSS from 0.06 to 0.2, exhibit lower probability of dust storm occurrence under strong wind conditions. The DSF in the surrounding areas of the arid Taklimakan desert in Xinjiang are much larger than SWF, and dust storms take place readily even at normal erosive wind conditions. The areas with high DSF are not spatially consistent with SWF distribution but more coincide with high DSS areas where sand deserts and farmland are concentrated. In the nearly four past decades, the DSS showed an overall increasing trend on different ground surfaces which may be related to local human activities and climatic warming.
... The Taklamakan Desert and Gobi comprise 70-80% of the basin area (Zan et al., 2014), and enormous quantities of dusts generated from these areas have been delivered to the Pacific Ocean and North America, and even to Greenland (Rea et al., 1998;Jaffe et al., 1999;Bory et al., 2002;Yumimoto et al., 2009;Zhang et al., 2020), by the Westerlies. Consequently, the Tarim Basin is an important global dust source (Zhang et al., 2003;Wang et al., 2004;Shao et al., 2011;Liu et al., 2014;Sun et al., 2017). The sediments in the basin are an important archive of the aridification of inland Asia, and of the interplay between the Westerlies and the Asian monsoon (Fang et al., 2002;Xia et al., 2007;Yang and Scuderi, 2010;Zhao et al., 2012). ...
... The cyanobacteria record from Lake Moon highlights the importance of dust storms in shaping the phytoplankton community structure and driving an early onset of cyanobacterial dominance in northeastern China. With regard to the intensification of human activity and climate change, the shrinking and drying of lakes in the Mongolian Plateau have led to the degradation of lakes and grassland which has resulted in the Mongolian Plateau becoming the major source of dust storms in northern China (Wang et al., 2004;Tao et al., 2015), with dust from the region even reaching North America (Husar et al., 2001). Therefore, the nutrient supply from dust storms has important ecological implications for mountain aquatic systems across northeastern China, as well as for other dust-influenced regions, and the process warrants further exploration. ...
Article
Cyanobacterial blooms in water bodies have occurred on a worldwide basis in the last few decades, and knowledge of their occurrence under natural conditions, and of the mechanisms responsible, is important for understanding their origin. However, little is known about the long-term trends in cyanobacterial abundance in the pre-industrial era, and its causes. Traditional microscope analysis of microfossil plankton is widely applied in paleoecology, yet the majority of phytoplankton (e.g., cyanobacteria) are not preserved as microfossils in sediments, although they can leave a fingerprint in the form of sedimentary ancient DNA (sedaDNA). Here, sedaDNA is used for the first time to reconstruct the history of phytoplankton communities in a crater lake in northern China over the past two millennia. Our data show that changes in phytoplankton community structure and diversity were linked to temperature and precipitation variations during ∼0–1400 Common Era (CE). However, after ∼1400 CE the cyanobacterial abundance increased to an unprecedented degree, and cyanobacteria (mainly composed of Synechococcus) became disproportionately dominant relative to other phytoplankton. This rise was concomitant with increased aeolian dust input by winds driven by an intensified Siberian High, which resulted in increased dust transport across the entire mid-latitude region of the Northern Hemisphere. This suggests that dust input can exceed natural climatic variability as the dominant control on lake ecosystems in regions subject to dust deposition. We suggest that future lake ecological management strategies in areas of dust deposition should consider not only the influence of climatic warming but also the impact of nutrient inputs delivered by dust storms.
... Spring is a very important season for central Asian dust transport period. Various studies have found that the spring season brings abundant aerosol-size dust particles from arid regions (Dong et al. 2014b;Sun et al. 2001;Wang et al. 2004). Moreover, it was found that Nr-Sr isotopic composition of Baidan Jaran Desert (Chen et al. 2007) and Qaidam basin (Lee et al. 2010;Yang et al. 2009) showed a very similar result with that from the Laohugou and other glaciers in the western Qilian Mountains (Dong et al. 2014b), which are situated in the west and the north region of the Laohugou Glacier No. 12. ...
Article
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In this work, samples of surface snow, surface ice, snow pit and meltwater from the Laohugou Glacier No. 12 on the northern edge of Tibetan Plateau (TP) were collected during the summer of 2015. The average concentration of Hg in surface snow/ice was 22.41 ng L⁻¹, while the percentage of dissolved mercury (HgD) was observed to be around 26%. An altitudinal magnification of Hg was not observed for surface snow; however, in contrast, a significant positive magnification of Hg with altitude was observed in the surface ice. A higher concentration of Hg corresponded with the dust layer of the snow pit. It was observed that about 42% of Hg was lost from the surface snow when the glacier was exposed to sunlight within the first 24 h indicating some Hg was emitted back to the atmosphere while some were percolated downwards. The result from the principal component analysis (PCA) showed that the sources of Hg in Laohugou Glacier No. 12 were from crustal and biomass burning. Finally, it was estimated that total export of Hg from the outlet river of Laohugou glacier No. 12 in the year 2015 was about 1439.46 g yr⁻¹ with yield of 22.77 μg m² yr⁻¹. This study provides valuable insights for understanding the behavior of Hg in the glacier of the northern Tibetan Plateau.
... Dust can also indirectly change cloud microphysical properties by affecting cloud condensation nuclei and ice nuclei, thereby influencing precipitation efficiency, and can alter the albedo of snow and ice surfaces, exerting an indirect influence on the energy budget of the Earth Chen et al., 2017;Rodríguez et al., 2012;Rosenfeld et al., 2001). Dust events are among the most serious environmental hazards in East Asia, where their effects increase with the population and economic growth (Liu et al., 2020;Wang et al., 2004). Dust concentrations are influenced by emissions, transport processes, and wet and dry deposition, all of which are influenced by meteorological factors, emissions are also related to surface factors (Pu and Ginoux, 2017;Tan et al., 2017;Che et al., 2019a;Gibergans-Báguena et al., 2020). ...
Article
East Asian dust aerosols play a vital role in the local and regional climate through its direct, indirect, and semidirect effects, but the dominant factors affecting the interannual variation of dust aerosols over East Asia and their regional differences remain unclear. This study verified the accuracy of MEERA-2 dust data in East Asia, analyzed the interannual trends of dust in East Asia from 2000 to 2019 using the MERRA-2 dust column mass density (DCMD) and identified the dominant factors affecting the interannual variation during the dusty season (March–July) by developing the regional multiple linear regression models, combined with correlation and partial correlation analysis. The comparison with the dust index (DI) calculated from ground-based observations of dust events frequency indicated that MERRA-2 DCMD exhibited high spatial agreement (R > 0.8) with ground-based observations in most regions (especially in the dust source region of North China). The trend analysis revealed that DCMD in East Asia decreased significantly after 2000, particularly in the dusty season (March–July). These significant decreases were generally highly correlated with increases in normalized differential vegetation index (NDVI), volumetric soil moisture (VSM), and precipitation (PPT) and with decreases in wind speed (WS). Furthermore, WS dominated the interannual variation in the dust concentration over the East Asian dust source regions and their downstream. By contrast, PPT, through its wet deposition effect, dominated the variation in the rest of the regions away from the dust source region. The study findings may help clarify the associations between local meteorological and surface factors and long-term variations in dust aerosols over East Asia.
... The Taihang Mountains in Hebei Province also hampered the PM 2.5 dispersions, further aggravating air pollutions in these areas [16]. High PM 2.5 concentrations as well appeared in the Xinjiang Autonomous Region due to the great quantity of dust aerosols coming from the Taklimakan Desert [17,52,53]. By contrast, the southern and northern provinces exhibited much better air quality with PM 2.5 concentrations basically below 30 µg/m 3 , such as Hainan, Guangdong, and Heilongjiang Provinces. ...
Article
Full-text available
Satellite-retrieved aerosol optical depth (AOD) data are extensively integrated with ground-level measurements to achieve spatially continuous fine particulate matters (PM2.5). Current satellite-based methods however face challenges in obtaining highly accurate and reasonable PM2.5 distributions due to the inability to handle both spatial non-stationarity and complex non-linearity in the PM2.5–AOD relationship. High-resolution (<1 km) PM2.5 products over the whole of China for fine exposure assessment and health research are also lacking. This study aimed to predict 750 m resolution ground-level PM2.5 in China with the high-resolution Visible Infrared Imaging Radiometer Suite (VIIRS) intermediate product (IP) AOD data using a newly developed geographically neural network weighted regression (GNNWR) model. The performance evaluations demonstrated that GNNWR achieved higher prediction accuracy than the widely used methods with cross-validation and predictive R2 of 0.86 and 0.85. Satellite-derived monthly 750 m resolution PM2.5 data in China were generated with robust prediction accuracy and almost complete coverage. The PM2.5 pollution was found to be greatly improved in 2018 in China with annual mean concentration of 31.07 ± 17.52 µg/m3. Nonetheless, fine-scale PM2.5 exposures at multiple administrative levels suggested that PM2.5 pollution in most urban areas needed further control, especially in southern Hebei Province. This work is the first to evaluate the potential of VIIRS IP AOD in modeling high-resolution PM2.5 over large-scale. The newly satellite-derived PM2.5 data with high spatial resolution and high prediction accuracy at the national scale are valuable to advance environmental and health researches in China.
... The Taklamakan Desert and Gobi comprise 70-80% of the basin area (Zan et al., 2014), and enormous quantities of dusts generated from these areas have been delivered to the Pacific Ocean and North America, and even to Greenland (Rea et al., 1998;Jaffe et al., 1999;Bory et al., 2002;Yumimoto et al., 2009;Zhang et al., 2020), by the Westerlies. Consequently, the Tarim Basin is an important global dust source (Zhang et al., 2003;Wang et al., 2004;Shao et al., 2011;Liu et al., 2014;Sun et al., 2017). The sediments in the basin are an important archive of the aridification of inland Asia, and of the interplay between the Westerlies and the Asian monsoon (Fang et al., 2002;Xia et al., 2007;Yang and Scuderi, 2010;Zhao et al., 2012). ...
Article
Provenance of surface sediments in the Tarim Basin is important for understanding the aridification of the Asian interior and the interplay between the Westerlies and the Asian monsoon. Although the desert sands in the Taklamakan Desert have been studied intensively, there is no consensus regarding their provenance, namely, the dispute exists between various sand sources in different parts of the desert and homogenization of the sands in the entire desert. Moreover, other surface sediments in the basin are poorly investigated. Here we examine the particle-size-specific rare earth element (REE) and trace element characteristics of various surface sediments from different regions of the basin. The results reveal that the <2 µm fraction has multiple sources from Central Asia as well as from the adjoining arid/semi-arid areas to the east, together with the abrasion of coarser particles from multiple regional sources. They are completely homogenized prior to deposition by the action of the Westerlies and the local wind systems. The 2-16 µm fraction of most of the sediments in the basin have a higher proportion of Central Asian dust and a relatively high degree of homogeneity. Westerlies and local wind systems remain a more important transport mechanism than the fluvial activity. In addition, the desert sands of 2-16 µm fraction in the Taklamakan Desert has a substantial contribution from material derived from the basement rocks. The 32-63 µm and >63 µm fraction are dominated by regional-derived materials, mainly from the adjacent mountains (e.g. Pamirs, Kunlun, Kuruktag, Altun, Tianshan Mountains), and the fluvial systems are an important additional transport mechanism. Our findings potentially provide an improved understanding of the dust cycle and atmospheric circulation patterns in Central Asia, and of the provenance of loess in North China.
... Moreover, the annual economic lost caused by hazardous dust event is US $265 million in China and US $5.6 billion in South Korea [26,27]. Therefore, continuous monitoring and modelling of dust are essential to understand the mechanisms of dust emission and transport and its impacts on regional climate in northeast Asia [22,[28][29][30]. ...
Article
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Spring dust frequency in northeast Asia has been investigated using various approaches to understand the mechanisms of dust emission and transport. However, little attention has been paid to the linkage between dust activity and the Siberian High (SH), particularly when the SH pressure system is highly variable. In this study, we characterize the possible physical mechanisms of dust emission and transport associated with the Siberian High Intensity (SHI) and Siberian High Position Index (SHPI) in March using 18 years of ground-based observations and reanalysis data. We found that when the SHI was strong and the SH’s center was farther east (“Strong–East period”), surface and atmospheric temperatures were cooler than when the SHI was weak and the SH’s center was farther west (“Weak-West period”), due to anomalous anticyclonic pressure and strong easterlies. As a result, a reduction in the meridional temperature gradient in the lower atmosphere suppressed dust emission and transport, due to stagnant atmospheric conditions. This anomalous anticyclonic pressure in the Strong-East case seems to reduce the development of extratropical cyclones (ETC) in northeast Asia, leading to a less effective dust transport. A case study with composite analysis also showed a similar physical mechanism: stagnant air accompanying weakened westerlies in the Strong-East period suppressed dust transport to South Korea. Our findings reveal that the intensity and position of the SH can be utilized to identify spring transboundary air pollutants in northeast Asia.
... Huang et al., 2014). Annually, about 800 Tg of dust over East Asia is injected into the atmosphere, 50% of which can be transported to downstream areas such as eastern China, Korea, Japan, and even Pacific Ocean by large-scale meteorological processes, leading to widespread dust events lasting for several days (Chun et al., 2001;Shao & Dong, 2006;X. Wang et al., 2004). ...
Article
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East Asia features frequent dust storms and intensive anthropogenic emissions. The mixing of natural dust and anthropogenic pollutants exerts complicated impacts on air pollution and regional climate. Studies have focused on chemical interactions of the mixed pollution, while the meteorological feedback and influences on atmospheric chemistry have not been fully investigated. Here, a comprehensive study on a widespread dust storm and its influence on the air quality downwind was conducted by combining multiple observations and modeling. We found that dust originated from Gobi Desert was mixed with anthropogenic pollutants after transported to the Yangtze River Delta (YRD). Through scattering and absorbing radiation, dust aerosol perturbed solar energy budget and led to a more stabilized planetary boundary layer (PBL). A reduction of 15% in PBL height (184 m) weakened the dispersion of locally emitted pollutants and increased primary pollution by 10% in YRD city clusters. Besides, the mixed plume over offshore areas warmed the entire lower atmosphere and increased surface evaporation. Accordingly, ozone formation was accelerated by ∼1 ppbv/h within PBL under higher temperature, and secondary aerosol was increased due to faster photochemical and heterogeneous oxidation. Such enhancements substantially contributed to air quality deterioration in YRD region. This work reveals the complexity of interactions between natural dust and anthropogenic pollutants through both atmospheric chemistry and meteorological feedbacks, which is of great importance in both regional air pollution and climate.
... Much of the variability in this dust system can be attributed to ENSO as well as to extreme events (land fall of tropical cyclones) (Bryant et al., 2007). 1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 Annual dust storm frequency In China, the record of dust events shows considerable inter-annual and spatial variability, but the regional aggregate (Fig. 12) indicates that their frequency was highest in the 1950s and the 1960s to 1970s, with relatively low frequencies from the 1980s to the 1990s (Wang et al., 2004). The general decline in dust events however masks important sub-regional variations, with a marked increase in dust events in Xinghai Province in the 1980s, suggesting the role of human impact in these areas. ...
Chapter
Aeolian processes, involving erosion, transportation, and deposition of sand and dust by the wind, occur in a variety of environments, including the coastal zone, semi-arid and arid regions (e.g., cold and hot deserts), and agricultural fields in many climates. Changes in climate over the next century are likely to significantly affect aeolian processes globally via changes in precipitation, vegetation cover, wind strength, and sea level. For these reasons, the focus of this chapter is on the response of aeolian processes to climate change and variability on annual to decadal timescales during the period of climate observations, and over the past few centuries, with a look toward the response of these systems to future climate change. Because water is an important limiting factor in most dryland environments, aeolian processes are strongly affected by the amount, type, and temporal and spatial distribution of precipitation, which in turn affect the supply, availability, and mobility of sediment. Dust emissions, sand transport, and dune mobility are all strongly influenced by antecedent precipitation that affects soil moisture and vegetation cover; although specific responses are often complex and non-linear. The future responses can be evaluated via process-response models developed on the basis of empirical studies of the effects of modern climate variability (e.g., drought cycles) on aeolian processes, validated by reference to the geomorphic and sedimentary record of landscape response to late Holocene and historical climate change.
... The occurrence of droughts generally results from many factors, such as meteorological anomalies, solar activity, land surface physical processes, and human activities (van Loon et al., 2016;Zhang et al., 2017). In Northwest China, the impact of human activities (e.g., socioeconomic factors) should never be ignored (Wang et al., 2004;Zhou et al., 2015). ...
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Northwest China is one of the most arid regions in the world and has experienced intriguing climate warming and humidification. Nonetheless , future climate conditions in Northwest China still remain uncertain. In this study, we applied an ensemble of the 12 latest model simulations of the Coupled Model Intercomparison Project Phase 6 (CMIP6) to assess future drought conditions until 2099 in Northwest China, as inferred from the Palmer Drought Severity Index (PDSI). Future drought conditions were projected under three climate change scenarios through the combination of shared socioeconomic pathways (SSPs) and representative concentration pathways (RCPs), namely, SSP126 (SSP1 þ RCP2.6, a green development pathway), SSP245 (SSP2 þ RCP4.5, an intermediate development pathway), and SSP585 (SSP5 þ RCP8.5, a high development pathway). For 2015e2099, drought severity showed no trend under SSP126, in contrast, for the SSP245 and SSP585 scenarios, a rapid increase during 2015e2099 was observed, especially under SSP585. We also found that the drought frequency in Northwest China under SSP585 was generally lower than that under SSP126 and SSP245, although the drought duration under SSP585 tended to be longer. These findings suggest the green development pathway in drought mitigation and adaptation strategies in Northwest China, an arid and agricultural region along the Silk Road.
... An increased aeolian dust concentration during the LGM has been observed elsewhere in Japan (Oba & Pedersen, 1999), China (Wang et al., 2004) and in other parts of the Northern Hemisphere (Harrison et al., 2001). ...
Article
The western coast of India (Kachchh) has ubiquitous preservations of Quaternary carbonate deposits popularly known as “Miliolites”. Field‐based detail documentation of the nature and distribution of miliolites supported by sedimentology and SEM microtextural studies indicates that the miliolites were primarily deposited by wind as aeolinites and are termed “Primary Miliolites (PM)”. These were subsequently fluvially eroded and deposited and such deposits are termed “Secondary Miliolites (SM)”. The PM are dated between 28 ka to 16 ka largely clustering around the Last Glacial Maxima (LGM). In comparison, the fluvially reworked SM occurs as valley‐fill deposits and were deposited episodically during 23 ka to 10 ka before present. Climatically, the deposition of PMs suggests enhanced aridity whereas SMs represent episodic strengthening of the Indian Summer Monsoon (ISM). The bedding attitudes of the PMs indicate that they were deposited predominantly by the northeasterly winds whereas the presence of the deflation lag deposits suggests downwind migration of sands during the equilibrium condition (reduced sediment supply). The aeolian parameters (based on the grain size and wind velocities) for PMs indicate high shear velocity (~ 23 to 48 cms‐1) and high transport rate (<0.1 to 0.2 g/cm‐sec). The short average flying distance implies that the biogenic sands were transported in multiple pulses (from coast to inland) at rates varying from ~200 mhr‐1 to ~1 kmhr‐1. Comparing our data with related occurrences along the biologically productive coasts in the mid‐latitudinal belt indicates that the regional/global aridity during the lowered sea level was responsible for inland occurrences of aeolinites, particularly during the LGM. The strengthened NE monsoon winds during the LGM was conducive to upwelling and production of biogenic carbonates along the coasts. The subsequent reworking of the aeolinites were mainly the results of local variability in precipitation.
... Lake Gonghai is located in the downwind region of the East Asian dust source region. Therefore, it was able to record dust storm activities from the dust source area, which is affected mainly by drought and strong winds (Sun et al. 2001;Wang et al. 2004;Tan et al. 2014;Xu 2017;Guo et al. 2018). In North China, dust storm events had a negative correlation with precipitation (Deng et al. 2013;Wang et al. 2017), and low antecedent winter rainfall led to drought in the following spring, resulting in an increase in DSF (Tan et al. 2014). ...
Article
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Dust storm variations over the past ~230 years were reconstructed on the northeast Loess Plateau using a sediment core from Lake Gonghai. The coarse component of the lake sediments (17.38–109.65 μm) was extracted using the grain size standard deviations method and could be used as a dust storm proxy. The reconstructed results suggest five dust storm peaks: in the 1810s, the late 1850s to the late 1880s, the late 1890s to the early 1920s, ~1950s to the early 1990s, and the late 2000s to the early 2010s. The 1950s–1990s had the highest frequency of dust storms over the past ~230 years, as a result of the combined effects of increased human activities, droughts, and strong winds. Before ~1950, the frequency of dust storms was influenced mainly by natural factors, such as drought events and high intensities of the Siberian High and the East Asian Winter Monsoon. After the 1950s, intensive human activity had a significant impact on dust storms, resulting in a relatively high frequency. However, because of a weakening trend in wind strengths resulting from global warming and ecological rehabilitation projects in North China, the frequency of dust storms has significantly decreased in the past two decades. This study highlights the significant effect of human activities on dust storm generation in Inner Asia and the variations in dust storms under global warming scenarios.
... Lake shrinkage and vegetation degradation have changed the hydrological cycle (i.e., the relationships between groundwater, rivers, and lakes) and exacerbated the deterioration of the ecological environment. Consequently, the livelihoods of many local people have been directly threatened through the occurrence of sand/dust storms, land salinization, landslides, and debris flows among other phenomena (Smith et al., 2016;Sun et al., 2021;Wang et al., 2004). ...
Article
Lakes and vegetation are important components of the hydro-ecological environment and sensitive indicators of anthropogenic climate change and human activities. For the first time, the lake area, vegetation cover change (obtained from Landsat satellite images), terrestrial water storage (TWS; estimated from the gravity recovery and climate experiment), and hydrochemistry, stable isotopes of different waterbodies were combined to analyze the long-term evolution and controlling factors of lake area and vegetation cover in the Nenjiang River basin, China. Between 1985 and 1999, the lake area experienced natural shrinkage due to climatic and hydrological changes, whereas artificial shrinkage related to increased human activities dominated during 2000–2019. The normalized difference vegetation index (NDVI) increased during 1988–1999 and was affected by hydrometeorological factors in the same year and lake area in the previous year. The rate of increase in the NDVI accelerated during 2000–2012 owing to the impact of human activities which is reflected by GDP, and the related artificial shrinkage of the lake area. The main hydrochemical type of lake water changed from Ca-HCO3 before 2000, which was similar to that of river water, to Na–HCO3 after 2000, which was the main hydrochemical type of groundwater. In addition, most of the lake water and groundwater samples were rich in H2SiO3, and a strong correlation between the TWS and lake area for the period 2003–2019 indicated that lake water was strongly affected by groundwater, which was related to deep circulation. Therefore, the decreased river water recharge owing to human activities made groundwater contribute more to lake water. This study can substantially improve the decision-making support for environmental protection and water resource management in ecologically diverse areas, specifically in arid and semi-arid areas.
... Qian et al. (2004) estimated the spatiotemporal distribution of dust storms in northern China, derived from an analysis of rotated orthogonal empirical functions of dust storm data from 1954 to 1998. Wang et al. (2004) state that in dust storms in China, dust can be emitted predominantly by deteriorated grasslands, the Gobi Desert, alluvial and lake sediments, and dry rivers and stream beds located in the surroundings of the deserts. In the case of North America, the dust storm concern has led to studies about the subject. ...
Article
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In arid and semiarid regions from the southwestern USA and vast areas of northwestern Mexico, Santa Ana wind events modify the environment with high temperatures, very low humidity, and dust storms representing a recurrent phenomenon that triggers asthma and other respiratory diseases. While research has emphasized Santa Ana wind effects on the USA side, northwestern Mexico has been less investigated. Numerical modeling of a severe dust storm in November 2018, applying the Weather Research and Forecasting model coupled with a chemistry module (WRF-Chem), revealed that erosion, transport, and dust storms extend along the peninsula and the Gulf of California. Santa Ana winds eroded large areas, transported desert conditions to urban zones, causing high dust concentrations and reducing the relative humidity below 10%, deteriorating climatic conditions favorable to wellness. In Tijuana, Mexicali, Ensenada, San Diego, and Los Angeles, PM10 and PM2.5 concentrations (particle matter with diameter below 10 µm and 2.5 µm) reached values over 2000 µg/m3 for PM10, with daily mean concentrations well above national standards, leading to poor air quality and representing a health threat even in short-term exposure. This Santa Ana event transported dust particles several hundreds of kilometers over urban areas, the Gulf of California, and the Pacific Ocean. Severe soil deterioration was simulated within the study area, reaching dust emissions above 700,000 t, including croplands from the northern part of Baja California and Sonora's coastal area.
... These questions are still needed to investigate and obtain precise figures for future strategies to reduce dust hazards. The DEs in China originate mainly from northwest China (the Taklamakan Desert and Inner Mongolia, IM), MG, and Kazakhstan (Zhang et al. 2003;Wang et al. 2004;Xuan et al. 2004;Shinoda et al. 2011). Approximately 70% of China's DEs originate from southwestern MG (the Gobi Desert and desert steppe) (Zhang and Gao 2007) along the borders of China. ...
... The dataset of dust storm time series in northern China was established about ten years ago, based on a combining criterion of visibility, wind speed, and the weather process [23,24]. It offers high-quality data for many subsequent studies [25][26][27]. (Table 1). Figure 2. ...
... The frequency and intensity of dust storms has been increasing over the past decade [1][2][3]. Forecasts project that their incidence will continue to increase because of both climate change and anthropogenic activities [4]. Dust storms occur from the combination of strong winds and loose dry soil surfaces in arid and semi-arid areas. ...
Article
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Dust storms are meteorological hazards associated with several adverse health impacts including eye irritations, respiratory and cardiovascular disorders, and vehicular road accidents due to poor visibility. This study investigated relations between admissions from a large, public hospital that serves people living in Northern Cape and Free State provinces, South Africa during 2011 to 2017, and meteorological variables (temperature and air quality) during two dust storms, one in October 2014 (spring) and the second in January 2016 (summer), identified from the media as no repository of such events exists for South Africa. Distributed nonlinear lag analysis and wave-let transform analysis were applied to explore the relationships between hospital admissions for respiratory and cardiovascular diseases, eye irritation, and motor vehicle accidents; maximum temperature , and two air quality 'proxy measures,' aerosol optical depth and Ångström exponent, were used as ground-based air quality data were unavailable. Eye irritation was the most common dust-related hospital admission after both dust storm events. No statistically significant changes in admissions of interest occurred at the time of the two dust storm events, using either of the statistical methods. Several lessons were learnt. For this type of study, ground-based air quality and local wind data are required; alternative statistical methods of analysis should be considered; and a central dust storm repository would help analyze more than two events. Future studies in South Africa are needed to develop a baseline for comparison of future dust storm events and their impacts on human health.
... Aus diesen Quellgebieten für Sand und Staub gelangen seit Jahrtausenden große Mengen Sedimente als Staubstürme in die zentralchinesischen Tiefländer (Staubsenken) und bildeten dort das fruchtbare Lößplateau (Pye, 1995). Bedingt durch eine zunehmend intensivierte Landnutzung wandeln sich jedoch diese Senkengebiete zunehmend ebenfalls zu Quellgebiete (Wang et al., 2004). ...
Conference Paper
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Ausgelöst durch die zunehmende Beweidung des semi-ariden Graslandes der Inneren Mongolei schreitet die Bodendegradierung durch Winderosion in diesen Gebieten voran. Verschiedene Parameter zur Beschreibung der Anfälligkeit des Bodens gegen Wind (Erodierbarkeit) wurden auf einer Beweidungsfläche erhoben und Mithilfe des in SAMT (Spatial Analysis and Modeling Tool) eingebunden Fuzzydevelopmenttools miteinander verknüpft. Daraus resultieren eine dauerhaft gültige Erodierbarkeitskarte, die die räumliche und langfristig gültige Verteilung potenzieller Winderosionsgefahr darstellt sowie eine Risikokarte mit Gefährdungsflächen für das Frühjahr 2006.
... Taklimakan desert, the world's second largest shifting sand desert with a total area of 337,000 km 2 , is one of the major source regions of dust storms in China [1], and its surrounding area has already become the most severe dust-storm-affected area due to the high frequency of dust storms [2][3][4]. During the dust storm period, large amounts of sand and dust particles greatly deteriorate air quality and influence people's health, and some viruses and toxic pollutants, such as the heavy metals, bacteria, and poisonous minerals blown by the wind and transported over long distances, are inhaled by people into their respiratory tracts and lungs and cause severe health effects [5][6][7]. ...
Article
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Dust storms have already become the most serious environmental problem on the south edge of the Taklimakan desert because of their frequent occurrences. To investigate the health effects of dust storms on public health in Moyu County, one of the most severe dust-storm-affected areas located at the south edge of the Taklimakan desert, China, primary data were collected from 1200 respondents by using a questionnaire survey for 15 health symptoms. The data were analyzed by comparing the mean tool (independent t-test and ANOVA) and the severity of different symptoms among different age groups. Principal component analysis (PCA) was applied to further analyze the multivariate relationships between meteorological factors, dust storm intensity, air pollution level, and severity degree of the different symptoms. The results show that significant correlations exist between dust storm intensity, air pollutants (PM2.5, PM10, O3, SO2, NO2, and CO), meteorological factors, and health symptoms. During dusty weather, no matter the age group, the number of respondents who suffered from different health symptoms was higher compared to non-dusty days. Three types of dusty days were considered in this study: suspended dust, blowing dust, and sand storms. The impacts of sand storm weather on public health are stronger than those from blowing dust weather, suspended dust weather (haze), and non-dust weather. The people in the age groups above 60 years and below 15 years were more sensitive to different dust weather than people in the age groups between 15 and 60. “Dry throat with bitter taste”, “Depression”, “Dry and itchy throat”, and “Mouth ulcer” are the main symptoms caused by dust storms.
... Dust storms are among the major meteorological disasters currently affecting global climate (Goudie and Middleton, 2006;Uno et al., 2009;Shao et al., 2011;Middleton, 2017) and mainly occur in arid and semiarid areas of the world (Wang et al., 2004;Shao and Dong, 2006;Akhlaq et al., 2012;Wang et al., 2017a). In these areas, the ground surface is exposed and loose material is abundant. ...
Article
Dust storms in Northwest China are a major component of global dust storms and it is important to be able to identify and quantitatively analyze their dust trajectories. In this study, the dust events, sources, and transport paths in the Hexi Corridor were identified using ground-measured PM10 data, Navy Aerosol Analysis and Prediction System (NAAPS) data, the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data. Based on these data, the dust trajectories were then screened. Dust events from five cities in the Hexi region were determined for 2015–2018. Next, five main areas affecting the Hexi region were defined; which included the Gobi region between Xinjiang and Mongolia (XG), Taklimakan Desert (TD), Kumtag Desert (KD), Qaidam Basin (QB), and Badain Jaran and Tengger Deserts (BJTD). We quantified the contributions of the dust trajectories for these five main areas and determined that the major areas that affect the Hexi region are the BJTD and KD, which are located close to the study area. The contribution of the dust trajectories in XG is smaller, owing to its higher vegetation coverage, greater precipitation, and larger particulate matter size. Of the five main areas that affect the Hexi region, the dust intensity in TD is the highest. However, its dust trajectory contribution to the study area is lower. This is because the dust is not elevated to the free atmosphere readily by the easterly wind, owing to the closed mountain basin location. The contribution of the dust trajectories in the QB to the study area is the lowest, mostly due to the low dust intensity in this region and the obstruction of dust trajectories by the Qilian Mountains.
... MAWA sand samplers, d. portable wind tunnel typical environment with lower air temperature and air pressure. The QTP is also one of the potential source areas for outbreaks of dust storms because of the strong wind environments, sparse vegetation cover, and many dried out fluvial, lacustrine, alluvial, and glacial sediments (Wang et al., 2004(Wang et al., , 2016. Therefore, the QTP is an ideal region for studying alpine dust emission. ...
Article
Dust emission is one of the important segments of the circulation of materials between lithosphere, atmosphere, and ocean systems. However, studies on dust emission have mainly concentrated on arid and semiarid regions with few studies focused on dust emission in alpine areas, where having lower air temperatures and lower air pressure environments. The lower air temperature and lower air pressure could significantly impact the air density and make the entrainment and transport of dust different from those at lower altitudes. The lack of accurate studies on dust emission in alpine regions has resulted in large uncertainties in the global dust budget and brought large challenges in controlling aeolian hazards in alpine regions. To bridge this gap, we took the air density as an important parameter to simulate dust emission in the Qinghai-Tibetan Plateau (QTP), where has typical low air-temperature and low air-pressure environments. The measured data showed that the lower air temperature and low air pressure affect the particle size distributions (PSDs) of aeolian sediment, the threshold velocity (TFV) as well as the dust emission rate. Herein, we introduced air density as an important factor to improve a dust emission model, and the validated results showed that the deviations of the simulated horizontal sand flux and vertical dust flux were less than 30% and 35%, respectively. Using the improved model, we could exactly depict the spatial and temporal distribution of dust emission in the QTP. The results shown, our model could exactly depict the spatial and temporal distribution of dust emission in the QTP. We believe that the improvement of the model could offer a new perspective on dust emission in environments with lower air temperature and lower air pressure, and the simulated results could provide valuable data for global dust budget estimation.
... Dust storm frequency has been increasing in central Asia (Goudie and Middleton 1992;Zhang et al. 2020). Some scholars claim that dust storm frequency in this region could be related to precipitation Wang et al. 2004;Tenzin et al. 2016). While others suggest that temperature is the most important factor (Liu et al. 2014;Grigholm et al. 2015;Zhou et al. 2019). ...
Article
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The frequency and intensity of dust storms in Iran has increased significantly in recent years. This study identifies the sources of dust using hybrid algorithms – probability density-index of entropy (PD-IOE), probability density-radial basic function neural network (PD-RBFNN), probability density-self-organizing map (PD-SOM), and probability density-fuzzy ARTMAP (PD-FAM). Hybrid models employed several effective environmental factors: land cover, slope, soil, land use, wind speed, geology, temperature, and precipitation. A random selection of 70% of the data points were used for training the spatial models and the remainder (30%) were used to test the effectiveness of the models to determine the best algorithm. The results reveal that the PD-FAM algorithm produced the most accurate predictions of dust sources. Geology, slope, and soil were the factors that were most effective predictors of dust generation in eastern Iran. Comprehensive management is needed to manage dust production in Iran and these findings may ease identification of locations most likely to produce dust.
... It is a regional name of desert pavement in Asia and mainly distributed in areas that experience strong winds in northwest China and Mongolia (Livingstone & Warren, 1996;Feng et al., 2014). Gobi is a major source area for dust storms in northern China (Wang et al., 2004Zhang et al., 2017), and the intense sediment flux causes serious damage, such as impeding traffic (Cheng et al., 2015;Huang et al., 2019), damaging electrical power system (Zhao et al., 2013), and burying cultural relics (Qu et al., 1997;Zhang et al., 2014). ...
Preprint
Wind-blown sand over sandy gobi with an abundant sediment supply can cause severe sand hazards. However, compared with the study of aeolian transport over gravel gobi with a limited sediment supply, less attention has been devoted to sandy gobi, and thus, our understanding of wind-blown sand movement on sandy gobi is still poor. Here, we report the results of observations of three transport events on a sandy gobi along the Hami-Lop Nor Railway based on high-frequency saltation particle count and horizontal sediment flux measurements coupled with instantaneous wind velocity measurements. The results reveal that, unlike the notably intermittent aeolian saltation over gravel gobi, continuous transport occurred on the sandy gobi. The mean saltation layer height was 0.23 ± 0.07 m, and it was positively related to both the grain size of surface particles and the wind velocity regardless of the gobi type. The sediment transport rates could be expressed as the power function Q ¼ ap/g[u* (u* 2-u*t 2)]b, and the scaling parameter (b) reached to 2.5, which is much larger than that of other gobi areas (b ¼ 1). Our findings suggest that the wind-blown sand over sandy gobi is much more severe than that over gravel gobi, and the Nanhu sandy gobi is the major sand source for sand hazards of the Hami-Lop Nor Railway. Sand-fixation measures such as checkerboard sand barriers with enhanced checkerboard size and barrier height should be the main subject of sand control systems for the Hami-Lop Nor Railway in sandy gobi.
... An increased aeolian dust concentration during the LGM has been observed elsewhere in Japan (Oba & Pedersen, 1999), China (Wang et al., 2004) and in other parts of the Northern Hemisphere (Harrison et al., 2001). ...
Article
The western coast of India (Kachchh) has ubiquitous preservations of Quaternary carbonate deposits popularly known as “Miliolites”. Field‐based detail documentation of the nature and distribution of miliolites supported by sedimentology and SEM microtextural studies indicates that the miliolites were primarily deposited by wind as aeolinites and are termed “Primary Miliolites (PM)”. These were subsequently fluvially eroded and deposited and such deposits are termed “Secondary Miliolites (SM)”. The PM are dated between 28 ka to 16 ka largely clustering around the Last Glacial Maxima (LGM). In comparison, the fluvially reworked SM occurs as valley‐fill deposits and were deposited episodically during 23 ka to 10 ka before present. Climatically, the deposition of PMs suggests enhanced aridity whereas SMs represent episodic strengthening of the Indian Summer Monsoon (ISM). The bedding attitudes of the PMs indicate that they were deposited predominantly by the northeasterly winds whereas the presence of the deflation lag deposits suggests downwind migration of sands during the equilibrium condition (reduced sediment supply). The aeolian parameters (based on the grain size and wind velocities) for PMs indicate high shear velocity (~ 23 to 48 cms‐1) and high transport rate (<0.1 to 0.2 g/cm‐sec). The short average flying distance implies that the biogenic sands were transported in multiple pulses (from coast to inland) at rates varying from ~200 mhr‐1 to ~1 kmhr‐1. Comparing our data with related occurrences along the biologically productive coasts in the mid‐latitudinal belt indicates that the regional/global aridity during the lowered sea level was responsible for inland occurrences of aeolinites, particularly during the LGM. The strengthened NE monsoon winds during the LGM was conducive to upwelling and production of biogenic carbonates along the coasts. The subsequent reworking of the aeolinites were mainly the results of local variability in precipitation.
Article
Long-range transport (LRT) reportedly carries air pollutants and microorganisms to downwind areas. LRT can be of various types, such as dust storm (DS) and frontal pollution (FP); however, studies comparing their effects on bioaerosols are lacking. This study evaluated the effect of LRT on viral and bacterial concentrations in Northern Taiwan. When LRT occurred and possibly affected Taiwan from August 2013 to April 2014, air samples (before, during, and after LRT) were collected in Cape Fugui (CF, Taiwan’s northernmost point) and National Taiwan University (NTU). Reverse-transcription quantitative polymerase chain reaction (RT-qPCR) was applied to quantify influenza A virus. qPCR and qPCR coupled with propidium monoazide were, respectively, used to quantify total and viable bacteria. Types and occurrence of LRT were confirmed according to the changing patterns of meteorological factors and air pollution, air mass sources (HYSPLIT model), and satellite images. Two Asian DS and three FP cases were included in this study. Influenza A virus was detected only on days before and during FP occurred on January 3–5, 2014, with concentrations of 0.87 and 10.19 copies/m³, respectively. For bacteria, the increase in concentrations of total and viable cells during Asian DSs (17–19 and 25–29 November 2013) was found at CF only (from 3.13 to 3.40 and from 2.62 to 2.85 log copies/m³, respectively). However, bacterial levels at NTU and CF both increased during FP and lasted for 2 days after FP. In conclusion, LRT increased the levels of influenza A virus and bacteria in the ambient air of Northern Taiwan, particularly at CF. During and 2 days (at least) after LRT, people should avoid outdoor activities, especially in case of FP.
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Introduced as a soil erosion deterrent, salt cedar has become a menace along riverbeds in the desert southwest. Salt cedar replaces native species, permanently altering the structure, composition, function, and natural processes of the landscape. Remote sensing technologies have the potential to monitor the level of invasion and its impacts on ecosystem services. In this research, we developed a species map by segmenting and classifying various species along a stretch of the Lower Gila River. We calculated metrics from high-resolution multispectral imagery and light detection and ranging (LiDAR) data to identify salt cedar, mesquite, and creosote. Analysts derived training and validation information from drone-acquired orthophotos to achieve an overall accuracy of 94%. It is clear from the results that salt cedar completely dominates the study area with small numbers of mesquite and creosote present. We also show that vegetation has declined in the study area over the last 25 years. We discuss how water usage may be influencing the plant health and biodiversity in the region. An examination of ground well, stream gauge, and Gravity Recovery and Climate Experiment (GRACE) groundwater storage data indicates a decline in water levels near the study area over the last 25 years.
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A challenge for understanding the environmental fate of atmospheric organic acids is to evaluate the impacts of their heterogeneous interactions with mineral dust aerosols in the atmosphere. However, the uptake of organic acids on authentic natural mineral dust is rarely investigated under atmosphere-relevant conditions. Herein, we investigated the uptake of acetic acid (AcA) onto a natural mineral dust from the Gobi desert, Gobi dust, under atmosphere-relevant conditions, combining both the gas-phase and adsorbed-phase approaches. Gobi dust is evidenced to reversibly and irreversibly adsorb AcA molecules under both dry and humid conditions. In the presence of moisture, the fraction of the reversibly adsorbed AcA is promoted, which addresses the impact of water molecules with AcA on minerals. Physisorbed AcA monomer, dimer and chemisorbed acetate are identified based on real-time surface monitoring using DRIFT spectroscopy. This study provides original data and insights on the impacts of heterogeneous interactions with mineral dust on the environmental fate of acetic acid. It also provides complete and visual mechanisms for a comprehensive understanding of the involved surface reactions. This study initiates the exploration of the heterogeneous kinetics of the fractions of reversibly and irreversibly adsorbed AcA on natural mineral dust under atmospheric conditions.
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The distribution and transportation characteristics of dust aerosol over the Tibetan Plateau (TP) and Taklimakan Desert (TD) were analyzed during 1980–2017 using MERRA-2 (second Modern-Era Retrospective analysis for Research and Applications) and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) products. The aerosol optical depth (AOD) of MERRA-2 were compared with those of AERONET (Aerosol Robotic Network) at six sites and the corresponding MISR (Multi-angle Imaging SpectroRadiometer) data. The correlation coefficients were 0.73–0.88 and 0.94, respectively. The yearly AOD over the IGP (Indo-Gangetic Plain) and the TD showed a significant increasing trend. The variations of seasonal AOD and dust AOD (DAOD) over the research region were similar, showing the values decreasing from north to south and the higher values appearing in spring and summer. The DAOD/AOD ratio exceeded 0.5 during March–August and throughout whole year in the north part of the TP and the TD, respectively. The duration, strength and area of the high DAOD region over the TD have enhanced during the past 38 years. From the CALIPSO observation, it showed the dust moving from the TD to the TP was mainly through the Qaidam Basin in the layer of 4–8 km aloft and could transport as south as 30°N, with the maximum lifting height in spring. In winter, the dust over TP was mainly from the Qaidam Basin due to the suppression effect of the inversion layer over the TD. The largest profile of dust extinction coefficient appeared in spring over the TD, while in summer over the TP. The distribution and annual regional averages of base, top and thickness of dust layer were calculated and presented. It shows a long-standing dust layer of about 1 km appearing over the TP with the maximum in spring.
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Dustfall samples from the western Chinese Loess Plateau (CLP) were collected from 2013 to 2016 at Jiuzhoutai for dustfall variation analysis. Results showed that the seasonal dustfall variations were non-significant in the region, indicating dustfall sources with inconsistent patterns largely contributed to the modern loess formation. The average rate of loess accumulation was approximately 0.34 mm/year, which is much higher compared to the other periods of the Holocene. In addition, the lack of regular patterns of dustfall contents in the coarse fraction (> 50 μm in diameter) indicates a proximal source with crustal origins, which is a dominant source for the modern loess. From 2013 to 2016, the dustfall from crustal origins increased by approximately 19%, and among those collected dustfall, approximately 24% came from pollutants, indicating that anthropogenic activities such as industrial pollutants and vehicle emissions played an important role in modern loess accumulation.
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Natural disasters such as dust storms are random phenomena created by complicated mechanisms involving many parameters. In this study, we used copula theory for bivariate modeling of dust storms. Copula theory is a suitable method for multivariate modeling of natural disasters. We identified 40 severe dust storms, as defined by the World Meteorological Organization, during 1982–2017 in Yazd province, central Iran. We used parameters at two spatial vertical levels (near-surface and upper atmosphere) that included surface maximum wind speed, and geopotential height and vertical velocity at 500, 850, and 1000 hPa. We compared two bivariate models based on the pairs of maximum wind speed–geopotential height and maximum wind speed–vertical velocity. We determined the bivariate return period using Student t and Gaussian copulas, which were considered as the most suitable functions for these variables. The results obtained for maximum wind speed–geopotential height indicated that the maximum return period was consistent with the observed frequency of severe dust storms. The bivariate modeling of dust storms based on maximum wind speed and geopotential height better described the conditions of severe dust storms than modeling based on maximum wind speed and vertical velocity. The finding of this study can be useful to improve risk management and mitigate the impacts of severe dust storms.
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The Tibetan Plateau experienced severe aeolian desertification during the mid‐ and late 20th century, but mitigation of this aeolian desertification has occurred since the 2000 despite a warming climate. The causes of these changes have been debated by scientists because of their potentially huge significance for China and Asia, as well as for global climate systems. Based on a review of previous studies and our own investigations, it appears that aeolian desertification from the 1970s to the 2000 was caused primarily by unsustainable and irrational human activities, and its mitigation since the 2000 was mainly attributable to a warmer and wetter climate, combined with decreasing wind intensity, for the plateau as a whole. However, the dominant factors for mitigation varied spatially. The government's ecological protection projects have been constructed in some places with dense population, and played a key role in the mitigation in these places. The plateau's climate will likely become warmer and wetter in the 21st century based on Coupled Model Intercomparison Project Phase 5 model simulations. If the simulation results are credible, mitigation of aeolian desertification will continue in the 21st century due to a combination of continuing grazing exclusion and rotational grazing, even without artificial revegetation. This article is protected by copyright. All rights reserved.
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A low‐level barrier jet (LLBJ) formed along the northeast slope of the Tibetan Plateau on 17 March 2010. The LLBJ was accompanied by a major dust event. Numerical simulations conducted with the Weather Research and Forecasting dust (WRF‐Dust) model show that the formation of the LLBJ was primarily due to mid‐level, southeastward descent of high momentum air, which impinged on the north slope of the Tibetan Plateau, resulting in ageostrophic flow acceleration under geostrophic adjustment. The LLBJ was reinforced by the Bernoulli effect, where the physical barrier associated with the Tibetan Plateau to the southwest and the virtual barrier associated with sloped, packed isentropic surfaces to the northeast combined to constrict the air flow, thus augmenting the acceleration of the air as it entered the Hexi Corridor. The simulations show that the LLBJ, which stayed close to the western entrance of the Hexi Corridor, gradually descended during the daytime until early evening. During this period, the core of the LLBJ stayed directly above the 302‐K isentropic surface. The LLBJ, which was located to the south of the main dust plume, was modulated by dust‐radiative heating and cooling. Over the main dust plume, as well as in the LLBJ region, radiative heating of the dust warmed the upper part of the boundary layer and cooled it below, which stabilized the boundary layer, decreased the boundary layer depth, and reduced the vertical mixing, causing the surface winds to weaken. As a consequence of the feedback between the circulation and the dust radiative forcing, the total dust emission was reduced by ~9.7‐11% and peaked 1‐2 hours earlier than without dust radiative effects, while the LLBJ’s intensity, which was 1‐2 m/s stronger, was better maintained within the boundary layer during the daytime until early evening. This article is protected by copyright. All rights reserved.
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The Chaoyang profile represents a rare multi-period, continuous and complete sequence of aeolian paleo-deposits with a stable sedimentary origin and multi-stage paleoclimatic cycles. Benchmark profiles including soil types at different pedogenic stages can be used for the recognition and classification of paleosols and paleoclimate reconstruction. The loess–paleosol sequence benchmark profile (LBP) is also helpful in comparing the results of paleoenvironment reconstruction from different ecological regions. In this study, a loess–paleosol profile derived from thick loess in Chaoyang city of Liaoning province, Northeast China, was investigated as a well-preserved LBP that included various paleosol types. To determine the nature and origin of the Chaoyang profile, the geographic, stratigraphic and morphological characteristics were described in the field. Bulk samples from 42 horizons were collected for chemical and physical analysis, and sub-sampling of 946 samples at 2 cm intervals from the surface to the bottom were taken to measure grain size distributions and magnetic susceptibility. Results showed that the 19.85 m thick loess–paleosol profile had been continuously deposited since 423 ka BP. The upper part (0–195 cm), or UPP, was predominantly of aeolian loess deposition origin but was mixed with water-reworked materials from a nearby secondary loess source. The middle part (195–228 cm), or MIP, was also indirectly affected by the water-reworking process through the leaching of materials from the overlying UPP. The lower part (228–1985 cm), or LOP, was characterized by four reddish stratigraphic layers interbedded with five yellowish ones, indicating several types of paleosols developed under different ecological environments. The multi-stage paleoclimatic cycles as evidenced by morphological and physical characteristics as well as age dating and magnetic susceptibility correlated well with the Lingtai section and LR04 benthic δ18O. Because of these attributes, the Chaoyang profile can be deemed as a benchmark loess–paleosol profile for the recognition and classification of paleosols and paleoclimate reconstruction in Northeast China. The differences in morphological and physical properties between paleosols and loess suggest different soil fertility and agronomic properties and need further studies to assess their functionality with climate fluctuation.
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The annual precipitation over the Tianshan Mountains experienced an inter‐decadal transition shift towards an increasing trend in the late 1980s. This study conducts attribution analysis from atmospheric circulation factors based on the Global Precipitation Climatology Centre (GPCC) dataset and NCEP/NACR reanalysis data. The results show that (1) Winter precipitation in the Tianshan Mountains is affected by multi‐decadal oscillations with periods of 26.8 and 44.7 years, and has entered a period of positive anomalies after 1988. Although the non‐linear trend of winter precipitation in the Tianshan Mountains firstly increased and then decreased after 1979, the multi‐decadal fluctuation of precipitation caused the Tianshan Mountains in winter to be in a wet period from the 1980s until 2011. (2) We find that the East Atlantic‐West Russia (EATL/WRUS) teleconnection pattern has a similar multi‐decadal variability as Tianshan precipitation in winter. The wet period of Tianshan in winter after 1988 is mainly due to the enhanced meridional feature of the EATL/WRUS triggering more water vapour flux from low‐latitude oceanic areas. (3) Summer precipitation in the Tianshan Mountains has an obvious multi‐decadal scale of 33.5 years and shows a non‐linear growth trend. Tianshan Mountains in summer entered a humid period after 1986. (4) The Scandinavia (SCAND) teleconnection pattern represents important circulation variability affecting Tianshan summer precipitation. The vigorous high pressure over the Ural Mountains and the low pressure over Central Asia during the SCAND negative phase in summer jointly lead to enhanced moisture transport from the Arctic Ocean to the Tianshan Mountains. (5) Apart from SCAND, the Silk Road pattern (SRP) and East Asia‐Pacific teleconnection (EAP) also impacted Tianshan summer precipitation during the periods 1964‐1984 and 1985‐2004. This article is protected by copyright. All rights reserved.
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The dynamic process of dust emission from gobi is a largely un-solved scientific question while it is essential for minimizing the dust hazards. In this study, field wind tunnel experiments have been performed to reveal the processes of dust emission from gobi on the top of the Mogao Grottoes. We found that the dust content of gobi is the dominant factor that determines the intensity of dust emission. The vertical PM10 flux increased exponentially with the increase of dust content on the gobi surface at a given wind speed. The impact energy of saltating particles is another control factor of the dust emission flux. The vertical PM10 flux due to saltation bombardment of the external sand supply was 5–13 times larger than that without the bombardment of sand supply. This study indicates that gobi on the top of the Mogao Grottoes is one of the main dust sources as it has an abundance of sand supply from Mingsha Mountain as well as its richness in dust content. Hence, it is imperative to expand the existing sand control system on the top of the Mogao Grottoes in order to minimize the impact of dust hazards on the Mogao Grottoes.
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The behavior and fates of environmental pollutants within the cryosphere and the associated environmental impacts are of increasing concerns in the context of global warming. The Tibetan Plateau (TP), also known as the "Third Pole", represents one of the most important cryospheric regions in the world. Mercury (Hg) is recognized as a global pollutant. Here, we summarize the current knowledge of Hg concentration levels, pools and spatio-temporal distribution in cryospheric environments (e. g., glacier, permafrost), and its transfer and potential cycle in the TP cryospheric region. Transboundary transport of anthropogenic Hg from the surrounding heavily-polluted regions, such as South and Southeast Asia, provides significant sources of atmospheric Hg depositions onto the TP cryosphere. We concluded that the melting of the cryo-sphere on the TP represents an increasing source of Hg and brings a risk to the TP environment. In addition, global warming acts as an important catalyst accelerating the release of legacy Hg from the melting cryosphere, adversely impacting ecosystems and biological health. Furthermore, we emphasize on the remaining gaps and proposed issues needed to be addressed in future work, including enhancing our knowledge on some key release pathways and the related environmental effects of Hg in the cryospheric region, integrated observation and consideration of Hg distribution, migration and cycle processes at a key region, and uses of Hg isotopic technical and Hg models to improve the understanding of Hg cycling in the TP cryospheric region.
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Introduction Payments for Ecosystem Services (PES) programs have been implemented globally to protect ecosystems while securing the well-being of affected people. Reasonable payment standards hold the key to successful PES programs. Although some approaches are available for determining payment standards, few studies have applied them for grassland conservation with location indicators and socioeconomic contexts properly considered.Methods Using China’s first pilot Grassland Ecological Compensation Policy (GECP) as an example, we analyzed the effects of payment levels, other natural and socioeconomic factors on herders’ willingness to participate in the GECP in Damao County in Inner Mongolia where grassland degradation is happening at an alarming rate due to overgrazing and cropland expansion.Outcomes Our results show that households with lower herding income, older age, higher education, larger grassland areas, and worse social relationships are more inclined to participate in the GECP. Conservation payment level, as well as natural and socioeconomic contextual factors, significantly affect the response of herdsmen, and a reasonable grassland payment standard with a 95% policy compliance rate should be 8.8 yuan mu−1.Discussion and Conclusion Our findings can inform governments to develop effective PES programs to balance the need of human well-being improvement and grassland conservation in China and beyond.
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Study region Chahannur Lake, an inland lake of the Inner Mongolia Plateau, is located in the typical agro-pastoral ecotone, China. Study focus Change of lake area is highly sensitive to climate change and human activities, but the internal driving mechanism so far remains unclear. In this study, the spatiotemporal distribution of Chahannur Lake over the past 30 years was accurately extracted using the NDVI data, and the corresponding driver analysis was conducted. New hydrological insights for the region Before 2000, Chahannur Lake was always remaining watery state throughout the year and the maximum area reached 90 km²; however, after 2000 it became a seasonal lake with a long-term dry state. During the observed period, the recovery of water body had only occurred in two stages both of which belonged to historically heavy rain years, and the maximum lake area was only 40 km². Although the climate has tended to be warm and humid after 2000, it cannot completely reverse the lake’s drying. Additionally, the irrigated arable increased by 392 km² in 2000–2017, and the increased arable consumed substantial groundwater for meeting agricultural demands, which consequently caused rapid shrinkage of the Lake. Notably, the increase of NDVI is widely distributed in irrigated arable with high water-consuming crops. Overall, groundwater over-exploitation and strong water consumption from crops have jointly led to the drying of Chahannur lake.
Article
Wind-blown sand over sandy gobi with an abundant sediment supply can cause severe sand hazards. However, compared with the study of aeolian transport over gravel gobi with a limited sediment supply, less attention has been devoted to sandy gobi, and thus, our understanding of wind-blown sand movement on sandy gobi is still poor. Here, we report the results of observations of three transport events on a sandy gobi along the Hami-Lop Nor Railway based on high-frequency saltation particle count and horizontal sediment flux measurements coupled with instantaneous wind velocity measurements. The results reveal that, unlike the notably intermittent aeolian saltation over gravel gobi, continuous transport occurred on the sandy gobi. The mean saltation layer height was 0.23 ± 0.07 m, and it was positively related to both the grain size of surface particles and the wind velocity regardless of the gobi type. The sediment transport rates could be expressed as the power function Q = ap/g[u∗ (u∗2-u∗t2)]b, and the scaling parameter (b) reached to 2.5, which is much larger than that of other gobi areas (b = 1). Our findings suggest that the wind-blown sand over sandy gobi is much more severe than that over gravel gobi, and the Nanhu sandy gobi is the major sand source for sand hazards of the Hami-Lop Nor Railway. Sand-fixation measures such as checkerboard sand barriers with enhanced checkerboard size and barrier height should be the main subject of sand control systems for the Hami-Lop Nor Railway in sandy gobi.
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Sand and dust storms (SDS) have long been considered as a type of disastrous weather. Minimizing the severe influence of SDS on the environment and human life has been the focus of many studies. In this paper, we report the principles and characteristics of SDS while mainly focusing on the monitoring technologies of the natural disaster. Space- and ground-based monitoring are two types of technologies widely used in SDS monitoring. The space-based monitoring technologies mainly refer to the satellite remote sensing technologies, which are able to obtain large-scale accurate ground monitoring within a few days. The ground-based monitoring technologies typically perform short-range and small-scale ground monitoring within a specific area. In recent years, artificial intelligence (AI) has been applied in SDS monitoring to solve the existing limitations in SDS monitoring by improving the accuracy and efficiency of the monitoring and prediction results. Although the applications of AI in SDS sensing and prediction are still at an early stage, AI-enabled hybrid systems are envisioned as a major developing trend for SDS monitoring in the future.
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The dust storm of April 14-17, 1998 in China was mainly associated with the frontal systems and the Mongolia cyclonic depression, which caused heavy dust fall at Beijing on April 16. In nearly fifteen hours, approximately 38.3 g/m² of dust fell on Beijing. This dust storm was of strong intensity, long duration, and with a wide coverage; it not only affected southern Mongolia and the central and southeastern China, but also the North Pacific Ocean. The source areas of the dust storm were from the Gobi areas of southern Mongolia and the Gobi and desert areas of Inner Mongolia, China. This dust storm is a good example of long-range transport and deposition of airborne materials, which provides a useful analogue for studying the dust sources and deposition in the geological record.
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Compilation and analysis of the past 40 years of dust storm reports from China allow estimation of the meteorological conditions of dust storms, dust transport routes, and eolian source regions. Our results indicate that dust storms in China are highly associated with the frontal systems and the Mongolian cyclonic depression. The spatial distribution of dust storms indicates that there are two dominant source regions of eolian dust raised from China and its surrounding regions. The major source is the gobi deserts in Mongolia and northern China. Another source region is the Taklimakan Desert in western China. However, dust entrained from the two sources makes different contributions to downwind deposition regions. In most cases, dust materials entrained from the gobi deserts of Mongolia and China can only be entrained to an elevation of 5000 m and then transported over long distances (~5000 km) by the westerlies. These materials are not the main sources of the dust deposited in the proximal region, such as the Chinese Loess Plateau, but they are important sources of the eolian fraction of pelagic sediment in the remote North Pacific Ocean.
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Results of a comparative analysis of a 4-year set of monthly samples of airfall dust with samples from surface alluvial fan deposits, desert sand dunes and late Pleistocene loess and palaeosols in Gansu Province, northern China, are summarized. They suggest a qualification of the conventional view that the sand deserts were the primary single source of the Quaternary loess. It is argued that silts deflated from the surfaces of the large and numerous piedmont alluvial fans in the Hexi Corridor, Gansu, constituted a major contribution to the loess column in the western region of the Chinese Loess Plateau. The present dust fall regime in the Hexi Corridor suggests that distribution and rate of accumulation of airfall silt in the present interglacial is similar to that in parts of the Pleistocene loess record.
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Entrainment, transport and deposition of dust in and around deserts has major geological implications. A consideration of the mechanics of dust transport and deposition shows that 'desert loess' can only accumulate in vegetated desert fringe areas which are relatively close to a major source of dust. Dust deposition can also contribute to the stabilization of active sand dunes, and infiltrated dust plays an important role in the early diagenesis of a wide range of desert sediments.
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The average mass concentration of the aerosols in Beijing during the dust storm in the spring of 2000 was ∼6000 μg · m−3, ∼30 times as high as that in the non-dust storm days. The enrichment factors of the pollution elements As, Sb and Se were higher than those in the non-dust storm days. This indicated that As, Sb and Se resulted from the pollution sources of those areas, through which the dust storm passed during their long-range transport, in addition to the local pollution sources in Beijing. The enrichment factors of the Pb, Zn, Cd and Cu were much less than those in the non-dust storm days, suggesting that the local pollution sources in Beijing area contributed to them mostly. The enrichment factors of elements Al, Fe, Sc, Mn, Na, Ni, Cr, V and Co were close to 1, showing that these elements originated from crust. The concentration of S in the dust storm was ∼10 μg · m−3,4 times as high as that in non-dust storm. S in the aerosols resulted from the adsorption of gaseous SO2 and the consequent transformation on it. The aerosols of the dust storm contained 16.1% and 76.9% of fine particles with the sizes less than 2.1 and 9.0 μm, respectively, while it had a large number of coarse particles. It was noted that a considerable portion of Fe(II) was detected from the dust storm. Fe(II) could easily dissolve in seawater to be nutrient for phytoplankton and would lead to the increase of the emission of dimethylsulfide (DMS) from the ocean. The feedbacks of Fe coupled with S in atmosphere might be the important mechanism that would affect the primary productivity in Pacific and/or the global climate change.
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Sand-dust storm is a special natural disaster that frequently occurrs in deserts and their surrounding areas. With the data published on Surface Meteorological Monthly Bulletin and Surface Chart during 1971-1996, the temporal-spatial distribution and annual variation of sand-dust storms are analyzed on the basis of the case study of atmospheric process. Furthermore, the tracks and source areas of sand-dust storms are determined assisted with GIS. The results show: Except parts of Qinghai Province, Inner Mongolia and Beijing, the sand-dust storms decrease greatly both in time and space in recent decades in China. Sand-dust storms occur most frequently in spring, especially in April. According to their source areas, the sand-dust storms are classified into two types, i.e. the inner-source and outer-source sand-dust storms. Most of the outer-source sand-dust storms move along the north and west tracks. For the north-track outer-source sand-dust storms, they always intrude into China across the Sino-Mongolian boundary from Hami, a city in the eastern part of Xinjiang, to Xilin Gol, a county in Inner Mongolia, while the west-track ones intrude into China both from southern Xinjiang and northern Xinjiang. The source areas of inner-source sand-dust storms are the Taklimakan Desert and its surrounding areas in southern Xinjiang, southern part of the Junggar Basin in northern Xinjiang, Hexi Corridor in the west of Gansu Province, the dry deserts of Inner Mongolia and the Qaidam Basin in Qinghai.
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In this paper, the daily 850 hPa geopotential high data of NCEP/NCAR reanalysis for 1948 ~ 1999 are used to find the vortex fluctuations, which represent daily cyclone activity in northern China. Three data sets, the grid cyclone frequency for 1948 ~ 1999, the 160-station temperature and precipitation for 1950 ~ 1998 are used to calculate the correlation with the 338-station dust-day frequency for 1954 ~ 1998 in China's mainland. The result shows that the frequency of dust-day is strongly corresponded with the low air-temperature in winter and cyclone activity in spring. Based on this relationship, an index describing dust-day frequency has been formulated. This dust index can well calibrate against the variability of dust-day in northern China, except for Xinjiang region in Northwest China.
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The mass-particle size distributions of 10 dust-carrying elements in aerosol particles were determined for 12 sites in desert regions of northern China. The desert dust is proved to be of origin of eolian loess deposited on the Loess Plateau. Their transport to the loess was mainly attributable to the non-dust storm processes under the interglacial climate condition. The impact of dust storm on the accumulation of the loess increased in the glacial stage. On the basis of the signatures of 4 dust elements (Al, Fe, Mg and Sc), Chinese dust is believed to have 3 major desert sources (northwestern deserts, northern high dust deserts and northern low dust deserts). With a chemical element balance model, an elemental tracer system is established to proportion the export of China-source dust.
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In previous studies, limited meteorological observations were used to investigate the temporal-spatial changes of dust storms in China. Here, the authors use the daily 850-hPa geopotential height of NCEP-NCAR reanalysis for 1948-99 to examine the vortex fluctuations, which represent daily cyclone activity in east Asia. They also use the 1000-hPa air temperature data to explain the decadal change of the cyclone activity. In addition, the grid cyclone frequency for 1948-99 and the temperature and precipitation for 1950-98 are used to calculate the correlation with the dust weather frequency (for 1954-98) in China.Results show that the interannual variability and long-term trend among dust storm frequency, dust weather frequency, air temperature, and cyclone frequency exist in northern China. In the eastern part of China, the frequencies of dust storms and dust weather in the 1950s-70s were about twice that after the mid-1980s. The reason for this feature may be due to the warming in Mongolia and cooling in northern China that reduced the meridional temperature gradient, resulting in the reduced cyclone frequency in northern China. In the Tarim Basin, the high-frequency dust storms have been attributed to less precipitation and to the arid-heating climate.The frequency of dust storms (dust weather) is strongly related to the low air temperature in the prior winter season and the high-frequency cyclone activity in the spring season for most parts of eastern China. Based on this relationship, an index describing the dust weather (dust storm) frequency has been formulated. This index can well calibrate the variability of dust weather (dust storms) in northern China, except for the Xinjiang region in far northwest China.
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This paper present the sixteen types of drilling fluid chemicals manufactured in china and describe some important chemicals in detail. The consumption of drilling fluid chemicals is listed on different types for each year. The tendency of consumption of chemicals is analyzed. According to API Classification of drilling fluid and characteristics of Chinese drilling fluid application, drilling fluids are classed in nine types. Explanation and formulations of nine types of drilling fluid are presented in this paper. The recent development of drilling fluids is presented in this paper. The recent development of drilling fluid chemicals and drilling fluid systems is analyzed. The mechanism and formulation of these new drilling fluids are presented. Nowadays, drilling fluid chemicals manufactured in china can satisfy the native market, some of them are exported to abroad market. Introduction The petroleum industry in China has gotten big development. In 1999, the total production of CNPC, SinoPEC and CNOOC in China had been 159,836,000 tons and the total drilling footage had reached 2466,900 meters (see table 1). Therefore the large quantity of drilling fluid chemicals are needed in drilling engineering. The development of drilling fluid chemicals can be classed as two stages. Before 1980s, the drilling fluid chemicals are introduced from foreigner country oil company and some similar chemicals are produced. Some chemicals used in civil engineering, such as CMC, starch, are introduced into drilling fluid. After 1980s, according to requirement of drilling engineering and geological characteristics in china, some new chemicals are developed and manufactured. Tendency of drilling fluid chemicals is that simple natural products are improved into modified products and natural products are replaced by synthetic products gradually. The non-dispersed polymer drilling fluid is main drilling fluid system in China. Classifications of drilling fluid chemicals The sixteen types of drilling fluid chemicals manufactured in china and some important chemicals are discribed as follow in detail. The consumption of drilling fluid chemicals is listed on different types for each year. Clay In early time, clay used in drilling fluid is natural bentonite. The bentonite is calcium based with low quality, resulting low viscosity and high filtrate. In recent decades, the bentonite is improved into high quality bentonite. Some of them can be used as API bentonite. Other kinds of clay, such as attapulgite, organic clay, are developed out for petroleum industry. Weighting Materials Main materials for increasing density of drilling fluid are barite, hematite, calcium carbonate. Various salts are solved into drilling or completion fluid for increasing density. Filtrate Reducer There are more than 50 trade brands of filtrate reducer in China. The consumption annually reaches over 30,000 tons. All these filtrate reducers can be arranged in 6 kinds. Carboxymethyl cellulose Including CMC-low viscosity, CMC-median viscosity and caustic CMC. Generally the degree of substitution is more than 0.5 and the degree of polymerization is 200?6000. Hydrolyzed polyacrylonitrile Including sodium salt(Na-HPAN), calcium salt (Ca-HPAN) and ammonium salt (NH 4-HPAN). The molecular weight is 20,000?110,000, the degree of polymerization is 235?376 and the degree of hydrolysis is 60%. Polymer with median molecular weight copolymer (PAC143, PAC142) of acrylamide and acrylate. Multiply- polymer (Sk-I, PAC144, JT888) of acrylamide, acrylate, acrylonitrile, acrylsulphonate and quaternary amine.
Article
Vast belts of forest planted across the northern arid lands of China, called ``The Great Green Wall,'' are probably one of the most aggressive weather modification programs in the twentieth century. The purpose is to reduce eolian transport of dust from the Gobi Desert. Preliminary data indicate a negative trend in dust-storm frequency and duration since the 1960s. Effects on atmospheric radiation and cloud microphysics appear to be statistically insignificant in the studied period. However, only time can show any long-term impact on our environment.
Article
Estimates of atmospheric dust deposition to five Asian/Pacific regions indicate that -800 Tg of Chinese desert dust is injected into the atmosphere annually; about 30% of this is redeposited onto the deserts, 20% is transported over regional scales, primarily within continental China. The remaining 50% of the dust is subject to long-range transport to the Pacific Ocean and beyond. Elemental tracers based on several dust- derived elements (A1, Fe, Mg, and Sc) reveal high-frequency variability in the contributions of the western desert sources versus northern high-dust and low-dust desert sources to eolian deposits from the center of the Loess Plateau. Comparisons of the patterns uncovered with climate signals from the remote North Atlantic region for the last glaciation show that shifts in source areas of Asian dust were synchronous with large-scale variations in atmospheric circulation.
Article
The dimension and environmental impact of the dust storm phenomenon has been realized only recently. There are few previous works on the climatic control of dust storm frequency, especially in the field of time series analysis. Actually, there is a poor correspondence of climatic parameter mean values and dust storm data. Although generally negative, rainfall — dust-storm correlations do not reveal the physical causes of dust storm generation, as is shown by lagged cross-correlation and spectral analysis. Temperature data may indicate seasonal variation of dust storms by extreme values, but they are no reliable defining factor owing to high persistence over shorter time series. The same is found for mean wind speeds, but negative interrelations with atmospheric pressure point to the importance of cyclogenesis and convective cells in dust storm generation in Asia. Three different seasonality patterns are described: (i) a single dust storm maximum in spring typical of summer rain areas; (ii) a single storm maximum in summer in areas with bimodal (winter and monsoonal) rainfall; (iii) an extended spring and summer dust storm maximum in areas with unimodal winter rains. Additional data from northern Africa fit into this pattern. Spectral energy of dust storm, rainfall, and temperature series for northern India and northern China (1976–1986) is mainly concentrated in the wavelength of seasonal variations, but some supra-seasonal signals indicate fluctuations between 3·6 and 5·5 years with various phase dislocations. In China, this interannual variability is supposed to be linked with dynamic shifts in circumpolar vortex dynamics.
Article
The mass-particle size distributions (MSDs) of 9 elements in ground-based aerosol samples from dust storm (DS) and non-dust storm (N-DS) periods were determined for 12 sites in 9 major desert regions in northern China. The masses of the 9 elements (Al, Fe, K, Mg, Mn, Sc, Si, Sr and Ti) in the atmosphere were dominated by local mineral dust that averaged 270 μg m−3, and the MSDs for the elements were approximately log-normal. On the basis of Al data, the < 10 μm particles account for ∼84% of the total dust mass over the deserts. Model-calculated (“100-step” method) dry deposition velocities (Vd) for the 9 dust-derived elements during N-DS periods ranged from 4.4 to 6.8 cm s−1, with a median value of 5.6 cm s-1. On the basis of a statistical relationship between D99% (the dust particle diameter corresponding to the uppermost 1% of the cumulative mass distribution) and Vd, one can also predict dry velocities, especially when D99% ranges from 30 to 70 μm. This provides a simple way to reconstruct Vd for dust deposits (like aeolian loess sediments in the Loess Plateau). The estimated daily dry deposition fluxes were higher during DS vs. N-DS periods, but in most cases, the monthly averaged fluxes were mainly attributable to N-DS dust. Two regions with high dust loading and fluxes are identified: the “Western High-Dust Desert” and the “Northern High-Dust Desert”, with Taklimakan Desert and Badain Juran Desert as their respective centers. These are energetic regions in which desert-air is actively exchanged, and these apparently are the major source areas for Asian dust.
Article
Sand-dust storm is a special natural disaster that frequently occurs in deserts and their surrounding areas. With the data published onSurface Meteorological Monthly Bulletin andSurface Chart during 1971–1996, the temporal-spatial distribution and annual variation of sand-dust storms are analyzed on the basis of the case study of atmospheric processes. Furthermore, the tracks and source areas of sand-dust storms are determined with the aid of GIS. The results show that except some parts of Qinghai Province and Inner Mongolia as well as Beijing, sand-dust storms decrease apparently in time and space in recent decades in China. Sand-dust storms occur most frequently in spring, especially in April. According to their source areas, sand-dust storms are classified into two types, i.e., the inner-source and outer-source sand-dust storms. Most of the outer-source sand-dust storms move along the north and west tracks. The north-track outer-source sand-dust storms always intrude into China across the Sino-Mongolian border from Hami, a city in the eastern part ofXinjiang, to Xilin Gol, a league in Inner Mongolia, while the west-track ones intrude into China from both southern and northern Xinjiang. The source lands of inner-source sand-dust storms concentrate in the Taklimakan Desert and its surrounding areas in southern Xinjiang, southern part of the Junggar Basin in north of Xinjiang, the Hexi Corridor in western Gansu Province, the dry deserts of Inner Mongolia and the Qaidam Basin in Qinghai.
Article
Systematical analyses of spring sandstorms in 2000 affecting Beijing area are carried out. Results revealed the key dynamic mechanisms of dust storm during its mobilization, lifting, horizontal advection and deposition processes. It turns out that in the processes of sandstorms influencing Beijing area in March–April 2000, the dynamic conditions for dust mobilization are significantly correlated with phenomena, such as cold air-related climatic activities, clay soils area of North China and surface friction velocity anomaly. The characteristics of sandstorm can be described by composite mode of dust particles mobilization-lifting-long-range transport. This paper will provide scientific evidences for further studies, prediction and harness of sandstorms in China.
Article
This paper deals with mineral dust emission inventory from surfaces of Northern China. The inventory was calculated with a US EPA formula by inputting the pre-processed Chinese data of pedology and climatology. Mainly, the emission factor (emission rate) of the dust particles whose diameters are less than 0.03 mm increases from east to west of the area by five orders of magnitude and there are two strong emission regions, one is in Takelamagan desert, Xinjiang Province, and the other in Central Gobi-desert, western part of inner-Mongolia plateau. The maximum rate is at center of the Takelamagan desert, i.e., 1.5 ton ha yr−1. Also, the total annual emission amount of the area is equal to some 25 million tons, and spring is the worst dust-emitting season in the area, which takes more than half of the annual emission amount. The results are in good agreement with the previous calculations using a different US EPA formula (Xuan, J., 1999. Dust emission factors for environment of Northern China. Atmospheric Environment 33, 1767–1776).
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The CC chemokine eotaxin not only attracts eosinophils to inflamed sites but also promotes adhesion, degranulation and reactive oxygen species production of eosinophils. Reactive oxygen species released from eosinophils are believed to injure epithelial cells at inflamed sites, resulting in airway hyperresponsiveness. Roxithromycin has been reported to have antiasthmatic effects, although its mechanism of action is not thoroughly understood. Therefore, the effect of roxithromycin on eotaxin-primed reactive oxygen species production from eosinophils was studied. Reactive oxygen species production by eosinophils cultured with or without roxithromycin was evaluated using luminol-dependent chemiluminescence. Roxithromycin inhibited the release of reactive oxygen species from eosinophils evoked with the calcium ionophore A23187, regardless of pretreatment with or without eotaxin. Roxithromycin may protect epithelial cells at inflamed sites, at least partly by inhibiting the release of reactive oxygen species from eosinophils.
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To investigate the relationship between methylenetetrahydrofolate reductase(MTHFR) gene polymorphism and diabetic nephropathy(DN). The technology of polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) was used to detect MTHFR gene C677T mutation in 85 healthy controls, 79 type-2 diabetics without DN, and 82 type-2 diabetics with DN confirmed by urine microalbuminous detection. The frequencies of MTHFR gene variant genotypes and alleles in the patients with DN patients were significantly higher than those in the patients without DN and those in healthy controls (P<0.01). MTHFR gene C677T mutation is probably one of the genetic risk factors for diabetic nephropathy in Chinese Hans.
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