Issues,Progress,and Recommendations in the Construction of Ecological Barrier on the Mongolian Plateau from the Perspective of Big Data

The Mongolian Plateau(MP),situated in the transitional zone between the Siberian taiga and the arid grasslands of Central Asia,plays a significant role as an Ecological Barrier(EB)with crucial implications for ecological and resource security in Northeast Asia.EB is a vast concept and a complex issue related to many aspects such as water,land,air,vegetation,animals,and people,et al.It is very difficult to understand the whole of EB without a comprehensive perspective,that traditional diverse studies cannot cover.Big data and artificial intelligence(AI)have enabled a shift in the research paradigm.Faced with these requirements,this study identified issues in the construction of EB on MP from a big data perspective.This includes the issues,progress,and future recommendations for EB construction-related studies using big data and AI.Current issues cover the status of theoretical studies,technical bottlenecks,and insufficient synergistic analyses related to EB construction.Research progress introduces advances in scientific research driven by big data in three key areas of MP:natural resources,the ecological environment,and sustainable development.For the future development of EB construction on MP,it is recommended to utilize big data and intelligent computing technologies,integrate extensive regional data resources,develop precise algorithms and automated tools,and construct a big data collaborative innovation platform.This study aims to call for more attention to big data and AI applications in EB studies,thereby supporting the achievement of sustainable development goals in the MP and enhancing the research paradigm transforming in the fields of resources and the environment.

Flooding(or breaching)of inter-connected proglacial lakes by cascading overflow in the arid region of Western Mongolia(Mt.Tsambagarav,Mongolian Altai)

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.

Characteristics of Spatial and Temporal Vegetation Index Variability and Its Responses to Temperature and Precipitation in Mongolia

The Mongolian Plateau,a vital ecological barrier in northern China,is of great importance for studying vegetation dynamics in Mongolia against the background of climate warming.Such studies can enhance our understanding of regional vegetation responses to global warming and contribute to the establishment of a stronger ecological barrier in northern China.Here,we analyzed the spatial and temporal characteristics of the NDVI(normalized difference vegetation index)in Mongolia using 8 km resolution GIMMS NDVI3g data from 1990 to 2022,along with temperature,precipitation,and elevation data.Trend analysis and correlation methods were used to examine the relationships between the NDVI and temperature,as well as precipitation.The results showed four important aspects of these relationships.(1)The NDVI in Mongolia increased significantly from 1990 to 2022 at a rate of 0.0015 yr^(-1)(P<0.05).(2)Mongolia’s NDVI increased from 1990 to 2022 in 60.73%of the country.Of this total,the area with a significant increase accounted for 31.67%and was concentrated on the eastern and western edges.The area experiencing a significant decrease accounted for 15.67%and was mainly located on the southwestern edges.(3)The NDVI analysis revealed significant increasing trends in all regions except for those at elevations of 1500-2000 m.The greatest rate of increase was observed between 500 and 1000 m,and the increasing trend weakened as elevation continued to increase before gradually becoming significant again.Additionally,the NDVI increased significantly across different slopes,and the rate of increase decreased as the slope increased.(4)From 1990 to 2022,Mongolia’s NDVI was mostly negatively correlated with temperature.This occurred over 66.75%of the total land area,with 17.21%of the region exhibiting a significant negative correlation,mainly in the southwest.Conversely,the NDVI demonstrated a positive correlation with precipitation,encompassing 86.71%of the total land area.Approximately 40.44%of the region had a significant positive correlation,primarily in the southwest.In conclusion,throughout the experimental period,the vegetation state in Mongolia improved.However,due to the warming and drying climate,more attention should be paid to vegetation degradation in the south-central region.

The Study of Mutual Benefits and Potential in China-Mongolia Agricultural Trade

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.

Understanding the oxidation chemistry of Ti_(3)C_(2)T_(x)(MXene)sheets and their catalytic performances

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.

Vegetation Changes from 2014 to 2023 in the Mongolian Plateau Permafrost Region under Climate Change

The permafrost region is one of the most sensitive areas to climate change.With global warming,the Mongolian Plateau permafrost is rapidly degrading,and its vegetation ecosystem is seriously threatened.To address this challenge,it is essential to understand the impact of climate change on vegetation at different permafrost degradation stages on the Mongolian Plateau.Based on the general permafrost distribution,in this study,we divided different permafrost regions and explored the response of vegetation to climate change at different stages of permafrost degradation by the idea of“space instead of time”from 2014 to 2023.The results of the study showed that:(1)Normalized difference vegetation index(NDVI)values showed a decreasing trend,and the proportion of the decreasing region was in the order of sporadic permafrost region>isolated and sparse permafrost region>continuous and discontinuous permafrost regions.(2)The main controlling factors of vegetation growth in permafrost regions are different,air temperature is the main controlling factor of vegetation growth in isolated and sparse permafrost region(r=-0.736)and sporadic permafrost regions(r=-0.522),and precipitation is the main controlling factor of vegetation growth in continuous and discontinuous permafrost region(r=-0.498).(3)The response of NDVI to climate change varies at different stages of permafrost degradation.In the early stages of permafrost degradation,increased land surface temperature(LST)and air temperature favored vegetation growth and increased vegetation cover,whereas increased precipitation impeded vegetation growth;as the permafrost degraded,increased LST and air temperature impeded vegetation growth,whereas increased precipitation promoted vegetation growth.

Spatial and temporal variability in vegetation cover of Mongolia and its implications

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.

Folk nomenclature of plants in Cistanche deserticola-associated community in South Gobi, Mongolia

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.

Growth of Scotch Pine （Pinus sylvestris L.） Plantation in Northern Mongolia

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.

Effects of climate variability and land use/land cover change on the Daihai wetland of central Inner Mongolia over the past decades

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.

Climate-Driven Changes in Lake Areas for the Last Half Century in the Valley of Lakes, Govi Region, Southern Mongolia

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.

Advanced Classification of Lands at TM and Envisat Images of Mongolia

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.

Holocene Climate Evolution of the Ugii Nuur Basin, Mongolia

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.

Assessment of early survival and growth of planted Scots pine(Pinus sylvestris) seedlings under extreme continental climate conditions of northern Mongolia

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.

Impacts of late Quaternary environmental change on the long-tailed ground squirrel(Urocitellus undulatus)in Mongolia

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.

Morphodynamic development of the Terkhiin Tsagaan Lake Depression,Central Mongolia:Implications for the relationships of Faulting,Volcanic Activity,and Lake Depression Formation

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.

Geoecological parameters indicate discrepancies between potential and actual forest area in the forest-steppe of Central Mongolia

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.

Impacts of Modern Glacier Changes on Surface Water Resources in Western and Northern Mongolia

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.

Above-ground Biomass Allocation in a Planted Forest in a Semi-arid Region of Northern Mongolia

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.

Preparation of Activated Carbons from Mongolian Lignite and Sub-Bituminous Coal by a Physical Method

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&#176;C to 700&#176;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&#176;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.