Background, aim, and scope With the advancement of urbanization and industrialization, persistent organic pollutants (POPs) released from anthropogenic activities have posed significant threats to the environment and human health. As emerging contaminants, POPs have been restricted under the Stockholm Convention on Persistent Organic Pollutants. In China, extensive studies have been conducted to identify environmental sources of POPs and assess associated human exposure risks. However, existing research has predominantly focused on East China, while studies in Northwest China remain limited. Meanwhile, ongoing global climate change, accompanied by increasing extreme weather events, may further intensify aridity in these regions and alter pollutant exposure pathways. Therefore, this study reviews the occurrence and exposure risks of POPs in arid areas of Northwest China. Materials and methods This review first outlines the physicochemical properties of major organochlorine pesticides (OCPs), with particular focus on hexachlorocyclohexane (HCHs) and dichlorodiphenyltrichloroethane (DDTs), as well as polycyclic aromatic hydrocarbons (PAHs), and briefly summarizes their toxic effects. It then introduces desert and sandy regions in China. Subsequently, the spatial distribution and sources of major OCPs and PAHs in the atmosphere and soil are summarized. Finally, the environmental exposure risks associated with these pollutants are discussed. Results Cities in Northwest China, such as Urumqi and Lanzhou, are less economically developed than Beijing, Shanghai, and Guangzhou. Except for markedly higher DDT concentrations in Beijing soils, levels of major OCPs in soil and air in northwestern cities are generally comparable to those in developed regions. In contrast, polycyclic aromatic hydrocarbons (PAHs) in soil and atmosphere are often higher in Northwest China. OCPs mainly derive from historical residues, with limited recent inputs in some areas, whereas PAHs primarily originate from biomass and fossil fuel combustion, with additional contributions from long-range transport. Overall, concentrations in most arid regions remain within safe ranges. Discussion Although health risks from OCPs and PAHs in arid regions are generally low, atmospheric concentrations show clear seasonal variation. OCPs are typically higher in summer due to temperature-driven volatilization from soil. Conversely, PAHs are lower in summer because enhanced photodegradation exceeds soil emissions, but higher in winter due to coal combustion for heating. Under continued global warming, rising temperatures in arid regions may enhance soil-to-air transfer of PAHs. While low-molecular-weight PAHs may degrade more rapidly, high-molecular-weight PAHs may accumulate in the atmosphere, potentially increasing respiratory exposure risks. Conclusions Atmospheric PAHs in Chinese cities show a clear north – south gradient, with higher concentrations in northern regions due to winter coal combustion and limited pollutant dispersion under low temperatures. Despite lower socioeconomic development in Northwest China compared with eastern coastal cities, OCP residues in soil and air are comparable, while PAH levels are often higher, likely reflecting regional differences in historical usage and pollutant behavior under arid conditions. POP sources in arid regions of Northwest China exhibit strong spatial heterogeneity. HCHs mainly originate from historical residues and lindane use, whereas DDTs are associated with industrial inputs and dicofol-related sources. PAHs primarily derive from biomass, coal, petroleum combustion, and traffic emissions, with additional influence from long-range atmospheric transport in desert petroleum areas such as Tazhong. Overall, POP sources follow a pattern dominated by local emissions with supplementary external inputs. Health risk assessments indicate generally low POP-related risks across most arid areas, although localized concerns remain. Potential carcinogenic risks from PAHs are observed in suburban Urumqi crops and in desert-adjacent cities, where elevated TSP-bound PAHs lead to lifetime inhalation cancer risks exceeding acceptable limits. Recommendations and perspectives Atmospheric and soil POP levels in most arid cities of China remain within safe limits, with elevated risks confined to areas near industrial or agricultural emission sources. However, crops in arid regions may present potential exposure risks and warrant closer monitoring. Airborne POP concentrations can increase in winter due to additional emission sources and reduced atmospheric dispersion. During dust and sandstorm events, personal protective measures are recommended, as PM₁₀ and PM_2.5 can carry substantial pollutant loads. Given limited regulation of emerging contaminants in China, priority pollutants should be identified for targeted regional control. Authorities should optimize functional zoning by separating residential areas from pollution sources, strengthen industrial management, promote green production, and enhance regulation of pesticide manufacture and use.]]> 2026/4/17 0:00:00 Background, aim, and scope Climate warming has accelerated glacier retreat worldwide, leading to the release of contaminants historically stored in glaciers into downstream environments. Perfluoroalkyl acids (PFAAs) are persistent pollutants that have been widely detected in glacial regions, yet their variation characteristics in meltwater with different hydrological sources remain poorly understood. This study aims to investigate the occurrence, spatial distribution, and seasonal variation of PFAAs in glacial meltwater from two contrasting basins on the Qinghai-Xizang Plateau: the Zhari Nam Co basin representing “old water” far from glacier termini and the Quemo Co basin representing “new water” close to glacier termini. Materials and methods A total of 43 glacial meltwater samples were collected from the two basins during the pre-ablation period (April −June) and post-ablation period (August−October) in 2021. Twelve PFAAs, including C₄—C₁₂ perfluoroalkyl carboxylic acids (PFCAs) and C₄, C₆, and C₈ perfluoroalkyl sulfonic acids (PFSAs) were analyzed to determine their concentration levels and compositional characteristics. In addition, ten hydrochemical parameters, including water temperature, pH, dissolved oxygen (DO), electrical conductivity (EC), total nitrogen (TN), ammonia nitrogen (NH3-N), total phosphorus (TP), arsenic (As), fluoride (F− ), and chloride (Cl− ), were measured, and correlation analysis together with principal component analysis (PCA) was applied to identify the factors influencing PFAAs variations. Results Total PFAAs concentrations ranged from 732—4375 pg/L (mean: 2086 pg/L) in the Zhari Nam Co basin and 593—7282 pg/L (mean: 2026 pg/L) in the Quemo Co basin, which are comparable to those reported in other remote regions worldwide and indicate relatively low contamination levels. In both basins, C₄—C₉ PFCAs and perfluorobutane sulfonic acid (PFBS) were the dominant components, while the predominant compounds differed between basins: PFBS dominated in the Zhari Nam Co basin, whereas perfluorobutanoic acid (PFBA) dominated in the Quemo Co basin. Compared with the pre-ablation period, the proportions of short-chain PFCAs decreased, whereas PFBS increased during the post-ablation period. Spatially, PFAAs concentrations generally increased first and then decreased along the flow direction in both basins. Discussion The seasonal shift in PFAAs composition suggests that continuous flushing by glacial meltwater may enhance the gradual release of PFAAs stored in river sediments and surrounding soils into runoff. Hydrochemical conditions also played important roles in regulating PFAAs distribution. Among the measured parameters, pH and fluoride showed the strongest correlations with PFAAs concentrations, indicating that hydrochemical processes significantly influence the transport of PFAAs in glacial meltwater. Conclusions Overall, PFAAs in meltwater close to glacier termini (“new water”) were mainly controlled by glacier melt intensity, whereas those in downstream meltwater (“old water”) were more strongly influenced by hydrological transport processes and hydrochemical conditions. Recommendations and perspectives This study improves the understanding of contamination characteristics and transport mechanisms of PFAAs in glacial meltwater on the Qinghai-Xizang Plateau. Long-term monitoring and integrated hydrological-geochemical studies are recommended to better quantify pollutant release from retreating glaciers and evaluate their potential environmental risks in alpine ecosystems.]]> 2026/4/17 0:00:00 Background, aim, and scope The rapid degradation of permafrost, driven by ongoing global warming, has become a significant concern, especially in high-altitude and polar regions. The warming of permafrost and glacier melting is causing the release of persistent organic pollutants (POPs) that have been historically stored in these areas. POPs, a class of toxic contaminants, pose serious risks to human health and ecosystems. As climate change accelerates, the secondary emission of these pollutants from permafrost and glaciers is becoming a growing environmental issue. This review aims to explore the secondary emissions and environmental migration of POPs resulting from permafrost degradation and glacier retreat under climate change. The goal is to understand how these changes affect the behavior and distribution of POPs and to evaluate the potential environmental risks they pose. The scope focuses on the secondary emissions of POPs from thawing permafrost and glaciers, particularly in vulnerable high-altitude ecosystems like the Qinghai-Xizang Plateau (QXP), and their subsequent migration into the environment. The findings aim to inform future research directions and environmental policies to address the growing risks associated with POPs under climate change. Materials and methods This review synthesizes various studies and findings on POPs stored in permafrost, glaciers, soil, and vegetation. The analysis draws upon data from multiple sources, including field studies, remote sensing, and climate models, to evaluate how climate warming influences the release and redistribution of POPs in different environmental matrices. The review focuses on how temperature rise, thawing of permafrost, glacier melting, and changes in land cover and water systems contribute to the mobilization of POPs. Seasonal variations in the release and migration of POPs are also discussed, with particular attention to how extreme weather events, such as storms and wildfires, may exacerbate this process. Results The results indicate that rising temperatures are reactivating POPs stored in permafrost and glaciers, with significant releases observed in regions such as the QXP. Melting ice and thawing ground release POPs including HCHs (hexachlorocyclohexanes), PCBs (polychlorinated biphenyls), and PAHs (polycyclic aromatic hydrocarbons) into the atmosphere and aquatic systems, with volatilization increasing during warmer periods. Extreme events such as wildfires further enhance the emission and dispersal of these pollutants. Discussion The discussion focuses on how climate change accelerates the release of POPs from their long-term storage in permafrost and glaciers. Warming temperatures enhance the volatility of these pollutants, making them more prone to release into the atmosphere, water bodies, and soils. The review identifies that, although the primary sources of POPs have been reduced through measures like the Stockholm Convention, the secondary release of POPs from thawing permafrost and glaciers has become an increasingly important source. The seasonal patterns of POPs release are also explored, with POP concentrations peaking during warmer months and in response to human activities like biomass burning. Additionally, extreme events, such as wildfires and glacier melt, are shown to significantly affect the migration of POPs, increasing their distribution and bioaccumulation in remote ecosystems. Conclusions The secondary emission of POPs from permafrost and glacier melt represents a significant environmental concern in the context of global climate change. Rising temperatures are enhancing the volatility of these pollutants, facilitating their release into the atmosphere, water bodies, and soil. This process, combined with seasonal changes and extreme events such as wildfires and glacier melt, exacerbates the migration and bioaccumulation of POPs in remote ecosystems, including those in the Arctic and the QXP. While efforts to reduce primary emissions, such as through the Stockholm Convention, have yielded positive results, the release of POPs from environmental reservoirs due to thawing permafrost and melting glaciers has emerged as a critical source of pollution that requires urgent attention. The impacts of these secondary emissions on ecosystems and human health are becoming increasingly apparent, underlining the need for immediate action. Recommendations and perspectives To address the growing challenge of POPs secondary emissions, future research should prioritize improving monitoring systems to track the release and movement of these pollutants. Enhanced monitoring networks should be established in vulnerable regions, such as the Arctic and QXP, where permafrost degradation and glacier melt are particularly pronounced. It is also essential to strengthen environmental regulations and policies aimed at mitigating the risks associated with POPs exposure, especially in remote and sensitive ecosystems. Comprehensive studies are needed to better understand the long-term impacts of these secondary emissions, including their bioaccumulation in food chains and their potential effects on human health. In the context of a warming climate, further interdisciplinary research, including studies on climate-driven factors, should be conducted to assess the full scope of POPs migration and to inform future climate and environmental management strategies. Addressing the complexities of secondary emissions in these regions will be critical to protecting both ecosystems and human health in the face of ongoing climate change.]]> 2026/4/17 0:00:00 Background, aim, and scope In recent years, despite declining atmospheric particulate matter (PM_2.5) mass concentrations, health risks have not decreased proportionally because highly toxic organic components persist, with respiratory exposure and toxic effects exhibiting pronounced diurnal differences. This study investigates the diurnal variations of PM_2.5, polycyclic aromatic hydrocarbons (PAHs), oxygenated PAHs (OPAHs), and nitro-aromatic compounds (NACs) in Xi’an from January to February 2022, together with their inhalation exposure levels and toxicity equivalents. The aim is to systematically evaluate the pollution characteristics and associated health risks of organic compounds in wintertime PM_2.5. Materials and methods Diurnal PM_2.5 samples were collected in Xi’an from January to February in 2022. 31 Organic components including PAHs, OPAHs and NACs were quantified using gas chromatography coupled with Orbitrap mass spectrometry (GC-Orbitrap MS). By integrating a human inhalation exposure model with the ADMETlab 3.0 toxicity prediction model, the diurnal variations of 19 toxicity endpoints and the relative contributions of the three compound classes were assessed. Results PM_2.5 concentrations in winter were generally higher during the daytime than at nighttime, or comparable between day and night. Conversely, the total concentration of organic components displayed a distinct “higher-at-night” trend, with nighttime concentrations (169.6 ng/m³ ) approximately 1.9 times higher than daytime levels (90.8 ng/m3 ). Correspondingly, the hourly toxic equivalent quantities (TEQs) for 19 health-related endpoints were significantly elevated at night. PAHs were the dominant contributors to cardiotoxicity and neurotoxicity, while NACs and OPAHs primarily contributed to skin sensitization and nephrotoxicity, respectively. Discussion The high daytime PM_2.5 mass concentrations suggest that the intense photochemical formation of secondary aerosols during the daytime may offset atmospheric dispersion processes, thereby maintaining high pollution levels. In contrast, the accumulation of organic components was likely driven by a lower boundary layer height and enhanced primary combustion emissions. Stronger solar radiation during the daytime facilitates the formation of secondary inorganic ions, resulting in a higher inorganic mass fractions that partially compensate for diurnal differences in total PM_2.5 mass. Regarding organic composition, high-molecular-weight PAHs were predominant, likely originating from petroleum combustion and vehicular emissions, while being less susceptible to photodegradation under sunlight. Distinct diurnal patterns were also observed in toxicity contributions. NACs exhibited strong toxicological specificity, potentially associated with electrophilic nitro functional groups that may trigger immune responses or interfere with endocrine receptors. The relative contribution of OPAHs to TEQs was higher during the daytime, which may be attributed to photochemical oxidation processes that promote the secondary formation of OPAHs. In contrast, PAHs contributed more significantly at night, consistent with primary emissions. Conclusions During winter, the daily average PM_2.5 concentration in Xi’an exceeded the national Grade Ⅱ air quality standard, with no significant diurnal variation in total mass; the average concentration at daytime was slightly higher than night. In contrast, PAHs and their derivatives exhibited clear nighttime elevation, with the nighttime concentration approximately 1.9 times higher than daytime. The day–night differences for OPAHs and NACs were less pronounced. The equivalent concentrations for the 19 toxicity endpoints were significantly higher at nighttime than daytime, indicating that different component classes contribute differently to health risks. Recommendations and perspective Winter nights in Xi’an represent a critical period of highconcentration exposure to organic pollutants and associated health risks. Effective mitigation strategies should therefore strengthen controls on nocturnal coal and biomass burning while also addressing daytime photochemical secondary pollution. In addition, health risk assessment of PAHs and their derivatives should extend beyond carcinogenicity to include multiple toxicity endpoints in a comprehensive risk management framework.]]> 2026/4/17 0:00:00 Background, aim, and scope Organic matter and heavy metal pollution in typical urban water bodies are closely associated with anthropogenic activities. Sediments act as an important sink for various pollutants in urban aquatic systems. Source apportionment studies of sediments contribute to the comprehensive management of urban water quality and help enhance the ecological service functions of aquatic landscapes. Positive Matrix Factorization (PMF) is an important method for the source apportionment of heavy metals in sediments; however, relying solely on individual metal elements to infer pollution sources involves considerable uncertainty. The spectral characteristics of dissolved organic matter (DOM) are commonly used to distinguish between nonpoint and point sources of pollution. Integrating heavy metal concentrations with DOM spectral characteristics in PMF analysis is expected to improve the reliability of source apportionment. Materials and methods Fifteen typical park lakes in Xi’an were selected for this study. Based on their water supply sources, the lakes were divided into four groups: Urban Park Group A1 (Daming Palace Taiye Pool, Xingqing Park, Tang Paradise, and Qujiang Pool); Fengyu Water System Park Group A2 (Hancheng Lake, Chang’an Park, and Fanchuan Park); Chanba Water System Park Group A3 (Yanming Lake, Taohua Pool, Xi’an Expo Park, and Chanba Wetland Park); and Urban Park Group A4 (Fengqing Park, Changle Park, Lianhu Park, and Revolution Park). Water and sediment samples were collected from each sampling site in the park lakes in January 2023. Sampling locations were arranged along the direction of water flow within each lake. Specifically, two sampling sites were established in Yanming Lake and Changle Park, while three sites per lake were established in the remaining lakes. The spectral characteristics of DOM and the distribution patterns of heavy metals in lake sediments were investigated using UV-Vis spectroscopy and excitation-emission matrix spectroscopy combined with parallel factor analysis (EEM-PARAFAC). Furthermore, source apportionment was conducted using the PMF model by integrating fluorescence components, spectral parameters, and heavy metal concentrations. Results The enrichment of heavy metals, particularly Zn, Cu, As, and Hg, was observed in the studied sediments. PARAFAC identified three fluorescence components: terrestrial humic-like substances (C1), tryptophan-like substances (C2), and tyrosinelike substances (C3), which are associated with sewage inputs and endogenous sources. Ultraviolet spectral parameters and EEM parameters indicated that sediment DOM was mainly influenced by terrestrial inputs and endogenous sources. Discussion The PMF analysis resolved four pollution source factors. In all lakes, the proportions of C2 and C3 were higher than that of C1. C3 was the dominant component in the Group A3, whereas C2 was the largest component in the Group A4. Factors 1—4 represent endogenous and sewage sources, atmospheric deposition sources, terrestrial sources, and mixed sources, respectively. Specifically, the Group A1 shows significant contributions from endogenous/sewage and terrestrial sources. The Group A2 is mainly influenced by non-point and sewage sources. The contributions of sewage and endogenous sources are prominent in the Group A3, while the Group A4 is primarily characterized by terrestrial sources. Conclusions This study elucidates the pollution status and source characteristics of typical landscape lakes in Xi’an and provides important data for integrated water pollution management. Furthermore, the results indicate that coupling DOM fluorescence characteristics with heavy metal concentrations in PMF analysis can improve the reliability of pollution source apportionment. Recommendations and perspectives The PMF model is applied to analyze the contributions of DOM characteristics, heavy metals, and pollution sources in sediments from typical landscape lakes in Xi’an. The results are consistent with the environmental conditions of each lake. This integrated approach can be applied to other water bodies to improve the accuracy of PMF-based source apportionment.]]> 2026/4/17 0:00:00 Background, aim, and scope In the 21st century, global warming has caused sustained regional high temperatures and extreme wildfire events. The growing frequency of wildfires poses significant threats to both human society and the ecological environment, making it crucial to understand wildfire patterns, mitigate their hazards, and establish effective prevention mechanisms. However, quantitative studies on pollutant emissions from wildfires remain relatively limited, and there are considerable challenges in detecting and tracking these events. This review summarizes the global trends of wildfire events from 2000 to 2022, with a particular focus on the formation and human exposure to two new types of pollutants: persistent organic pollutants (POPs) and environmental persistent free radicals (EPFRs) in wildfire smoke. Materials and methods This paper analyzes future changes in wildfire regimes, highlighting the transport pathways and impact mechanisms of increased and complex emissions across different environmental matrices. Additionally, it examines the risks of both outdoor and indoor exposure to POPs and EPFRs resulting from wildfires. Results The results indicate that the risk of wildfires continues to rise, with global fire areas expanding rapidly and fire seasons extending into autumn and winter. Moreover, fire variability enhances the global circulation and polar transport of POPs and EPFRs, leading to increased migration speed and distance of these pollutants. Additionally, as a major source of free radicals and persistent pollutants, wildfires may significantly increase their share of emissions across all sources, thereby exacerbating atmospheric pollution and disrupting the radiation balance. Moreover, poorly ventilated indoor air can also be impacted by wildfire smoke, leading to the accumulation of pollutants indoors and the formation of new emission sources, which pose increased health risks to humans. Discussion In the context of global warming, wildfires are expected to become an increasingly significant source of pollutant emissions, presenting substantial challenges to efforts aimed at mitigating climate change. Studies have demonstrated that the pollutants emitted by wildfires exhibit heightened toxicity compared to those from other sources, which is compounded by their widespread dispersal through atmospheric circulation. As a result, these pollutants can affect both regional and global air quality, with particular consequences for vulnerable populations. In the future, environmental health concerns related to wildfire emissions will intensify, necessitating frequent and comprehensive assessments of the health risks associated with these pollutants. These risks, which include respiratory illnesses and cardiovascular diseases, are expected to grow, especially in areas where wildfire seasons become longer and more severe. Furthermore, the impact of these emissions on ecosystem health and biodiversity is equally concerning, as the release of particulate matter and toxic gases can disrupt local ecosystems and alter the dynamics of plant and animal populations. To address these challenges, it is essential to develop effective strategies for monitoring, mitigating, and adapting to the evolving environmental and health risks posed by wildfires. Conclusions Increased fuel availability, higher temperatures, and human activities have heightened the likelihood of wildfires, resulting in a significant expansion of burn areas and an extended wildfire season. The emissions from wildfires further intensify global circulation and the polar transport of pollutants. In addition to the emissions from wildfires, high temperatures also cause the volatilization of organic compounds trapped in the soil. Furthermore, driven by global atmospheric circulation, this likely leads to changes in POPs and EPFRs in the Antarctic and Arctic regions. Recommendations and perspectives As the climate continues to warm, increasingly frequent, larger, and more intense wildfires may become a significant source of organic pollutant emissions. Additionally, regional effects from biomass burning could amplify global impacts, highlighting the need for more in-depth research into the factors driving wildfire occurrence, in order to better understand the environmental behavior of POPs and EPFRs from wildfires.]]> 2026/4/17 0:00:00 Background, aim, and scope Microplastics are plastic particles with a diameter of less than 5 mm. Microplastics are emerging contaminants resulting from human activities, which have attracted significant attention from both the scientific community and the general public. Microplastics have been listed as one of the four major emerging pollutants in China. Microplastics have been detected in various matrices, including air, soil, lake water, rivers, and even in food and drinking water, posing potential health risks to humans. Atmospheric environment serves as both a significant source and sink for microplastics, with fine particle matters (PM_2.5) acting as a crucial carrier for microplastics in the atmosphere. The inhalation of microplastics contained within PM_2.5 presents potential hazards to the respiratory system. However, researchers have yet to quantify the amount of microplastics inhaled through PM_2.5. In this study, personal exposure samplers were employed to simulate the process of human inhalation of microplastics via PM_2.5. The factors influencing the concentration of microplastics in the atmosphere under varying environmental conditions were analyzed. The primary aims of this study were to determine the levels and profiles of microplastics in atmospheric PM_2.5 and evaluate the human exposure to these pollutants through air inhalation. Materials and methods In this study, conducted in Beijing, China, an individual exposure particulate matter sampler was used to simulate human breathing and continuously collect microplastics in ambient air under daily working and living environments. The sampling period was from September 2023 to April 2024, and a total of 40 valid PM_2.5 samples were collected and analyzed. For sample testing, thermal decomposition pretreatment was first performed on the collected PM_2.5 samples, followed by gas chromatography-mass spectrometry to accurately identify and quantify five primary types of microplastics in PM_2.5. Results The total concentration of the five types of microplastics in atmospheric PM_2.5 ranged from approximately 3.6 μg/m³ to 976 μg/m³ , including a high content (up to 505 μg/m³ ) of low-density polyethylene (PE). The individual exposure to microplastics via inhalation of PM_2.5 ranged from 52 μg/m³ to 14054 μg/d. Both weather conditions and human activities can clearly affect the concentrations and distribution of microplastics. Under moderate to severe pollution conditions, PM_2.5 was found to contain high concentrations (400—600 μg/m³ ) of five types of microplastics. In areas with intense human activities and high population density, the microplastics concentrations soared to 976 μg/m³ , with individual exposure levels reaching 14054 μg/d. Discussion The study on five common types of microplastics in ambient air reveals that the concentration of atmospheric microplastics is influenced by multiple factors due to the inherent instability of the atmospheric environment. Notably, the concentration of PE in PM2.5 is generally higher than that of other microplastics. In three-quarters of the samples, the concentration of PE exceeds that of the other four types of microplastics by one to two orders of magnitude. Meteorological conditions such as wind, haze, and sandstorms are primary factors affecting ambient air quality and play a significant role in determining the concentration and distribution of microplastics. Additionally, population density and human activities are crucial factors influencing the concentration of microplastics in air. Conclusions Our study reveals a significant correlation between elevated atmospheric PM_2.5 concentrations (under severe pollution conditions such as sandstorms) and increased microplastic levels. Notably, even during periods of relatively low pollution (characterized by clear skies and strong winds), microplastic concentrations also exhibit a substantial rise. Furthermore, due to the increased usage of plastic products, microplastic concentrations tend to rise significantly with higher population densities. In this research, we employed personal exposure samplers to simulate the human inhalation of microplastics contained within PM_2.5. By analyzing microplastic concentrations across various venues, we were able to assess the potential human exposure to microplastics. Recommendations and perspectives In future research, it is imperative to identify the sources of microplastics by investigating the factors influencing their concentration. This approach will enable the development of targeted strategies to minimize human exposure to inhalable microplastics and mitigate the potential for severe health risks associated with microplastic pollution.]]> 2026/4/17 0:00:00 Background, aim, and scope Pharmaceuticals and personal care products (PPCPs) represent a class of emerging contaminants that have been increasingly used in industrial production and daily life amid rapid economic growth and rising living standards, leading to their widespread occurrence in aquatic environments. Prolonged presence of PPCPs may impair the growth and reproduction of aquatic organisms and induce the development of drug resistance in environmental microbes. While PPCPs have been frequently detected in the mainstream of the Yangtze River Basin and large lake reservoirs, existing studies have mostly focused on the Yangtze mainstream, Jialing River, Dongting Lake, and the Yangtze River Delta, with scarce data available on relatively small tributaries such as the Shengshui River and Linjiang River. To comprehensively clarify the PPCP pollution status in surface waters of the main stream and tributaries of the Yangtze River in Chongqing, this study targeted the Shengshui River and Linjiang River, selected 8 typical PPCPs with high consumption and widespread social concern as the target compounds via systematic investigation, and aimed to elucidate their temporal and spatial distribution characteristics, identify potential pollution sources, and assess their ecological risks. This research is expected to provide essential data support for ecological risk identification and the formulation of regional PPCP prevention and control strategies in this area. Materials and methods Surface water samples were collected at 27 sampling sites across the main stream and tributaries of the Yangtze River in Chongqing in early August 2022 (wet season) and early March 2023 (dry season). The target PPCPs in the samples were analyzed using an online solid-phase extraction coupled with ultra-high performance liquid chromatography-triple quadrupole mass spectrometry (online SPE-UPLC-MS/MS) system. The risk quotient (RQ) method was employed to evaluate the ecological risks of the detected PPCPs. Results Temporally, five PPCPs (propranolol (PR), bezafibrate (BZB), clindamycin (CLI), codeine (CDI), and diethyltoluamide (DEET)) were detected in the dry season, where as all 8 target PPCPs (PR, BZB, CLI, ROX (roxithromycin), CDI, IND (indomethacin), DEET and MIC (miconazole)) were detected in the wet season. The detection rates of CDI and DEET exceeded 50% in the wet season, while those of ROX and DEET were over 50% in the dry season. The macrolide antibiotics CLI and ROX had detection rates of 42% and 54% in the dry season, respectively, but were nearly undetectable in the wet season. PR, a commonly used β-blocker for hypertension, had detection rates of 4% and 29% in the wet and dry seasons, respectively, and CDI, an analgesic and anti-inflammatory drug, had detection rates of 63% and 38% in the wet and dry seasons, respectively. BZB (a lipid-lowering drug), IND (an analgesic and anti-inflammatory drug), and MIC (a disinfectant) exhibited low detection rates of less than 10% across both seasons. DEET and CDI were identified as the primary pollutants, with the average concentration of DEET reaching 80.8 ng/L in the wet season and that of CDI hitting 69.4 ng/L in the dry season. Spatially, the Linjiang River had the highest total PPCP concentrations, followed by the Yangtze mainstream, while the Shengshui River had the lowest. Overall, the ecological risks posed by the target PPCPs in the study area were relatively low. Discussion As a core economic development zone in the upper Yangtze River, Chongqing has seen PPCPs from agricultural cultivation, livestock and poultry breeding, and domestic sewage discharge enter the aquatic environment with its rapid economic growth. All target PPCPs were detected to varying degrees in this study, and a comparison with domestic and international surface water data showed that most PPCP concentrations in the study area were at low levels, with DEET, ROX, and CDI at moderate levels. The temporal and spatial distribution of PPCPs was found to be associated with multiple factors, including human activity patterns, hydrological conditions, and climatic factors. PPCP concentrations in surface water were diluted by high water discharge and concentrated by low water volume; temperature also affected microbial activity and thus PPCP degradation, with higher temperatures potentially reducing PPCP concentrations. Seasonal fluctuations in human demand for PPCPs also led to distinct seasonal variations in their distribution. Correlation analysis revealed a significant relationship (P≤0.05) between water temperature (WT), pH, electrical conductivity (EC), dissolved oxygen (DO), and PPCP concentrations. Land use type analysis suggested that PPCPs in the study area primarily originated from agricultural activities and domestic sewage. Conclusions PPCPs were detected to varying degrees in both the wet and dry seasons, with the insect repellent DEET and the analgesic and anti-inflammatory drug CDI being the most prevalent pollutants. The total PPCP concentrations in the Shengshui River and Linjiang River were higher in the dry season, while those in the Yangtze River (Chongqing section) mainstream were higher in the wet season. The average total PPCP concentration in surface waters followed the order: Linjiang River＞Yangtze mainstream＞Shengshui River. PPCP concentrations and distributions were influenced by aquatic environmental conditions, and the pollutants in the study area were primarily derived from agricultural non-point source pollution, untreated domestic sewage, and effluents from sewage treatment plants. Notably, moderate ecological risks from CDI, MIC, and ROX were observed at certain sampling sites in the lower reaches of the Linjiang River during the dry season. Recommendations and perspectives CDI, MIC, and ROX were identified as the priority PPCPs of concern in the surface waters of the Yangtze River tributaries in Chongqing. Enhanced routine risk monitoring is recommended, particularly for the lower reaches of the tributaries during the dry season, to mitigate potential ecological risks posed by these contaminants.]]> 2026/4/17 0:00:00 Background, aim, and scope Aerosols such as black carbon (BC) and sulfate (SO²⁻ ₄ ), can influence the radiation balance and atmospheric quality upon entering the atmosphere, making them significant contributors to global warming and air pollution. Atmospheric circulation transports these aerosols, thereby extending their environmental impact far beyond the source regions. The aim of this study is to investigate the BC and SO²⁻ ₄ transport pathways, influence range and intensity around the Qinghai-Xizang Plateau (QXP). Materials and methods This study covers a 12-month period from March 2021 to February 2022. First, monitoring data from the China’s air quality monitoring sites were selected. By comparing PM10, PM_2.5, and other data values, the days with the most severe air pollution over the QXP and its adjacent areas were identified for each month. The column mass density (CMD) of BC and SO²⁻ ₄ , together with collocated wind flux data derived from the MERRA2 aerosol diagnostics dataset, were utilized to characterize the seasonal spatial distribution of BC and SO²⁻ ₄ and to identify their potential source regions. The AERONET (Aerosol Robotic NET work) global ground-based observations were used for auxiliary validation. Finally, the Aerosol Mixing Ratio (AMR) data from MERRA2 combined with CALIPSO lidar observations were used to reveal the vertical distribution characteristics of aerosols and to investigate their transport pathways. Results The results showed that BC and SO²⁻ ₄ around QXP exhibited higher concentrations and wider distribution in winter and spring. The CMD of BC can reach up to 14 mg/m² , whereas the CMD of SO²⁻ ₄ is significantly higher, reaching up to 80 mg/m² . In spring, the near-surface model of the AMR of SO²⁻ ₄ and BC data indicated that the east-central part of Indian Peninsula (2.7 μg/kg and 0.3 μg/kg) and the eastern part of the Indochinese Peninsula (1.6 μg/kg and 0.8 μg/kg) were the potential emission sources to the QXP. Aerosol pollutants primarily reach the QXP mainly through the southern slopes of the Himalayas. Additionally, the SO²⁻ ₄ and BC aerosols from the southern regions of the Indian Peninsula and the Indochinese Peninsula can be transported to the southern QXP by cyclones in these areas. Discussion Aerosol pollutants were frequently observed in the QXP and often interact with both local emissions and those from surrounding regions. The development of low-pressure systems at high altitudes is considered a key mechanism for enhancing the crossHimalayan transport of pollutants into the QXP, representing a major pathway for long-range atmospheric transport. Pollutants located at high altitudes over the southern Indochinese Peninsula have the potential to reach the Indian Peninsula. Moreover, pollutants originating from both ground level and high-altitude areas of the Indian Peninsula can be transported northward to the southern QXP. These findings suggest that the contribution of emissions from the Indochinese Peninsula and surrounding regions to pollutant levels in the QXP may have been underestimated in previous studies. Conclusions The concentrations of SO²⁻ ₄ and BC in the QXP were significantly higher in winter and spring, and SO²⁻ ₄ was much higher than BC. New discovery was that BC and SO2− 4 in the southern part of the Indian Peninsula and Indochinese Peninsula can be transported to south of the QXP by cyclones. Recommendations and perspectives In winter and spring, lower precipitation increases the transport efficiency of industrial and biomassburning aerosols from the Indian Peninsula and the Indochinese Peninsula to the QXP. Addressing this issue requires long-term, dynamic aerosol monitoring to build a scientific foundation for coordinated international environmental policies.]]> 2026/4/17 0:00:00 Background, aim, and scope PM₁₀ is a critical air pollutant that adversely affects human health and poses significant public health risks, particularly during dust storm events when its concentrations tend to spike abruptly. As a city located in the arid and semi-arid region of Nei Mongol, Wuhai City is particularly vulnerable to dust storms, which frequently trigger severe PM₁₀ pollution episodes. Effective prediction of PM₁₀ levels, especially during these high-impact events, is therefore crucial for timely public warnings and air quality management in this region. Based on hourly monitoring data in Wuhai City from 2019 to 2023, this study evaluated the predictive performance of Long Short-Term Memory (LSTM), Gated Recurrent Unit (GRU), and Extreme Gradient Boosting (XGBoost) models driven exclusively by meteorological inputs. The models’ predictive performance for PM₁₀ was compared under dust and non-dust conditions. Additionally, SHapley Additive exPlanations (SHAP) values were employed to quantify the contribution of meteorological drivers. The scope of this study is defined by its deliberate limitation to meteorological data, which tests the sufficiency of these variables for prediction and enhances model portability in data-scarce regions. Materials and methods This study utilized hourly PM₁₀ and meteorological observation data from Wuhai City, spanning 2019 to 2023. The meteorological features included atmospheric pressure, temperature, relative humidity, and wind-related variables. Three models were developed for LSTM, GRU, and XGBoost. Model performance was evaluated using the coefficient of determination (R² ), mean absolute error (MAE), and root mean square error (RMSE). The SHAP framework was applied to enhance model interpretability and quantify the contribution of each meteorological feature to the predictions. Results All three models demonstrated robust predictive skill (R² : 0.813—0.816), with the GRU performing best across all error metrics. The model’s fit on dust days improved significantly (R² ≈0.92) compared to that on non-dust days. However, systematic underestimations of predicted peak concentrations persisted, with the error magnitudes nearly doubling. This highlights a critical limitation in forecasting the severity of extreme pollution events. Discussion Atmospheric pressure was the most influential predictor across all weather conditions. The importance of instantaneous maximum wind speed spiked during dust days, directly reflecting the physical mechanism of local dust entrainment. In addition, relative humidity exhibited a suppressive effect on PM₁₀ by enhancing particle deposition and reducing suspension, whereas higher temperatures promoted PM₁₀ concentrations through boundary layer development and increased turbulence, which facilitated particle lifting and dispersion. These findings highlight that both large-scale meteorology and local meteorological extremes jointly regulate PM₁₀ variability, with their effects being especially pronounced under dust conditions. Conclusions This study confirms that machine learning models driven solely by meteorological data are a viable option for PM₁₀ prediction, particularly for early warning systems in data-scarce regions. Recommendations and perspectives To improve the prediction of extreme PM₁₀ peaks, future research should focus on integrating multisource data. Incorporating satellite remote sensing data and more advanced meteorological parameters could provide crucial information to better quantify dust emission and transport, thereby improving the reliability of forecasts for severe air pollution events.]]> 2026/4/17 0:00:00 Background, aim, and scope Soil heavy metal pollution caused by transportation activities in ecologically fragile regions has become a growing environmental concern. The total length of the Wuzijing section of the Qingyin Expressway (G20) is 188.88 km and it in Shaanxi Province traverses five counties (Wubu,Suide, Zizhou, Hengshan, and Jingbian) and 19 towns in Yulin City. This section crosses three typical geomorphological units with the loess zone, the transitional zone, and the desert zone, characterized by high ecological sensitivity. However, the specific characteristics and potential ecological risks of heavy metal pollution resulting from traffic activities in this region remain unclear. To investigate the extent, risk, and sources of heavy metal contamination induced by traffic activities, and to provide a scientific basis for regional soil pollution control, this study collected 34 surface soil samples (0—20 cm) from the road corridor across the three geomorphic units. The concentrations of eight heavy metals (Cd, Cr, Cu, Mn, Ni, Pb, Zn, and As) were determined. Materials and methods The pollution load index (PLI), the geo-accumulation index (I_geo), principal component analysis (PCA), and the absolute principal component scores-multilinear regression (APCS-MLR) model were employed to assess pollution levels and identify potential sources. Results The results showed that the concentrations of Pb, Cr, and Ni in soils exceeded their respective background values across all geomorphic units. PLI identified Pb (PLI: 1.98—4.12) and Cr (PLI: 0.68—1.96) as the primary pollutants; and the I_geo assessment showed that Pb pollution reached a moderate level in the loess zone (I_geo=1.16), while Pb was at a slight pollution level in the transitional and desert zone (I_geo for 0.92 and 0.91, respectively). Source apportionment revealed that Mn, Pb, and Ni contamination in the loess zone was mainly attributable to traffic emissions with a variance contribution of 42.788%; in the transitional zone, As, Mn, Pb, and Ni were primarily influenced by a combined source of traffic and agricultural activities with a variance contribution of 70.430%. Discussion The enrichment of Pb was closely associated with traffic emissions, which aligns with the high contribution of traffic sources to Pb in the loess zone (65.25%) and the Pb concentration exceeding the background value by 2.98 times. This also explains the moderate Pb pollution level (I_geo>1) observed in the loess zone. In the transitional zone, Pb was influenced by both traffic and agricultural sources (70.430% contribution from mixed sources). The presence of As-commonly regarded as an indicator of agricultural activity-alongside Mn, Pb, and Ni in the same source further supports the contribution of agricultural practices to heavy metal accumulation in this zone. Conclusions In summary, anthropogenic activities, particularly traffic emissions and agricultural production, are the primary drivers of heavy metal pollution in the loess and transitional zone. In contrast, heavy metal contamination in the desert zone reflects a more complex pattern, predominantly governed by natural geological background and climatic conditions, with superimposed effects from localized human activities. These spatial differences are closely linked to variations in geomorphic characteristics and the intensity of human disturbances across the three regions. Recommendations and perspectives This study elucidates the pollution characteristics and dominant sources of heavy metals in soils from distinct geomorphic units along an expressway in an ecologically fragile region. The findings provide critical insights for developing targeted pollution control strategies. Specifically, the loess zone needs to strengthen traffic pollution control, the transition zone needs to balance traffic emission reduction and clean agricultural production, and the desert zone needs to pay attention to the superimposed risks of human activities under natural background conditions.]]> 2026/4/17 0:00:00 Background, aim, and scope The ecological environment in the desert area is fragile, and industrial activities are easy to cause pollutant enrichment, resulting in higher ecological risks. In recent years, heavy metal pollution in industrial parks in desert areas has gradually drawn people’s attention. Therefore, this paper aims to evaluate the enrichment status and pollution risk of heavy metals in M Industrial Park in desert areas. In order to provide data support for the management of industrial activities in fragile ecological environment areas, such as desert areas, and provide theoretical support for the planning and management of industrial activities. Materials and methods In this paper, the core park of China’s national energy and chemical base was the research object, and the enrichment and distribution characteristics of eight kinds of soil heavy metals (Cd, Cr, Pb, As, Cu, Zn, Ni and Mn) in four functional areas (industrial area, wasteland area, farmland area and residential area). Results (1) The Cd exceeds the standard most seriously in the study area, followed by As and Cu, and the average content of the remaining elements does not reach the soil background value in Shaanxi Province. (2) In terms of spatial distribution, the eight heavy metals show a trend that the northern part is higher than the southern part, and the western part is higher than the eastern part. The heavily polluted sample sites are mainly distributed in industrial and residential areas. There are significant differences in the soil heavy metal contents of the four functional areas, with most of the soil heavy metal contents showing an overall trend of residential area＞ wasteland area＞industrial area＞farmland area. (3) The Nemero comprehensive pollution index shows that the study area reaches heavy pollution, while for single elements, Cd reaches heavy pollution and As are moderate; the results based on potential ecological risk evaluation also show that Cd reaches strong ecological risk, while the mean value of comprehensive potential ecological risk coefficient of the whole study area is 168.42, which is a slight ecological risk level, but the difference between sample points is obvious. About half of these sample sites show moderate ecological risk in terms of potential ecological risk index (RI). (4) The heavy metal pollution in the surface soil of the study area mainly comes from three sources: Cr, Ni, Cu, Mn elements are soil parent material sources, Pb and Zn elements are traffic sources, and As and Cd are industrial sources. Discussion The results indicate that there are some heavy metal elements in the study area with concentrations higher than the standard value, among which Cd exceeds the standard most severely, which is related to the unfavorable soil texture for heavy metal enrichment in desert areas. The research results indicate that the heavy metal content in most of the study area is below the standard value. Cd contamination stands out as the primary issue. Its distribution is associated with soil properties, which hinder the accumulation of heavy metals. The pollution of residential and industrial areas in different functional areas is the most serious. This is because the residential area is located in the middle of the two main traffic arteries, which is adjacent to the coal chemical enterprises in the functional division, and is greatly affected by industrial activities and traffic. In recent years, the continuous expansion of industrial parks has led to an increase in the enrichment level of heavy metals in surrounding areas. For example, the accumulation of garbage in barren areas leads to higher pollution levels, and heavy metals in the park are mainly caused by industrial activities. Conclusions Among the eight heavy metal elements measured, Cd exceeded the standard the most severely in the study area. In terms of spatial distribution, the concentrations of these 8 heavy metal elements showed a trend of being higher in the north than in the south and higher in the west than in the east. There are significant differences in soil heavy metal content among the four functional areas, with most soils having the highest overall heavy metal content in residential areas and the lowest in agricultural areas. Recommendations and perspectives The above results indicate that the soil heavy metals in the desert coal-related industrial park and its surrounding areas pose a significant ecological risk, and necessary treatment should be implemented while strengthening monitoring and prevention.]]> 2026/4/17 0:00:00 Background, aim, and scope As a key development city in western China, Anshun City boasts prominent potential in selenium (Se)-rich resource endowment. However, existing research remains insufficient regarding the distribution characteristics and concentration levels of selenium in regional agricultural soils, as well as its correlations with natural controlling factors including geological background, climatic conditions, and soil types. To a certain extent, this research gap has restricted the scientific planning, rational development, and efficient utilization of local selenium-rich resources. In view of this, this study implemented detailed geochemical surveys and large-scale field sampling, combined with advanced analytical testing techniques and modern information technology, to systematically reveal the selenium concentration, spatial distribution patterns, and key influencing factors of selenium in agricultural soils across Anshun City. Furthermore, this study aimed to evaluate the resource status of clean selenium-rich farmland and selenium-rich agricultural products, with the core objective of providing robust theoretical support and practical guidance for the sustainable utilization of selenium-rich resources in the region, as well as promoting the sound development of selenium-enriched agriculture in western China. Materials and Methods Extensive field sampling was conducted to collect surface soil samples 28003 and corresponding agricultural product samples across the study area. Selenium and heavy metal concentrations in both soil 475 and agricultural 475 product samples were determined using advanced analytical techniques, including X-ray Fluorescence Spectrometry (XRF) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Subsequent data processing and spatial analysis were performed using professional geostatistical and geographic information software, namely SPSS, ArcGIS, and MapGIS, to conduct statistical analysis, geochemical mapping, and spatial distribution visualization of selenium and heavy metals. Results The average selenium content in the surface soil of Anshun City is 0.51 mg/kg, which is higher than the selenium-rich soil standard (0.4 mg/kg). The selenium content is closely related to the types of soil-forming parent rocks, with the highest selenium content found in soils derived from basalt and diabase. The cultivated land with selenium-rich soil in the city totals 2275.33 km² , accounting for 76.53% of the total cultivated land area. The selenium-rich cultivated land is mainly concentrated in a strip along the northern line of Pingba District, Xixiu District, and Zhenning County, with a relatively low rate of heavy metal content exceeding standards. Overall, the seleniumrich rate of agricultural products sampled in Puding County, Xixiu District, and Pingba District is 39.08%, while in other regions, it is 20.25%. The selenium-rich rate of agricultural products from selenium-rich cultivated land is generally moderate, and due to the influence of heavy metal elements in the soil, there are localized areas where the heavy metal content in agricultural products exceeds standards. Discussion (1) The selenium content in the cultivated soil of Anshun City is abundant but unevenly distributed. Selenium is ubiquitous in the surface soil, with an average content higher than the selenium-rich soil standard. The selenium-rich cultivated land resources are vast, and the spatial distribution of selenium is mainly influenced by soil-forming parent rocks, especially those derived from basalt, diabase, and black shale (coal-bearing strata), which have the highest selenium content, reaching 0.78 mg/kg and 0.72 mg/kg, respectively. (2) The overall heavy metal content in the cultivated soil of Anshun City is relatively low, but there are localized areas where arsenic and cadmium content exceed standards. In particular, cadmium content is mainly affected by the weathering of soil-forming parent rocks. Due to its immobility, cadmium accumulates in place during the weathering process, potentially leading to increasing cadmium content in weathering products over time. Therefore, heavy metal pollution prevention should be considered in future cultivated land utilization and planning to avoid risks to agricultural product safety and human health in areas exceeding standards. (3) Anshun City is rich in selenium-rich cultivated land resources, accounting for 76.53% of the total cultivated land area. The clean selenium-rich areas are mainly distributed along the northern line of Pingba District, Xixiu District, and Zhenning County. The selenium-rich rate of agricultural products varies depending on crop types and selenium content distribution in the soil. In the development of selenium-rich agricultural products, it is urgent to strengthen regional planning and prioritize the development of planting in areas with high selenium content. Conclusions Surface soils in Anshun City are characterized by favorable selenium enrichment, with a large proportion of selenium-rich farmland concentrated in contiguous high-quality zones, laying a solid foundation for the large-scale development of local selenium-rich agriculture. Although the overall soil heavy metal concentration is low, localized exceedance phenomena require close attention and effective prevention during resource development. Findings regarding the selenium enrichment rate of agricultural products provide a scientific basis for optimized regional planting layout. Recommendations and Perspectives In the future, Anshun City should further strengthen the protection and rational development of selenium-rich resources, formulate scientific selenium-rich industry development plans, and promote the large-scale, standardized, and branded development of selenium-rich agricultural industries. Meanwhile, research on the formation mechanism, enrichment patterns, and development and utilization technologies of selenium-rich resources should be intensified to provide scientific and technological support for the sustainable development of selenium-rich industries. In addition, for localized areas severely affected by arsenic and cadmium and where the heavy metal content in agricultural products exceeds standards, the agricultural planting structure should be adjusted to prioritize the cultivation of non-edible economic or ornamental crops. Alternatively, corresponding soil remediation technologies should be adopted to promote the sustainable and high-quality development of local characteristic agricultural industries.]]> 2026/4/17 0:00:00 Background, aim, and scope Selenium is a vital nutrient with profound positive impacts on human health, and has been officially recognized as one of the essential trace nutrients for the human body by the World Health Organization (WHO); it exerts anti-cancer and antioxidant effects, and effectively enhances human immune function. Against the overarching backdrop of national food security, the targeted development of selenium-enriched agriculture in black rock series parent rock regions across China is urgently warranted. It is imperative to clarify the distribution and enrichment characteristics of selenium and heavy metal elements in regional soils, and implement targeted soil environment improvement measures, so as to upgrade cultivated land quality and lay a solid foundation for safeguarding national food security. The findings of this study are expected to promote the sustainable development of the regional ecological environment, support the development and optimization of selenium-enriched agricultural products, pave a characteristic and high-efficiency agricultural development path, and provide critical scientific support for the construction of local characteristic agricultural industrial bases and the cultivation of pillar industries that boost rural incomes. Materials and methods This study was conducted based on the results of the first round of geochemical survey and evaluation for cultivated land quality in Guizhou Province. Relying on the collected geological, environmental and geochemical data of a typical vegetable industrial park in Guizhou Province, a total of 572 surface cultivated soil samples and 21 agricultural product samples were collected from the park. A systematic assessment was carried out on the geochemical quality grades of selenium and heavy metal elements in the park’s soils, as well as the selenium enrichment and heavy metal safety effects of corresponding agricultural products. Results The results showed that the selenium-rich cultivated land in the park was rich in soil resources. The average selenium content in the surface soil was 0.60 mg/kg. The total selenium-rich characteristic cultivated land was 33.15 km² , accounting for 70.06% of the cultivated land area of the park. At the same time, the content of heavy metal elements in the soil of the park is relatively low, and only the cadmium element is locally high. On the whole, the overall soil properties in the park with the black clay rock of the Huohong Formation interbedded with limestone, marl and sandstone as the soil-forming parent rock are relatively high, and the heavy metal elements are mainly of Class I level while enriching selenium. Discussion Through sampling and testing of some agricultural products in the park, it was found that some heavy metals in the collected eggplant and rice samples exceeded the standard, and the selenium-rich ratio of the samples was low. The study believes that this phenomenon is closely related to the varieties of crops planted in the park and the soil pH. In the subsequent crop planting process of the park, full consideration should be given to the characteristics of the soil geochemical environment, following the laws of nature, adhering to the scientific concept of development, and planting suitable characteristic crops to effectively promote the development of selenium-rich characteristic, healthy and safe agricultural products. Conclusions (1) The content of selenium in the surface soil of the park is high. The geochemical comprehensive grade of soil environmental quality is mainly class Ⅰ, followed by class Ⅱ. Only the cadmium element is locally high, which is mainly affected by the distribution of soil parent rock. (2) Rice has a relatively strong ability to enrich elements in root soil, especially cadmium and selenium. However, eggplant has a stronger ability to enrich mercury and a weaker ability to enrich selenium. Different agricultural products have different absorption capacity of elements in soil. (3) Soil pH is one of the factors affecting the enrichment ability of crops to related elements in root soil. When the soil pH value is between 6 and 7, the enrichment ability is the strongest, especially cadmium and selenium. Recommendations and perspectives Based on the park’s soil-forming parent rock and soil pH characteristics, plant selenium-accumulating crops in the “high-selenium and low-cadmium areas” of Huohong Formation, promote low-cadmium varieties and avoid planting eggplants in carbonate rock “high-selenium and high-cadmium areas”. Reduce cadmium activity by applying lime or biochar, collaborate with research institutions to screen “high-selenium and low-heavy metal” varieties and establish a cultivation technology system. Supplement element absorption data of typical crops in Southwest China, build a “soil, irrigation water and agricultural products” monitoring network, label products with “parent rock+production area” information, and promote the transformation of geological resources into farmers’ income.]]> 2026/4/17 0:00:00 Background, aim, and scope Evaluation of ecological environment quality plays an important role in formulating environmental protection policies and land resource utilization plans. Based on specific indicator systems and quality standards, ecological environment quality evaluation refers to the assessment of the overall condition of a regional ecological environment and its impacts. Zhangye City is a typical oasis city located in the Hexi Corridor of northwest China, characterized by drastic land-use transformations and a fragile ecological environment. Although numerous studies have focused on land-use change or ecological environment quality assessment in Zhangye City, a comprehensive study on the spatiotemporal changes in ecological environment quality and their driving factors based on the geodetector is still lacking. Therefore, this study takes Zhangye City as the study area, evaluates ecological environment quality and analyzes its driving factors using the ecological environment quality index (EV) model and the geodetector, aiming to provide a scientific basis for land resource utilization and ecological environment protection in Zhangye City. Materials and methods Based on land-use data from seven periods (1990, 1995, 2000, 2005, 2010, 2015, and 2020), this study evaluates the spatial distribution and temporal changes in ecological environment quality in Zhangye City using the ecological environment quality index assessment. The driving factors influencing changes in ecological environment quality are further analyzed using the geodetector. Results (1) The areas of farmland and construction land in Zhangye City increased continuously from 1990 to 2020, with the conversion of unused land and grassland to farmland being the dominant transformation type. (2) The regional ecological environment quality index in Zhangye City remained relatively stable, ranging from 0.2779 to 0.2807 during 1990—2020. Land transformation types with higher contribution rates to improvements in ecological environment quality mainly included the conversion of sandy land and Gobi land to dry farmland. (3) Changes in ecological environment quality in Zhangye City resulted from the combined effects of socioeconomic and natural factors, with socioeconomic factors playing a dominant role. According to explanatory power, the driving factors were ranked as follows: change in population density > change in GDP (Gross Domestic Product) > elevation > change in grain yield. Discussion (1) Changes in regional ecological environment quality are closely associated with land-use transformations. Spatially, areas with high ecological environment quality in Zhangye City are mainly distributed in the Qilian Mountains in the southwest, where forest land and grassland dominate, whereas areas with low ecological environment quality are primarily located in the northeastern plains, dominated by unused land. (2) From 1990 to 2020, the ecological environment quality of Zhangye City was higher than the average level of the Hexi Corridor. (3) Changes in ecological environment quality in Zhangye City during 1990—2020 were driven by multiple factors, and the interaction mechanisms among these factors were complex. Conclusions The spatial distribution pattern of ecological environment quality in Zhangye City remained relatively stable from 1990 to 2020, with an overall “V-shaped” temporal trend. Changes in ecological environment quality were jointly driven by socioeconomic and natural factors, with socioeconomic factors exerting a dominant influence. Recommendations and perspectives The ecological environment quality index assessment effectively reflects the relationship between regional land use and ecological environment quality. When land-use types are transformed from unused land to farmland, large areas without vegetation cover are converted into vegetated land, resulting in an increase in the ecological environment quality index. However, it should also be noted that the expansion of farmland and irrational land-use practices may still lead to a decline in ecological environment quality, and may even result in the reversion of farmland to Gobi land and sandy land.]]> 2026/4/17 0:00:00 Background, aim, and scope The Late Cenozoic represents the most recent geological interval in which climate change, tectonic activity, and river evolution are well-preserved in sedimentary archives. Establishing precise chronological control over these processes is therefore essential for reconstructing Earth system dynamics. However, K-Ar dating of tephra, commonly used for constraining ages beyond about 200 ka, is often precluded by the absence of suitable volcanic layers in many continental sequences. Electron spin resonance (ESR) dating of quartz offers a promising alternative. Among quartz paramagnetic centers (e.g., E′ ₁, Ti-Li, Ge), the Al center is currently regarded as the most robust signal for ESR dating of Late Cenozoic sediments, particularly those of Pliocene to Early Pleistocene age. Nevertheless, its application to pre-Quaternary are remains poorly constrained. To address this gap, we applied quartz Al center ESR dating to fluvial sediments recovered from borehole YNZK01 in the Yinchuan Basin (NE Qinghai-Xizang Plateau), targeting an age range spanning the Late Miocene to Early Pliocene. Materials and methods Ten fluvial sediment samples were collected from 721 m to 962 m of borehole YNZK01 (about 1200 m deep). The lithology consists predominantly of clayey siltstone. Quartz was extracted and purified following standard protocols. ESR measurements were performed on the Al center using a Bruker EMX spectrometer. Dose-response curves were fitted using both single-saturation-exponential (SSE) and exponential-plus-linear (EXP+LIN) models. Environmental dose rates were calculated based on measured U, Th, and K concentrations and cosmic-ray contributions. Results The SSE yielded statistically superior or comparable fits to EXP+LIN for the Al center under low gamma ray doses (<12000 Gy). ESR ages range from (2.230±0.602) Ma to (3.568±0.453) Ma and agree with the independently established magnetostratigraphic framework within analytical uncertainties (age discrepancies: 11%—33%). Crucially, none of the ten samples exhibited signal saturation, even at added gamma ray doses up to 50000 Gy, confirming the suitability of the Al center for dating Late Cenozoic fluvial sediments. Discussion For the upper seven samples, ESR ages align closely with interpolated magnetostratigraphic ages within error bounds. In contrast, the three deepest samples yield ESR ages significantly older than their magnetostratigraphic interpolation results. Three non-exclusive explanations are proposed: (1) post-depositional mobility of U, Th, and K in deep fluvial-lacustrine strata may introduce substantial uncertainty into environmental dose-rate calculations; (2) existing equivalent dose (De) fitting functions may inadequately describe the radiation response of ancient, low-sensitivity sediments, thereby biasing De estimation; and (3) incomplete correction for residual signal intensity in the Al center could lead to slight overestimation of burial age. Despite these discrepancies, the bottom-three ESR ages retain stratigraphic and chronological utility as conservative upper bounds. Future work should prioritize (1) calibration using independently dated reference materials and (2) theoretical and experimental refinement of De modeling, especially for pre-Quaternary sediments, to improve accuracy and reduce systematic biases. Conclusions Quartz Al center ESR dating provides a viable and increasingly reliable geochronological tool for Late Pliocene and early Pleistocene fluvial deposits where tephra or other absolute dating methods are absent. Its demonstrated robustness against signal saturation and compatibility with magnetostratigraphy underscore broad applicability across continental sedimentary archives. Recommendations and perspectives For Late Cenozoic sediments, optimal gamma dose ranges for Al center ESR dating fall below 12000 Gy to ensure high-fidelity De determination and minimize model-dependent uncertainties.]]> 2026/4/17 0:00:00 Background, aim, and scope The Qinghai-Xizang Plateau, often referred to as the “Third Pole of the Earth,” is one of the highest and most extreme environments on the planet, characterized by cold and harsh climatic conditions. Prehistoric human activities on this plateau have attracted considerable attention due to the complex interactions between humans and their environment. Investigating how prehistoric populations survived and adapted to such extreme conditions, as well as the coupling relationship between human activities and environmental change, is crucial for understanding human resilience and adaptability. This study focuses on the Canxiong Gashuo (CXGS) site, located along the Tongtian River in the hinterland of the Qinghai-Xizang Plateau, with the aim of exploring the relationship between environmental evolution and prehistoric human activities since the Holocene. Materials and methods Environmental proxies, including grain size, magnetic susceptibility, chromaticity, and pollen, as well as charcoal samples for radiocarbon dating, were collected from the CXGS profile with a 105-cm depth. Analytical approaches from chronology, environmental archaeology, and palynology were employed to reconstruct paleoenvironmental conditions and assess human-environment interactions. Results The results indicate that the basal age of the CXGS profile is about 9.85 cal. ka BP, during the Holocene Climatic Optimum (8.3—7.8 cal. ka BP), the regional climate was warm and humid, promoting extensive vegetation cover. These favorable conditions likely supported seasonal hunting activities by microlithic populations in the plateau hinterland. In contrast, during the Late Holocene (3.5—1.2 cal. kaBP), sediment grain size became coarser and magnetic susceptibility decreased, while multiple environmental proxies suggest a shift toward cooler and drier conditions. Discussion The environmental records from the CXGS profile suggest that during the Holocene Climatic Optimum, warm and humid conditions with dense vegetation cover created a favorable ecological setting. Combined with archaeological evidence such as microlithic tools, this indicates that prehistoric populations likely engaged in seasonal hunting and gathering, possibly migrating between high and low altitudes. During the Late Holocene, coarser sediment grain size and intensified aeolian activity reflect increasing aridity and cooling across the Qinghai-Xizang Plateau. Despite these harsher conditions, evidence of human activity became more prominent. The introduction of barley cultivation and yak domestication provided critical subsistence strategies, enabling prehistoric populations to persist under increasingly adverse climatic conditions. This highlights the remarkable adaptability of humans to extreme environments. Conclusions The warm and humid climate during the Holocene Climatic Optimum, along with improved vegetation cover, provided suitable conditions for microlithic populations to conduct seasonal hunting and gathering activities, likely involving altitudinal mobility. In the Late Holocene, although the climate became colder and drier, the introduction of cold-resistant crops and the development of pastoralism, particularly the domestication of yaks, facilitated the expansion and intensification of human activities. These adaptive strategies significantly enhanced human occupation and resilience on the plateau. Recommendations and perspectives This study provides new insights into how prehistoric populations adapted to harsh climatic conditions and sustained their livelihoods in the hinterland of the Qinghai-Xizang Plateau. The high-resolution environmental records presented here offer important evidence for understanding human adaptive strategies in extreme environments. Future research should integrate spatial and temporal distributions of regional archaeological sites to further investigate the routes and driving mechanisms of seasonal migration patterns in prehistoric populations.]]> 2026/4/17 0:00:00 Background, aim, and scope Silicate weathering represents a fundamental sink of atmospheric CO₂ and contributes to the long-term stability of Earth’s climate. However, the response of this process to the rapid increase in atmospheric CO₂ since the Industrial Revolution remains poorly constrained. Therefore, this study aims to clarify the relationship between silicate weathering and recent climate change. To achieve this, we analyzed lake sediments from the Qinghai-Xizang Plateau, using Mg isotopes as a tracer of chemical weathering intensity in this high-elevation, minimally disturbed, and climate-sensitive archive. Materials and methods This study focuses on a 30.3 cm short sediment core from Dagze Co on Qinghai-Xizang Plateau. The core was dated using the 210Pb-137Cs method and analyzed for its silicate mineral components, elemental geochemistry, and Mg isotope compositions. Results The δ²⁶Mg values vary in two distinct stages: StageⅠ(AD 1855—1930) exhibits significant fluctuations, decreasing from −0.16‰ to −1.15‰ and then increasing to −0.30‰; Stage Ⅱ (AD 1930—1985) shows relatively stable fluctuations, varying around −0.60‰. Similarly, the illite/chlorite and Rb/Sr ratios also display a two-stage variation. In StageⅠ (AD 1855—1930): the illite/chlorite ratio fluctuates markedly between 0 and 11, while the Rb/Sr ratio shows a trend of initially increase and then decrease, ranging from 6 and 10. In StageⅡ (AD 1930—1985): the illite/chlorite ratio between 5 and 8 with reduced amplitude, and the Rb/Sr ratio fluctuates narrowly around 8 before decreasing to 6.7. Discussion The controls on Mg isotopic variations and their response to regional climate are discussed. First, as Dagze Co is semi-closed and receives detrital material mainly from the Bocangzangbu River, the sediment source can be considered stable. The weak correlation (R² =0.0115) between Zr/Rb and δ²⁶Mg suggests limited influence of grain-size sorting on δ²⁶Mg. Instead, the δ²⁶Mg variation in the silicate fraction reflects chemical weathering intensity, which is further supported by the weathering proxies (illite/chlorite ratio and Rb/Sr ratios). Second, based on Mg isotopic variations, weathering intensity, can be divided into two stages: StageⅠ (AD 1855—1930) and StageⅡ (AD 1930—1985). These stages correspond to regional variations in paleotemperature and paleo-precipitation variation, highlighting the dominant role of climate in controlling silicate weathering intensity. Conclusions These results indicate that Mg isotopes in lacustrine clastic sediments have the potential to trace weathering intensity and climatic evolution in the catchment. Recommendations and perspectives Based on our study of Dagze Co, we suggest that continental weathering is likely to intensify in the future under rising global CO₂ levels and ongoing warming.]]> 2026/4/17 0:00:00 Background, aim, and scope The Hainan gibbon (Nomascus hainanus) is a critically endangered primate species endemic to China. Assessing habitat suitability for this species is critical for conservation initiatives. The maximum entropy (MAXENT) model, although known for its predictive capabilities, lacks ecological interpretability.To address this limitation, we integrate the Geographical Detector (GD) into MAXENT to assess habitat suitability for the Hainan gibbon. From a landscape ecology perspective, this study also explores the habitat connectivity of Hainan gibbons and identifies crucial potential habitat patches. Materials and methods Based on 175 occurrence records of the Hainan gibbon, we constructed a habitat suitability assessment model using the MAXENT model and introduced Moran’s I index and the Optimal Parameters-based Geographical Detector (OPGD) to further analyze the distribution patterns of habitat suitability index and dominant environmental variables. Subsequently, we investigated the ecological quantitative relationships between environmental variables and the habitat suitability of the Hainan gibbon, along with the interactions between the environmental variables. Overall connectivity indices (IIC (integral index of connectivity) and PC (probability of connectivity)) assess functional habitat connectivity, and the patch importance index (dPC) analyzes the importance of each habitat patch. Results The results showed the most suitable habitat covers 26.04 km² (8.69%), concentrated in the Futou Ridge−Heiling Ridge−Yajiada Ridge region and Dongbeng Ridge in the central and northeastern protected areas. Sub-suitable habitat spans 72.11 km² (24.05%), mainly in the central and northern regions. Moran’s I for the Habitat Suitability Index is 0.963, indicating significant spatial clustering. ROC (receiver operating characteristic) curve validation yields an average AUC (area under the curve) of 0.952, indicating high predictive performance. Bioclimatic variables (with a total contribution of 54.6% and an overall q-value of 0.7389) and human disturbance variables (with a total contribution of 28.0% and an overall q-value of 0.5035) exert a substantial influence on the habitat suitability assessment of Hainan gibbons. Interaction detector reveals joint effects, with distance to residential areas and bio12 (annual precipitation) having the highest explanatory power (joint contribution of 0.6809). Ecological detector shows significant differences in environmental variable impacts. Functional connectivity varies under different daily movement distances, reaching maximum potential at dispersal distances exceeding 1500 m. Suitable habitat patches are scattered, with the most important habitat cluster in the Futou Ridge−Heiling Ridge−Yajiada Ridge area (15.85 km² ) and the second in the west of Yajiada Ridge (6.33 km² ). Discussion Hainan gibbons exhibit climate preferences in response to food source requirements, with elevation, precipitation, and temperature crucial in determining vegetation types and food plant abundance. The spatial distribution of suitable food sources and resting plants overlaps with potential suitable habitats. Variables like precipitation in the driest quarter (bio17) correlate with the time of wild foraging by Hainan gibbons. Plant growth conditions are superior near water sources, leading to higher abundance of food plants for Hainan gibbons in areas close to rivers. Human activities impact habitat distribution, with higher elevations experiencing less disturbance. Infrastructure development such as road construction, power lines, and farming activities within Bawangling has fragmented suitable habitats like Futou Ridge, Yajiada Ridge, and Heiling Ridge, creating discontinuous regions and resulting in the “isolation” of populations. The distribution of roads also acts as a barrier hindering the migration and dispersal of Hainan gibbon populations towards suitable habitat patches in the northeast, such as Dongbeng Ridge and the western Yajiada Ridge. Conclusions The most suitable habitat for Hainan gibbons is distributed in the central part of the protected area, specifically in the Futou Ridge−Heiling Ridge−Yajiada Ridge area, and in the northeastern part of Bawangling in the Dongbeng Ridge region. The Sub-suitable habitat is mainly distributed in the central and northern regions of Bawangling. While the habitat suitability for Hainan gibbons exhibits significant spatial clustering, the distribution of suitable habitat patches is relatively scattered, and the functional connectivity among these suitable habitats is poor. Bioclimatic variables and human disturbance variables significantly influence the habitat suitability assessment for Hainan gibbons. Hainan gibbons show a preference for areas with high annual precipitation, moderate temperature differences, higher elevations, steeper slopes, proximity to water bodies, and locations far from human activities. The introduction of OPGD further validates the objectivity of selected environmental variables and the accuracy of MAXENT model results, reducing the subjectivity in discretizing environmental variables and addressing the ecological interpretability gap in MAXENT. Recommendations and perspectives Future research can incorporate additional environmental variables, such as land cover and vegetation types, obtained through remote sensing imagery and field surveys, to further enhance the accuracy of habitat suitability assessments for the Hainan gibbon. Conservation efforts should focus on seven suitable habitat patches within the research area that are larger than 0.1 km² . To enhance connectivity, artificial ecological corridors will be established to link high-suitability habitat patches, especially in regions like Dongbeng Ridge−Futou Ridge, Futou Ridge−Heiling−Yajiada Ridge. When constructing ecological corridors, efforts will be made to choose tree species that align with local phenology and provide stable food resources for Hainan gibbons. Simultaneously, there will be a focus on preserving and restoring potential natural forest corridors. Long-term monitoring and restoration efforts will be implemented in sub-suitable habitat areas, with the aim of transforming them into suitable habitats in the later stages.]]> 2026/4/17 0:00:00 Background, aim, and scope The Chinese Loess Plateau (CLP), recognized for its ecological vulnerability and sensitivity to climatic fluctuations, faces growing challenges under the influence of global warming. Notably, the rising occurrence of extreme precipitation events has emerged as a major threat to regional socio-economic development and public safety. While Global Climate Models (GCMs) are widely employed to forecast future precipitation trends, their limited spatial resolution often hampers their effectiveness in capturing localized hydrometeorological extremes. In response, this study explored the potential of advanced deep learning approaches to improve precipitation downscaling over the CLP, with a specific focus on evaluating their ability to replicate the characteristics of extreme rainfall events at regional scales. Materials and methods The research utilized high-resolution daily precipitation data derived from the IMERG (i.e., Integrated Multi-satellite Retrievals for Global Precipitation Measurement (GPM)), featuring a temporal granularity of 0.5 h and a spatial resolution of 0.1°×0.1°. To inform the downscaling process, large-scale atmospheric predictors were sourced from the ERA5 reanalysis dataset, encompassing variables such as air temperature (T ), specific humidity (Q), geopotential height (Z ), meridional (U ) and, zonal (V ) wind velocities, provided at a coarser 2°×2° resolution. Precipitation downscaling was conducted through a comparative framework that integrated two deep learning architectures— Convolutional Neural Networks (CNN) and Residual Dense Block Networks (RDBNet)—alongside a traditional Generalized Linear Model (GLM). The dataset was partitioned into a calibration period (2001—2015) and a validation period (2016—2020) to assess model performance. Results Deep learning models exhibited a clear advantage in replicating both average precipitation patterns and the intensity of extreme rainfall events. Notably, the CNN1 architecture outperformed other models across multiple extreme precipitation indices, including R95p (annual total precipitation from days >95%), R99.5p (annual total precipitation from days >99.5%), and RX5day (maximum cumulative precipitation >5 days). Discussion The comparative analysis revealed distinct strengths and limitations among the modeling approaches. Deep learning techniques, particularly CNN and RDBNet, leveraged non-linear feature extraction capabilities that allow for more nuanced representation of complex precipitation dynamics. In contrast, the GLM, though interpretable, showed limited skill in replicating extreme event magnitudes. While all models demonstrated varying degrees of efficacy, the deep learning architectures consistently outshone the linear baseline, especially in simulating the intensity and temporal structure of highimpact precipitation episodes over the CLP. Conclusions The findings confirmed the superior performance of deep learning models in capturing extreme precipitation features across the CLP. By improving the spatial accuracy and sensitivity of downscaling processes, these approaches contributed to a more refined understanding of regional hydrological risks under climate change. The insights also established a methodological foundation for advancing precision in future climate projections and risk mitigation strategies. Recommendations and perspectives While this study highlighted the advantages of deep learning over linear models in the context of the CLP, the generalizability of these findings warrants further investigation. Future research should expand the scope to encompass diverse climatesensitive regions and explore a broader range of deep learning architectures. Furthermore, coupling deep learning downscaling with GCM-based future scenarios holds promise for enhancing regional precipitation forecasting under changing climate conditions.]]> 2026/4/17 0:00:00 Background, aim, and scope At present, the growth of industrial production activities and motor vehicle ownership has caused acid rain pollution frequently to threaten human health. Zhejiang Province, as one of the important urban agglomerations in the Yangtze River Delta region, has a high industrial production output value and urbanization level. However, the long-term evolution process of acid rain pollution and its distribution characteristics in this region have not been sufficiently studied. This study covers the period from 2011 to 2021, utilizing data from 13 rain observation stations across Zhejiang Province, namely Shaoxing Station, Zhoushan Dinghai Station, Taizhou Hongjia Station, Wenzhou Station, Lishui Station, Yunhe Station, Jinhua Station, Jinhua Yiwu Station, Quzhou Station, Hangzhou Station, Hangzhou Lin’an Station, Huzhou Station, and Jiaxing Station, to analyze spatial and temporal variations of acid rain pollution and its underlying causes through mathematical statistical methods, and attempts to investigate the spatial and temporal characteristics of acid rain pollution in the region and to analyze the potential causes. Materials and methods The data of thirteen rain observation stations in Zhejiang Province was obtained to discuss the evolution of acid rain pollution from 2011 to 2021 through a series of mathematical statistical methods. Results The results showed that from 2011 to 2021, the acid rain pollution situation in Zhejiang Province continued to improve, the frequency of acid rain decreased from 43.2% to 21.6%. There are obvious seasonal changes in the acid rain pollution status. In summer, the acid rain pollution was light and occurred mostly in the eastern coastal areas of Zhejiang; winter was the most serious season for acid rain pollution, with a frequency of occurrence of 45%. Discussion The acidity of the province’s precipitation was gradually weakening, and the phenomenon of worsening acid rain pollution was still occurring in individual years, but such a phase did not last long. With the accelerated progress of urbanization and industrialization, the phenomenon of acid rain has been aggravated in the southwest of Zhejiang, continuously optimizing the structure of energy consumption is an important measure to improve the province’s acid rain pollution. Meteorological conditions, on the other hand, directly affect the diffusion and transportation of pollutants, leading to differences in the chemical composition of acid rain. In summer, southeast winds from the East China Sea prevail in Zhejiang, and the air masses were relatively clean, which played a role in alleviating acid rain pollution in the inland areas of Zhejiang. However, a large number of sulfate ions were carried by marine aerosols, thus still causing serious acid rain pollution in the coastal areas of Zhejiang. The most important precursors of acid rain formation are SO₂ and NOx. The SO₂ emissions in Zhejiang Province decreased much more than NO_x, reaching 91.9% during the 13th Five-Year Plan period. However atmospheric NOx will titrate ozone and control the atmospheric ozone concentration to some extent. Excessive pursuit of NOx emission reduction may increase the oxidizable of the ambient atmosphere and promote the formation of acidic pollutants. Conclusions Although the emission of SO₂ was decreased dramatically, the increase in precipitation pH was not obvious, indicating that the type of acid rain pollution was gradually transitioning to sulfuric acid-nitric acid type. Meanwhile, the increasing trend of acid rain pollution in southwest Zhejiang may be related to the increasing level of industrial development from year to year. Recommendations and perspectives This study provide the valuable insight into the causes of acid rain pollution in Zhejiang Province, and highlight the importance of reducing SO₂ and NOx emissions in order to alleviate acid rain pollution in the future.]]> 2026/4/17 0:00:00 Background, aim, and scope The intertwined challenges of water scarcity and soil erosion continue to impede both ecological sustainability and socioeconomic advancement across the Chinese Loess Plateau. Following the launch of the “Grain for Green” initiative, the region has experienced substantial shifts in land use, highlighting the urgent need to elucidate how soil water content and soil quality vary across representative land use categories. This study aimed to evaluate these variations within the hilly-gully region of the Chinese Loess Plateau and to determine the land use configurations most conducive to sustainable vegetation restoration in environments constrained by limited water availability. Materials and methods Field-based investigations were carried out at the Nangou Ecological Experimental Station in Yan’an, Shaanxi Province, situated within the Chinese Loess Plateau. Soil samples were collected to assess both water content and a range of physicochemical properties. Four representative land use types (pure forest land, mixed forest land, grassland, and farmland) were selected as the research objects. Seasonal monitoring of stratified soil moisture levels was conducted from March to October 2022, supplemented by continuous measurements using precision moisture sensors. A total of fifteen soil quality indicators were selected for analysis, including bulk density, particle size distribution (clay, silt, and sand), pH, cation exchange capacity, organic matter, total carbon, total nitrogen, total phosphorus, microbial biomass carbon, and four enzymes (urease, sucrase, alkaline phosphatase, and glucosidase). These parameters were measured to calculate the soil quality index (SQI), aiming to quantify the variation patterns of soil quality across different land-use types. To quantify soil quality, principal component analysis (PCA) in conjunction with the fuzzy membership function method was employed to derive a composite soil quality index and classify quality grades accordingly. Results (1) Statistically significant differences in soil water content were observed among the various land use types (p<0.05), with the descending order being: grassland (22.6 mm)>farmland (20.9 mm)>mixed forest (20.0 mm)>pure forest (19.9 mm); (2) A threshold response to precipitation was identified, whereby daily rainfall events of 10—30 mm/d significantly increased soil moisture levels within the root-active zone (50—70 cm depth); (3) The calculated soil quality indices were 0.57 for mixed forest, 0.49 for pure forest, 0.50 for grassland, and 0.38 for farmland, collectively reflecting a generally suboptimal soil quality status across the study area. Discussion Forested land is characterized by a complex vegetation architecture and extensively developed root systems, both of which contribute to elevated rates of evapotranspiration and substantial canopy interception. These features collectively lead to increased soil water consumption. In contrast, grassland exhibits superior water retention capacity, largely attributable to its dense surface coverage, enhanced rainfall interception, reduced evapotranspiration and surface runoff, along with greater infiltration efficiency. Farmland, in comparison, is subject to intensive anthropogenic disturbance and experiences heightened surface runoff, leading to lower soil moisture levels. Under conditions of limited precipitation, rainfall can offset plant water demand and temporarily enhance soil moisture. However, excessive rainfall often saturates the soil profile and amplifies runoff, thereby diminishing overall soil water storage. The generally poor soil quality observed across the study area is primarily linked to its sandy, porous texture, low cation exchange capacity, and limited ability to retain both water and nutrients. Forested areas, subjected to minimal anthropogenic disturbance, exhibited greater litter accumulation and higher nutrient content in the soil. Notably, mixed forest plots showed more rapid litter decomposition and elevated soil organic matter levels relative to pure forest plots, leading to improved soil quality ratings. Conversely, long-term cultivation practices in farmland intensified human impact and accelerated organic matter mineralization, thereby contributing to a decline in soil quality. Conclusions These results provide essential empirical support for the effective management and sustainable utilization of water and soil resources on the Chinese Loess Plateau. Grassland has been identified as a more appropriate land use option for water-limited regions, while forested land demonstrates greater potential for enhancing soil quality relative to farmland. Recommendations and perspectives Continuous monitoring of soil moisture dynamics and soil quality is essential throughout the process of vegetation restoration, accompanied by timely modifications to vegetation composition as needed. In ecologically vulnerable and arid regions, a strategic combination of controlled afforestation and the expansion of low water-demand grassland is advocated to support the long-term sustainability of both water resources and ecosystem recovery.]]> 2026/4/17 0:00:00 Background, aim, and scope Stable isotopes in loess carbonates serve as highly important and wellestablished proxies for reconstructing paleoclimate and paleoenvironments. However, the specific climatic significance and reliability of some isotopic indicators require further investigation. This paper systematically reviews the research advances in both traditional stable isotopes and non-traditional stable isotopes in loess carbonates to provide methodological insights and theoretical support. Materials and methods In this paper, the studies of stable isotopes (δ¹³C, δ¹⁸O and ⁸⁷Sr/⁸⁶Sr) and non-traditional stable isotopes (δ²⁶Mg, δ⁷ Li and δ ¹¹B) in loess carbonates are reviewed, and their significance in climate change is summarized. The literature search for this review was conducted primarily using the Web of Science and Elsevier ScienceDirect. Keywords such as loess carbonate, isotopes, climate, monsoon, and environment were employed to retrieve relevant publications.Results Related studies have reported the paleoclimatic and paleoenvironmental significance of traditional and non-traditional stable isotopes in loess carbonates. Discussion Traditional stable isotopes ( ¹³C, ¹⁸O and ⁸⁷Sr/⁸⁶Sr) have matured as proxies for reconstructing paleovegetation types, paleoatmospheric CO₂ levels, paleotemperature/ precipitation, and chemical weathering intensity, while the clumped isotopes (Δ₄₇) provide an independent method for quantitative paleothermometry. Moreover, the potential of some nontraditional stable isotopes ( ²⁶Mg, ⁷ Li and ¹¹B) for tracing the evolution of the East Asian monsoon and chemical weathering processes has received preliminary validation. However, the reliability of carbon isotopes in reconstructing C₃/C₄ plant relative abundance remains under debate, and the indicative significance of some non-traditional stable isotopes on climate is not clear. Conclusions In the past few decades, researchers have expanded the scope of stable isotopes in loess carbonates to explore new indicators for climate change. The research on the stable isotope of carbonate in loess has obtained mature and perfect research methods and theoretical basis. The C, O, Sr, Mg, Li and B isotopes in loess carbonate are reliable proxies for studying climate change. They are valuable in tracing the chemical weathering process of loess, the evolution of East Asian monsoon, and abrupt climatic events. However, there are still some shortcomings in stable isotope studies of carbonate in loess. Recommendations and perspectives Future research should deepen understanding isotopic fractionation mechanisms and analyzing affecting factors of traditional proxies, and expand the research potential of non-traditional stable isotopes in loess carbonates. Efforts should be directed toward promoting the loess isotopes in paleoclimatic and paleoenvironmental reconstructions across multiple temporal and spatial scales, as well as advancing quantitative reconstruction methods.]]> 2026/4/17 0:00:00 Background, aim, and scope As the world’s second most potent greenhouse gas, methane exerts a profound and highly accelerated impact on global climate change, possessing a short-term global warming potential significantly higher than that of carbon dioxide. Given that the broader oil and gas industry represents one of the most critical anthropogenic sources of methane emissions worldwide, it is absolutely imperative to comprehensively advance and accelerate methane mitigation efforts within this specific sector. Consequently, acquiring an accurate understanding and a systematic summary of the current status, historical trajectories, and future trends of methane emissions within China’s oil and gas industry is a fundamental prerequisite. This robust understanding is crucial for achieving effective methane emission reduction targets and for guiding the strategic development, deployment, and practical application of advanced methane monitoring, precise environmental assessment, and innovative emission reduction technologies tailored to the region. Materials and methods This paper comprehensively reviews the current operational and environmental status of methane emissions originating from the global and domestic oil and natural gas industry. By systematically summarizing recent advancements in both top-down and bottom-up emission accounting methodologies, the study evaluates the efficacy of current measurement approaches. Furthermore, it rigorously identifies the primary limitations, methodological gaps, and systemic inconsistencies currently embedded within existing accounting frameworks. This systematic analysis provides a critical baseline for future methodological refinements, regulatory policy development, and the eventual standardization of industry-wide reporting protocols. Results Our findings indicate that routine process venting— alongside fugitive equipment leaks and incomplete flaring—constitutes the primary pathway for global methane emissions from the oil and natural gas industry. Within this global context, China currently ranks sixth worldwide in total sectoral emissions, highlighting a significant area for potential climate action and regulatory focus. However, current national-scale and regional estimates of these methane emissions still suffer from remarkably large uncertainties. This statistical unreliability is primarily driven by the conspicuous absence of precise, localized, and directly measured emission factors that accurately reflect China’s specific operational realities. By meticulously comparing the advantages, operational disadvantages, and inherent uncertainties of various traditional and modern monitoring approaches, we further analyzed the developmental trajectory and practical application progress of emerging detection technologies. Notably, technologies such as unmanned aerial vehicle (UAV) mobile monitoring and stable isotope tracing have shown promising performance. These advanced techniques facilitate precise regional flux assessments, enable dynamic spatial mapping, and significantly improve the identification and source attribution of ground-level emission sources. Discussion Although an increased volume of continuous, high-precision field monitoring data is universally recognized as crucial for establishing reliable, localized emission factors and compiling highly robust national emission inventories, practical implementation still faces severe hurdles. Nationwide field monitoring activities across complex oil and gas infrastructure remains substantially constrained by immense human resource requirements and significant financial burdens. Consequently, national inventories are frequently forced to rely on limited empirical measurements and generalized emission factors, which fail to capture temporal and spatial variability. Standardized site-level measurements, when strategically combined with targeted high-frequency monitoring, can significantly improve local inventories and help accurately prioritize the highest-emitting sources for immediate mitigation and resource allocation. Conclusions Based on an exhaustive review and critical synthesis of current evaluation methodologies, we emphatically highlight the urgent necessity of establishing a comprehensive, standardized, and scalable site-level accounting method for methane emissions. This integrated site-level framework is not merely an incremental improvement; rather, it serves as the indispensable technical pathway required to accurately evaluate the overall methane emission contribution from the entire national oil and gas industry. Recommendations and perspectives In light of the current application prospects, technological capabilities, and logistical limitations of site-level methane monitoring and accounting methods, a series of targeted, actionable recommendations are proposed to refine and optimize this comprehensive accounting framework. Overall, we firmly believe that this comprehensive summary provides an essential theoretical basis and practical roadmap for the advancement of accurate methane emission assessments and the accelerated implementation of robust mitigation measures across China’s vital oil and natural gas industry]]> 2026/4/17 0:00:00