Sonomdagva Chonokhuu

Traditional ecological ditch technology is unable to enhance the water quality purification effect of highly salty water and improve the salt tolerance of plants. BA (Bacillus amyloliquefaciens) has a positive effect in alleviating salt stress and promoting plant growth. However, the mechanism by which BA enhances plant stress resistance and improves nutrient removal efficiency in the ecological ditch system under high salt stress conditions remains unclear. The experiment constructed two ecological ditches of [P(substrate + plants) and PM (substrate + plants + BA)], and four different salinity treatments (5 g/L, 10 g/L, 15 g/L and 20 g/L) were set up to investigate the removal efficiency of nitrogen and phosphorus in water, and plant growth and physiological indicators, antioxidant enzyme activities and inorganic salt ion concentrations under different salinity stresses by adding BA. It also clarified the relationship between plant growth physiology and the response of water nutrient salts. The results show that the PM treatments for purifying nutrients performed significantly better than the P treatments under different salinity stresses, the removal rates of TN, TP and NH4⁺-N increased by 13.61–22.50%, and the effect was the best at a salinity of 15 g/L. BA enhanced the salt tolerance by increasing the activities of SOD (superoxide dismutase), POD (peroxidase) and CAT (catalase) of plants, reducing the content of MDA (malondialdehyde), lowering the concentration of Na⁺ and increasing the concentration of K⁺, improving the growth and activity of plant roots. Meanwhile, through a comprehensive evaluation, it was determined that BA has the most significant promoting effect on the growth of reed (Phragmites australis), and stronger plant root system is the key to improving the overall purification efficiency of the system. This research provides a theoretical basis for enhancing the water purification effect of high salinity water through ecological ditch technology.

Bacillus amyloliquefaciens (BA) has a positive effect in alleviating salt stress and promoting plant growth. However, the mechanism by which BA enhances plant stress resistance and improves nutrient removal efficiency in ecological ditch systems under high salt stress remains unclear. The experiment constructed two ecological ditch of [P (substrate + plants) and PM (substrate + plants + BA)], and four different salinity treatments (5 g/L, 10 g/L, 15 g/L and 20 g/L) were set up to investigate the removal efficiency of nitrogen and phosphorus in water, and plant growth and physiological indicators, antioxidant enzyme activities and inorganic salt ion concentrations under different salinity stress by adding BA. It also clarified the relationship between plant growth physiology and the response of water nutrient salts. The results show that the PM treatments for purifying nutrients performed significantly better than the P treatments under different salinity stress, the removal rates of TN, TP and NH4⁺-N increased by 13.61% - 22.50%, and the effect was the best at a salinity of 15 g/L. Bacillus amyloliquefaciens enhanced the salt tolerance by increasing the activities of superoxide dismutase(SOD), peroxidase(POD) and catalase(CAT) of plants, reducing the content of malondialdehyde(MAD), lowering the concentration of Na+ and increasing the concentration of K+, improving the growth and activity of plant roots. Meanwhile, through a comprehensive evaluation, it was determined that BA has the most significant promoting effect on the growth of reed, and stronger plant root system is the key to improving the overall purification efficiency of the system.

This study focuses on the quantitative simulation of the spatiotemporal distribution characteristics of permafrost area, providing scientific value for Mongolian Plateau permafrost dynamics. Understanding the permafrost area of the Mongolian Plateau and accurately predicting future changes in permafrost area are crucial for sustainable environmental development. In this study, ERA5-Land surface temperature (LST) combined with the temperature at the top of permafrost (TTOP) model are used to calculate the annual permafrost area from 1980 to 2024. In addition, this study used the long short-term memory (LSTM) model to predict permafrost area on the Mongolian Plateau from 2025 to 2100. In this study, it is concluded that (1) the study area is not uniformly covered with permafrost, and its distribution is mainly limited to the northern part of the Mongolian Plateau, with a permafrost area of 53.20 × 10⁴ km²; (2) the permafrost area is estimated with an accuracy and precision of 0.94 when compared to the baseline value derived from borehole permafrost data; (3) under the CMIP6 three different shared socioeconomic pathway (SSP) 1-2.6, 2-4.5, and 5-8.5 future scenarios, the distribution of permafrost area shows a downward trend. This study provides a theoretical reference for distribution permafrost area in geographical space, which can help achieve the sustainable development of ice and snow resources.

Mongolia is the source of major transboundary rivers in Northeast Asia, including the Selenge and Kherlen, making its water management vital for both domestic sustainability and downstream water security. However, increasing pressures from climate change, mining, and urbanization are contributing to water scarcity and pollution. These challenges reveal structural weaknesses in its transboundary water governance system. This paper examines Mongolia’s transboundary water resource management through international water law and governance frameworks, focusing on institutional challenges: At the legal level, there is a gap between domestic water rights systems and transboundary obligations. At the information-sharing level, hydrological data exchange mechanisms are limited. At the coordination level, inter-agency responsibilities are fragmented and central-local coordination remains weak. At the capacity level, governance is constrained by limited funding, technology, and human resources. In response, the paper proposes reforms to strengthen legal standards, improve data sharing and coordination, enhance institutional authority, increase technical and financial cooperation, and expand engagement in multilateral water governance frameworks. The paper concludes that while Mongolia’s institutional challenges are structural, they can still be addressed. It suggests combining domestic reforms, stronger bilateral cooperation, and multilateral engagement to turn transboundary water resources from a vulnerability into an opportunity for regional cooperation. Монгол Улсын хил дамнасан усны нөөцийн менежментийн байгууллагын хүндрэлүүд ба оновчтой болгох арга замууд Монгол Улс нь Сэлэнгэ, Хэрлэн зэрэг Зүүн Хойд Азийн хил дамнасан томоохон гол мөрний усны эх бүрэлдэх цэг бөгөөд усны нөөцийн менежмент нь дотоодын экологийн аюулгүй байдал, тогтвортой хөгжил төдийгүй доод урсгалын бүс нутаг дахь улс орнуудын усны аюулгүй байдалд ч чухал ач холбогдолтой. Гэвч уур амьсгалын өөрчлөлт, уул уурхай, хотжилтын дарамтын улмаас усны хомсдол, бохирдлын эрсдэл нэмэгдэж байгаа нь хил дамнасан усны засаглалын тогтолцоонд сул тал болж байна. Энэхүү өгүүлэлд олон улсын усны эрх зүй болон засаглалын хүрээний зарчимд тулгуурлан Монгол Улсын хил дамнасан усны нөөцийн менежмент, институцийн тулгамдсан асуудлыг системтэйгээр шинжилсэн: Хууль, эрх зүйн түвшинд дотоодын усны засаглалын тогтолцоо болон хил дамнасан үүрэг хариуцлагын хооронд зөрүүтэй; мэдээлэл солилцооны түвшинд гидрологийн өгөгдөл солилцох тогтолцоо хангалтгүй; зохицуулалтын түвшинд байгууллагуудын чиг үүрэг хуваагдмал, төв болон орон нутгийн уялдаа сул хэвээр байгаа бол чадавхын түвшинд санхүүжилт, технологи, хүний нөөцийн хязгаарлагдмал байдал нь үр дүнтэй засаглалын хэрэгжилтийг сулруулж байна. Иймээс тус өгүүлэлд эрх зүйн орчныг сайжруулах, мэдээлэл солилцоо болон уялдаа холбоог бэхжүүлэх, институцийн эрх мэдлийг нэмэгдүүлэх, техникийн болон санхүүгийн хамтын ажиллагааг өргөжүүлэх, мөн олон талт усны засаглалын тогтолцоонд илүү идэвхтэй оролцох зэрэг шинэчлэлийн арга замуудыг тусгасан. Дүгнэхэд, Монгол Улсад тулгамдаж буй тогтолцооны сорилтууд нь өргөн хэмжээний бүтцийн шинжтэй боловч даван туулах боломжгүй зүйл биш юм. Дотоодын шинэчлэл, хоёр талын хамтын ажиллагаа болон олон талт оролцоог хослуулах замаар хил дамнасан усны нөөцийг эмзэг байдал бус, бүс нутгийн хамтын ажиллагааны боломж, давуу тал болгон ашиглах нөхцөлийг бүрдүүлэх боломжтой. Түлхүүр үг: Монгол Улс; Хил дамнасан усны нөөц; Институцийн тулгамдаж буй асуудлууд, Оновчтой шинэчлэлийн арга замууд; Олон улсын усны эрх зүй; Гол мөрний сав газрын нэгдсэн менежмент

Soil contamination by heavy metals represents a growing environmental and public health concern in cold–dry rural settlements where coal-based household heating remains dominant. This study investigates how coal combustion alters soil element dynamics and associated human health risks by applying a process-oriented, integrated soil system assessment in a residential area of Uliastai city, western Mongolia. Surface soils (0–10 cm) from 38 sites were analyzed using ICP-OES and ICP-MS to determine major and trace element concentrations. Multivariate statistical analysis (principal component analysis, PCA) was combined with contamination indices (enrichment factor and geo-accumulation index) and human health risk assessment to explicitly link contamination sources, transport pathways, soil retention processes, and potential human exposure. Results reveal a clear separation between anthropogenically influenced metals (As, Pb, Cd, Zn, and Cu) and elements predominantly controlled by geogenic background conditions (Cr, Co, and Ni). Very high to extreme enrichment and geo-accumulation levels for As, Pb, Zn, Cd, and Cu indicate substantial anthropogenic alteration of surface soil metal pools. Comparison of soil, coal, and ash compositions identifies coal combustion ash as the primary source of metal enrichment, acting as a concentrated reservoir that is redistributed to soils via atmospheric deposition and surface processes. Human health risk assessment shows that the most enriched metals, particularly As and Pb, dominate both non-carcinogenic and carcinogenic risks, with inhalation and ingestion pathways contributing most strongly to potential exposure. The findings demonstrate that soil contamination in Uliastai reflects systemic changes in soil functioning driven by household energy practices rather than isolated concentration exceedances. By integrating source identification, contamination intensity, and health risk within a unified soil system framework, this study provides mechanistic insight into soil–human interactions and offers a transferable approach for assessing soil impacts in coal-dependent rural environments.

Soil contamination by heavy metals represents a growing environmental and public health concern in cold–dry rural settlements where coal-based household heating remains dominant. This study investigates how coal combustion alters soil element dynamics and associated human health risks by applying a process-oriented, integrated soil system assessment in a residential area of Uliastai city, western Mongolia. Surface soils (0–10 cm) from 38 sites were analyzed using ICP-OES and ICP-MS to determine major and trace element concentrations. Multivariate statistical analysis (principal component analysis, PCA) was combined with contamination indices (enrichment factor and geo-accumulation index) and human health risk assessment to explicitly link contamination sources, transport pathways, soil retention processes, and potential human exposure. Results reveal a clear separation between anthropogenically influenced metals (As, Pb, Cd, Zn, and Cu) and elements predominantly controlled by geogenic background conditions (Cr, Co, and Ni). Very high to extreme enrichment and geo-accumulation levels for As, Pb, Zn, Cd, and Cu indicate substantial anthropogenic alteration of surface soil metal pools. Comparison of soil, coal, and ash compositions identifies coal combustion ash as the primary source of metal enrichment, acting as a concentrated reservoir that is redistributed to soils via atmospheric deposition and surface processes. Human health risk assessment shows that the most enriched metals, particularly As and Pb, dominate both non-carcinogenic and carcinogenic risks, with inhalation and ingestion pathways contributing most strongly to potential exposure. The findings demonstrate that soil contamination in Uliastai reflects systemic changes in soil functioning driven by household energy practices rather than isolated concentration exceedances. By integrating source identification, contamination intensity, and health risk within a unified soil system framework, this study provides mechanistic insight into soil–human interactions and offers a transferable approach for assessing soil impacts in coal-dependent rural environments.

Gross primary productivity (GPP) is a key carbon flux in the global carbon cycle, and understanding the inhibitory effects of drought on GPP and its underlying mechanisms is crucial for understanding carbon–climate feedback. However, current research has not sufficiently addressed the threshold dynamics and regional differentiation of GPP responses to the synergistic effects of meteorological drought (MD) and soil moisture drought (SD), particularly in the drought-sensitive Mongolian Plateau. This study focuses on the Mongolian Plateau from 1982 to 2021, using the standardized precipitation index (SPI) and standardized soil moisture index (SSI) to characterize MD and SD, respectively. The study combines the three-threshold run theory, cross-wavelet analysis, Spearman correlation analysis, and copula models to systematically investigate the variation characteristics, propagation patterns, and the probability and thresholds for triggering GPP loss under different time scales (monthly, seasonal, semi-annual, and annual). The results show that (1) both types of droughts exhibited significant intensification trends, with SD intensifying at a faster rate (annual scale SSI12 trend: −0.34/10a). The intensification trend strengthened with increasing time scales. MD exhibited high frequency, short duration, and low intensity, while SD showed the opposite characteristics. The most significant aridification occurred in the central region. (2) The average propagation time from MD to SD was 11.22 months. The average response time of GPP to MD was 10.46 months, while the response time to SD was significantly shorter (approximately 2 months on average); the correlation between SSI and GPP was significantly higher than that between SPI and GPP. (3) The conditional probability of triggering mild GPP loss (e.g., th percentile) was relatively high for both drought types, and the probability of loss increased as the time scales extended. Compared to MD, SD was more likely to induce severe GPP loss. Additionally, the drought intensity threshold for triggering mild loss was lower (i.e., mild drought could trigger it), while higher drought intensity was required to trigger severe and extreme losses. Therefore, this study provides practical guidance for regional drought early-warning systems and ecosystem adaptive management, while laying an important theoretical foundation for a deeper understanding of drought response mechanisms.

The Mongolian Plateau, a region where nomadic and agrarian civilizations intersect, exemplifies regional sustainable development and natural resource utilization through the spatiotemporal distribution of cultivated land. However, large-scale, long-term, high-precision extraction of cultivated land has not been systematically conducted in this area. This study integrated remote sensing technology with machine learning methodologies to develop an automated extraction process based on spectral, textural, and topographical features. We monitored changes in cultivated land across eight time periods from 1990 to 2023 within the Selenge River Basin, utilizing Google Earth Engine and 3527 scenes derived from Landsat and Sentinel satellite imagery. The area of cultivated land fluctuated between 6332.78 km² and 14,799.22 km², representing 2.26% to 5.29% of the total area. Cultivated land exhibited a significant decline prior to 2005 and gradually increased after 2010, largely influenced by agricultural policy reforms. Traditional nomadic areas showed a spatial pattern of reconstruction, characterized by a significant transformation to agricultural land. The overall accuracy exceeded 90%, and kappa coefficients remained above 0.83. Consistency checks and comparisons of different integration methods further validate the feasibility and reliability of the research methods and results. This approach holds promise for application across the entire Mongolian Plateau and other arid and semi-arid regions for monitoring cultivated land dynamics.