Deserts Of Mongolia Research Articles

Benefits and ecological restoration implications of hanging grass fences in Mongolian desert steppe

Benefits and ecological restoration implications of hanging grass fences in Mongolian desert steppe

Silibinin Suppresses Inflammatory Responses Induced by Exposure to Asian Sand Dust.

Asian sand dust (ASD), generated from the deserts of China and Mongolia, affects Korea and Japan during spring and autumn, causing harmful effects on various bio-organs, including the respiratory system, due to its irritants such as fine dust, chemicals, and toxic materials. Here, we investigated the therapeutic effects of silibinin against ASD-induced airway inflammation using mouse macrophage-like cell line RAW264.7 and a murine model. ASD was intranasally administered to mice three times a week and silibinin was administered for 6 days by oral gavage. In ASD-stimulated RAW264.7 cells, silibinin treatment decreased tumor necrosis factor-α production and reduced the expression of p-p65NF-κB, p-p38, and cyclooxygenase (COX)-2, while increasing heme oxygenase (HO)-1 expression. In ASD-exposed mice, silibinin administration reduced inflammatory cell count and cytokines in bronchoalveolar lavage fluid and decreased inflammatory cell infiltration in lung tissue. Additionally, silibinin lowered oxidative stress, as evidenced by decreased 8-hydroxy-2'-deoxyguanosin (8-OHdG) expression and increased HO-1 expression. The expression of inflammatory-related proteins, including p-p65NF-κB, COX-2, and p-p38, was markedly reduced by silibinin administration. Overall, silibinin treatment reduced the expression of p-p65NF-κB, COX-2, and p-p38 in response to ASD exposure, while increasing HO-1 expression both in vitro and in vivo. These findings suggest that silibinin mitigates pulmonary inflammation caused by ASD exposure by reducing inflammatory signaling and oxidative stress, indicating its potential as a therapeutic agent for ASD-induced pulmonary inflammation.

Source contributions to two super dust storms over Northern China in March 2021 and the impact of soil moisture

Two extremely devastating super dust storms (SDS) hit Mongolia and Northern China in March 2021, causing many deaths and substantial economic damage. Accurate forecasting of dust storms is of great importance for avoiding or mitigating their effects. One of the most critical factors affecting dust emissions is soil moisture, but its value in desert exhibits significant uncertainty. In this study, model experiments were conducted to simulate dust emissions using four soil moisture datasets. The results were compared with observations to assess the effects of soil moisture on the dust emission strength. The Integrated Source Apportionment Method (ISAM) was used to track the dust sources and quantify the contribution from each source region to the dust load over the North China Plain (NCP), Korea peninsula, and western Japan. The results show large differences in the dust load depending on the soil moisture datasets used. The high soil moisture in the NCEP dataset results in substantial underestimation of the dust emission flux and PM10 concentration. Despite a minor overestimation of PM10 concentrations in many Northern China cities, the ERA5 dataset yields the best simulation performance. During the two SDS events, about 7.5 Mt dust was released from the deserts in Mongolia and 2.8 Mt from the deserts in China. Source apportionment indicates that the Mongolian Gobi Desert is the dominant source of PM10 in the NCP, Korea peninsula, and western Japan, accounting for 60 %–80 %, while Inner Mongolia contributed 10 %–20 %.

High-resolution UAV maps of the Gobi Desert provide new insights into the Upper Cretaceous of Mongolia

The Gobi Desert of southern Mongolia is home to an incredibly rich record of dinosaurs and other vertebrate fossils from the latest Cretaceous Period. Together, more than a dozen sites in several basins have produced one of the richest palaeofaunas known from this interval anywhere in the world. Most of this diversity has been recovered from the fluvial deposits of the Nemegt Formation. Despite historic and ongoing research in southern Mongolia, accurate maps and geological data for the main fossil sites are still lacking, limiting our ability to investigate how local palaeoecological dynamics influenced Nemegt taxa, their geographic distribution, and their evolutionary patterns. One of these sites, Guriliin Tsav, has produced more than a hundred significant fossil specimens to date, but still remains one of the lesser known Nemegt localities. In part this is because many expeditions have instead focused on the nearby Bügiin Tsav, one of the largest and richest localities for the Nemegt Formation. To address this gap, a project was initiated in 2018 to produce a high-resolution topographic map of Guriliin Tsav using Unmanned Aerial Vehicles (UAV), and consequently, to plot the geographic and stratigraphic distributions of palaeontological resources on this map. In so doing, we also collected stratigraphic and taphonomic data from the area, allowing for the first detailed palaeoecological interpretation of Guriliin Tsav and a comparison with other localities of southern Mongolia. Here we present the results of this project, and also discuss new topographic and stratigraphic data from Bügiin Tsav. This sheds new light into the temporal and geographic distribution of vertebrate taxa in the latest Cretaceous of Mongolia.

Trans-Boundary Dust Transport of Dust Storms in Northern China: A Study Utilizing Ground-Based Lidar Network and CALIPSO Satellite

During 14–16 March 2021, a large-scale dust storm event occurred in the northern region of China, and it was considered the most intense event in the past decade. This study employs observation data for PM2.5 and PM10 from the air quality monitoring station, the HYSPLIT model, ground-based polarized Lidar networks, AGRI payload data from Fengyun satellites and CALIPSO satellite Lidar data to jointly explore and scrutinize the three-dimensional spatial and temporal characteristics of aerosol transport. Firstly, by integrating meteorological data for PM2.5 and PM10, the air quality is assessed across six stations within the Lidar network during the dust storm. Secondly, employing a backward trajectory tracking model, the study elucidates sources of dust at the Lidar network sites. Thirdly, deploying a newly devised portable infrared 1064 nm Lidar and a pulsed 532 nm Lidar, a ground-based Lidar observation network is established for vertical probing of transboundary dust transport within the observed region. Finally, by incorporating cloud imagery from Fengyun satellites and CALIPSO satellite Lidar data, this study revealed the classification of dust and the height distribution of dust layers at pertinent sites within the Lidar observation network. The findings affirm that the eastward movement and southward compression of the intensifying Mongolian cyclone led to severe dust storm weather in western and southern Mongolia, as well as Inner Mongolia, further transporting dust into northern, northwestern, and northeastern parts of China. This dust event wielded a substantial impact on a broad expanse in northern China, manifesting in localized dust storms in Inner Mongolia, Beijing, Gansu, and surrounding areas. In essence, the dust emanated from the deserts in Mongolia and northwest China, encompassing both deserts and the Gobi region. The amalgamation of ground-based and spaceborne Lidar observations conclusively establishes that the distribution height of dust in the source region ranged from 3 to 5 km. Influenced by high-pressure systems, the protracted transport of dust over extensive distances prompted a gradual reduction in its distribution height owing to sedimentation. The comprehensive analysis of pertinent research data and information collectively affirms the precision and efficacy of the three-dimensional aerosol monitoring conducted by the ground-based Lidar network within the region.

Quantifying the effects of exceptional fossil preservation on the global availability of phylogenetic data in deep time.

Fossil deposits with exceptional preservation ("lagerstätten") provide important details not typically preserved in the fossil record, such that they hold an outsized influence on our understanding of biodiversity and evolution. In particular, the potential bias imparted by this so-called "lagerstätten effect" remains a critical, but underexplored aspect of reconstructing evolutionary relationships. Here, we quantify the amount of phylogenetic information available in the global fossil records of 1,327 species of non-avian theropod dinosaurs, Mesozoic birds, and fossil squamates (e.g., lizards, snakes, mosasaurs), and then compare the influence of lagerstätten deposits on phylogenetic information content and taxon selection in phylogenetic analyses to other fossil-bearing deposits. We find that groups that preserve a high amount of phylogenetic information in their global fossil record (e.g., non-avian theropods) are less vulnerable to a "lagerstätten effect" that leads to disproportionate representation of fossil taxa from one geologic unit in an evolutionary tree. Additionally, for each taxonomic group, we find comparable amounts of phylogenetic information in lagerstätten deposits, even though corresponding morphological character datasets vary greatly. Finally, we unexpectedly find that ancient sand dune deposits of the Late Cretaceous Gobi Desert of Mongolia and China exert an anomalously large influence on the phylogenetic information available in the squamate fossil record, suggesting a "lagerstätten effect" can be present in units not traditionally considered lagerstätten. These results offer a phylogenetics-based lens through which to examine the effects of exceptional fossil preservation on biological patterns through time and space, and invites further quantification of evolutionary information in the rock record.

The Great Gobi A Strictly Protected Area: Characterization of Soil Bacterial Communities from Four Oases.

Understanding how microbial communities survive in extreme environmental pressure is critical for interpreting ecological patterns and microbial diversity. Great Gobi A Strictly Protected Area represents an intriguing model for studying the bacterial community since it is a protected and intact wild area of the Mongolian desert. In this work, the composition of a bacterial community of the soil from four oases was characterized by extracting total DNA and sequencing through the Illumina NovaSeq platform. In addition, the soil's chemical and physical properties were determined, and their influence on shaping the microbial communities was evaluated. The results showed a high variability of bacterial composition among oases. Moreover, combining specific chemical and physical parameters significantly shapes the bacterial community among oases. Data obtained suggested that the oases were highly variable in physiochemical parameters and bacterial communities despite the similar extreme climate conditions. Moreover, core functional microbiome were constituted by aerobic chemoheterotrophy and chemoheterotrophy, mainly contributed by the most abundant bacteria, such as Actinobacteriota, Pseudomonadota, and Firmicutes. This result supposes a metabolic flexibility for sustaining life in deserts. Furthermore, as the inhabitants of the extreme regions are likely to produce new chemical compounds, isolation of key taxa is thus encouraged.

Impact of climate warming on soil microbial communities during the restoration of the inner Mongolian desert steppe.

Grazer exclosure is widely regarded as an effective measure for restoring degraded grasslands, having positive effects on soil microbial diversity. The Intergovernmental Panel on Climate Change (IPCC) predicts that global surface temperatures will increase by 1.5-4.5°C by the end of the 21st century, which may affect restoration practices for degraded grasslands. This inevitability highlights the urgent need to study the effect of temperature on grassland soil microbial communities, given their critical ecological functions. Here, we assessed the effects of heavy grazing (control), grazer exclosure, and grazer exclosure plus warming by 1.5°C on soil microbial community diversity and network properties as well as their relationships to soil physicochemical properties. Our results showed that grazer closure increased soil microbial richness relative to heavy grazing controls. Specifically, bacterial richness increased by 7.9%, fungal richness increased by 20.2%, and the number of fungal network nodes and edges increased without altering network complexity and stability. By contrast, grazer exclosure plus warming decreased bacterial richness by 9.2% and network complexity by 12.4% compared to heavy grazing controls, while increasing fungal network complexity by 25.8%. Grazer exclosure without warming increased soil ammonium nitrogen content, while warming increased soil nitrate nitrogen content. Soil pH and organic carbon were not affected by either exclosure strategy, but nitrate nitrogen was the dominant soil factor explaining changes in bacterial communities. Our findings show that grazer exclosure increases soil microbial diversity which are effective soil restoration measures for degraded desert steppe, but this effect is weakened under warming conditions. Thus, global climate change should be considered when formulating restoration measures for degraded grasslands.

The Characteristics of Rainfall-Runoff Generation and Its Influencing Factors in a Desert Steppe, China

Understanding the effect of land surface characteristics on rainfall-runoff generation is crucial in mastering the mechanisms of soil and water conservation. To characterize rainfall-runoff generation in desert steppes and to quantify the contribution of different influencing factors, a field-simulated experiment with three land degradation levels and three rainfall intensities (RIs) was conducted in the Inner Mongolia Desert Steppe. The results revealed that rainfall-runoff generation in different degraded plots at various RIs differed significantly. The runoff was generated faster and accumulated larger volumes under high RIs and heavy degradation levels (HDs) in comparison with generation under moderate/light degradation levels (MDs/LDs) and moderate/low RIs. The accumulated runoff over 40 min under a high RI on the HD plot is 153.37 L, which is much larger (0.77 L) than that under a low RI on the LD plot. The result from the structural equation model (SEM) indicated that RI is the most important factor directly driving rainfall-runoff generation, and its standardized path coefficient reached a value of 0.52. The vegetation condition is the second direct factor, with a standardized path coefficient of −0.51. However, the soil water content (SWC) has an indirect impact on rainfall-runoff generation through affecting vegetation conditions. So, interactions also exist between variables such as vegetation and soil. Therefore, the rainfall-runoff generation in the desert steppe may be mitigated through an enhancement of the vegetation and soil properties or through optimizing the interaction relationship between soil and vegetation.

Spatial and temporal variation patterns of summer grazing trajectories of Sunit sheep

GPS is an important tool for real-time monitoring of individual livestock. Analysis of the spatial and temporal changes in the grazing trajectory of Sunit sheep provided a scientific basis for the rational use of Inner Mongolia desert grassland resources and optimal breeding of livestock. In this study, GPS collars were used to track Sunit sheep in the Inner Mongolia desert grassland. These data were combined with ground measurement data and spatial remote sensing data to investigate the spatial and temporal variation patterns of sheep grazing tracks. The results showed that the distance travelled by sheep in June was significantly different from that in July and August (p < 0.05). The effective daily foraging time was mainly concentrated in the time ranges of 7:00–10:00 and 15:00–18:00 in June and August, and in the time ranges of 7:00–9:00 and 16:00–19:00 in July, for more active grazing behavior in the morning and evening hours. The degree of nuclear density of foraging track points was significantly different from the edible forage biomass (p < 0.05), with the average daily walking distance negatively correlated with the total grass biomass (R2 = 0.49). Overall, the results of this study confirm that GPS-positioning technology can be applied to study the spatial and temporal variation patterns of sheep and suggest new strategies for more effective grassland management in this region.

Range-wide evolutionary relationships and historical demography of brown bears (Ursus arctos) revealed by whole-genome sequencing of isolated central Asian populations.

Phylogeographic studies uncover hidden pathways of divergence and inform conservation. Brown bears (Ursus arctos) have one of the broadest distributions of all land mammals, ranging from Eurasia to North America, and are an important model for evolutionary studies. Although several whole genomes were available for individuals from North America, Europe and Asia, limited whole-genome data were available from Central Asia, including the highly imperilled brown bears in the Gobi Desert. To fill this knowledge gap, we sequenced whole genomes from nine Asian brown bears from the Gobi Desert of Mongolia, Northern Mongolia and the Himalayas of Pakistan. We combined these data with published brown bear sequences from Europe, Asia and North America, as well as other bear species. Our goals were to determine the evolutionary relationships among brown bear populations worldwide, their genetic diversity and their historical demography. Our analyses revealed five major lineages of brown bears based on a filtered set of 684,081 single nucleotide polymorphisms. We found distinct evolutionary lineages of brown bears in the Gobi, Himalayas, northern Mongolia, Europe and North America. The lowest level of genetic diversity and the highest level of inbreeding were found in Pakistan, the Gobi Desert and Central Italy. Furthermore, the effective population size (Ne ) for all brown bears decreased over the last 70,000 years. Our results confirm the genetic distinctiveness and ancient lineage of brown bear subspecies in the Gobi Desert of Mongolia and the Himalayas of Pakistan and highlight their importance for conservation.

Variations of PM2.5-bound elements and their associated effects during long-distance transport of dust storms: Insights from multi-sites observations

Dust storms are a significant concern because of their adverse effects on ambient air quality and human health. To investigate the evolution of dust storms during long-distance transport and its impacts on air quality and human health risks in cities along the transport pathway, we monitored the major fraction of dust (i.e., particle-bound elements) online in four cities in northern China during March 2021. Three dust events originating from the Gobi Desert of North China and Mongolia and the Taklimakan Desert of Northwest China were captured. We investigated the source regions of dust storms using daily multi-sensor absorbing aerosol index products, backward trajectories, and specific element ratios, identified and quantified sources of particle-bound elements using Positive Matrix Factorization model, and calculated the carcinogenic and non-carcinogenic risks of elements using a health risk assessment model. Our results indicated that under the influence of dust storms, mass concentrations of crustal elements increased up to dozens of times in cities near the dust source and up to ten times in cities farther from the source. In contrast, anthropogenic elements increased less or even decreased, depending on the relative contributions of the increase caused by accumulation of dust itself and entrainment along the transport path and the decrease caused by dilution of high wind speeds. Si/Fe ratio was found to be a valuable indicator for characterizing the attenuation of the amount of dust along its transport pathways, especially for the case originated from northern source regions. This study highlights the significant role of source regions, intensity and attenuation rates of dust storms, and wind speeds in determining the increased levels of element concentrations during dust storms and its associated impacts on downwind areas. Furthermore, non-carcinogenic risks of particle-bound elements increased at all sites during dust events, emphasizing the importance of personal exposure protection during dust storms.

Quantifying the Coupled Effect between Soil Moisture and Climate in the Desert Steppe Environment of Inner Mongolia, China

Soil moisture is an important variable affecting land surface and climate interactions. This study used cross-wavelet and wavelet coherence methods to analyze the relationship between soil moisture and climatic factors in the study area based on the soil moisture data sequence and corresponding meteorological data observed on the surface of the desert steppe in Inner Mongolia. The results showed that soil moisture had a relatively high- or low-value period for months or even years. Soil moisture was significantly different between different slope positions and soil layers. The fluctuation and mean of soil moisture decreased gradually with the deepening of soil depth. The relationship between soil moisture and meteorological factors varied with time scales. The influence of precipitation on soil moisture was significant at time scales of 1–6 months and 10–15 months, while air temperature and soil temperature showed stable and continuous periodic influence on soil moisture at the time scale of 10–15 months. Climate indexes for the Pacific region, Pacific Decadal Oscillation (PDO), and North Atlantic Oscillation index (NAO) were the main climatic factors controlling soil moisture in the Inner Mongolia desert steppe and strongly correlated with soil moisture primarily on time scales of 4–7 months and 10–15 months. Pacific Decadal Oscillation (PDO) and Indian Ocean basin-wide warming (IOBW) showed a strong lag effect on soil moisture.

Cessation of grazing stabilizes productivity through effects on species asynchrony and stability of shrub/semi-shrub plants in arid grasslands

Grasslands are globally abundant and important ecosystems, supporting considerable biodiversity and the livelihoods of herders. However, many grasslands have become degraded through overgrazing. Cessation of grazing can have significant effects on grassland biodiversity and ecosystem functioning, yet, to date, there is no consensus about how grazing cessation affects temporal stability of plant community productivity or the underlying mechanisms driving effects. In this study, we evaluated the effects of grazing cessation on the temporal stability of annual net primary productivity (ANPP) in the plant communities, using a 15-year field experiment conducted in an Inner Mongolian desert steppe landscape. Plant diversity, species asynchrony and the temporal stability of ANPP of functional groups were analyzed to explore the driving mechanisms of temporal stability of plant community ANPP during periods without grazing. The results showed that plant ANPP and its temporal stability of whole community, shrubs/semi-shrubs and perennial forbs were greater in areas when grazing had ceased compared with areas under continuous grazing. Grazing cessation increased both species asynchrony and species richness at the community level. Structural equation modelling (SEM) was used to better understand the mechanisms behind the result and showed that grazing cessation increased temporal stability of community ANPP by increasing species asynchrony and the temporal stability of shrubs/semi-shrubs ANPP. Temporal stability of whole community ANPP were not related to species richness. Our study also found that the effects of grazing cessation on temporal stability of community ANPP was largest during the initial five years, while the latter ten years of grazing cessation had few additional effects on temporal stability of community ANPP. Together, our results suggest that species asynchrony and the temporal stability of shrubs/semi-shrubs ANPP may be the key drivers affecting temporal stability of community ANPP during grazing cessation, and short-term grazing cessation may be more impactful than medium- or longer term grazing cessation.

Color Terms in Mongolian Place Names: A Typological Perspective

With their implications for human perception and conceptualization of the physical environment, place names have been largely analyzed from a cognitive perspective. This article aims to extend such cross-disciplinary studies by investigating the use of color terms in place names. The authors use a large-scale database of 214,805 toponyms of Mongolia to identify place names that feature color terms, both basic and non-basic, and compare them with previous literature on the toponymy of other countries and languages. Our results can be summed up in three major findings. (1) The most frequently attested color terms in Mongolian toponymy (namely, ‘black,’ ‘white,’ and ‘red’) prove to be identical to the most salient “toponymic colors” in other territories and cultures as can be seen from the analysis of previous research. The phenomenon of similar behavior of color terms in place names across different languages and cultures requires an explanation based on the universal cognitive mechanisms of color perception and development of color terminology. (2) Color terms are more frequently found in the toponymy of desert and steppe areas of Mongolia than in continental climate areas, which can be explained by the topographic properties of these two zones and universal cognitive mechanisms of place naming. Along with that, it was found that all Mongolian place names feature a unified set of color terms regardless of the region and topographic environment. (3) Against the typological background, Mongolian toponyms appear to be culture-specific in that they largely feature animal coat colors, as nomadic lifestyle and stock-raising have always been an essential part of the culture and, in the past, had a major impact on the color terminology of Mongolians. Such onomastic investigation into place names with color terms helps broaden our understanding of the cognitive mechanisms of place naming in different cultures and contributes to the color studies in cognitive sciences.

Vegetation characteristics and soil properties in grazing exclusion areas of the Inner Mongolia desert steppe

In arid and semi-arid desert steppe areas, grazing exclusion with fencing is widely regarded as an effective strategy for restoring degraded vegetation and enhancing the quality of degraded soil. In this study, we hypothesized that grazing exclusion caused by fencing enhances both vegetation and soil properties, and that the longer an area is fenced, the more considerable the improvement. We conducted an observational study wherein random sampling was utilized to select 9 plots fenced for ten or more years, 25 plots fenced for four to nine years, 25 plots fenced for one to three years and 29 free-grazing plots within an area of approximately 63,000 km2 of Inner Mongolia desert steppe. A one-way ANOVA revealed no significant differences in the characteristics of grassland vegetation or soil properties between grasslands fenced for one to three years and free-grazing grassland. After 4 years of fencing, noticeable increases in above-ground biomass, litter content, Simpson index, soil organic carbon, and available nitrogen were observed. Significant positive differences in vegetation coverage, height, species richness, soil available phosphorus, and available potassium were associated with plots with a minimum of 10 years of fencing. The soil layer with the greatest difference in the fenced-in areas for soil organic carbon was at 0–25 cm. For available nitrogen and available phosphorus, fencing produced the most significant differences in the 0–20 cm soil layer, while for available potassium, fencing produced the most significant differences in the 0–30 cm soil layer. However, the fencing did not indicate any statistically significant differences in terms of clay, silt, and sand content in any soil layer. The data support our hypothesis that grazing exclusion improves both vegetation and soil properties, and that longer periods of grazing exclusion result in greater degrees of improvement. This research offers technical guidance for the reasonable choice of fencing time across a vast area of the Inner Mongolian desert steppe.

The Witness Tree project: A portfolio

The Witness Tree is a photography project about the effects of climate change around the world. From the melting ice of Antarctica to the wildfires of Australia to the encroaching deserts of Inner Mongolia, I am drawn to precious and precarious places that mark the shifting boundaries between nature and the effects of our not-so-natural disasters. I want to show the eerie, discordant landscapes in our stormy, drying world. I want to capture this life before it goes away and because I want it to live.

Holocene desertification, traditional ecological knowledge, and human resilience in the eastern Gobi Desert, Mongolia

Dryland regions are particularly challenging for human survival over the course of deep time. This is true for institutionally complex communities as well as small-scale societies that have existed in semi-arid regions throughout the Holocene. This paper examines some of the successful strategies employed by small-scale mobile communities which enhanced their ability to thrive in drylands over the course of thousands of years. Small-scale societies living in drylands must rely on the transmission of Traditional Ecological Knowledge across generations. Some of this knowledge relates to the availability and use of wetlands and other more ephemeral water sources, the exploitation of a diverse range of resources, and the potential for natural storage of food resources as a buffer against regularly occurring drought years in these regions. We compare this understanding with our environmental archeological findings at the Mid-Holocene site of Zaraa Uul in the eastern Gobi Desert of Mongolia. At the site of Zaraa Uul, we show how hunter-gatherer groups returned to a campsite near the edge of a wetland environment over the course of at least two phases during the Mid-Holocene. Here they took advantage of a greater diversity of animal species and plants, including small-grained-grasses and sedges, which could enhance their caloric intake and increase the potential for storable commodities which could be collected as needed from their natural habitat.

Emission, transport, deposition, chemical and radiative impacts of mineral dust during severe dust storm periods in March 2021 over East Asia

A Regional Air Quality Model System (named RAQMS) coupled with a developed dust model driven by WRF was applied to synthetically investigate the emission, transport, deposition, budget, and chemical and radiative effects of mineral dust during the severe dust storm periods of 10–31 March 2021. Model results were validated against a variety of ground, vertical and satellite observations, which demonstrated a generally good model ability in reproducing meteorological variables, particulate matter and compositions, and aerosol optical properties. The first dust storm (DS1), which was the severest one since 2010 was originated from the Gobi Desert in southern Mongolia on 14 March, with the dust emission flux reaching 2785 μg m−2 s−1 and the maximum dust concentration exceeding 18,000 μg m−3 in the dust deflation region. This dust storm resulted in remarkably high hourly PM10 observations up to 7506 μg m−3, 1887 μg m−3, and 2704 μg m−3 in Beijing, Tianjin, and Shijiazhuang on 15 March, respectively, and led to a maximum decrease in surface shortwave radiation up to 313.4 W m−2 (72 %) in Beijing. The second dust storm (DS2) broke out in the deserts of eastern Mongolia, with lower dust emission than the first one. The extinction of shortwave radiation by dust aerosols led to a reduction in photolysis rate and consequently decreases in O3 and secondary aerosol concentrations over the North China Plain (NCP), whereas total sulfate and nitrate concentrations consistently increased due to heterogeneous reactions on dust surfaces over the middle reaches of the Yellow River and the NCP region during DS1. Sulfate and nitrate formation through heterogeneous reactions were enhanced in the dust backflow on 16–17 March by approximately 18 % and 24 % on average in the NCP. Heterogeneous reactions and photolysis rate reduction by mineral dust jointly led to average changes in sulfate, nitrate, ammonium, and secondary organic aerosol (SOA) concentrations by 13.0 %, 13.5 %, −12.3 %, and −4.4 %, respectively, in the NCP region during DS1, larger than the changes in the Yangtze River Delta (YRD). The maximum dry deposition settled in the 7–11 μm size range in downwind land and ocean areas, while wet deposition peaked in the 4.7–7 μm size range in the entire domain. Wet deposition was approximately twice the dry deposition over mainland China except for dust source regions. During 10–31 March, the total dust emission, dry and wet depositions were estimated to be 31.4 Tg, 13.78 Tg and 4.75 Tg, respectively, with remaining 12.87 Tg of dust aerosols (41 % of the dust emission) suspending in the atmosphere or transporting to other continents and oceans.

基于高光谱荒漠草原的微斑块光谱特征分析与提取

In hyperspectral remote sensing images, desert steppe vegetation, bare soil, and rat holes appear as micro-patches. The spectral feature analysis of micro-patches is the basis for identification and classification and also the basis for quantitative remote sensing monitoring of ground objects. Inner Mongolia desert steppe micro-patch as the research object extracts the spectral reflectance of different micro-patches, performs various vegetation index calculations, quantitatively analyzes the spectral characteristics of different micro-patches, and proposes a micro-patch spectral analysis method. Classification of high-resolution hyperspectral images of desert steppe surface micropatches. The results show that: (1) There are pronounced differences in the spectral reflectance of the three types of surface micro-patches. The vegetation has apparent characteristics in the green wave reflection peak and the red wave absorption valley. The spectral reflectance of the bare soil is higher than that of the mouse hole, and the two have been increasing. The trend is increasing slowly; (2) The proposal and application of the MSA index can effectively realize the identification and classification of surface micropatches, and the Kappa coefficient has reached 0.906 through confusion matrix verification. The above spectral analysis method realizes the classification and identification of complex ground objects using near-ground remote sensing images. It provides new ideas and methods for accurate quantitative statistics of desert grassland ecological information.