This study investigates the glacial lake outburst flood(GLOF)hazards in the Tsambagarav mountain range in Western Mongolia,focusing on the Khukhnuruu Valley and its interconnected proglacial lakes.Over the last 30 yea...This study investigates the glacial lake outburst flood(GLOF)hazards in the Tsambagarav mountain range in Western Mongolia,focusing on the Khukhnuruu Valley and its interconnected proglacial lakes.Over the last 30 years,significant glacier retreats,driven by rising temperatures and changing precipitation patterns,have led to the formation and expansion of several proglacial lakes.Fieldwork combined with satellite data and meteorological analysis was used to assess the dynamics of glacier and lake area changes,with particular focus on the flood events of July 2021.The research reveals a substantial reduction in glacier area,particularly in the Khukhnuruu E complex,where glacier area decreased by 19.3%.The study highlights the influence of increasing temperatures and summer precipitation,which have accelerated ice melt,contributing to the expansion and eventual breaching of lakes.Additionally,lake area changes were influenced by the steepness of the terrain,with steeper slopes exacerbating peak discharge during floods.Of the studied seven lakes(Lake 1 to Lake 7),Lake 1 experienced the most dramatic reduction,with a decrease in area by 73.51%and volume by 84.84%,followed by Lake 7.This study underscores the region's vulnerability to climate-induced hazards and stresses the need for a comprehensive early warning system and disaster preparedness measures to mitigate future risks.展开更多
This article aims to explore the mutual benefits and potential of agricultural trade between China and Mongolia,analyzing the current situation of agricultural resources,trade history,and policy environment of the two...This article aims to explore the mutual benefits and potential of agricultural trade between China and Mongolia,analyzing the current situation of agricultural resources,trade history,and policy environment of the two countries.The study finds that China-Mongolia agricultural trade shows significant economic complementarity.Trade activities not only promote economic growth in both countries but also deepen social and cultural exchanges.However,technical standards,political risks,and logistics costs remain major challenges facing trade cooperation.By strengthening policy coordination,investing in agricultural technology and infrastructure,and expanding the variety and markets of trade,the potential for cooperation in China-Mongolia agricultural trade can be further enhanced.These measures will help improve the efficiency and benefits of bilateral trade,achieving a win-win development.展开更多
Transition metal carbides and nitrides(MXenes)nanosheets are attractive two-dimensional(2D)materials,but they suffer from oxidation/degradation issues during storage and/or applications due to their sensitivity to wat...Transition metal carbides and nitrides(MXenes)nanosheets are attractive two-dimensional(2D)materials,but they suffer from oxidation/degradation issues during storage and/or applications due to their sensitivity to water and oxygen.Despite the great research progress,the exact oxidation kinetics of Ti_(3)C_(2)T_(x)(MXene)and their final products after oxidation are not fully understood.Herein,we systematically tracked the oxidation process of few-layer Ti_(3)C_(2)T_(x) nanosheets in an aqueous solution at room temperature over several weeks.We also studied the oxidation effects on the electrocatalytic properties of Ti_(3)C_(2)T_(x) for hydrogen evolution reaction and found that the overpotential to achieve a current density of 10 mA cm^(-2)increases from 0.435 to 0.877 V after three weeks of degradation,followed by improvement to stabilized values of around 0.40 V after eight weeks.These results suggest that severely oxidized MXene could be a promising candidate for designing efficient catalysts.According to our detailed experimental characterization and theoretical calculations,unlike previous studies,black titanium oxide is formed as the final product in addition to white Ti(IV)oxide and disordered carbons after the complete oxidation of Ti_(3)C_(2)T_(x).This work presents significant advancements in better understanding of 2D Ti_(3)C_(2)T_(x)(MXene)oxidation and enhances the prospects of this material for various applications.展开更多
In this paper, we attempted to determine the most stable or unstable regions of vegetation cover in Mongolia and their spatio-temporal dynamics using Terra/MODIS Normalized Difference Vegetation Index （NDVI） dataset...In this paper, we attempted to determine the most stable or unstable regions of vegetation cover in Mongolia and their spatio-temporal dynamics using Terra/MODIS Normalized Difference Vegetation Index （NDVI） dataset, which had a 250-m spatial resolution and comprised 6 periods of 16-day composited temporal resolution data （from 10 June to 13 September） for summer seasons from 2000 to 2012. We also used precipitation data as well as biomass data from 12 meteorological stations located in 4 largest natural zones of Mongolia. Our study showed that taiga and forest steppe zones had relatively stable vegetation cover because of forest characteristics and relatively high precipitation. The highest coefficient of variation （CV） of vegetation cover occurred frequently in the steppe and desert steppe zones, mainly depending on variation of precipitation. Our results showed that spatial and temporal variability in vegetation cover （NDVI or plant biomass） of Mongolia was highly dependent on the amount, distribution and CV of precipitation. This suggests that the lowest inter-annual CV of NDVI can occur dur- ing wet periods of growing season or in high precipitation regions, while the highest inter-annual CV of NDVI can occur during dry periods and in low precipitation regions. Although the desert zone received less precipitation than other natural zones of the country, it had relatively low variation compared to the steppe and desert steppe, which could be attributed to the very sparse vegetation in the desert.展开更多
Cistanche deserticola is an important medicinal plant in Mongolia.Despite its significant role in local healing systems,little traditional knowledge had been reported.The present study investigated folk names of C.des...Cistanche deserticola is an important medicinal plant in Mongolia.Despite its significant role in local healing systems,little traditional knowledge had been reported.The present study investigated folk names of C.deserticola and other species of the same community in Umnugobi Province,South Gobi region of Mongolia,based on ethnobotanical approaches.The high correspondence between folk names and scientific names of plant species occurring in Cistanche-associated community shows the scientific meaning of folk nomenclature and classification in Mongolia.The Mongolian and folk names of plants were formed on the basis of observations and understanding of wild plants including their morphology,phenology and traditional uses as well.Results from this study will support the conservation of C.deserticola itself,a rare and endangered plant species listed in the Monglian Red Data Book.Our documentation of folk nomenclature based on 96 plant species in the Cistanche community,as a part of traditional knowledge associated with biodiversity,will be very helpful for making strategy of plant biodiversity conservation in Mongolia.展开更多
The growth of Scotch pine in Northem Mongolian plantations was studied to determine variation in heights, diameters at breast height （DBH）, and main and annual volume increment of stem volumes in relation to plantat...The growth of Scotch pine in Northem Mongolian plantations was studied to determine variation in heights, diameters at breast height （DBH）, and main and annual volume increment of stem volumes in relation to plantation age. The study was conducted in the Tujyin Nars region, where six plantations ranging from 9 to 25 years old were selected for the assessment. Results indicate that the growth of Scotch pine on the plantations did not vary by site, and that more intensive annual increment in height was observed on Scotch pine plantations between the ages of 8 to 15 years. The amount of annual height increment and radial growth improves regularly up to 9 to 11 years of age and then the intensity of annual increment declines due to competition for light and nutrients. Additionally, there was a reduction in the number of trees per ha. Results suggest that it is necessary to implement forestry thinning which aimed at improving growth of Scotch pine on the plantations because intensity of annual increment in height and diameter reduces regularly due to restriction of growing condition.展开更多
The wetland ecosystem and its driving mechanism are significance impact on the ecological environment and the sustainable development of semi-arid regional economy.Agricultural and industrial land use/land cover chang...The wetland ecosystem and its driving mechanism are significance impact on the ecological environment and the sustainable development of semi-arid regional economy.Agricultural and industrial land use/land cover change(LUCC) is also important for wetland system.The Daihai wetland(DW)in Inner Mongolia has been suffering from severe environmental problems such as water resource shortages and wetland areas decrease.We analyzed spatiotemporal LUCC at the catchment scale of Daihai Lake,which has recently exhibited a dramatic loss of water area,and investigated the potential role of climatic changes and human activities in the wetland loss.From 1976 to 2015,the arable land and construction land increased by 71.72 and 15.81 km2,with ranges of 18.72% and 39.61%,respectively.Meanwhile,the wetland area decreased by 84.47 km2,accounting for 29.07% of the area in1976.From 1960 to 2015,the area of Daihai Lake decreased by 100.73 km^2,diminishing to 37.09% of the area in 1960,and the lake storage accordingly shrank from 12.9×10~8 to approximately 3.9×10~8 m^3.The lake level also rapidly declined.From 1962 to2014,the lake water mineralization,total nitrogen(TN),and total phosphorus(TP) increased by 2410,7.86,and 0.182 mg L-1,respectively.The pollution sources included not only mineral fertilizers and pesticides,but also livestock,poultry breeding,aquaculture,and rural household waste.The lake area decreased with increasing agricultural development,Daihai power plant(DHPP) water consumption,and catchment climatic dryness.Thus,the urgent implementation of effective restoration and mitigation measures are needed.展开更多
This study presents the changes in lake areas in the Valley of Lakes, the Govi region, southern Mongolia. The recent changes in lake areas show decreases depending on vulnerability of lake basins and response of Govi ...This study presents the changes in lake areas in the Valley of Lakes, the Govi region, southern Mongolia. The recent changes in lake areas show decreases depending on vulnerability of lake basins and response of Govi landscape to the present climatic warming. During the recent 44 - 45 years (from 1970 to 2014 or 2015), modern lakes have encountered the present rapid increase in temperature, water evaporation and drying up that induced the reduction in lake areas in the Valley of Lakes. The finding of the reduction in lake areas is consistent with the trends on increasing in temperature since 1995 and fluctuating precipitation since 1975. Investigations with detailed chronology of lake sediment are needed from the lakes to review a more complete evolution of lake basins during the Late Quaternary paleoclimatic history in Mongolia and Central Asia.展开更多
The aim of this study is to fuse high resolution optical and microwave images and classify urban land cover types using a refined Mahalanobis distance classifier. For the data fusion, multiplicative method, Brovey tra...The aim of this study is to fuse high resolution optical and microwave images and classify urban land cover types using a refined Mahalanobis distance classifier. For the data fusion, multiplicative method, Brovey transform, intensity-huesaturation method and principal component analysis are used and the results are compared. The refined method uses spatial thresholds defined from local knowledge and the bands defined from multiple sources. The result of the refined Mahalanobis distance method is compared with the result of a standard technique and it demonstrates a higher accuracy. Overall, the research indicates that the combined use of optical and microwave images can notably improve the interpretation and classification of land cover types and the refined Mahalanobis classification is a powerful tool to increase classification accuracy.展开更多
In order to evaluate the Holocene palaeoenvironmental evolution of the Ugii Nuur basin, central Mongolia, investigations on chemical and mineralogical properties of lacustrine sediments were carried out on a 630 cm se...In order to evaluate the Holocene palaeoenvironmental evolution of the Ugii Nuur basin, central Mongolia, investigations on chemical and mineralogical properties of lacustrine sediments were carried out on a 630 cm sediment core from lake Ugii Nuur. The interpretation of the record is based on a principal component analysis （PCA） of the elemental composition of the samples. The results show that lacustrine deposition started at 10.6 kyr BP. Low lake level conditions were identified during the Early Holocene （10.6-7.9 kyr BP）. The Mid Holocene （7.9-4.2 kyr BP） was characterized by generally higher lake levels and thus higher moisture supply, but it experienced strong climatic fluctuations. Arid conditions prevailed from 4.2-2.8 kyr BP and were followed by a stable, more humid phase until today.展开更多
Environmental factors play vital roles in successful plantation and cultivation of tree seedlings.This study focuses on problems associated with reforestation under extreme continental climatic conditions.The objectiv...Environmental factors play vital roles in successful plantation and cultivation of tree seedlings.This study focuses on problems associated with reforestation under extreme continental climatic conditions.The objectives were to assess relative seedling performance(survival and growth)with respect to plantation age,and to analyze the influence of specific climatic factors during the early stages of Scots pine(Pinus sylvestris L.)plantations.The study was carried out in reforested areas of the Tujyin Nars region of northern Mongolia on six Scots pine plantations ranging from 5 to 10 years.In each of the six plantations,five 900 m^2 permanent sample plots were established and survival rates and growth performance measured annually over 7 years.Results show high variation in survival among the plantations(p<0.001,F=29.7).Seedling survival in the first year corresponded directly to the number of dry days in May.However,survival rate appeared to stabilize after the second year.The insignificant variation of height categories throughout the observation period indicated low competition among individuals.Two linear mixed-effect models show that height and radial growth were best explained by relative air humidity,which we consider to be a reliable indicator of site-specific water availability.Insufficient amounts and uneven distribution of rainfall pose a major threat during the first year of plantation establishment.Humidity and water availability are decisive factors for a successful seedling plantation.This highlights the impact of drought on forest plantations in northern Mongolia and the importance of developing climate resilient reforestation strategies.展开更多
Impacts of Quaternary environmental changes on mammal faunas of central Asia remain poorly understood due to a lack of comprehensive phylogeographic sampling for most species.To help address this knowledge gap,we cond...Impacts of Quaternary environmental changes on mammal faunas of central Asia remain poorly understood due to a lack of comprehensive phylogeographic sampling for most species.To help address this knowledge gap,we conducted the most extensive molecular analysis to date of the long-tailed ground squirrel （Urocitellus undulatus Pallas 1778） in Mongolia,a country that comprises the southern core of this species＇ range.Drawing on material from recent collaborative field expeditions,we genotyped 128 individuals at two mitochondrial genes （cytochrome b and cytochrome oxidase Ⅰ;1797 bp total）.Phylogenetic inference supports the existence of two deeply divergent infraspecific lineages （corresponding to subspecies U.u.undulatus and U.u.eversmanni）,a result in agreement with previous molecular investigations but discordant with patterns of range-wide craniometric and external phenotypic variation.In the widespread western eversmanni lineage,we recovered geographically-associated clades from the：（a） Khangai,（b） Mongolian Altai,and （c） Govi Altai mountain ranges.Phylogeographic structure in U.u.eversmanni is consistent with an isolation-by-distance model;however,genetic distances are significantly lower than among subspecies,and intra-clade relationships are largely unresolved.The latter patterns,as well as the relatively higher nucleotide polymorphism of populations from the Great Lakes Depression of northwestern Mongolia,suggest a history of range shifts into these lowland areas in response to Pleistocene glaciation and environmental change,followed by upslope movements and mitochondrial lineage sorting with Holocene aridification.Our study illuminates possible historical mechanisms responsible for U.undulatus genetic structure and contributes to a framework for ongoing exploration of mammalian response to past and present climate change in central Asia.展开更多
Data on the origin and morphology of lake depressions caused by volcanism are scarce in Mongolia.Previous studies focused on climate change patterns based on Terkhiin Tsagaan Lake sediment.We present a result of exist...Data on the origin and morphology of lake depressions caused by volcanism are scarce in Mongolia.Previous studies focused on climate change patterns based on Terkhiin Tsagaan Lake sediment.We present a result of existing reconstructions of lake depression development and changes in the hydrology system during the Khorgo volcanic activation and the Holocene environmental change.A depression of the Terkhiin Tsagaan Lake is formed by a lava flow barrier from the Khorgo volcano.However,the Khorgo volcanic eruption and the lake depression that could shape a large lake have arisen instead from a fault.The morphometric analysis and field measurements indicate that the derivation of the Terkhiin Tsagaan Lake depression and Khorgo volcano may have evolved from movement on a sinistral strike-slip fault,which is about 70 km long.The southern mountains and rivers were displaced from northwest to southeast along the Terkh Fault.The offset along Terkh Fault is 4.02-5.28 km in the depression of the Terkhiin Tsagaan Lake.After movement,a wide valley of the Terkh River developed in the present landscape.The active Khorgo Volcano formed along the Khorgo Fault.The Terkhiin Tsagaan Lake is formed by blocked water from the PaleoTerkh River after lava damming from the Khorgo Volcano.The initial paleo-lake area was about 195.7km^(2),which was three times larger than the modern lake.The current water volume of the Terkhiin Tsagaan Lake is 0.351 km^(3) while the volume of the paleo-lake was 2.248 km^(3).Based on this volume indicator the paleo-lake was 6.4 times larger than the current lake.Overflowing water from the lake depression formed the Suman River by a drying canyon through the lava plateau,but the canyon is along the Terkh Fault.Changes in the water volume of Terkhiin Tsagaan Lake and erosion of Suman River canyon are inversely related to each other.We present the morphometric relationships between the lava plateau of Khorgo Volcano and development of Terkhiin Tsagaan Lake depression.展开更多
Background:Forest distribution in the forest-steppe of Mongolia depends on relief,permafrost,and climate,and is highly sensitive to climate change and anthropogenic disturbance.Forest fires and logging decreased the f...Background:Forest distribution in the forest-steppe of Mongolia depends on relief,permafrost,and climate,and is highly sensitive to climate change and anthropogenic disturbance.Forest fires and logging decreased the forest area in the forest-steppe of Mongolia.The intention of this study was to identify the geoecological parameters that control forest distribution and living-tree biomass in this semi-arid environment.Based on these parameters,we aimed to delineate the area that forest might potentially occupy and to analyse the spatial patterns of actual and potential tree biomass.Methods:We used a combination of various geographic methods in conjunction with statistical analyses to identify the key parameters controlling forest distribution.In several field campaigns,we mapped tree biomass and ecological parameters in a study area within the Tarvagatai Nuruu National Park(central Mongolia).Forest areas,topographic parameters and vegetation indices were obtained from remote sensing data.Significant correlations between forest distribution and living-tree biomass on one hand,and topographic parameters,climate data,and environmental conditions on the other hand,were used to delineate the area of potential forest distribution and to estimate total living-tree biomass for this area.Results:Presence of forest on slopes was controlled by the factors elevation,aspect,slope,mean annual precipitation,and mean growing-season temperature.Combining these factors allowed for estimation of potential forest area but was less suitable for tree-biomass delineation.No significant differences in mean living-tree biomass existed between sites exposed to different local conditions with respect to forest fire,exploitation,and soil properties.Tree biomass was reduced at forest edges(defined as 30m wide belt),in small fragmented and in large forest stands.Tree biomass in the study area was 20×10^(9) g(1,086 km^(2) forest area),whereas the potential tree biomass would reach up to 65×10^(9) g(>3168 km^(2)).Conclusions:The obtained projection suggests that the potential forest area and tree biomass under the present climatic and geoecological conditions is three times that of the present forest area and biomass.Forest fires,which mostly affected large forest stands in the upper mountains,destroyed 43% of the forest area and 45% of the livingtree biomass in the study area over the period 1986-2017.展开更多
Water trapped in glaciers and in lakes impounded by landforms created by glaciers (glacial lakes) are an important component of the hydrology and water resources in high mountain areas of Central Asia. Changes in mode...Water trapped in glaciers and in lakes impounded by landforms created by glaciers (glacial lakes) are an important component of the hydrology and water resources in high mountain areas of Central Asia. Changes in modern glaciers and glacial lakes are an important component of the hydrology of watersheds in the Mongolian Altai and Khuvsgul Mountain Ranges, western and northern Mongolia, respectively. Here we focus on Mt. Ikh Turgen and Mt. Munkh Saridag, isolated mountains of the Mongolian Altai and Khuvsgul Mountain Ranges, respectively. We use remote sensing to track changes in modern glaciers over time with mapping at scales of 1:200,000 for Mt. Ikh Turgen and 1:90,000 for Mt. Munkh Saridag based on imagery from Google Earth, 30 m resolution Aster Digital Elevation Model (DEM) and 30 m resolution Landsat 5 TM. Mt. Ikh Turgen lost 45.6% of its total glacier area between 1970 (41.4 km2) and 2011 (18.9 km2) and the Equilibrium Line Altitude (ELA) of the glaciers increased in elevation by 98 m and 144 m on north and south aspects, respectively. Mt. Munkh Saridag lost 57.3% of its total glacier area between 1970 (901 m2) and 2007 (381 m2) and the local ELA rose by 47 m and 80 m on north and south aspects, respectively. These mountains are located at similar latitudes, and so the greater percentage loss of glacier area in Mt. Munkh Saridag and faster changes in ELAs in Mt. Ikh Turgen may reflect variations in elevation and aspect, duration of solar radiation, and vulnerability to solar radiation, as well as variations in glacier scale. This study demonstrates the importance of spatial analyses of modern glaciers in understanding the context of hydrological changes within which any sustainable water resource management plan must be situated.展开更多
Investigation of the above-ground biomass allocation patterns on Scots pine plantations is critical for quantifying the productivity and carbon cycle of forest ecosystems. We estimated above-ground biomass and net pri...Investigation of the above-ground biomass allocation patterns on Scots pine plantations is critical for quantifying the productivity and carbon cycle of forest ecosystems. We estimated above-ground biomass and net primary production of a 25-year-old Pinus sylvestris L. （Scots pine） plantation, in a semi-arid region of Mongolia. The above-ground biomass of sample trees was divided into stem wood, stem bark, live branches, dead branches and needles. Total biomass for the stand was only 18.03 Mg ha1, of which 47.6% was found in stem wood, 25.8% in live branches and 14.8% in needles. The growth rate of the Scots pine plantation in the study region was relatively low compared with other regions. In the study area, it was observed that the rate of biomass accumulation in the plantation was very slow; this can be explained by very limited growing conditions and intensive crown closure. The results from this study indicate that it may be necessary to carry out thinning to increase biomass production by reducing competition between trees in the Scotch pine plantation.展开更多
Preparation of activated carbons by a physical activation technique is performed using the methods of coal pyrolysis and gasification at different temperatures. As increasing pyrolysis temperature from 520°C ...Preparation of activated carbons by a physical activation technique is performed using the methods of coal pyrolysis and gasification at different temperatures. As increasing pyrolysis temperature from 520°C to 700°C, the yield of activated carbons from the Khuut (KH) sub-bituminous coal is lowered, and amount of micropores increases gradually;however there is no development of mesopores by the KH coal pyrolysis. When the KH coal has a small loss during its physical activation due to difficulty and inactivity of its macrostructure decomposition, the smaller porosity is developed in the resulting carbons. The Aduunchuluun (AD) lignite is activated by pyrolysis and gasification at the highest temperature of 700°C in the present study. It is identified that the gasification of AD lignite develops well a porous structure with the highest surface area of 522 m2/g which is three times larger than that (155 m2/g) of the activated carbon produced by pyrolysis of the same lignite. The IR and SEM analysis confirm a significant difference in chemical and structural changes between the AD, KH raw coals and corresponding carbon samples in the physical activation processes.展开更多
This study provides a map of glacial geomorphology of Mt. Asralt Khairkhan and Mt. Baga Khentii Saridag in Khentii Mountain Range in northeastern Mongolia. In the Khentii Mountain Range, only two types of glacial land...This study provides a map of glacial geomorphology of Mt. Asralt Khairkhan and Mt. Baga Khentii Saridag in Khentii Mountain Range in northeastern Mongolia. In the Khentii Mountain Range, only two types of glacial landforms including glacial cirques and terminal moraines are observed for the paleoglacial reconstructions of Mt. Asralt Khairkhan and Mt. Baga Khentii Saridag, and are mapped based on a mapping from 30 m resolution ASTER DEM and Landsat 8 satellite imagery. Spatial distribution of the glacial landforms indicates that the Khentii Mountain Range has experienced valley glaciations with small ice caps centered on the high mountains. The glacial cirques mark numerous glacial erosional landforms, while the terminal moraines indicate glacial advances and depositional landforms at outlets of valleys. Outer limits of these glacial landforms show their maximum glaciation of 10.0 km2 and 0.7 km2 for Mt. Asralt Khairkhan and Mt. Baga Khentii Saridag, respectively. This study demonstrates that spatial analysis of the glacial landforms is crucial for reviewing the paleoglacier extent. The map of the glacial geomorphology will be a key for further detailed studies in paleoglaciology and paleoclimate of the mountain range.展开更多
The present study focuses on the Lower Cretaceous Khukhteeg Formation (Central Mongolia), which yields palynological assemblage that is used to understand the paleoclimate. Palynology samples from the Khovil opencast ...The present study focuses on the Lower Cretaceous Khukhteeg Formation (Central Mongolia), which yields palynological assemblage that is used to understand the paleoclimate. Palynology samples from the Khovil opencast mine Choir-Nyalga Basin in the Central Mongolia have been analyzed for palynomorphs with SEM. The assemblage is dominated by pollen to conifers, such as Pinaceae, Podocarpaceae and Taxodiaceae, indicating the vegetation of conifer forests. The assemblage contains abundant spores Schizaeaceae, Cyatheaceae, which are generally associated with wet habitats. According to the detailed analyses, the plant community indicates that warm and humid subtropical paleoclimate controlled the study area during the Early Cretaceous.展开更多
Upgrading heavy and residual oils into valuable lighter fuels has attracted much attention due to growing worldwide demand for light petroleum product. This study focused on hydrocracking process for atmospheric resid...Upgrading heavy and residual oils into valuable lighter fuels has attracted much attention due to growing worldwide demand for light petroleum product. This study focused on hydrocracking process for atmospheric residue (AR) of Mongolian crude oil in the first time compared to those of other countries. Residue samples were hydrocracked with a commercial catalyst at 450℃, 460℃, 470℃ for 2 hours under hydrogen pressure of 10 MPa. The AR conversion and yield of light fraction (LF) reached to 90.6 wt% and 53.9 wt%, at 470℃ by the hydrocracking for atmospheric residue of Tamsagbulag crude oil (TBAR). In each sample, the yield of MF was the highest at 460℃ temperature, which is valuable lighter fuel product. The polyaromatic, polar hydrocarbons and sulfur compounds were concentrated in the MF and HF because the large amount of light hydrocarbons produced from TBAR as the increasing of the hydrocracking temperature. The content of n-paraffinic hydrocarbons was decreased in HF of TBAR, on effect of hydrocracking temperature. This result suggests the longer molecules of n-paraffin (С20-С32) in HF were reacted better, than middle molecules of n-paraffin (С12-С20) in MF during the hydrocracking reaction. Because the hydrocarbon components of feed crude oils were various, the contents of n-paraffinic hydrocarbons in MF and HF of TBAR and DQAR were similar, but MEAR’s was around 2 times lower and the hydrogen consumption was the highest for the MEAR after hydrocracking.展开更多
基金funded by the National University of Mongolia under grant agreement P2023(grant number P2023-4578)。
文摘This study investigates the glacial lake outburst flood(GLOF)hazards in the Tsambagarav mountain range in Western Mongolia,focusing on the Khukhnuruu Valley and its interconnected proglacial lakes.Over the last 30 years,significant glacier retreats,driven by rising temperatures and changing precipitation patterns,have led to the formation and expansion of several proglacial lakes.Fieldwork combined with satellite data and meteorological analysis was used to assess the dynamics of glacier and lake area changes,with particular focus on the flood events of July 2021.The research reveals a substantial reduction in glacier area,particularly in the Khukhnuruu E complex,where glacier area decreased by 19.3%.The study highlights the influence of increasing temperatures and summer precipitation,which have accelerated ice melt,contributing to the expansion and eventual breaching of lakes.Additionally,lake area changes were influenced by the steepness of the terrain,with steeper slopes exacerbating peak discharge during floods.Of the studied seven lakes(Lake 1 to Lake 7),Lake 1 experienced the most dramatic reduction,with a decrease in area by 73.51%and volume by 84.84%,followed by Lake 7.This study underscores the region's vulnerability to climate-induced hazards and stresses the need for a comprehensive early warning system and disaster preparedness measures to mitigate future risks.
文摘This article aims to explore the mutual benefits and potential of agricultural trade between China and Mongolia,analyzing the current situation of agricultural resources,trade history,and policy environment of the two countries.The study finds that China-Mongolia agricultural trade shows significant economic complementarity.Trade activities not only promote economic growth in both countries but also deepen social and cultural exchanges.However,technical standards,political risks,and logistics costs remain major challenges facing trade cooperation.By strengthening policy coordination,investing in agricultural technology and infrastructure,and expanding the variety and markets of trade,the potential for cooperation in China-Mongolia agricultural trade can be further enhanced.These measures will help improve the efficiency and benefits of bilateral trade,achieving a win-win development.
基金supported by the Australian Research Council (DE220100521 and DP200101217)supported by Fellow research grant of National University of Mongolia (No.P2021-4197)+2 种基金the support of Griffith University internal grantssupport from King Abdullah University of Science and Technology (KAUST)through the Ibn Rushd Postdoctoral Fellowship Awardsupport from the US Office of Naval Research (ONR),Office of Naval Research Global (ONRG)under the grant N62909-23-1-2035。
文摘Transition metal carbides and nitrides(MXenes)nanosheets are attractive two-dimensional(2D)materials,but they suffer from oxidation/degradation issues during storage and/or applications due to their sensitivity to water and oxygen.Despite the great research progress,the exact oxidation kinetics of Ti_(3)C_(2)T_(x)(MXene)and their final products after oxidation are not fully understood.Herein,we systematically tracked the oxidation process of few-layer Ti_(3)C_(2)T_(x) nanosheets in an aqueous solution at room temperature over several weeks.We also studied the oxidation effects on the electrocatalytic properties of Ti_(3)C_(2)T_(x) for hydrogen evolution reaction and found that the overpotential to achieve a current density of 10 mA cm^(-2)increases from 0.435 to 0.877 V after three weeks of degradation,followed by improvement to stabilized values of around 0.40 V after eight weeks.These results suggest that severely oxidized MXene could be a promising candidate for designing efficient catalysts.According to our detailed experimental characterization and theoretical calculations,unlike previous studies,black titanium oxide is formed as the final product in addition to white Ti(IV)oxide and disordered carbons after the complete oxidation of Ti_(3)C_(2)T_(x).This work presents significant advancements in better understanding of 2D Ti_(3)C_(2)T_(x)(MXene)oxidation and enhances the prospects of this material for various applications.
基金funded by the Green Gold Phase IV Project of the Swiss Development Cooperation AgencyA partial support for this study has also been provided by the Asia Research Center,Mongolia
文摘In this paper, we attempted to determine the most stable or unstable regions of vegetation cover in Mongolia and their spatio-temporal dynamics using Terra/MODIS Normalized Difference Vegetation Index （NDVI） dataset, which had a 250-m spatial resolution and comprised 6 periods of 16-day composited temporal resolution data （from 10 June to 13 September） for summer seasons from 2000 to 2012. We also used precipitation data as well as biomass data from 12 meteorological stations located in 4 largest natural zones of Mongolia. Our study showed that taiga and forest steppe zones had relatively stable vegetation cover because of forest characteristics and relatively high precipitation. The highest coefficient of variation （CV） of vegetation cover occurred frequently in the steppe and desert steppe zones, mainly depending on variation of precipitation. Our results showed that spatial and temporal variability in vegetation cover （NDVI or plant biomass） of Mongolia was highly dependent on the amount, distribution and CV of precipitation. This suggests that the lowest inter-annual CV of NDVI can occur dur- ing wet periods of growing season or in high precipitation regions, while the highest inter-annual CV of NDVI can occur during dry periods and in low precipitation regions. Although the desert zone received less precipitation than other natural zones of the country, it had relatively low variation compared to the steppe and desert steppe, which could be attributed to the very sparse vegetation in the desert.
基金This research was supported by the National Natural Science Foundation of China(31761143001,31870316)the Natural Science Foundation of Beijing(7202109)+4 种基金Minzu University of China(KLEMZZ201904,KLEM-ZZ201906,YLDXXK201819)the Ministry of Ecology and Environment of China(2019HB2096001006)Jiansheng Fresh Herb Medicine R&D Foundation(JSYY-20190101-043)the Ministry of Education of China(B08044)Colleagues and Dr.Bayartungalag from the institute of Geography and Geoecology,Mongolian Academy of Sciences provided assistances in the field surveys.Yingjie Song at Minzu University of China provided useful comments.We are grateful to all of them.
文摘Cistanche deserticola is an important medicinal plant in Mongolia.Despite its significant role in local healing systems,little traditional knowledge had been reported.The present study investigated folk names of C.deserticola and other species of the same community in Umnugobi Province,South Gobi region of Mongolia,based on ethnobotanical approaches.The high correspondence between folk names and scientific names of plant species occurring in Cistanche-associated community shows the scientific meaning of folk nomenclature and classification in Mongolia.The Mongolian and folk names of plants were formed on the basis of observations and understanding of wild plants including their morphology,phenology and traditional uses as well.Results from this study will support the conservation of C.deserticola itself,a rare and endangered plant species listed in the Monglian Red Data Book.Our documentation of folk nomenclature based on 96 plant species in the Cistanche community,as a part of traditional knowledge associated with biodiversity,will be very helpful for making strategy of plant biodiversity conservation in Mongolia.
文摘The growth of Scotch pine in Northem Mongolian plantations was studied to determine variation in heights, diameters at breast height （DBH）, and main and annual volume increment of stem volumes in relation to plantation age. The study was conducted in the Tujyin Nars region, where six plantations ranging from 9 to 25 years old were selected for the assessment. Results indicate that the growth of Scotch pine on the plantations did not vary by site, and that more intensive annual increment in height was observed on Scotch pine plantations between the ages of 8 to 15 years. The amount of annual height increment and radial growth improves regularly up to 9 to 11 years of age and then the intensity of annual increment declines due to competition for light and nutrients. Additionally, there was a reduction in the number of trees per ha. Results suggest that it is necessary to implement forestry thinning which aimed at improving growth of Scotch pine on the plantations because intensity of annual increment in height and diameter reduces regularly due to restriction of growing condition.
基金sponsored by the Natural Science Foundation of China (No. 41662011, 41967052 and 61661045)Natural Science Foundation of Inner Mongolia (2019ZD10, 2019GG020)。
文摘The wetland ecosystem and its driving mechanism are significance impact on the ecological environment and the sustainable development of semi-arid regional economy.Agricultural and industrial land use/land cover change(LUCC) is also important for wetland system.The Daihai wetland(DW)in Inner Mongolia has been suffering from severe environmental problems such as water resource shortages and wetland areas decrease.We analyzed spatiotemporal LUCC at the catchment scale of Daihai Lake,which has recently exhibited a dramatic loss of water area,and investigated the potential role of climatic changes and human activities in the wetland loss.From 1976 to 2015,the arable land and construction land increased by 71.72 and 15.81 km2,with ranges of 18.72% and 39.61%,respectively.Meanwhile,the wetland area decreased by 84.47 km2,accounting for 29.07% of the area in1976.From 1960 to 2015,the area of Daihai Lake decreased by 100.73 km^2,diminishing to 37.09% of the area in 1960,and the lake storage accordingly shrank from 12.9×10~8 to approximately 3.9×10~8 m^3.The lake level also rapidly declined.From 1962 to2014,the lake water mineralization,total nitrogen(TN),and total phosphorus(TP) increased by 2410,7.86,and 0.182 mg L-1,respectively.The pollution sources included not only mineral fertilizers and pesticides,but also livestock,poultry breeding,aquaculture,and rural household waste.The lake area decreased with increasing agricultural development,Daihai power plant(DHPP) water consumption,and catchment climatic dryness.Thus,the urgent implementation of effective restoration and mitigation measures are needed.
文摘This study presents the changes in lake areas in the Valley of Lakes, the Govi region, southern Mongolia. The recent changes in lake areas show decreases depending on vulnerability of lake basins and response of Govi landscape to the present climatic warming. During the recent 44 - 45 years (from 1970 to 2014 or 2015), modern lakes have encountered the present rapid increase in temperature, water evaporation and drying up that induced the reduction in lake areas in the Valley of Lakes. The finding of the reduction in lake areas is consistent with the trends on increasing in temperature since 1995 and fluctuating precipitation since 1975. Investigations with detailed chronology of lake sediment are needed from the lakes to review a more complete evolution of lake basins during the Late Quaternary paleoclimatic history in Mongolia and Central Asia.
文摘The aim of this study is to fuse high resolution optical and microwave images and classify urban land cover types using a refined Mahalanobis distance classifier. For the data fusion, multiplicative method, Brovey transform, intensity-huesaturation method and principal component analysis are used and the results are compared. The refined method uses spatial thresholds defined from local knowledge and the bands defined from multiple sources. The result of the refined Mahalanobis distance method is compared with the result of a standard technique and it demonstrates a higher accuracy. Overall, the research indicates that the combined use of optical and microwave images can notably improve the interpretation and classification of land cover types and the refined Mahalanobis classification is a powerful tool to increase classification accuracy.
文摘In order to evaluate the Holocene palaeoenvironmental evolution of the Ugii Nuur basin, central Mongolia, investigations on chemical and mineralogical properties of lacustrine sediments were carried out on a 630 cm sediment core from lake Ugii Nuur. The interpretation of the record is based on a principal component analysis （PCA） of the elemental composition of the samples. The results show that lacustrine deposition started at 10.6 kyr BP. Low lake level conditions were identified during the Early Holocene （10.6-7.9 kyr BP）. The Mid Holocene （7.9-4.2 kyr BP） was characterized by generally higher lake levels and thus higher moisture supply, but it experienced strong climatic fluctuations. Arid conditions prevailed from 4.2-2.8 kyr BP and were followed by a stable, more humid phase until today.
基金supported by the Partnerships for Enhanced Engagement in Research(PEER)Science Cycle 2 Grant#296’Building research and teaching capacity to aid climate change and natural resource management at the National University of Mongolia(NUM)’
文摘Environmental factors play vital roles in successful plantation and cultivation of tree seedlings.This study focuses on problems associated with reforestation under extreme continental climatic conditions.The objectives were to assess relative seedling performance(survival and growth)with respect to plantation age,and to analyze the influence of specific climatic factors during the early stages of Scots pine(Pinus sylvestris L.)plantations.The study was carried out in reforested areas of the Tujyin Nars region of northern Mongolia on six Scots pine plantations ranging from 5 to 10 years.In each of the six plantations,five 900 m^2 permanent sample plots were established and survival rates and growth performance measured annually over 7 years.Results show high variation in survival among the plantations(p<0.001,F=29.7).Seedling survival in the first year corresponded directly to the number of dry days in May.However,survival rate appeared to stabilize after the second year.The insignificant variation of height categories throughout the observation period indicated low competition among individuals.Two linear mixed-effect models show that height and radial growth were best explained by relative air humidity,which we consider to be a reliable indicator of site-specific water availability.Insufficient amounts and uneven distribution of rainfall pose a major threat during the first year of plantation establishment.Humidity and water availability are decisive factors for a successful seedling plantation.This highlights the impact of drought on forest plantations in northern Mongolia and the importance of developing climate resilient reforestation strategies.
基金funded primarily by grants from the National Science Foundation(USADBI-9411976 supplement(1999),DEB-0717214(2009-2012),DEB-1258010(2015-2016))+2 种基金B.S.M. was partially supported by a Peter Buck Predoctoral Fellowship during the 2015 Mongolian expeditionsupported by the National Science Foundation(DEB-1258010)the American Society of Mammalogists(ASM Fellowship to B.S.M.)
文摘Impacts of Quaternary environmental changes on mammal faunas of central Asia remain poorly understood due to a lack of comprehensive phylogeographic sampling for most species.To help address this knowledge gap,we conducted the most extensive molecular analysis to date of the long-tailed ground squirrel （Urocitellus undulatus Pallas 1778） in Mongolia,a country that comprises the southern core of this species＇ range.Drawing on material from recent collaborative field expeditions,we genotyped 128 individuals at two mitochondrial genes （cytochrome b and cytochrome oxidase Ⅰ;1797 bp total）.Phylogenetic inference supports the existence of two deeply divergent infraspecific lineages （corresponding to subspecies U.u.undulatus and U.u.eversmanni）,a result in agreement with previous molecular investigations but discordant with patterns of range-wide craniometric and external phenotypic variation.In the widespread western eversmanni lineage,we recovered geographically-associated clades from the：（a） Khangai,（b） Mongolian Altai,and （c） Govi Altai mountain ranges.Phylogeographic structure in U.u.eversmanni is consistent with an isolation-by-distance model;however,genetic distances are significantly lower than among subspecies,and intra-clade relationships are largely unresolved.The latter patterns,as well as the relatively higher nucleotide polymorphism of populations from the Great Lakes Depression of northwestern Mongolia,suggest a history of range shifts into these lowland areas in response to Pleistocene glaciation and environmental change,followed by upslope movements and mitochondrial lineage sorting with Holocene aridification.Our study illuminates possible historical mechanisms responsible for U.undulatus genetic structure and contributes to a framework for ongoing exploration of mammalian response to past and present climate change in central Asia.
基金funded by the National University of Mongolia(P2021-4178)funded by the National Natural Science Foundation of China(nos.41961144020,91755213,41967052)+1 种基金additional funding by 111 Project(BP0719022)MOST Special Fund MSFGPMR02-3 from the State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences(Wuhan),China。
文摘Data on the origin and morphology of lake depressions caused by volcanism are scarce in Mongolia.Previous studies focused on climate change patterns based on Terkhiin Tsagaan Lake sediment.We present a result of existing reconstructions of lake depression development and changes in the hydrology system during the Khorgo volcanic activation and the Holocene environmental change.A depression of the Terkhiin Tsagaan Lake is formed by a lava flow barrier from the Khorgo volcano.However,the Khorgo volcanic eruption and the lake depression that could shape a large lake have arisen instead from a fault.The morphometric analysis and field measurements indicate that the derivation of the Terkhiin Tsagaan Lake depression and Khorgo volcano may have evolved from movement on a sinistral strike-slip fault,which is about 70 km long.The southern mountains and rivers were displaced from northwest to southeast along the Terkh Fault.The offset along Terkh Fault is 4.02-5.28 km in the depression of the Terkhiin Tsagaan Lake.After movement,a wide valley of the Terkh River developed in the present landscape.The active Khorgo Volcano formed along the Khorgo Fault.The Terkhiin Tsagaan Lake is formed by blocked water from the PaleoTerkh River after lava damming from the Khorgo Volcano.The initial paleo-lake area was about 195.7km^(2),which was three times larger than the modern lake.The current water volume of the Terkhiin Tsagaan Lake is 0.351 km^(3) while the volume of the paleo-lake was 2.248 km^(3).Based on this volume indicator the paleo-lake was 6.4 times larger than the current lake.Overflowing water from the lake depression formed the Suman River by a drying canyon through the lava plateau,but the canyon is along the Terkh Fault.Changes in the water volume of Terkhiin Tsagaan Lake and erosion of Suman River canyon are inversely related to each other.We present the morphometric relationships between the lava plateau of Khorgo Volcano and development of Terkhiin Tsagaan Lake depression.
基金funded by the Volkswagen Foundation(project-no.871759)by the German Research Council(Deutsche Forschungsgemeinschaft,DFG),(project no.385460422).
文摘Background:Forest distribution in the forest-steppe of Mongolia depends on relief,permafrost,and climate,and is highly sensitive to climate change and anthropogenic disturbance.Forest fires and logging decreased the forest area in the forest-steppe of Mongolia.The intention of this study was to identify the geoecological parameters that control forest distribution and living-tree biomass in this semi-arid environment.Based on these parameters,we aimed to delineate the area that forest might potentially occupy and to analyse the spatial patterns of actual and potential tree biomass.Methods:We used a combination of various geographic methods in conjunction with statistical analyses to identify the key parameters controlling forest distribution.In several field campaigns,we mapped tree biomass and ecological parameters in a study area within the Tarvagatai Nuruu National Park(central Mongolia).Forest areas,topographic parameters and vegetation indices were obtained from remote sensing data.Significant correlations between forest distribution and living-tree biomass on one hand,and topographic parameters,climate data,and environmental conditions on the other hand,were used to delineate the area of potential forest distribution and to estimate total living-tree biomass for this area.Results:Presence of forest on slopes was controlled by the factors elevation,aspect,slope,mean annual precipitation,and mean growing-season temperature.Combining these factors allowed for estimation of potential forest area but was less suitable for tree-biomass delineation.No significant differences in mean living-tree biomass existed between sites exposed to different local conditions with respect to forest fire,exploitation,and soil properties.Tree biomass was reduced at forest edges(defined as 30m wide belt),in small fragmented and in large forest stands.Tree biomass in the study area was 20×10^(9) g(1,086 km^(2) forest area),whereas the potential tree biomass would reach up to 65×10^(9) g(>3168 km^(2)).Conclusions:The obtained projection suggests that the potential forest area and tree biomass under the present climatic and geoecological conditions is three times that of the present forest area and biomass.Forest fires,which mostly affected large forest stands in the upper mountains,destroyed 43% of the forest area and 45% of the livingtree biomass in the study area over the period 1986-2017.
文摘Water trapped in glaciers and in lakes impounded by landforms created by glaciers (glacial lakes) are an important component of the hydrology and water resources in high mountain areas of Central Asia. Changes in modern glaciers and glacial lakes are an important component of the hydrology of watersheds in the Mongolian Altai and Khuvsgul Mountain Ranges, western and northern Mongolia, respectively. Here we focus on Mt. Ikh Turgen and Mt. Munkh Saridag, isolated mountains of the Mongolian Altai and Khuvsgul Mountain Ranges, respectively. We use remote sensing to track changes in modern glaciers over time with mapping at scales of 1:200,000 for Mt. Ikh Turgen and 1:90,000 for Mt. Munkh Saridag based on imagery from Google Earth, 30 m resolution Aster Digital Elevation Model (DEM) and 30 m resolution Landsat 5 TM. Mt. Ikh Turgen lost 45.6% of its total glacier area between 1970 (41.4 km2) and 2011 (18.9 km2) and the Equilibrium Line Altitude (ELA) of the glaciers increased in elevation by 98 m and 144 m on north and south aspects, respectively. Mt. Munkh Saridag lost 57.3% of its total glacier area between 1970 (901 m2) and 2007 (381 m2) and the local ELA rose by 47 m and 80 m on north and south aspects, respectively. These mountains are located at similar latitudes, and so the greater percentage loss of glacier area in Mt. Munkh Saridag and faster changes in ELAs in Mt. Ikh Turgen may reflect variations in elevation and aspect, duration of solar radiation, and vulnerability to solar radiation, as well as variations in glacier scale. This study demonstrates the importance of spatial analyses of modern glaciers in understanding the context of hydrological changes within which any sustainable water resource management plan must be situated.
文摘Investigation of the above-ground biomass allocation patterns on Scots pine plantations is critical for quantifying the productivity and carbon cycle of forest ecosystems. We estimated above-ground biomass and net primary production of a 25-year-old Pinus sylvestris L. （Scots pine） plantation, in a semi-arid region of Mongolia. The above-ground biomass of sample trees was divided into stem wood, stem bark, live branches, dead branches and needles. Total biomass for the stand was only 18.03 Mg ha1, of which 47.6% was found in stem wood, 25.8% in live branches and 14.8% in needles. The growth rate of the Scots pine plantation in the study region was relatively low compared with other regions. In the study area, it was observed that the rate of biomass accumulation in the plantation was very slow; this can be explained by very limited growing conditions and intensive crown closure. The results from this study indicate that it may be necessary to carry out thinning to increase biomass production by reducing competition between trees in the Scotch pine plantation.
文摘Preparation of activated carbons by a physical activation technique is performed using the methods of coal pyrolysis and gasification at different temperatures. As increasing pyrolysis temperature from 520°C to 700°C, the yield of activated carbons from the Khuut (KH) sub-bituminous coal is lowered, and amount of micropores increases gradually;however there is no development of mesopores by the KH coal pyrolysis. When the KH coal has a small loss during its physical activation due to difficulty and inactivity of its macrostructure decomposition, the smaller porosity is developed in the resulting carbons. The Aduunchuluun (AD) lignite is activated by pyrolysis and gasification at the highest temperature of 700°C in the present study. It is identified that the gasification of AD lignite develops well a porous structure with the highest surface area of 522 m2/g which is three times larger than that (155 m2/g) of the activated carbon produced by pyrolysis of the same lignite. The IR and SEM analysis confirm a significant difference in chemical and structural changes between the AD, KH raw coals and corresponding carbon samples in the physical activation processes.
文摘This study provides a map of glacial geomorphology of Mt. Asralt Khairkhan and Mt. Baga Khentii Saridag in Khentii Mountain Range in northeastern Mongolia. In the Khentii Mountain Range, only two types of glacial landforms including glacial cirques and terminal moraines are observed for the paleoglacial reconstructions of Mt. Asralt Khairkhan and Mt. Baga Khentii Saridag, and are mapped based on a mapping from 30 m resolution ASTER DEM and Landsat 8 satellite imagery. Spatial distribution of the glacial landforms indicates that the Khentii Mountain Range has experienced valley glaciations with small ice caps centered on the high mountains. The glacial cirques mark numerous glacial erosional landforms, while the terminal moraines indicate glacial advances and depositional landforms at outlets of valleys. Outer limits of these glacial landforms show their maximum glaciation of 10.0 km2 and 0.7 km2 for Mt. Asralt Khairkhan and Mt. Baga Khentii Saridag, respectively. This study demonstrates that spatial analysis of the glacial landforms is crucial for reviewing the paleoglacier extent. The map of the glacial geomorphology will be a key for further detailed studies in paleoglaciology and paleoclimate of the mountain range.
文摘The present study focuses on the Lower Cretaceous Khukhteeg Formation (Central Mongolia), which yields palynological assemblage that is used to understand the paleoclimate. Palynology samples from the Khovil opencast mine Choir-Nyalga Basin in the Central Mongolia have been analyzed for palynomorphs with SEM. The assemblage is dominated by pollen to conifers, such as Pinaceae, Podocarpaceae and Taxodiaceae, indicating the vegetation of conifer forests. The assemblage contains abundant spores Schizaeaceae, Cyatheaceae, which are generally associated with wet habitats. According to the detailed analyses, the plant community indicates that warm and humid subtropical paleoclimate controlled the study area during the Early Cretaceous.
文摘Upgrading heavy and residual oils into valuable lighter fuels has attracted much attention due to growing worldwide demand for light petroleum product. This study focused on hydrocracking process for atmospheric residue (AR) of Mongolian crude oil in the first time compared to those of other countries. Residue samples were hydrocracked with a commercial catalyst at 450℃, 460℃, 470℃ for 2 hours under hydrogen pressure of 10 MPa. The AR conversion and yield of light fraction (LF) reached to 90.6 wt% and 53.9 wt%, at 470℃ by the hydrocracking for atmospheric residue of Tamsagbulag crude oil (TBAR). In each sample, the yield of MF was the highest at 460℃ temperature, which is valuable lighter fuel product. The polyaromatic, polar hydrocarbons and sulfur compounds were concentrated in the MF and HF because the large amount of light hydrocarbons produced from TBAR as the increasing of the hydrocracking temperature. The content of n-paraffinic hydrocarbons was decreased in HF of TBAR, on effect of hydrocracking temperature. This result suggests the longer molecules of n-paraffin (С20-С32) in HF were reacted better, than middle molecules of n-paraffin (С12-С20) in MF during the hydrocracking reaction. Because the hydrocarbon components of feed crude oils were various, the contents of n-paraffinic hydrocarbons in MF and HF of TBAR and DQAR were similar, but MEAR’s was around 2 times lower and the hydrogen consumption was the highest for the MEAR after hydrocracking.
