Human Activities Research Articles

The interplay between prehistoric vegetation, climatic fluctuations and anthropogenic activities in Central China

The interaction between climate, hydrological environment, and human activities in prehistoric times has consistently attracted significant interest. However, the process and mechanism of this interaction remain unclear due to a lack of detailed materials that provide information on both human activity and environmental evolution. Here we present a comprehensive dataset of optically stimulated luminescence (OSL) dating and pollen analysis derived from lacustrine facies deposits in the vicinity of the Dongzhao Site in Central China, which is a key region for the origin and development of Chinese civilization. These data have revealed the existence of multiple cycles of environment-human interaction during prehistoric periods. The gradual improvement in the climate and minor fluctuations facilitated the settlement of prehistoric populations in the region, fostering uninterrupted cultural development for millennia since the early Holocene. The increase in population and intensification of human activities significantly affected regional vegetation, resulting in a decrease in the number of trees around 4.0 ka BP. Environmental changes influenced the prehistoric architectural style, resulting in a decrease in houses with “wood bone and mud walls” that were prevalent during the Yangshao periods (7.0–5.0 ka BP) due to a lack of trees. Our research once again highlights the perpetual cycle of interdependence and interaction between natural environments and human activities.

Understanding wildfire occurrence and size in Jalisco, Mexico: A spatio-temporal analysis

In recent years, the growing frequency and severity of wildfires, influenced by both human activities and climate change, have posed significant challenges worldwide. Among the regions most affected by wildfires in Mexico is the state of Jalisco, which has the largest accumulated burned area in the last five decades. In this paper, we present an in-depth analysis of the spatio-temporal patterns of wildfire occurrence and size in the state of Jalisco, spanning the period from 2001 to 2020. Our approach included modeling the spatial distribution of the area burned by wildfires, employing Bayesian methodology with Integrated Nested Laplace Approximation (INLA) and Stochastic Partial Differential Equations (SPDE). Our findings highlight the critical roles of vegetation, temperature, and human activities in shaping wildfire behavior. Additionally, our model suggests four distinct wildfire-prone regions within the state. The insights gained from this study can serve as a foundation for future research and localized studies, aiding in the development of more targeted and effective wildfire management strategies in Jalisco.

Detecting and attributing the impact of human activities on grassland aboveground biomass in China's Loess Plateau

Human activities significantly influence grassland ecosystem functions, particularly plant biomass. However, the direction and magnitude of these effects remain insufficiently explored. Herein, we quantitively assessed both the positive and negative effects of various human activities on grassland aboveground biomass (AGB) in China's Loess Plateau from 2000 to 2022. The results indicated that the magnitudes of positive effects increased by 0.29 g m−2 per year, whereas the negative effects decreased by 0.31 g m−2 per year. Spatially, 32 % of the grasslands experienced significant positive effects, whereas the rest grasslands faced negative effects. Notably, only 20 % of the areas with negative effects showed worsening trends mainly due to ecological restoration, sustainable agriculture, and population migration. Agricultural production activities and population changes emerged as dominant factors, with some activities, like livestock farming, exhibiting dual effects (i.e., positive and negative effects) on AGB. These findings underscore the complexity of human activities in affecting the grassland production function and highlight the necessity for balanced management strategies to sustain grassland productivity and resilience.

Autoreactive B cells remain active despite clinical disease control in rheumatoid arthritis

BackgroundAutoimmune diseases (AIDs) are frequently hallmarked by the presence of autoreactive B cell responses which are involved in disease pathogenesis. However, the dynamics of such responses and their relation to clinical disease activity in humans is poorly understood. Rheumatoid arthritis (RA), a prototypic chronic AID, is hallmarked by B cell responses directed against citrullinated proteins. ObjectiveTo determine the relation between the activity of the anti-citrullinated protein antibody (ACPA) B cell response and clinical disease activity in ACPA+ patients with RA. MethodsExpression of B cell activation markers by ACPA+, tetanus toxoid (TT)+ and ACPA− memory B cells (MBCs) from peripheral blood of ACPA+ RA patients receiving different treatments was analyzed by flow cytometry. Results were correlated to clinical disease activity. ResultsCompared to TT+ and ACPA− MBCs, ACPA+ MBCs displayed a highly activated phenotype as evidenced by increased expression of Ki-67, CD86, CD80, CD19 and CD20 and reduced expression of CD32. The activated phenotype of ACPA+ MBCs did not associate with clinical disease activity in a cross-sectional analysis of RA patients treated with various therapeutic agents. Also, in a longitudinal analysis of patients treated with Janus kinase (JAK) inhibitors, ACPA+ MBCs retained their activated phenotype despite effective control of inflammation and clinical disease. ConclusionACPA+ MBCs remain active despite clinical disease control in patients with RA across a range of interventions. This persistent activity indicates the absence of immunological remission and might explain why ACPA+ patients rarely reach sustained drug-free remission and frequently flare upon drug tapering.

Patterns of nitrate load variability under surface water-groundwater interactions in agriculturally intensive valley watersheds

Nitrate pollution is a significant environmental issue closely related to human activities, complicated hydrological interactions and nitrate fate in the valley watershed strongly affects nitrate load in hydrological systems. In this study, a nitrate reactive transport model by coupling SWAT-MODFLOW-RT3D between surface water and groundwater interactions at the watershed scale was developed, which was used to reproduce the interaction between surface water and groundwater in the basin from 2016 to 2019 and to reveal the nitrogen transformation process and the evolving trend of nitrate load within the hydrological system of the valley watershed. The results showed that the basin exhibited groundwater recharge to surface water in 2016-2019, particularly in the northwestern and northeastern mountainous regions of the valley watershed and the southern Beishan Reservoir vicinity. Groundwater recharge to surface water declined by 20.17% from 2016 to 2019 due to precipitation. Nitrate loads in the hydrologic system of the watershed are primarily derived from human activities (including fertilizer application from agricultural activities and residential wastewater discharges) and the nitrogen cycle. Nitrate loads in surface water declined 16.05% from 2016 to 2019. Nitrate levels are higher in agricultural farming and residential areas on the eastern and northern sides of the watershed. Additionally, hydrological interactions are usually accompanied by material accumulation and environmental changes. Nitrate levels tend to rise with converging water flows, a process that becomes more pronounced during precipitation events and cropping seasons in agriculturally intensive valley watersheds. However, environmental changes alter nitrogen transformation processes. Nitrogen fixation, nitrification, and ammonification intensify nitrogen inputs during river pooling, enhancing nitrogen cycling fluxes and elevating nitrate loads. These processes are further enhanced during groundwater recharge to surface water, leading to evaluated nitrate load. Enhanced denitrification, dissimilatory nitrate reduction to ammonium (DNRA), anaerobic ammonia oxidation, and assimilation promote the nitrogen export from the system and reduce the nitrate load during surface water recharge to groundwater.

Potential Non-carcinogenic and Carcinogenic Health Risks of Elements of Health Concern Bioaccumulated in Seafood from Local Fish Rafts in Trang Province, Thailand

Marine ecosystems are increasingly contaminated by pollutants from human activities which could impact seafood quality. This study investigated the levels of six potentially toxic elements of health concern including arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), nickel (Ni), and lead (Pb). Analyses of those elements were conducted in eleven commercially available seafood species collected from local fish rafts in Trang province, Thailand. The findings revealed variations of element of health concern content among species, with H. raphidea exhibiting significantly high levels. Human health risks were assessed for estimated daily intake and non-carcinogenic and carcinogenic risks. The results indicate potential risks associated with As consumption, especially in the case of H. raphidea. Children (3.0 – 5.9 years) had the greatest vulnerable risks in comparison to other age groups. The levels of elements of health concern in most seafood samples were within safe limits. However, the continuous surveillance, monitoring, and management of these contaminants in seafood are needed, particularly in vulnerable populations.

Risk assessment and source tracing of heavy metals in major rice-producing provinces of Yangtze River Basin

Heavy metal contamination in rice constitutes a global concern, its migration is influenced by environmental factors as well as socioeconomic activities. However, tracing its origins within complex context remains a significant challenge. The concentrations of five heavy metals (HMs) in 1754 samples from major rice-producing provinces were analyzed, and their pollution characteristics, associated health risks and temporal-spatial variations were discussed. Potential sources were classified by positive matrix factorization (PMF) models, considering correlations with human activities, climatic conditions, and interaction within ecosystems. The results showed that cadmium (Cd) and arsenic (As) were the primary contributors to pollution risk, with the borders between Hunan and central Jiangxi, as well as northeast Jiangxi and northwest Anhui, identified as critical areas for risk management. PMF serves as an effective methodology for identifying the sources of HMs in rice. Industrial activities, particularly mining and transportation, represent the predominant sources of Cd and lead (Pb), accounting for 75.6% of the total pollution. Conversely, agricultural practices and natural factors constitute the primary sources of As, contributing to the remaining 24.4%. It is noteworthy that the rapid industrial development has facilitated the expansion of the freight industry, consequently increasing the risk associated with Pb. Furthermore, effective governmental policy management can mitigate the risks related to HMs. Our research highlights the influence of industrial development on HMs risk in various regions and the moderating role of policy formulation. SYNOPSIS: Minimal research exists on the impact of regional economic development on heavy metals in rice. This study reports mining and transportation activities increase carcinogenic risks caused by Cd and Pb in rice during industrialization.

Potential distribution of Detarium microcarpum under different climate change scenarios in Burkina Faso

Climate change and human activities are major drivers influencing species distribution, posing significant challenges for woody species that provide essential ecosystem goods and services. Therefore, a thorough understanding of climate impacts on species distribution is crucial for more effective management. This study aims to assess the effect of climate change on the current and future distribution of Detarium microcarpum. This study was conducted in Burkina Faso. The maximum entropy (MaxEnt) approach was used to simulate the current and future distributions of the species. The future distribution of the species was assessed through four global climate models: HadGEM3-GC3.1-LL, ACCESS-CM2, CNRM-CM6-1 and MIROC6 under two Shared Socioeconomic Pathways (SSPs) scenarios, SSP2-4.5 and SSP5-8.5 at the horizons 2061–2080 and 2081–2100. The area under the curve (AUC ˃ 0.80) and True Skill Statistic (TSS=0.7) revealed a high level of prediction for the current and future scenarios. The results showed that the mean temperature of the Wettest Quarter (bio8) and Isothermality (bio3) were the most important environmental variables which affect D. microcarpum distribution. The results show that the current suitability area for the species covers 65.6 % of the country area with respectively high suitability (36.73 %) and low suitability (29.16 %). Based on the outcomes of the prediction, the high suitable areas for D. microcarpum conservation will decrease on average by 5,92 % of their current area under future climate change, regardless of the scenario and model used, except for the MIROC6 model under the SSP5-8.5 scenario, which will increase its current area from 0.56 % to 1.7 %. The result of this study underscores the significant effect of the future climate on the suitable area of D. microcarpum. Specific actions should be taken to ensure the suitable conservation of this valuable multipurpose species.

Long-term impacts of embankments on coastal marsh vegetation and carbon sequestration

Coastal marshes, encompassing saltmarshes and freshwater marshes, are important environments for carbon sequestration and coastal protection; however, they are at risk due to climate change, sea level rise and human activity. Freshwater wetlands sit inland of saltmarshes and are often characterised by high biodiversity and productivity. Increasingly, conservation efforts are focussed on freshwater habitats, sometimes even at the expense of saltmarshes, through the construction of defences and embankments. However, these sea defences have unintended consequences on both coastal freshwater and saltmarshes. In this study we investigate the implications of an embankment on a freshwater marsh and saltmarsh from Gibraltar Point, UK using a palaeoecological approach. A multiproxy approach was used on archives from the freshwater marsh and saltmarsh to reconstruct the marsh geomorphological characteristics before and after the embankment was built. In the Freshwater marsh our results show the development of a transitional marsh over the past 200 years with ecological and morphological changes mainly dictated by storm surges with some influence from the seawall installation (ca. 1880 CE). The Old Saltmarsh shows the succession of a mature saltmarsh including rising elevation and vegetation development with negligible impact from the embankment construction. Whilst sea defences contribute to potential future coastal squeeze, by truncating areas of valuable freshwater marsh and cutting them off from their external sediment supply, they create risk to future inundation by sea-level rise. Natural development into freshwater marshes habitats have a greater potential for more biodiverse and multifunctional ecosystems and improved carbon storage capacity whilst enhancing coastal protection.

Attributing climate variability, land use change, and other human activities to the variations of the runoff-sediment processes in the Upper Huaihe River Basin, China

Study regionsThe Wangjiaba (WJB) watershed, located in the upper Huaihe River Basin in China. Study focusAn attributing framework has been proposed combining the Double Mass Curve (DMC) and the Soil and Water Assessment Tools (SWAT) model to identify the contributions of climate variability, Land use (LU) change, and Other Human Activities (OHA) to the variations in runoff-sediment processes within the WJB. New hydrological insights for the regionThe studied period was able to be separated into three sub-periods (P1: 1981~1991, P2: 1992~2009, and P3: 2010~2019) using the DMC, and the SWAT model could simulate runoff and Sediment Yields Load (SYL) properly during different sub-periods after calibration. Generally, the runoff, SYL, and Suspended Sediment Concentration (SSC) within the WJB exhibited a decrease trend with a change rate of −1.3mm a-1, −8.49×104 t a-1, and −0.01kgm-3 a-1, respectively. Substantially, climate variability decreases runoff, SYL, and SSC from P1 to P3; LU change decreases runoff, SYL, and SSC from P2 to P3; OHA decreases SYL and SSC from P1 to P2, but increases SYL and SSC from P2 to P3. It should be noticed that the OHA has increased the SYL significantly especially over the downstream of WJB from P2 to P3. It is essential to enhance soil erosion prevention measures in the future under the background of global climate change.

Atlas of the Oman pollen flora – Pollen morphology of the arid Arabian Peninsula vegetation

A precise and consistent fossil pollen identification is crucial for the reconstruction of (long-term) vegetation and climate dynamics. The inspection of local reference material serves as the best basis for meaningful results. Digital pollen reference collections, especially for the hyper arid regions of North Africa and the Arabian Peninsula are still sparse. Therefore, we want to contribute a descriptive and illustrated atlas of pollen from plants of the Sultanate of Oman. The atlas comprises around 400 pollen taxa on 43 plates from various habitats (e.g., mountains, wadis, deserts, coastal areas, and places shaped by human activities) characteristic for the arid environments of the Arabian Peninsula. It covers approximately 45% of all plant genera found in Oman. We provide high-resolution images of 402 taxa of 70 families as well as useful information on habitus, pollination, and habitat for each plant species as a useful guide for environmental reconstructions and interpretations from palynological investigations as well as the identification of pollen in honey.

Hydrological drought assessment of the Yellow River Basin based on non-stationary model

Study Regionthe Yellow River Basin Study FocusNon-stationary hydrological conditions are becoming increasingly common due to climate change and human activities, and pose a novel challenge to the management of water resources and related risks, especially for large basins. However, prevalent research on drought assessment often ignores the non-stationary characteristics of hydrological processes. In this study, we investigated the stationarity of the runoff of the Yellow River Basin (YRB), the second-longest basin in China. We used an approach for assessing non-stationary droughts based on the generalized additive model for location, scale, and shape to establish a standardized runoff index containing covariates (SRI_cov) to identify hydrological droughts in the basin from 1986 to 2015. New Hydrological Insights for the RegionThe results show that the runoff was non-stationary in the YRB. Based on SRI_cov, hydrological drought predominantly occurred in the entire YRB in spring. From 1986, the number of months in which droughts occurred in the YRB exhibited a general trend of increase and peaked around 2002. After that, the total number of droughts significantly decreased but extreme droughts had become more prominent since 2005. The drought was more severe in the middle reaches of the Yellow River, and was characterized by a high frequency, intensity, and severity. Our analysis enhances the understanding of hydrological modeling and drought assessment under non-stationary conditions.

Estimating groundwater recharge across Africa during 2003–2023 using GRACE-derived groundwater storage changes

Study Region:Africa, with its diverse climatic zones from the humid Congo Basin to the arid Sahara Desert, where groundwater is influenced by climate variability, land use, and human activities. Study Focus:The main objective is to estimate groundwater recharge across Africa from 2003 to 2023 using a novel approach that uses GRACE-derived groundwater storage changes. New Hydrological Insights for the Region:This study provides new insights into the spatial patterns and temporal variability of groundwater recharge across Africa, highlighting the influence of climate variability on the continent’s groundwater resources. Key findings include distinct regional differences in recharge, with higher values in humid regions like the Congo Basin and lower values in arid regions like the Sahara Desert. Substantial interannual variability in recharge is largely driven by year-to-year variations in precipitation and modulated by major modes of climate variability, especially the Pacific Decadal Oscillation. The sensitivity of groundwater recharge to hydroclimatic extremes, with droughts causing significant declines and wet periods leading to above-average replenishment. Regions with low recharge rates or high variability, such as Northern Africa, are particularly vulnerable to climate change impacts and unsustainable groundwater abstraction. The findings emphasize the need for sustainable groundwater management strategies that consider the spatial and temporal variability of recharge, as well as the potential impacts of climate change on groundwater resources.

Occurrence, fate, and ecological risk of PAEs, PFASs, antibiotics in industrial, urban and rural WWTPs in Shaanxi Province, China

The wastewater treatment plants (WWTPs) were considered as a hub of transit from human activities as a source to the aquatic ecosystems as a sink of emerging contaminants (ECs). This study investigated the fate of phthalate esters (PAEs), per- and polyfluoroalkyl substances (PFASs) and antibiotics in the influent and effluent of WWTPs in industrial, urban and rural in Shaanxi province (China). The first most abundant monomer of these three types of ECs were the same in industrial, urban and rural WWTPs. The composition of PAEs in the influent of urban and rural WWTPs were quite different from that of industrial WWTPs. The removal efficiency of PAEs and PFASs in urban WWTPs were higher than those in rural and industrial WWTPs. The annual mass load of PFASs in rural WWTPs was lower than that in industrial and urban WWTPs. The risk quotient (RQ) of PAEs was high, with most of them exceeding 1. While the RQ of PFASs was low, exceeding 0.1 only in some industrial WWTPs. The frequency of high risk of total antibiotics in urban and rural WWTPs was higher than that in industrial WWTPs. This study provided field survey data and guidance to strengthen the management of ECs in the region.

Influence of rainfall on size-resolved bioaerosols around a livestock farm

Bioaerosols, capable of transporting microorganisms, can impact human health and agriculture by spreading to nearby communities. Their transmissions are influenced by various factors, including weather conditions and human activities. However, the scarcity of detailed, taxon-specific data on bioaerosols' sizes limits our ability to assess risks associated with bioaerosols' generation and spread. This study examined the composition and size of bioaerosols at a livestock farm and a non-agricultural site, focusing on how bioaerosols evolve at different locations and meteorological conditions. The location had an impact on bioaerosol samples. We conducted 16S rRNA gene amplicon sequencing to identify bacteria genera in bioaerosols. We observed consistently higher concentrations of bioaerosols across all sizes at the livestock farm, and samples from the livestock farm exhibited greater bacterial diversity, where we identified Staphylococcus and Corynebacterium as the most abundant species. The effects of rainfall on bioaerosol diversity are complex, suggesting a dynamic interplay between bioaerosol removal and generation. After rainfall, the bioaerosol fraction of particles larger than 2.5 μm increased by nearly 400 % compared to post-rain levels. Conversely, for bioaerosols below 1 μm size, the fraction decreased by 50 %. Furthermore, the sequencing results showed that precipitation differentially responded to the abundance of various genera in the bioaerosols. Moreover, even for the same genus, the response to precipitation varied depending on the size of the bioaerosols. Our research reveals how size, location, and environmental conditions influence bioaerosol dynamics, enhancing our understanding of bioaerosol formation and transmission.

Individual variation of boldness in free-ranging bottlenose dolphins (Tursiops truncatus) interacting with scuba divers in French Polynesia

Marine wildlife tourism is known to affect target species across multiple spatial and temporal scales, from short-term behavioral responses to changes in relative abundance and habitat use patterns. However, despite a growing number of population-, community-, and group-level studies, a limited number of them have focused their research on individual responses to wildlife tourism, particularly on free-ranging cetaceans.Between 2018 and 2020, we investigated the behavioral responses of 20 non-provisioned bottlenose dolphins (Tursiops truncatus) to recreational scuba divers in Rangiroa Atoll, French Polynesia, to understand whether these individuals that had been repeatedly exposed to scuba diving tourism on at least one year exhibited temperament traits along the ‘shyness-boldness’ axis. We also considered potential variation in boldness in relation to sex, age, and tourist-site fidelity.The study documented individual differences in the dolphins’ boldness. There was no variation in boldness according to sex and tourist-site fidelity, but age significantly influenced the dolphins’ boldness with immature dolphins being bolder than mature individuals. The more extreme case of boldness involved four dolphins that tolerated repeated physical interactions with scuba divers.In Rangiroa, scuba diving tourism promotes repeated intrusive interactions with dolphins that might make bold individuals particularly vulnerable to collateral threats associated with human activities. It is therefore crucial to consider individual variation in the dolphins’ behavioral responses to tourism to implement optimal tourism management measures. We suggest in the discussion recommendations to help minimize the risks for both the dolphins and humans associated with repeated close interactions.

The dynamic patterns of critical ecological areas in the Yellow River Basin are driven primarily by climate factors but threatened by human activities

While the identification of critical ecological areas (CEAs) has been limited by the availability of resources, funds, and land space, these areas are central for maintaining the contributions from nature and ecosystem biodiversity. Thus, in this study, CEAs were systematically identified and classified via long-term ecosystem assessment with a multifunctionality–stability–integrity framework in the Yellow River Basin (YRB). The intensity and pathways of the driving factors of CEA dynamics were also determined by the geographical detector model (GDM) and the partial least squares structural equation model (PLS-SEM). The results revealed a gradual decrease in the proportion of CEAs in the upper and lower reaches from 2005 to 2020, in contrast with a significant increase in the middle reaches. The CEAs were distributed mainly in the Sanjiangyuan and Ziwuling regions and the Qingling, Qilian, Lvliang and Taihang Mountains. The areas with low, medium, and high levels of CEAs accounted for 12.48%, 17.73% and 12.54%, respectively, of the YRB. Moreover, climate factors, especially precipitation, were the foremost drivers influencing the dynamic patterns of CEAs. However, notably, the CEAs in the YRB experienced continuous degradation from 2005 to 2020 due to intensified human activities. Our results confirmed the important role of climate factors in determining the distribution of CEAs while underscoring the necessity of mitigating human disturbances to maintain ecosystem functions. These investigations of the dynamics and drivers of CEAs based on long-term multi-dimensional ecosystem assessments could provide useful insights for developing ecological conservation and sustainable development strategies.

Seasonal pattern of diel variability of CO2 efflux from a large eutrophic lake

Lake is commonly acknowledged as a contributor to atmospheric CO2. Current manual sampling for estimations of CO2 emissions from lakes predominantly relies on daytime CO2 efflux (FCO2) assessments, which tends to overlook the diel variability of FCO2. This potentially introduces bias into CO2 emission estimates. The magnitude of diel FCO2 difference between seasons and the relative importance of underlying drivers in large eutrophic lakes remain inadequately explored. Here, we estimated FCO2 based on the water quality and meteorological data from Lake Taihu, a large eutrophic lake in China, with a temporal resolution of 4 h throughout the year 2021. The lake was a CO2 source with an efflux of 0.56 ± 0.66 mmol C/m2/h. We observed a 14.07 % increase in nocturnal FCO2 compared to daytime levels annually. During the non-growing season, nocturnal FCO2 exceeds daytime levels by 12.72 %, rising to 39.84 % in the algae-growing season (April to September). Piecewise structural equation models highlight gas transfer velocity as a key driver of diel FCO2 changes, with seasonal algal growth intensifying diel CO2 partial pressure variability by enhancing gross primary production, thereby amplifying diel FCO2 fluctuations. We suggest that ongoing lake eutrophication, driven by global climate change and human activities, may introduce additional uncertainties in lake CO2 emission estimates.

Attribution analysis of hydrological drought after the impoundment of the Danjiangkou reservoir in the Hanjiang River basin

Study regionHanjiang River Basin, China Study focusUnder the joint influences of human activities and climate change, droughts frequently occur in the Hanjiang River Basin (HRB). Quantifying the driving forces contribution on hydrological drought is crucial to enhance the early warning ability. This study employed the standardized streamflow index (SSI) to assess hydrological drought. The Soil and Water Assessment Tool (SWAT) model was utilized to reconstruct natural streamflow based on hydrological and meteorological data. By comparing the variations of drought characteristics in simulated and observed scenarios, the impacts of human activities and climate change to hydrological drought were quantified. New hydrological insights for the study regionThe SWAT model is capable of effectively simulating the natural streamflow conditions of the HRB with NSE>0.7, R2>0.8, logNSE>0.7 and |PBIAS|<20%. Hydrological drought has intensified as a prolonged duration and greater severity affected by human activities and climate change. During the whole impact period (1968-2022), the duration and severity increased by 66.22% and 81.16% compared to baseline period (1956-1967). The year 1991 is detected as the mutation point. From 1968 to 1990 climate change has been the main factor in exacerbating hydrological drought. Since 1991, the influence of human activities has gradually exceeded the influence of climate change. These findings provide valuable insights for watershed integrated water resources management and water security.

Analysis of vegetation dynamics from 2001 to 2020 in China's Ganzhou rare earth mining area using time series remote sensing and SHAP-enhanced machine learning

Rare earth mining, essential for modern industries and economic growth, often leads to severe environmental degradation. Previous research has explored the ecological impacts of rare earth mining but has not fully investigated the intricate interplay and subdivisions of environmental and anthropogenic factors driving vegetation changes over extended periods. This study addresses this gap by employing time series remote sensing and SHAP-enhanced machine learning to analyze vegetation dynamics in China's Ganzhou rare earth mining area from 2001 to 2020. Using the kNDVI derived from Landsat data, we identified three distinct vegetation trajectory types: pro-environment, des-environment, and res-environment. An ensemble machine learning model combined with SHAP analysis revealed the cropland area proportion, PM10 levels, and shrubland area proportion as the most influential factors affecting vegetation across all mining types. Additionally, after 2012, the palmer drought severity index and downward surface shortwave radiation emerged as positive contributors to vegetation health, while population pressure had a more substantial negative influence in des-environment areas. Our findings highlight spatial heterogeneity in vegetation recovery patterns and highlight the complex interactions among land cover changes, air quality, climate factors, and human activities in shaping vegetation dynamics. This study provides valuable insights for developing targeted, context-specific restoration strategies in rare earth mining areas, contributing to more sustainable mining practices and global environmental management.