Nitrous oxide (N2O) emissions from inland waters remain highly uncertain, particularly in agricultural landscapes where intensive nitrogen loading and progressive eutrophication may enhance sedimentary N transformation. Although diffusion is generally considered the dominant pathway for aquatic N2O release, the contribution of bubble-mediated transport remains poorly constrained. Here, we quantified dissolved N2O concentrations emission pathways across six shallow eutrophic lakes located within the Hetao Irrigation District, northern China. Dissolved N2O was consistently supersaturated during all sampling campaigns, indicating that these lakes acted as persistent atmospheric N2O sources. Mean diffusive flux and ebullition fluxes were 11.8 ± 0.4 µmol m−2d−1 and 28.0 ± 5.0 µmol m−2d−1, respectively. Ebullition fluxes accounted for approximately 70% of the measured total flux, although this estimate is subject to uncertainties associated with flux partitioning approaches. Ebullition N2O release was associated with sediment nitrogen availability, sediment temperature, and atmospheric pressure, suggesting that biological production and physical gas release jointly regulate this pathway. Our findings resolve a critical uncertainty regarding N2O emission pathways in the widespread occurrence of shallow agricultural water bodies and indicate that projected warming and continued eutrophication are likely to further amplify N2O release from these systems.

The electrochemical sulfide oxidation reaction (SOR) has attracted increasing attention as a promising route for integrated energy conversion and environmental remediation. Herein, an energy-efficient strategy for electrocatalytic sulfide oxidation is reported by coupling the SOR with the hydrogen evolution reaction (HER) during seawater electrolysis. A bifunctional catalyst system was fabricated by sequentially growing molybdenum disulfide and flake-like copper(I) sulfide on nickel foam (NF). The resulting electrode exhibits excellent catalytic activity and operational stability. By integrating the thermodynamically favorable sulfide oxidation with HER in seawater, continuous hydrogen production was sustained for 340 h at a current density of 100 mA cm-2, requiring only 0.53 V. Moreover, the catalyst enables efficient treatment of low-concentration sulfur-containing wastewater. This integrated system shows significant potential for practical seawater hydrogen production, offering substantial economic benefits while facilitating environmental remediation.

Sandy lakes are ecologically vulnerable to anthropogenic and climatic stressors. Although lacustrine groundwater discharge (LGD) is recognized as a crucial component of lake hydrology and nutrient cycling, its specific role in regulating environmental vulnerability in these sensitive ecosystems remains poorly quantified. This study employed an integrated approach, combining hydrochemical analysis, water source identification, and a radon (222Rn) isotope mass balance model, to investigate the sources and drivers of major pollutants in saline-salt lakes of the Mu Us Sandy Land. Particular emphasis was placed on the impact of LGD on lake water (LW) quality. The enrichment of nitrogen substances and Mg2+ represented the primary environmental issue within the watershed. Total nitrogen (TN), primarily derived from manure application, and total phosphorus (TP), originating from industrial activities, were identified as the major pollutants of groundwater (GW) and LW. Spatially, saline lakes exhibited better water quality than salt lakes, and lakes in the upper and middle reaches generally had better quality than those downstream. Temporally, water quality variations were closely linked to changes in lake surface area, which were predominantly controlled by precipitation-the primary source of lake recharge, accounting for 65.6% of total inflow. The concentration of 222Rn decreased progressively from GW to porewater and then to LW (2030.17, 1477.41, and 40.61 Bq/m3, respectively), indicating active LGD processes, with a mean LGD rate of 63.60 mm/d within the watershed. This process delivered fluxes of 1.88, 7.92, and 3.18 g/m2/ d for TN, NO3-, and Mg2+, respectively, facilitating their accumulation in the lakes. The ratio of GW input height to lake depth revealed that shallower lakes received a greater proportion of water and nutrient inputs via LGD and consequently exhibited poorer water quality, highlighting the substantial regulatory role of LGD on lake environments. Random forest analysis further indicated that mitigation strategies should target the root causes, namely, industrial/agricultural pollution sources and the LGD pathway. Controlling inputs from these terrestrial sources is therefore essential to reduce pollutant loading in GW and limit their influx into lakes.

The ammonia oxidation reaction (AOR) represents an effective strategy for the energy-efficient and environmentally benign synthesis of high-value nitrites, while simultaneously serving as a promising alternative to the oxygen evolution reaction (OER) for hydrogen production. Herein, Prussian blue analogues doped with Ni and Cu (NiCu-PBAs) are synthesized via a hydrothermal method and subsequently electrochemically activated to induce surface reconstruction, forming a NiOOH/Cu(OH)2 heterostructure. Ultraviolet photoelectron spectroscopy and density functional theory calculations reveal that a built-in electric field is established at the heterointerface, which modifies charge distribution of NiOOH phase, enhances NH3 adsorption, and lowers the reaction energy barrier for AOR. The reconstructed NiCu-PBAs ((R)NiCu-PBAs) deliver excellent AOR activity, attaining a current density of 10 mA cm- 2 at 1.38 V vs. RHE and a nitrite selectivity of 88.9%. Moreover, when serving as both anode and cathode, the coupled AOR-hydrogen evolution system only requires 1.55 V to reach 10 mA cm- 2 in a two-electrode configuration, significantly lower than the 1.68 V needed for conventional HER-OER water splitting. This corresponds to an energy saving of approximately 15% for hydrogen production, while concurrently generating value-added nitrite. This work offers a viable strategy for design of low-cost, high-performance non-noble metal catalysts toward the sustainable synthesis of nitrite and production of hydrogen.

The relationship between lacustrine groundwater discharge (LGD) and dissolved organic matter (DOM) dynamics remains insufficiently understood, particularly during the freezing season. In this study, the spatial and seasonal variability and controlling factors of DOM in surface water and groundwater were investigated in a representative ice-covered lake basin (Ulansuhai Lake, China). Specifically, the effects of LGD on DOM sources and transport during non-freezing and freezing seasons were examined using fluorescence excitation-emission matrix spectroscopy coupled with parallel factor analysis (EEM-PARAFAC) and a 222Rn mass balance model (RMBM). During the non-freezing season, DOM was primarily composed of humic-like components (C1-C3), whereas during the freezing season, in addition to humic-like components (C1-C3), protein-like component (C4) was also identified. Quantitative source apportionment indicated that effluent (mean: 39%), soil (mean: 27%), fertilizers (mean: 20%), and plants (mean: 14%) were the dominant DOM sources. During the non-freezing season, LGD was relatively weak (mean LGD rate: 5.12 mm/d), and canal water served as the primary recharge source for both groundwater and lake water; consequently, allochthonous humic-like substances (components C1-C3) dominated the DOM pool. In contrast, during the freezing season, LGD intensified markedly (mean LGD rate: 17.49 mm/d), becoming the sole recharge source for the lake and amplifying the relative contribution of protein-like DOM (C4). Moreover, hydrological conditions and vegetation cover further regulated DOM dynamics by modulating LGD processes. Overall, this study highlights the crucial role of LGD in governing DOM dynamics and demonstrates the effectiveness of integrating optical techniques with isotopic mass balance modelling to elucidate biogeochemical processes under seasonally variable environmental conditions.

Lakes in cold regions that experience seasonal ice cover are potential hotspots of greenhouse gas (GHG) emissions. However, the synergistic roles of groundwater, as a concealed external source, and dissolved organic matter (DOM) in regulating CH4 and CO2 dynamics and emissions remain poorly understood. Based on year–round observations at Ulansuhai Lake, this study revealed seasonal differences in the regulatory effects of lacustrine groundwater discharge (LGD) and microbially derived DOM. During the ice–free period, the LGD rate was low (5.53 mm/d). CO2 dynamics were primarily controlled by microbial decomposition of DOM, whereas CH4 dynamics were mainly influenced by direct LGD input and were positively correlated with DOM aromaticity and humification. During the ice–covered period, the LGD rate increased markedly, reaching a maximum of 18.09 mm/d, and became the sole external source of CO2. In contrast, CH4 was predominantly regulated by DOM, driven positively by humic component C2 and the humification index (HIX), a process facilitated by anaerobic microbial fermentation. Flux calculations indicated that, during the ice–free period, water–air emissions of both gases exceeded the corresponding LGD–derived inputs. However, when considering only the LGD pathway, its regulatory effect was stronger for CH4 than for CO2. During ice cover, water–air gas exchange ceased, while LGD–derived CO2 inputs (0.049–1.720 mmol/m2/d), together with CH4 produced via DOM–driven anaerobic fermentation, sustained greenhouse gas accumulation beneath the ice. These findings identify LGD as a concealed driver of CH4 and CO2 emissions with seasonal shifting roles and highlight its importance in carbon budget assessments of seasonally ice–covered lakes in cold regions. This study advances understanding of groundwater–derived carbon inputs in lake carbon cycling and provides both hydrological and biogeochemical insights for compiling greenhouse gas emission inventories from seasonally ice–covered lakes.

Despite its environmental and health relevance, the origin and mobilization of fluoride (F−) in lake-groundwater systems have been scarcely quantified. This study integrated hydrochemistry, Bayesian isotope mixing modeling (MixSIAR) based on 87Sr/86Sr and δ11B, a 222Rn mass balance model (RMBM), and microbial ecological analysis to investigate F− dynamics in the Bahannao Lake Group (BLG), a representative lake-groundwater system in Inner Mongolia, China. Analysis of 291 water samples showed that high-F− waters were mainly associated with HCO − 3–Na+ hydrochemical types, reflecting the alkaline conditions favorable for F− enrichment. Isotope-based source apportionment suggested that evaporite dissolution, silicate weathering, and anthropogenic inputs may collectively contribute to Sr and B release and associated F− enrichment. The RMBM estimated a F− flux associated with groundwater discharge of 24.68 mg/m2/d, suggesting that groundwater discharge may represent a potential pathway facilitating F− transport within the lake-groundwater system. Microbial communities exhibited distinct patterns between lake water and groundwater, reflecting strong habitat-specific environmental filtering under contrasting hydrochemical conditions. Overall, this study provides insights into the coupled hydrogeochemical and ecological processes influencing F− distribution in lake–groundwater systems and highlights the importance of integrating geochemical tracing, hydrological modeling, and microbial ecology for understanding regional water quality.

Single-atom catalysts (SACs) have exhibited great potential for CO2 electroreduction (CO2RR), but designing highly active and cost-effective SACs remains a challenge. In this study, a pyrolysis strategy with space-limiting materials as the precursors is developed to synthesize a highly active Ni-SAs/NC catalyst, and an atomic Ni loading of 2.16 wt% is achieved. The coordination style of Ni atoms is determined to be Ni-N-3 by XAS. During the CO2RR test, a CO Faradaic efficiency of 98.21 % at -0.8 V vs. RHE can be achieved with a turnover frequency of 2378 h(-1). A long-term stability can also be obtained with negligible deactivation in 24 h, surpassing most of previously reported non-noble metal catalysts. In addition, a novel dual-function reaction system was fabricated to integrate CO2RR with electrochemical oxidation processes (EAOPs) for pollutants degradation. With delta-MnO2/NF as the anode, 100 % of 40 ppm RhB can be degraded within 30 min in the range of -0.6 V similar to -1.0 V. This system can thus enable the reduction of CO2 to CO and degradation of pollutants in the anodic cell simultaneously. The introduction of EAOPs as the anodic reaction provides a more cost-effective method for electrochemical CO2 reduction.

Shallow lakes are major contributors to atmospheric CH4 and CO2 emissions. However, limited research has systematically assessed the three primary emission pathways, diffusion, ebullition, and plant-mediated transport, across heterogeneous lacustrine habitats within these ecosystems. This study combined field surveys and gas stable carbon isotopic analyses to quantify CH4 and CO2 emissions through multiple pathways (diffusion, ebullition, and plant-mediated) in different habitats, including open water (OW), emergent vegetation (E), submerged vegetation (S), and submerged and macrofilamentous algal symbiosis (SA), in Lake Ulansuhai during the growing season. Compared with the remaining three habitats, habitat SA had the highest CH4 emission (17.41 f 20.65mmol m-2 d-1) and the lowest CO2 emission (50.27 f 40.03mmol m-2 d-1). CH4 emissions peaked during the peak growth season in July, whereas CO2 emissions peaked at the end of the growing season in October. The vegetated habitats had nine times more CH4 than the non-vegetated habitats. The CH4 flux from the vegetated habitats was primarily plant-mediated (mean 74 %), followed by ebullition (17 %). The fractionation factor (alpha C) values of delta 13C-CH4 and delta 13C-CO2 in the dissolved gas and bubbles indicated more acetoclastic methanogenesis, with CO2 likely derived from organic matter remineralization and biometabolism. This indicates that the plants promoted methanogenesis by providing substrates, contributing to the high CH4 emissions from Lake Ulansuhai. This study improves the accuracy of regional carbon emission estimates in multi-habitat aquatic systems and further elucidates how aquatic plants influence carbon emissions.

Understanding carbon burial in lake sediments is essential for evaluating long-term carbon sinks, particularly in closed-basin saline lakes of arid and semi-arid regions. This study analyzes 5 sediment cores from Lake Daihai, a terminal saline lake in Inner Mongolia, to investigate the temporal and spatial variations of organic (TOC) and inorganic carbon (TIC) concentrations and burial rates over the past century. Sediment chronologies based on the CRS model and 137Cs markers confirm continuous accumulation. Results show that TIC dominates the total sedimentary carbon pool, contributing 61 % of total burial, with a mean ICAR (from 58.4 g C m-2 yr-1 in 1950s to 104.9 g C m-2 yr-1 in 2020s) significantly exceeding OCAR (from 84.9 in 1950s to 172.7 g C m-2 yr-1 in 2020s). Source apportionment suggests that TOC primarily originates from soil (25.5 %), sewage (24.4 %), and phytoplankton (16.3 %), reflecting both anthropogenic and autochthonous contributions. Since the early 2000s, both TOC and TIC concentrations and burial rates have increased sharply, coinciding with accelerated GDP growth, peak population, and substantial lake surface shrinkage (reduced by 58.4 %). Partial Least Squares Path Modeling analysis reveals that lake trophic status positively influences both TOC (R = 0.48) and TIC (R = 0.78), while land use has contrasting effects TOC (R = -0.34) but positively influencing TIC (R = 0.53) through enhanced carbonate delivery. The land use reduces TOC may though limiting organic matter retention but increases TIC via enhanced carbonate input and precipitation. These results provide a framework for understanding carbon cycling in closed-basin lakes of arid regions subject to increasing human and climatic pressures.

Lakes are emission hotpots of nitrous oxide (N2O), however, this phenomenon remains poorly constrained. Eutrophication is widespread in lakes, yet its contribution to N2O emissions is still not well understood. Here, we investigate the spatiotemporal variations of N2O concentrations, fluxes and indirect emission factors (EF5r) and their drivers in Ulansuhai lake, a shallow eutrophic lake located in a semi-arid region in northern China, during 2019-2020. The mean concentration of N2O in water was 20.0 ± 6.7 nmol/L, with a mean diffusive N2O flux of 16.50 ± 21.52 µmol/(m2·day), indicating that this lake acted as a persistent source of atmospheric N2O. Estimated indirect emission factors (EF5r) (mean value 0.0037 ± 0.0060) were significantly higher than the default values (0.0026) used in Intergovernmental Panel on Climate Change (IPCC) emission inventories. The N2O concentrations, fluxes and EF5r exhibited substantial seasonal variations and small spatial variations. N2O concentrations and fluxes were positively correlated with the trophic status and EF5r increased with increasing nutrient concentrations in the water. These findings demonstrate the role of eutrophication in influencing the N2O dynamics and confirm that eutrophication can exacerbate N2O emissions.

Electrosynthesis of hydrogen peroxide (H2O2) via the two-electron oxygen reduction reaction (2e(-)ORR) route is regarded as a promising substitute for the conventional anthraquinone method. In this study, a core-shell Ni@carbon material with adjustable shell thickness was synthesized using a simple hydrothermal-calcination method with the formation of metal organic framework (MOF) as the intermediate. During the calcination process, sea-urchin like morphology was obtained with nickel nanoparticles as the core and nitrogen-doped carbon nanotubes (NCNTs) as the shell. The optimized Ni@NCNTs-1.5 material exhibits a high H2O2 selectivity of >90 % in a wide potential range of 0.2-0.6 V, and a H2O2 concentration of 797 mg/L can be achieved within 120 min in 0.1 M KOH. The generated H2O2 can maintain almost 100 % degradation of 10 ppm Rhodamine B within 12 h. Theoretical calculations unveil that the synergistic effect between encapsulated nickel nanoparticles (Ni NPs) and N-doped carbon layers effectively regulates the charge distribution, resulting in optimal binding strength of *OOH intermediate, thus leading to the high selectivity of H2O2. This work provides an efficient strategy for the synthesis of electrocatalysts with high performance for 2e(-)ORR.

Assessing the impact of freeze-thaw cycles on nutrient transfer in lakes is crucial for addressing the global eutrophication of freshwater ecosystems in cold and arid regions. However, available information about the dynamics of nitrogen (N) and phosphorus (P) release during intact freeze-thaw cycles, especially in the sediment-porewater-water column continuum of lakes, is limited. This study collected the samples during ice-covered (January) and non-ice-covered (April, July, and October) periods. The changes in total nitrogen (TN) and total phosphorus (TP) were analyzed to estimate their release fluxes from the sediment-water interface. Both redundancy analysis (RDA) and variance partitioning analysis (VPA) were used to explore the effects of environmental variables on N and P. The results indicated that during the ice-covered period (ICP), the surface water content of different forms of N and P was lower than that of the overlying water, whereas the opposite was true during the non-ice-covered period (NICP). The overall trend for the different forms of N was TN > DIN > NH4-N > NO3-N > NO2-N, and for P, it was TP > PP > DTP > DOP>DIP. The vertical profiles of the porewater TN and TP generally demonstrated an increase followed by a decrease from the surface to the bottom, with an inflection point at 15 cm. Sediment TN and TP trends over time matched porewater trends, with both being spatially highest at the lake inlet. ICP sediments acted as sinks for TN and TP, and NICP sediments acted as sources. N and P in the water column were significantly correlated mainly with physicochemical indicators, whereas sediment contributed positively to TN and TP in the porewater. VPA indicated that environmental factors explained 46.45 % of the variation in TN and TP in the porewater. These findings emphasize the importance of freeze-thaw cycling processes in driving N and P nutrient enrichment, source-sink effects, and multi-media coupling in shallow lakes in arid plateau regions.

Greenhouse gases (GHGs) emitted or absorbed by lakes are an important component of the global carbon cycle. However, few studies have focused on the GHG dynamics of eutrophic saline lakes, thus preventing a comprehensive understanding of the carbon cycle. Here, we conducted four sampling analyses using a floating chamber in Daihai Lake, a eutrophication saline lake in Inner Mongolia Autonomous Region, China, to explore its carbon dioxide (CO2) and methane (CH4) emissions. The mean CO2 emission flux (FCO2) and CH4 emission flux (FCH4) were 17.54 ± 14.54 mmol/m2/day and 0.50 ± 0.50 mmol/m2/day, respectively. The results indicated that Daihai Lake was a source of CO2 and CH4, and GHG emissions exhibited temporal variability. The mean CO2 partial pressure (pCO2) and CH4 partial pressure (pCH4) were 561.35 ± 109.59 µatm and 17.02 ± 13.45 µatm, which were supersaturated relative to the atmosphere. The regression and correlation analysis showed that the main influencing factors of pCO2 were wind speed, dissolved oxygen (DO), total nitrogen (TN) and Chlorophyll a (Chl.a), whereas the main influencing factors of pCH4 were water temperature (WT), Chl.a, nitrate nitrogen (NO3--N), TN, dissolved organic carbon (DOC) and water depth. Salinity regulated carbon mineralization and organic matter decomposition, and it was an important influencing factor of pCO2 and pCH4. Additionally, the trophic level index (TLI) significantly increased pCH4. Our study elucidated that salinity and eutrophication play an important role in the dynamic changes of GHG emissions. However, research on eutrophic saline lakes needs to be strengthened.

Lakes and ponds in boreal regions are considerable natural sources of greenhouse gases (GHGs), including carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O). Although the seasonal variability of GHG emissions from boreal lakes is crucial for improving global emission models, emissions during the freezing period have not received sufficient attention. Focusing on two representative boreal lakes in China-Ulansuhai and Daihai-this study investigated variations in GHG emissions during both the non-freezing and freezing periods. The concentrations of CO2 and CH4 in lake porewater during the non-freezing period were observed to be 50 to 74 times higher than those during the freezing period. In both lakes, CO2 and CH4 emissions predominantly occurred at the water-air interface, with N2O absorption. The Global Warming Potential (GWP) of GHGs in Ulansuhai was 234.35×104 kg/yr, with CO2, CH4, and N2O contributing 12.0 %, 87.4 %, and 0.6 %, respectively. In Daihai, the GWP was 40.47×103 kg/yr, with CO2 CH4, and N2O contributing 40.4 %, 24.5 %, and 35.1 %, respectively. Notably, the GHG 'storage' capacities of Ulansuhai and Daihai were 227.51 × 105 kg/yr and 9.23 × 102 kg/yr, respectively. In both lakes, dissolved organic carbon and total nitrogen in the porewater exhibited a negative relationship with GHG concentrations. Compared to lake Ulansuhai, salinity exhibited a stronger correlation with GHGs in lake Daihai, which has high salinity. Our research reveals that the freezing period and the salinity (in high salinity lakes) have distinct impacts on GHG emissions in boreal lakes. The findings are crucial for understanding the contributions of boreal lakes to GHG emissions and their potential impact on climate change, and provide vital information for developing conservation and management strategies regarding these ecosystems.

Phytoplankton play an irreplaceable role as producers in maintaining lake ecosystems. Nevertheless, scant attention has been given to investigating the dispersion of phytoplankton communities and the factors influencing them across expansive areas. In this study, we present the results of a survey on the distribution of phytoplankton community and the effects of different driving factors in 11 lakes along Inner Mongolia in July-August 2020. Non-metric multidimensional scaling analysis and variance decomposition (VPA) were used to elucidate the distribution of phytoplankton communities and the response of drivers. A total of 169 species of phytoplankton from 8 phyla were detected. Both the abundance and diversity of phytoplankton in the Inner Mongolia lakes showed a trend of high in the east and low in the west (with Daihai Lake as the boundary). The Margalef index of phytoplankton significantly negatively correlated with salinity (r = -0.707, P < 0.05) and total dissolved solids (r = -0.720, P < 0.05), and both density and biomass highly significantly positively correlated with the suspended solids, Chlorophyll a and trophic level index. The VPA explained 38.9% of the changes in the phytoplankton community with the highest rate of explanation of land use. Therefore, preventing anthropogenic impacts, as well as reducing nutrient loads, can effectively ensure the ecological diversity of lake phytoplankton in lake populations with large geographical spans and varying levels of nutrients.

Lakes are important component of the regional carbon cycle and a significant sources of greenhouse gases (GHGs) to the atmosphere. However, the regional variations in carbon dioxide (CO 2 ) and methane (CH 4 ) emissions, as well as the factors regulating these emissions are poorly constrained. To investigate the regional GHG emission from lakes and their potential influencing factors, we conducted field measurements in 13 lakes in Inner Mongolia from July to August 2020. We found that the studied lakes were predominantly sources of atmosphere CO 2 and CH 4 . The CO 2 partial pressure ( p CO 2 ) exhibited supersaturation in 80 % of samplings, but all samplings of CH 4 partial pressure ( p CH 4 ) showed supersaturation. Moreover, the average p CH 4 is 40 times greater than that in the atmosphere. The lakes emitted substantial amounts CO 2 and CH 4 with average values of 25.8 +/- 4.9 mmol m - 2 d -1 and 2.1 +/- 0.3 mmol m - 2 d -1 , respectively. At the regional scale, the dynamics of p CO 2 and p CH 4 are regulated by combination of various environmental factors. CO 2 emissions from studied lakes decreased with the catchment net primary productivity (NPP), normalized difference vegetation index (NDVI), and nighttime lights which is indicative of urbanization. Conversely, CH 4 fluxes increased with NPP, NDVI, and nighttime lights. We conclude that terrestrial carbon -cycling related variables and human activities significantly affect CO 2 and CH 4 emissions from lakes by transporting different nutrients, but they show opposite trends. Our results also exhibited that the freshwater lakes are the main contributors of CH 4 , while saline lakes are the main contributors of CO 2 . We suggest that increased human activity leads to changes in terrestrial carbon -cycle related processes which affects lake carbon emissions by altering the amount of nutrients input to the lakes.

In arid and semi-arid typical grasslands, water is a crucial limiting factor, while grazing and mowing are the primary utilization methods. In this study, the evapotranspiration, soil water storage and ecological water use characteristics of typical grassland communities（Stipa grandis community and Leymus chinensis community） in Inner Mongolia were measured under different utilization methods. The results showed that mowing significantly reduced evapotranspiration, soil water storage, and ecological water use in typical grassland S. grandis community compared to other utilization methods（P＜0.05）. The evapotranspiration of typical grassland S. grandis and L. chinensis communities both reached the maximum in the middle of the growing season（July） and the evapotranspiration of the communities under moderate grazing conditions was the highest under different utilization methods. In addition, the enclosure enhanced soil water storage and ecological water use in the S. grandis community. Soil water storage and ecological water use were significantly higher（P＜0.05） in the S. grandis and L. chinensis communities under light grazing condition than other grazing utilizations. Exploring the ecological water use responses of major communities in typical grasslands to different utilization methods can provide fundamental insights into the water cycle dynamics of grassland ecosystems and promote sustainable management of water resources.

Lakes play important roles in sustaining the ecosystem and economic development in Inner Mongolia Autonomous Region of China, but the spatial patterns and driving mechanisms of water quality in lakes so far remain unclear. This study aimed to identify the spatial changes in water quality and the driving factors of seven lakes (Juyanhai Lake, Ulansuhai Lake, Hongjiannao Lake, Daihai Lake, Chagannaoer Lake, Hulun Lake, and Wulannuoer Lake) across the longitudinal axis (from the west to the east) of Inner Mongolia. Large-scale research was conducted using the comprehensive trophic level index (TLI (Σ)), multivariate statistics, and spatial analysis methods. The results showed that most lakes in Inner Mongolia were weakly alkaline. Total dissolved solids and salinity of lake water showed obvious zonation characteristics. Nitrogen and phosphorus were identified as the main pollutants in lakes, with high average concentrations of total nitrogen and total phosphorus being of 4.05 and 0.21 mg/L, respectively. The values of TLI (Σ) ranged from 49.14 to 71.77, indicating varying degrees of lake eutrophication, and phosphorus was the main driver of lake eutrophication. The lakes of Inner Mongolia could be categorized into lakes to the west of Daihai Lake and lakes to the east of Daihai Lake in terms of salinity and TLI (Σ). The salinity levels of lakes to the west of Daihai Lake exceeded those of lakes to the east of Daihai Lake, whereas the opposite trend was observed for lake trophic level. The intensity and mode of anthropogenic activities were the driving factors of the spatial patterns of lake water quality. It is recommended to control the impact of anthropogenic activities on the water quality of lakes in Inner Mongolia to improve lake ecological environment. These findings provide a more thorough understanding of the driving mechanism of the spatial patterns of water quality in lakes of Inner Mongolia, which can be used to develop strategies for lake ecosystem protection and water resources management in this region.