Spatial analysis and GIS mapping of regional hotspots and potential health risk of fluoride concentrations in groundwater of northern Tanzania

Challenges for sustainable development goal of land degradation neutrality in drylands: Evidence from the Northern Slope of the Tianshan Mountains, China

The SDG 15.3.1 target of Land Degradation Neutrality (LDN) only has 15 years from conception (in 2015) to realization (in 2030). Therefore, investigating the effectiveness and challenges of LDN has become a priority, especially in drylands, where fragile ecosystems intersect with multiple disturbances. In this study, solutions are proposed and validated based on the challenges of LDN. We chose the Northern Slope of the Tianshan Mountains as a case study and set baselines in 2005 and 2010. The region and degree of land change (including degraded, stable, and improved) were depicted at the pixel scale (100 × 100 m), and LDN realization was assessed at the regional scale (including administrative districts and 5000 × 5000 m grids). The results showed a significant disparity between the two baselines. The number of areas that realized the LDN target was rare, regardless of the scale of the administrative districts or grids. Chord plots, Spearman's correlation, and curve estimation were employed to reveal the relationship between LDN and seven natural or socioeconomic factors. We found that substantial degradation was closely related to the expansion of unused, urban, and mining land and reduction in water, glaciers, and forests. Further evidence suggests that agricultural development both positively and negatively affects LDN, whereas urbanization and mining activities are undesirable for LDN. Notably, the adverse effects of glacier melting require additional attention. Therefore, we consider the easy-to-achieve and hard-to-achieve baselines as the mandatory and desirable targets of LDN, respectively, and focus further efforts in three aspects: preventing agricultural exploitation from occupying ecological resources, defining reasonable zones for urbanization and mining, and reducing greenhouse gas emissions to mitigate warming. Overall, this study is expected to be a beneficial addition to existing LDN theoretical systems and serve as a case validation of the challenges of LDN in drylands.

Impaired neurogenesis induced by fluoride via the Notch1 signaling and effects of carvacrol intervention

The negative regulation on neurogenesis has been implicated in fluoride neurotoxicity, while the evidence is limited. To explore whether fluoride interferes with neurogenesis via the Notch1 signaling and the potential alleviation effects of carvacrol (CAR), we conducted in vivo and in vitro experiments, as well as epidemiological analyses in this study. The results showed that urinary fluoride levels and circulating Notch1 levels were associated with IQ levels in boys. NaF-treated rats had fewer neurons, lower densities of dendritic spines, depressed neurogenesis, and impaired learning and memory abilities. In vitro experiments using undifferentiated PC12 cells mimicking neurogenesis revealed that NaF suppressed differentiation and neurite outgrowth. Besides, Notch1 signaling activation was detected in vivo and in vitro. The latter was confirmed using an in vitro model supplemented with DAPT, a potent Notch1 inhibitor. Furthermore, CAR supplementation negatively regulated NICD1 and Hes1 expressions and promoted hippocampal neurogenesis, thereby improving neurological functions in NaF-treated rats. These findings indicated that the inhibition of neurogenesis in hippocampi induced by fluoride via Notch1 signaling activation may be one of the underlying mechanisms of its neurotoxicity, and that CAR significantly alleviated the neurotoxicity of NaF via the Notch1 signaling.

Spatial distribution, geochemical processes of high-content fluoride and nitrate groundwater, and an associated probabilistic human health risk appraisal in the Republic of Djibouti

In the northern East African Rift System, the Republic of Djibouti relies exclusively on groundwater, with levels of fluoride (up to 14 mg/L) and nitrate (up to 256 mg/L) posing potential health risks. To address this, 362 samples were considered, including 133 shallow groundwater samples, along with new and previously published data dating back to 2012 on deep (88) and thermal (141) groundwater samples. To understand the enrichment mechanisms, dissolved anion and cation constituents, geochemical and thermodynamic tools, and stable isotope ratios, such as δ2H(H2O), δ18O(H2O), δ15N(NO3-), and δ18O(NO3-), were used. In particular, two activity diagrams (Mg2+ vs. Ca2+ and Na+ vs. Ca2+), focused on aqueous and solid fluoride species in an updated thermodynamic dataset of 15 fluoride-bearing minerals, are shown for the first time. The dataset offers new and valuable insights into fluoride geochemistry (classic thermodynamic datasets combined with geochemical codes rely solely on fluorapatite and fluorite F-bearing minerals). Activity diagrams and geochemical modeling indicate that mineral dissolution primarily drives groundwater fluoride enrichment in all water types, whereas the elevated nitrate levels may stem from organic fertilizers like animal manure, as indicated by nitrate isotopes and NO3-/Cl- vs Cl- diagrams. Despite the arid climate and 2H18O enrichment in shallow waters, evaporation seems to play a minor role. Monte Carlo simulations and sensitivity analysis were used to assess the health risks associated with elevated F- and NO3- concentrations. Mapping-related spatial distribution analysis identified regional contamination hotspots using a global Moran's I and GIS tools. One fluoride and three nitrate contamination hotspots were identified at a p-value of 0.05. Groundwater chemistry revealed that 88 % of groundwater being consumed exceeded the permissible levels for fluoride and nitrate, posing potential health risks, particularly for teenagers and children. This study pinpoints specific areas with excessive nitrate and fluoride contamination, highlighting a high non-carcinogenic risk.

Assessing territorial space conflicts in the coastal zone of Wenzhou, China: A land-sea interaction perspective

Territorial space conflicts (TSCs) in coastal zones stem from the intricate interaction between the land-sea dual system, significantly impacting the sustainable development of these areas. To accurately identify TSCs, our study proposed a theoretical framework based on a land-sea interaction perspective. We also assessed TSCs using the territorial space conflicts index and a social network analysis model. We demonstrated the proposed spatial conflicts assessment methodology through a case study of Wenzhou, a typical city on the east coast of China. Our results indicate that the distribution of TSCs gradually decreased from the coastal zone to the inland zone, with significant variation in the distribution of different conflict types across different zones. The findings also reveal that territorial space use had diverse impacts on the space conflict network, making it urgent to take targeted measures. In the future, it is crucial to comprehensively consider the overall pattern and distribution characteristics of current TSCs, as well as the spatial spillover effect of the overall network, to develop targeted coping strategies and regulation mechanisms that promote the integration and high-quality development of coastal territorial space systems. To maintain a sustainable coastal zone process, we proposed a set of optimization paths for alleviating TSCs and promoting the coordinated development of land and sea regions in China based on our study.

Exploring the Dynamic Invasion Pattern of the Black-Headed Fall Webworm in China: Susceptibility to Topography, Vegetation, and Human Activities

The fall webworm (FWW), H. cunea (Drury) (Lepidoptera: Erebidae: Arctiidae), is an extremely high-risk globally invasive pest. Understanding the invasion dynamics of invasive pests and identifying the critical factors that promote their spread is essential for devising practical and efficient strategies for their control and management. The invasion dynamics of the FWW and its influencing factors were analyzed using standard deviation ellipse and spatial autocorrelation methods. The analysis was based on statistical data on the occurrence of the FWW in China. The dissemination pattern of the FWW between 1979 and 2022 followed a sequence of "invasion-occurrence-transmission-outbreak", spreading progressively from coastal to inland regions. Furthermore, areas with high nighttime light values, abundant ports, and non-forested areas with low vegetation cover at altitudes below 500 m were more likely to be inhabited by the black-headed FWW. The dynamic invasion pattern and the driving factors associated with the fall webworm (FWW) provide critical insights for future FWW management strategies. These strategies serve not only to regulate the dissemination of insects and diminish migratory tendencies but also to guarantee the implementation of efficient early detection systems and prompt response measures.

Geospatial analysis of groundwater arsenic and fluoride in Quaternary aquifers of southern Ontario, Canada

The geological setting of an area plays a critical role in the transfer and ultimate distribution of hydrochemical constituents present in groundwater. In southern Ontario, Canada, the present physiography was significantly influenced by glacial processes during the Quaternary period. The heterogeneous nature and complex pattern of shallow subsurface glacial overburden sediments, likely affect the fate of different groundwater constituents. In this study, arsenic (As) and fluoride (F-) concentrations from 515 water wells, that are constructed within overburden sediment, were analyzed with the physiographic map of southern Ontario along with other related variables. Geospatial mapping and several spatial statistical analyses were performed to examine the possible geological influence on As and F- distribution and water-well susceptibility at a regional scale. Key findings suggest four physiographic settings were significant variables influencing the distribution of As and F- in differently constructed bored/dug and drilled wells. Bored/dug wells in Bevelled Till Plains and bored/dug wells in Undrumlinized and Bevelled Till Plains were found to be relatively susceptible to As and F- contamination respectively. In contrast, bored/dug and drilled wells in Drumlinized Till Plains and Drumlins and drilled wells in Sand Plains seemed to be relatively safe from F- and As respectively. The statistical regression analyses suggested that other variables, such as the application of phosphate fertilizer and the textures of till, influenced the spatial distribution of As and F- as well as which types of wells (bored/dug or drilled) were impacted. The geospatial mapping and statistical cluster analysis indicated that the possible sources of elevated As and F- in drilled wells are the clasts of underlying bedrock. The relationship between physiographic settings and impacted overburden wells in southern Ontario provides planners with an approach to water-well susceptibility assessments at the regional scale, which in turn can guide further local analysis for water resource management.

Can we redevelop ammonia nitrogen contaminated sites without remediation? The key role of subsurface pH in human health risk assessment

Nitrogen fertilizer supports global food production, but its manufacturing results in substantial ammonia nitrogen (AN) contaminated sites which remain largely unexplored. In this study, ten representative AN contaminated sites were investigated, covering a wide range of subsurface pH, temperature, and AN concentration. A total of 7232 soil samples and 392 groundwater samples were collected to determine the concentration levels, migration patterns, and accurate health risks of AN. The results indicated that AN concentrations in soil and groundwater reached 12700 mg/kg and 12600 mg/L, respectively. AN concentrations were higher in production areas than in non-production areas, and tended to migrate downward from surface to deeper soil. Conventional risk assessment based on AN concentration identified seven out of the ten sites presenting unacceptable risks, with remediation costs and CO2 emissions amounting to $1.67 million and 17553.7 tons, respectively. A novel risk assessment model was developed, which calculated risks based on multiplying AN concentration by a coefficient fNH3 (the ratio of NH3 to AN concentration). The mean fNH3 values, primarily affected by subsurface pH, varied between 0.02 and 0.25 across the ten sites. This new model suggested all investigated sites posed acceptable health risks related to AN exposure, leading to their redevelopment without AN-specific remediation. This research offers a thorough insight into AN contaminated site, holds great realistic significance in alleviating global economic and climate pressures, and highlights the need for future research on refined health risk assessments for more contaminants.

Analysis of heavy metal and polycyclic aromatic hydrocarbon pollution characteristics of a typical metal rolling industrial site based on data mining

With the transformation and upgrading of industries, the environmental problems caused by industrial residual contaminated sites are becoming increasingly prominent. Based on actual investigation cases, this study analyzed the soil pollution status of a remaining sites of the copper and zinc rolling industry, and found that the pollutants exceeding the screening values included Cu, Ni, Zn, Pb, total petroleum hydrocarbons and 6 polycyclic aromatic hydrocarbon monomers. Based on traditional analysis methods such as the correlation coefficient and spatial distribution, combined with machine learning methods such as SOM + K-means, it is inferred that the heavy metal Zn/Pb may be mainly related to the production history of zinc rolling. Cu/Ni may be mainly originated from the production history of copper rolling. PAHs are mainly due to the incomplete combustion of fossil fuels in the melting equipment. TPH pollution is speculated to be related to oil leakage during the industrial use period and later period of vehicle parking. The results showed that traditional analysis methods can quickly identify the correlation between site pollutants, while SOM + K-means machine learning methods can further effectively extract complex hidden relationships in data and achieve in-depth mining of site monitoring data.

Industrial fluoride emissions and their spatial characteristics in the Nansi Lake Basin, Eastern China

Excessive fluoride emissions threaten ecological stability and human health. Previous studies have noted that industrial sources could be significant. However, quantifying industrial fluoride emissions has not been yet reported. In this study, both bottom-up and top-down approaches were used to estimate the fluoride emissions in the Nansi Lake Basin. Global and local spatial autocorrelation were adopted to reveal the spatial agglomeration effects. The fluoride emissions calculated by the bottom-up approach were larger than those calculated by the top-down method. The highest fluoride input mainly occurred in Zoucheng and Mudan. The highest fluoride emissions mainly occurred in Zoucheng and Rencheng using the bottom-up approach. The highest fluoride emissions mainly occurred in Zoucheng and Yanzhou using the top-down approach. Mining and washing of bituminous coal and anthracite (BAW) was the most significant source of fluoride input and emissions. A significant spatial agglomeration effect of fluoride emissions was found. These findings could provide a method for accurate industrial fluoride emission estimation, complement the critical data on the fluoride emissions of main industrial sectors, and provide a scientific basis for tracing fluoride sources.

Insights into biogeochemistry and hot spots distribution characteristics of redox-sensitive elements in the hyporheic zone: Transformation mechanisms and contributing factors

Biogeochemical hot spots play a crucial role in the cycling and transport of redox-sensitive elements (RSEs) in the hyporheic zone (HZ). However, the transformation mechanisms of RSEs and patterns of RSEs hot spots in the HZ remain poorly understood. In this study, hydrochemistry and multi-isotope (N/C/S/O) datasets were collected to investigate the transformation mechanisms of RSEs, and explore the distribution characteristics of RSEs transformation hot spots. The results showed that spatial variability in key drivers was evident, while temporal change in RSEs concentration was not significant, except for dissolved organic carbon. Bacterial sulfate reduction (BSR) was the primary biogeochemical process for sulfate and occurred throughout the area. Ammonium enrichment was mainly caused by the mineralization of nitrogenous organic matter and anthropogenic inputs, with adsorption serving as the primary attenuation mechanism. Carbon dynamics were influenced by various biogeochemical processes, with dissolved organic carbon mainly derived from C3 plants and dissolved inorganic carbon from weathering of carbonate rocks and decomposition of organic matter. The peak contribution of dissolved organic carbon decomposition to the DIC pool was 46.44 %. The concentration thresholds for the ammonium enrichment and BSR hot spots were identified as 1.5 mg/L and 8.84 mg/L, respectively. The distribution pattern of RSEs hot spots was closely related to the hydrogeological conditions. Our findings reveal the complex evolution mechanisms and hot spots distribution characteristics of RSEs in the HZ, providing a basis for the safe utilization and protection of groundwater resources.

A correlational study of uranium in groundwater with other physicochemical parameters using GIS mapping in Godda district of Jharkhand, India

The present research concentrates on the cumulative use of GPS and GIS technologies, which are excellent resources for analyzing and monitoring divergent physicochemical parameters in groundwater, including pH, TDS, EC, ORP, Ca+2, Mg+2, NO3-, F-, SO4-2, Cl- and PO4-3 with explicit regard to uranium. Garmin GPS is used to record the locations of the sampling points in the Godda study area. The research aims to offer a thorough understanding of the relationship between soil and water, its impact on public health and the extent to which water can be used in various ways based on its quality. Utilizing the inverse distance weighted (IDW) technique, it is examined how these groundwater parameters and the Water Quality Index (WQI) can be estimated spatially. Additionally, a correlation analysis of the water quality parameters is computed to estimate the local population's cancer risk living in the study area. Except for calcium and magnesium, which are present in excess concentrations throughout the study area with the highest values of 325 and 406 mg/l, respectively at Amediha and Meherma, the results showed that the maximum concentration parameters are within limits with the standard. The main reason might be the area's predominance of Alfisol soil type. The radioactive element uranium is found to be in a limited  range. Chemo-toxicity and radiological risk assessment of the whole area lie far below the restricted cancer risk limit i.e., 30 ppb with the highest concentration of 14 ppb in the 'Sunderpahari' region, following the results obtained. The WQI for the area ranges from 'good' to 'very poor.' The results were favorable but a few sites such as 'Boarijor' and its surroundings, require additional attention to enhance groundwater quality. Given uranium's low availability in groundwater the region's cancer risk assessment is below average.

GIS-statically-based modelling the groundwater quality assessment coupled with soil and terrain attributes data

In this study, we investigated the application of Geographic Information Systems (GIS) for groundwater quality assessment through the integration of statistical models with soil and topographical data. Our primary objectives were to identify soil parameters and topographical attributes contributing to groundwater quality assessment and to evaluate the potential of geostatistics and GIS for spatial analysis of groundwater resources. Groundwater samples were collected from 43 agricultural wells, and surface soil layer samples (0-20 cm) were obtained near each well. We measured groundwater quality parameters and relevant soil properties. Our approach involved the utilization of multiple linear regression (MLR) and principal component regression (PCR), combined with topographical terrain attributes and soil data, for modeling groundwater electrical conductivity (GEC). Our findings revealed significant correlations between GEC and soil electrical conductivity (EC) (r = 0.89) as well as soil carbonate (CaCO3) (r = 0.68). Among the ten topographical attributes considered, the terrain wetness index (TWI) exerted the highest influence on GEC (r = 0.57), followed by the slope (r = -0.47). Further analysis demonstrated that the MLR model outperformed the PCR model in both the development and calibration datasets, with an achieved R2value of 0.89 and a root mean square error (RMSE)of 150 μScm-1 for MLR, compared to an R2 of 0.85 and an RMSE of 170 μScm-1 for PCR when coupled with soil and attribute data for GEC prediction. The resulting GEC map generated from the MLR model displayed spatial variations, ranging from 605 μScm-1 in the northern region to 1275 μScm-1 in the central part of the study site. In conclusion, our study demonstrated the effectiveness of combining statistical modeling with geostatistics and GIS for groundwater quality assessment, providing valuable insights for resource management and environmental planning.

Ecological correlates and predictors of Lassa fever incidence in Ondo State, Nigeria 2017-2021: an emerging urban trend

Lassa fever (LF) is prevalent in many West African countries, including Nigeria. Efforts to combat LF have primarily focused on rural areas where interactions between rodents and humans are common. However, recent studies indicate a shift in its occurrence from rural to urban areas. We analysed secondary data of reported LF outbreaks from 2017 to 2021 in Ondo State, Nigeria to identify the distribution pattern, ecological variations, and other determinants of disease spread from the ward level using nearest neighbour statistics and regression analysis. Data utilised include LF incidence, ecological variables involving population, nighttime light intensity, vegetation, temperature, market presence, road length, and building area coverage. ArcGIS Pro 3.0 software was employed for spatial analysis. Results revealed spatio-temporal clustering of LF incidents between 2017 and 2021, with an increasing trend followed by a decline in 2021. All wards in Owo Local Government Area were identified as LF hotspots. The ecological variables exhibited significant correlations with the number of LF cases in the wards, except for maximum temperature. Notably, these variables varied significantly between wards with confirmed LF and those without. Therefore, it is important to prioritise strategies for mitigating LF outbreaks in urban areas of Nigeria and other LF-endemic countries.

Environmental fate and ecological impact of the potentially toxic elements from the geothermal springs

Potentially toxic elements from geothermal springs can cause significant pollution of the surrounding environment and pose potential risk to the ecosystem. The fate of potentially toxic elements in the water-soil-plant system in the Yangbajain geothermal field on the Tibetan Plateau, China was investigated to assess their impact on the eco-environment. The concentrations of Be, F, As, and Tl were highly elevated in the headwaters of the Yangbajain geothermal springs, and their concentrations in the local surface water impacted by the geothermal springs reached 8.1 μg/L (Be), 23.9 mg/L (F), 3.83 mg/L (As), and 8.4 μg/L (Tl), respectively, far exceeding the corresponding thresholds for surface and drinking water. The absence of As-Fe co-precipitation, undersaturated F-, and weak adsorption on minerals at high geothermal spring pH may be responsible for the As- and F-rich drainage, which caused pollution of local river. As concentrations in the leaves of Orinus thoroldii (Stapf ex Hemsl.) Bor were up to 42.7 μg/g (dry weight basis), which is an order of magnitude higher than the allowable limit in animal feeds. The locally farmed yaks are exposed to the excessive amount of F and As with high exposure risk through water-drinking and grass-feeding.

Levels, origins and probabilistic health risk appraisal for trace elements in drinking water from Lhasa, Tibet

Due to the lack of monitoring systems and water purification facilities, residents in western China may face the risk of drinking water pollution. Therefore, 673 samples were collected from Lhasa's agricultural and pastoral areas to reveal the status quo of drinking water. We used inductively coupled plasma-mass spectrometry to determine trace elements concentrations for water quality appraisal, source apportionment, and health risk assessment. The results indicate that concentrations of V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Ba, and Pb are below the guidelines, while As concentrations in a few samples exceed the standard. All samples were classified into "excellent water" for drinking purpose based on Entropy-weighted water quality index. Thereafter by principal component analysis, three potential sources of trace elements were extracted, including natural, anthropogenic, and mining activities. It is worth noting that geotherm and mining exploitation does not threaten drinking water safety. Finally, health risks were assessed using Monte Carlo technique. We found that the 95th percentiles of hazard index are 1.80, 0.80, and 0.79 for children, teenagers, and adults, indicating a non-carcinogenic risk for children, but no risks for the latter two age groups. In contrast, the probabilities of unacceptable cautionary risk are 7.15, 2.95 and 0.69% through exposure to Cr, Ni, As, and Cd for adults, children, and teenagers. Sensitivity analyses reveal As concentration and ingestion rate are most influential factors to health risk. Hence, local governments should pay more attention to monitoring and removal of As in the drinking water.

Rice husk biochar - A novel engineered bio-based material for transforming groundwater-mediated fluoride cycling in natural environments

Biochar, a promising carbon-rich and carbon-negative material, can control water pollution, harness the synergy of sustainable development goals, and achieve circular economy. This study examined the performance feasibility of treating fluoride-contaminated surface and groundwater using raw and modified biochar synthesized from agricultural waste rice husk as problem-fixing renewable carbon-neutral material. Physicochemical characterizations of raw/modified biochars were investigated using FESEM-EDAX, FTIR, XRD, BET, CHSN, VSM, pH_pzc, Zeta potential, and particle size analysis were analyzed to identify the surface morphology, functional groups, structural, and electrokinetic behavior. In fluoride (F-) cycling, performance feasibility was tested at various governing factors, contact time (0-120 min), initial F- levels (10-50 mg L^-1), biochar dose (0.1-0.5 g L^-1), pH (2-9), salt strengths (0-50 mM), temperatures (301-328 K), and various co-occurring ions. Results revealed that activated magnetic biochar (AMB) possessed higher adsorption capacity than raw biochar (RB) and activated biochar (AB) at pH 7. The results indicated that maximum F- removal (98.13%) was achieved using AMB at pH 7 for 10 mg L^-1. Electrostatic attraction, ion exchange, pore fillings, and surface complexation govern F- removal mechanisms. Pseudo-second-order and Freundlich were the best fit kinetic and isotherm for F- sorption, respectively. Increased biochar dose drives an increase in active sites due to F- level gradient and mass transfer between biochar-fluoride interactions, which reported maximum mass transfer for AMB than RB and AB. Fluoride adsorption using AMB could be described through chemisorption processes at room temperature (301 K), though endothermic sorption follows the physisorption process. Fluoride removal efficiency reduced, from 67.70% to 53.23%, with increased salt concentrations from 0 to 50 mM NaCl solutions, respectively, due to increased hydrodynamic diameter. Biochar was used to treat natural fluoride-contaminated surface and groundwater in real-world problem-solving measures, showed removal efficiency of 91.20% and 95.61%, respectively, for 10 mg L^-1 F- contamination, and has been performed multiple times after systematic adsorption-desorption experiments. Lastly, techno-economic analysis was analyzed for biochar synthesis and F- treatment performance costs. Overall, our results revealed worth output and concluded with recommendations for future research on F- adsorption using biochar.

Evaluation of oral and dermal health risk exposures of contaminants in groundwater resources for nine age groups in two densely populated districts, Nigeria

Human health and the sustainability of the socioeconomic system are directly related to water quality. As anthropogenic activity becomes more intense, pollutants, particularly potentially harmful elements (PHEs), penetrate water systems and degrade water quality. The purpose of this study was to evaluate the safety of using groundwater for domestic and drinking purposes through oral and dermal exposure routes, as well as the potential health risks posed to humans in the Nnewi and Awka regions of Nigeria. The research involved the application of a combination of the National Sanitation Foundation Water Quality Index (NSFWQI), HERisk code, and hierarchical dendrograms. Additionally, we utilized the regulatory guidelines established by the World Health Organization and the Standard Organization of Nigeria to compare the elemental compositions of the samples. The physicochemical parameters and NSFWQI evaluation revealed that the majority of the samples were PHE-polluted. Based on the HERisk code, it was discovered that in both the Nnewi and Awka regions, risk levels are higher for people aged 1 to <11 and >65 than for people aged 16 to <65. Overall, it was shown that all age categories appeared to be more vulnerable to risks due to the consumption than absorption of PHEs, with Cd > Pb > Cu > Fe for Nnewi and Pb > Cd > Cu > Fe for water samples from Awka. Summarily, groups of middle age are less susceptible to possible health issues than children and elderly individuals. Hierarchical dendrograms and correlation analysis showed the spatio-temporal implications of the drinking groundwater quality and human health risks in the area. This research could help local government agencies make informed decisions on how to effectively safeguard the groundwater environment while also utilizing the groundwater resources sustainably.

Prediction of elevated groundwater fluoride across India using multi-model approach: insights on the influence of geologic and environmental factors

Elevated fluoride in groundwater is a severe problem in India due to its extensive occurrence and detrimental health impacts on the large population that thrives on groundwater. Although fluoride is primarily a geogenic pollutant, existing model-based studies lack the amalgamation of the influence of geologic factors, specifically tectonics, for identifying groundwater fluoride distribution. This drawback encourages the present study to investigate the association of the tectonic framework with fluoride in a multi-model approach. We have applied three machine learning models (random forest, boosted regression tree, and logistic regression) to predict elevated groundwater fluoride based on fluoride measurements across India. The random forest model outperformed other models with an accuracy of 93%. Tectonics was found to be one of the most important predictors alongside "depth to water table." Two major areas of high risk identified were the northwest parts and the south-southeast cratonic peninsular region. The random forest model also performed significantly well over the validation dataset. We estimate that nearly 257 million people are exposed to elevated fluoride risk in India. We endeavor that the findings of our study would be an effective tool for identifying the areas at risk of elevated fluoride and also assist in undertaking effective groundwater management strategies.

Controlling factors and health risks of groundwater chemistry in a typical alpine watershed based on machine learning methods

Groundwater is a key water resource in alpine watersheds, but its quality is deteriorating due to human activities. The Golmud River watershed is a representative alpine watershed in Northwest China, and it was chosen to explore groundwater chemistry, associated controlling factors, source contributions, and potential health risks. The analysis includes the use of a self-organizing map (SOM), positive matrix factorization (PMF), ionic ratios, and a Monte Carlo simulation. The content of total dissolved solids in phreatic water was higher in the dry season and increased from the mountainous zone to the fine-soil plain-overflowing zone. Additionally, the water type varied from HCO3- to Cl- types whereas confined groundwater was chemically stable and of a HCO3- type. The SOM results showed a visual correlation between the ions in groundwater. The combination of SOM, PMF, and ionic ratios identified water-rock action as a dominant factor of groundwater chemistry. It was also found that Clusters I and III were mainly influenced by silicate weathering (a total contribution of 38.4 %), whereas evaporation was dominant in Cluster VI (a contribution of 32.5 %). Anthropogenic pollution was mainly associated with clusters V and IV and was related to industrial and agricultural activities during the snowmelt and wet seasons, and fluorine deposition formed by residential coal heating during the dry season (contributions of 1.4 % and 23.8 % in Clusters V and IV, respectively). The sudden increases in B3+ and Li+ in Cluster II were due to inputs from small tributaries (a contribution of 3.9 %). The probabilistic health risk assessment showed that fluoride posed a greater non-carcinogenic risk to human health than Sr2+, B3+, and NO3-, and its potential threat to children was more significant during the dry season than in other seasons. It is necessary for local governments to establish urgent fluoride emission control policies within the Golmud River watershed.

Contrasting behaviors of groundwater arsenic and fluoride in the lower reaches of the Yellow River basin, China: Geochemical and modeling evidences

Genesis of the contrasting distributions of high arsenic (>10 μg/L) and fluoride (>1 mg/L) groundwater and their negative correlations remain poorly understood. We investigated spatial distributions of groundwater arsenic and fluoride concentrations in the lower reaches of the Yellow River basin, Henan Province, China, using bivariate statistical analyses and geochemical simulations. Results suggest that high arsenic and fluoride groundwater showed contrasting distributions with few overlapped area. Groundwater arsenic concentrations were significantly negatively correlated with oxidation-reduction potential (ORP) values and positively with NH₄⁺ and Fe(II) concentrations, while the opposites were true for groundwater fluoride concentrations. These may suggest that high arsenic groundwater is related to stronger organic matter degradation and Fe(III) oxide reduction, while groundwater fluoride enrichment occurs with less extent of organic matter degradation. Geochemical calculations supported that groundwater fluoride enrichment was governed by extent of fluorite dissolution, which was constrained by varied saturation indices of fluorite in groundwater. However, groundwater arsenic mobility may be explained by different solubility of Fe(III) oxides. Higher Fe(III) oxide solubility corresponding to goethite and lepidocrocite was related to higher arsenic concentrations, while hematite was too low in solubility to produce high arsenic groundwater. The study presented both geochemical and modeling evidences for the contrasting behaviors of groundwater arsenic and fluoride concentrations in anoxic aquifers.

Geogenic contaminants and groundwater quality around Lake Victoria goldfields in northwestern Tanzania

Geogenic contamination of groundwater is frequently associated with gold mining activities and related to drinking water quality problems worldwide. In Tanzania, elevated levels of trace elements (TEs) have been reported in drinking water sources within the Lake Victoria Basin, posing a serious health risk to communities. The present study aims to assess the groundwater quality with a focus on the concentration levels of geogenic contaminants in groundwater around the Lake Victoria goldfields in Geita and Mara districts. The water samples were collected from community drinking water sources and were analysed for physiochemical parameters (pH, EC, Eh), major ions, and trace elements. The analysed major ions included Na⁺, K⁺, Ca²⁺, Mg²⁺, SO₄^2-, HCO₃^- and Cl^- whereas the trace elements were As, Al, Li, Ba, B, Ti, V, U, Zr, Sr, Si, Mn Mo, Fe, Ni, Zn, Cr, Pb, Cd, and V. The present study revealed that the concentration levels of the major ions were mostly within the World Health Organization (WHO) drinking water standards in the following order of their relative abundance; for cations, Ca²⁺∼Na⁺>Mg²⁺>K⁺ and for anions was HCO₃^- > SO₄^2- > NO₃^-, Cl^- > PO₄^3-. Statistical and geochemical modelling software such as 'R Studio', IBM SPSS, geochemical workbench, visual MINTEQ were used to understand the groundwater chemistry and evaluate its suitability for drinking purpose. The concentration of As in groundwater sources varies between below detection limit (bdl) and 300 μg/L, with highest levels in streams followed by shallow wells and boreholes. In approximately 48% of the analysed samples, As concentration exceeded the WHO drinking water guideline and Tanzania Bureau of Standards (TBS) guideline for drinking water value of 10 μg/L. The concentration of the analyzed TEs and mean values of physicochemical parameters were below the guideline limits based on WHO and TBS standards. The Canadian Council of Ministries of the Environment Water Quality Index (CCME WQI) shows that the overall water quality is acceptable with minimum threats of deviation from natural conditions. We recommend further geochemical exploration and the periodic risk assessment of groundwater in mining areas where high levels of As were recorded.

State-of-the-art of research progress on adsorptive removal of fluoride-contaminated water using biochar-based materials: Practical feasibility through reusability and column transport studies

Fluoride (F^-) is one of the essential elements found in soil and water released from geogenic sources and several anthropogenic activities. Fluoride causes fluorosis, dental and skeletal growth problems, teeth mottling, and neurological damage due to prolonged consumption, affecting millions worldwide. Adsorption is an extensively implemented technique in water and wastewater treatment for fluoride, with significant potential due to efficiency, cost-effectiveness, ease of operation, and reusability. This review highlights the current state of knowledge for fluoride adsorption using biochar-based materials and the limitations of biochar for fluoride-contaminated groundwater and industrial wastewater treatment. Biochar materials have shown significant adsorption capacities for fluoride under the influence of low pH, biochar dose, initial concentration, temperature, and co-existing ions. Modified biochar possesses various functional groups (-OH, -CC, -C-O, -CONH, -C-OH, X-OH), in which enhanced hydroxyl (-OH) groups onto the surface plays a significant role in fluoride adsorption via electrostatic attraction and ion exchange. Regeneration and reusability of biochar sorbents need to be performed to a greater extent to improve removal efficiency and reusability in field conditions. Furthermore, the present investigation identifies the limitations of biochar materials in treating fluoride-contaminated drinking groundwater and industrial effluents. The fluoride removal using biochar-based materials at an industrial scale for understanding the practical feasibility is yet to be documented. This review work recommend the feasibility of biochar-based materials in column studies for fluoride remediation in the future.

Comprehensive assessment of water quality and associated health risks in an arid region in south Iran

This study aims at investigating the quality of drinking water and evaluating the non-carcinogenic risk of fluoride and nitrate ions in drinking water, and fluoride in tea in Zarrin Dasht, Iran. We focus on tea since it is the most popular drink among Iranian people and in the study region. We collected and analyzed 23 drinking water samples and 23 tea samples from different locations in the study region. Based on the water quality index, the consumed drinking water does not have a good quality in most Zarrin Dasht areas. Accordingly, the water quality index (WQI) is poor and very poor in 70% and 13% of the water samples, respectively. The average fluoride concentration of the tea samples is 2.71 mg/L. The mean values of Fluoride Hazard Index (HI_fluoride) are 3.77, 2.77, and 2.33 for children, teenagers, and adults, respectively, which are higher than the safe limit of 1. The Nitrate Hazard Index (HI_nitrate) is higher than the safe limit of 1 in 8.7% of the samples. The results of the Monte Carlo simulation demonstrate that HI_fluoride and HI_nitrate are higher than 1 in all the groups, except for adults. According to the results of the sensitivity analysis, ingestion rate and body weight have a large effect on HI_fluoride and HI_nitrate, but body weight is inversely associated with sensitivity. According to the Piper diagram, saline water is the predominant type in Zarrin Dasht. Besides, the results of the principal component analysis (PCA) show a high correlation between fluoride and pH, which could be related to the effect of pH on fluoride dissolution and ion exchange. Therefore, appropriate measures are recommended to be taken in order to reduce the amount of fluoride in the drinking water resources of this region. Reduction of tea consumption can also be considered an important factor in decreasing the amount of fluoride intake.

Identification of low fluoride areas using conceptual groundwater flow model and hydrogeochemical system analysis in the aquifer system on the flanks of an active volcano: Mount Meru, Northern Tanzania

This study investigates the localities of low and high F- groundwaters in the aquifer system on the flanks of Mount Meru to come up with guidelines to provide groundwater that can be used for drinking water supply without health impacts on the population. Our study focuses on parts of the flanks which were only partially or not at all covered by previous research. Results show that the groundwater chemistry of F--rich NaHCO3 alkaline groundwater in the area is controlled by dissolution of weathering aluminosilicate minerals, dissolution of F--bearing minerals, the precipitation of carbonate minerals as secondary products and the dissolution of magmatic gases. The low F- groundwaters which can be used for drinking water supply without health impacts under the WHO limit (1.5 mg/L) are the low-fluoride springs from the high altitude recharge areas on the eastern and north-western flanks of Mount Meru inside Arusha National Park, whereas on the western flank the groundwater meets the Tanzanian limit (4.0 mg/L). On the south-western flank, the shallow aquifer composed of alluvium deposits at lower elevations, shows F- values that meet the Tanzanian limit. One of the three investigated deep boreholes on this flank also meets the Tanzanian limit, suggesting a possibility of finding relatively low F- groundwaters in the deep aquifer. Yet, in general, the deposits at lower elevations are found to contain high to very high F- values, whereas the deposits at high elevations contain groundwater of low F- values. Thus, the internal texture and grain size of geological formations, the burial depth of these formations and the water residence times are the factors determining the groundwater mineralisation and F- concentrations in the area. The study identified that the deep hydrothermal system has influence on the high F- groundwaters on the eastern and north-eastern flanks of Mount Meru.

Spatial variability of the sources and distribution of fluoride in groundwater of the Sanya alluvial plain aquifers in northern Tanzania

Groundwater contamination from geogenic sources poses challenges to many countries, especially in the developing world. In Tanzania, the elevated fluoride (F^-) concentration and related chronic fluorosis associated with drinking F^- rich water are common in the East African Rift Valley regions. In these regions, F^- concentration is space dependence which poses much uncertainty when targeting safe source for drinking water. To account for the spatial effects, integrated exploratory spatial data analysis, regression analysis, and geographical information systems tools were used to associate the distribution of F^- in groundwater with spatial variability in terrain slopes, volcanic deposits, recharge water/vadose materials contact time, groundwater resource development for irrigated agriculture in the Sanya alluvial plain (SAP) of northern Tanzania. The F^- concentration increased with distance from steep slopes where the high scale of variation was recorded in the gentle sloping and flat grounds within the SAP. The areas covered with debris avalanche deposits in the gentle sloping and flat grounds correlated with the high spatial variability in F^- concentration. Furthermore, the high spatial variability in F^- correlated positively with depth to groundwater in the Sanya flood plain. In contrast, a negative correlation between F^- and borehole depth was observed. The current irrigation practices in the Sanya alluvial plain contribute to the high spatial variability in F^- concentration, particularly within the perched shallow aquifers in the volcanic river valleys. The findings of this study are important to the overall chain of safe water supply process in historically fluorotic regions. They provide new insights into the well-known F^- contamination through the use of modern geospatial methods and technologies. In Tanzania's context, the findings can improve the current process of drilling permits issuance by the authority and guide the local borehole drillers to be precise in siting safe source for drinking water.

Meta-analysis of uranium contamination in groundwater of the alluvial plains of Punjab, northwest India: Status, health risk, and hydrogeochemical processes

Despite numerous studies, there are many knowledge gaps in our understanding of uranium (U) contamination in the alluvial aquifers of Punjab, India. In this study, a large hydrogeochemical dataset was compiled to better understand the major factors controlling the mobility and enrichment of uranium (U) in this groundwater system. The results showed that shallow groundwaters (<60 m) are more contaminated with U than from deeper depths (>60 m). This effect was predominant in the Southwest districts of the Malwa, facing significant risk due to chemical toxicity of U. Groundwaters are mostly oxidizing and alkaline (median pH: 7.25 to 7.33) in nature. Spearman correlation analysis showed that U concentrations are more closely related to total dissolved solids (TDS), salinity, Na, K, HCO₃^-, NO₃^- Cl^-, and F^- in shallow water than deep water, but TDS and salinity remained highly correlated (U-TDS: ρ = 0.5 to 0.6; U-salinity: ρ = 0.5). This correlation suggests that the salt effect due to high competition between ions is the principal cause of U mobilization. This effect is evident when the U level increased with increasing mixed water species (Na-Cl, Mg-Cl, and Na-HCO₃). Speciation data showed that the most dominant U species are Ca₂UO₂(CO₃)^2- and CaUO₂(CO₃)^3-, which are responsible for the U mobility. Based on the field parameters, TDS along with pH and oxidation-reduction potential (ORP) were better fitted to U concentration above the WHO guideline value (30 μg.L^-1), thus this combination could be used as a quick indicator of U contamination. The strong positive correlation of U with F^- (ρ = 0.5) in shallow waters indicates that their primary source is geogenic, while anthropogenic factors such as canal irrigation, groundwater table decline, and use of agrochemicals (mainly nitrate fertilizers) as well as climate-related factors i.e., high evaporation under arid/semi-arid climatic conditions, which result in higher redox and TDS/salinity levels, may greatly affect enrichment of U. The geochemical rationale of this study will provide Science-based-policy implications for U health risk assessment in this region and further extrapolate these findings to other arid/semi-arid areas worldwide.

Fluoride ions sorption using functionalized magnetic metal oxides nanocomposites: a review

Fluoride is an anionic pollutant found superfluous in surface or groundwater as a result of anthropogenic actions from improper disposal of industrial effluents. In drinking water, superfluous fluoride has been revealed to trigger severe health problems in humans. Hence, developing a comprehensive wastewater decontamination process for the effective management and preservation of water contaminated with fluoride is desirable, as clean water demand is anticipated to intensify considerably over the upcoming years. In this regard, there have been increased efforts by researchers to create novel magnetic metal oxide nanocomposites which are functionalized for the remediation of wastewater owing to their biocompatibility, cost-effectiveness, relative ease to recover and reuse, non-noxiousness, and ease to separate from solutions using a magnetic field. This review makes an all-inclusive effort to assess the effects of experimental factors on the sorption of fluoride employing magnetic metal oxide nanosorbents. The removal efficiency of fluoride ions onto magnetic metal oxides nanocomposites were largely influenced by the solution pH and ions co-existing with fluoride. Overall, it was noticed from the reviewed researches that the maximum sorption capacity using various metal oxides for fluoride sorption was in the order of aluminium oxides >cerium oxides > iron oxides > magnesium oxides> titanium oxides, and most sorption of fluoride ions was inhibited by the existence of phosphate trailed by sulphate. The mechanism of fluoride sorption onto various sorbents was due to ion exchange, electrostatic attraction, and complexation mechanism.

Fluoride Stimulates Anxiety- and Depression-like Behaviors Associated with SIK2-CRTC1 Signaling Dysfunction

Using Sprague-Dawley rats and rat PC12 cells treated with sodium fluoride (NaF), we investigated the effects of SIK2-CRTC1 signaling on the neurobehavioral toxicity induced by fluoride. The in vivo results demonstrated that NaF treatment induced anxiety- and depression-like behaviors in juvenile rats, resulting in histological and ultrastructural abnormalities in the rat hippocampus and medial prefrontal cortex. Moreover, NaF exposure induced neuronal loss and excessive apoptosis. We also found that NaF elevated the expression of SIK2 and reduced the expression of CRTC1, brain-derived neurotrophic factor (BDNF), and VGF. The in vitro results showed that NaF suppressed cell viability, induced SIK2-CRTC1 signaling dysfunction, and caused excessive apoptosis in PC12 cells. Notably, targeted knockout of SIK2 with SIK2-siRNA or blocking of SIK2-CRTC1 signaling with 7,8-dihydroxyflavone (7,8-DHF) (as well as venlafaxine) can reduce apoptosis and increase cell viability in vitro. These findings suggest that neuronal death resulting from abnormal SIK2-CRTC1 signaling contributes to neurobehavioral toxicity induced by fluoride.

Sensitive assessment of groundwater-associated, multi-exposure health hazards in a fluoride-enriched region of West Bengal, India

Ninety groundwater samples were collected from Khayrasole and Rajnagar blocks of Birbhum district, West Bengal, India, during pre-monsoon and post-monsoon in 2016 to assess the hazards of fluoride in groundwater. Fluoride concentration fluctuated from 0.3 to 17.6 mg/L, with 70% of samples reported beyond the modified regional optimal fluoride level (0.7 mg/L) with a statistically significant level of p < 1.7E-24. The average cation and anion concentrations exhibited a descending order of Ca²⁺ > Mg²⁺ > Na⁺ > K⁺ and HCO₃^- > Cl^- > SO₄^2- > NO₃^- > F^-, respectively. Notably, groundwater quality in 50% of the places ranged from poor to unfit for drinking purposes in terms of water quality index. The mean total hazard index (THI) was 1.1 for adults and 1.9 for children, signifying a greater chance of non-carcinogenic threats to both age groups. In calculating the THI, ingestion and dermal pathways accounted for approximately 96% and 3% health hazards, respectively. The Monte Carlo simulation and sensitivity analysis identified that the diurnal water ingestion rate, exposure duration, and fluoride concentration were the significant sensitive variables that triggered most groundwater-associated non-carcinogenic health issues, signifying more risks among children. Further, dental health surveys (N = 746), following Dean's norms for classification based on regional optimal fluoride level, designated the borderline grade of the community dental hazard. The subsequent hydrogeochemical characterization directed that dissolution from fluoride-bearing minerals and water-rock interaction, such as halite dissolution and calcite-dolomite precipitation, were the governing factors for F^- enrichment in groundwater. This study will serve as baseline data for delineating fluoride-induced dental and other health hazards through sensitivity and spatial analysis in the GIS platform for hazard zonation and effective groundwater quality management.

Hydrochemistry, quality and potential health risk appraisal of nitrate enriched groundwater in the Nanchong area, southwestern China

Assessments for groundwater quality and potential health risk are significant for better utilization and exploitation. In the present study, seventy groundwater samples were collected from domestic tube wells and public water-supply wells in the Nanchong area, southwestern China. The integration of statistical analysis, ion correlation, geomodelling analysis, entropy water quality index and health risks assessment were compiled in this study. Statistical analysis indicated the cations followed the concentration order as Ca²⁺ > Na⁺ > Mg²⁺ > K⁺, while anions' concentrations were HCO₃^- > SO₄^2- > Cl^- > NO₃^- > F^- based on Box and Whisker plot. Piper triangle diagram proposed the hydrochemical type was characterized as Ca-HCO₃. Correlations of ions and geomodelling revealed the concentrations of major ions were mainly determined by calcite dissolution and ion exchange process and NO₃^- concentrations were controlled by agriculture activities. Entropy water quality index computation demonstrated that 96% of groundwater samples possessed the EWQI values of 29-95, and thus were suitable for drinking purpose. The HI_Total values for 66% groundwater samples exceeded the acceptable limit for non-carcinogenic risk (HI =1) for infants, followed by 41% for children, 37% for adult males, and 30% for adult females. The non-carcinogenic human health risk of different population groups followed the order of infants > children > adult males > adult females. In future, targeted measures for human health risks of NO₃^- will focus on the improvements for agricultural activities, including reducing the use of nitrogenous fertilizer, changing irrigation pattern, etc. Our study provides the vital knowledge for groundwater management in the Nanchong and development of the Cheng -Yu Economic Circle.

Health risks from groundwater arsenic on residents in northern China coal-rich region

Shanxi Province of northern China is a typical mining concentration and arsenism area. Years of mining activities have resulted in serious regional groundwater problems in Shanxi. Therefore, it is of great significance to know the health risk of groundwater arsenic on residents under the background of mining activities. Kriging interpolation was used to illustrate the spatio-temporal dynamics of the health risks on groundwater arsenic based on a ten-year investigation. The groundwater arsenic concentrations decreased over time and the distribution of high arsenic concentrations shrank. High arsenic concentrations were mainly distributed in the northern and middle basin areas. The forecasted area of high risks in coal mining areas was 5623 km², which was larger than that in non-coal mining areas. The residents living around mining areas were more vulnerable to exposure to groundwater arsenic. Further, the output map outlines the high-risk zones in order to protect the safety of drinking water for residents. This study may be helpful for the policy-makers to adopt a lower limit for groundwater arsenic to the worst affected regions and groups.

Statistical Modeling for Spatial Groundwater Potential Map Based on GIS Technique

In arid and semi-arid lands like Iran water is scarce, and not all the wastewater can be treated. Hence, groundwater remains the primary and the principal source of water supply for human consumption. Therefore, this study attempted to spatially assess the groundwater potential in an aquifer in a semi-arid region of Iran using geographic information systems (GIS)-based statistical modeling. To this end, 75 agricultural wells across the Marvdasht Plain were sampled, and the water samples’ electrical conductivity (EC) was measured. To model the groundwater quality, multiple linear regression (MLR) and principal component regression (PCR) coupled with elven environmental parameters (soil-topographical parameters) were employed. The results showed that that soil EC (SEC) with Beta = 0.78 was selected as the most influential factor affecting groundwater EC (GEC). CaCO3 of soil samples and length-steepness (LS factor) were the second and third effective parameters. SEC with r = 0.89 and CaCO3 with r = 0.79 and LS factor with r = 0.69 were also characterized for PC1. According to performance criteria, the MLR model with R2 = 0.94, root mean square error (RMSE) = 450 µScm−1 and mean error (ME) = 125 µScm−1 provided better results in predicting the GEC. The GEC map indicated that 16% of the Marvdasht groundwater was not suitable for agriculture. It was concluded that GIS, combined with statistical methods, could predict groundwater quality in the semi-arid regions.

Land-use change caused by anthropogenic activities increase fluoride and arsenic pollution in groundwater and human health risk

Groundwater pollution is becoming a more serious issue because of various anthropogenic activities. A large proportion of the population living in the urbanized and industrialized world is exposed daily to hazardous materials. However, despite the knowledge that protecting groundwater is necessary, little is known about the role of land-use change for human health risks. In this study, we analyzed the temporal and spatial variation of groundwater fluoride (F) and arsenic (As) during 2010-2018 in Shanxi Province of Northern China. Distribution areas of high F and As increased from 2010 to 2018 and spread over time. We assessed human health risk by calculating carcinogenic risk and non-carcinogenic risk. The results showed that F exposure, frequency of high concentration, and risk from 2016 to 2018 were higher than that in 2010-2015, and similar results were obtained for As exposure. Further, land-use change caused by anthropogenic activities increased F and As pollution in groundwater and placed humans at a higher health risk. Our study sheds light on anthropogenic activities that could increase human health risks caused by groundwater F and As via changing land-use. The study provides supports and suggestions for policy-makers to reduce groundwater pollution and prevent adverse health risks to residents.

Using geographically temporally weighted regression to assess the contribution of corruption governance to global PM2.5

In the face of the global haze crisis, exploring the driving force of political factors for controlling minute atmospheric particles has become essential for managing PM_2.5 pollution. In this study, the political drivers of haze pollution were examined by combining kernel density estimation, exploratory spatial data analysis, and a geographically temporally weighted regression model. The results showed that global haze pollution was increasing annually, and that differences and similarities in PM_2.5 pollution between different countries coexisted. Furthermore, the multi-dimensional driving elements of haze pollution showed obvious spatial and temporal non-stationarity, and different driving factors present multiple distribution trends. In general, the strengthening of anti-corruption measures addressed PM_2.5 concentration, but the direction and intensity of political drivers differed due to factors such as economic development, national culture, and natural conditions. Therefore, African countries should endeavor to control corruption, so as to achieve economic development and control haze pollution. However, from the perspective of political factors, it is likely North American countries will not be able to effectively control haze pollution.

Spatial heterogeneity in the association between particulate matter air pollution and low birth weight in South Korea

As many studies showed the spatial heterogeneity in the association between particulate matter (PM) air pollution and low birth weight (LBW), few studies focused on the variation of local associations at the national scale and related areal characteristics. This study aimed to explore different approaches to estimating local effects of PM with an aerodynamic diameter ≤10 μm (PM₁₀) on LBW across 235 districts in South Korea, to investigate the spatial pattern of local associations, and to examine the relationship with local socio-demographic and environmental characteristics. LBW was identified in 5,692,650 mothers from birth certificate data for 2001-2013. We estimated individual annual-average concentrations of PM₁₀ at centroids of mothers' residential districts by using a previously-validated prediction model. Then, we estimated district-specific odds ratios of LBW for PM₁₀ using modified geographically weighted logistic regression. Here, we applied four approaches with different neighborhood definitions: the distance-based approach within 20- and 40-km bandwidth and the hybrid approach replacing with adjacent districts for urban districts <100 km². In addition, we compared district-specific socioeconomic indicators and emission estimates across three groups of districts that showed significantly positive, no, and significantly negative associations. Medians of district-specific estimates of four approaches were similar to the global estimate and between each other. However, their variability differed with some unreasonably high estimates when a small distance was applied as the neighborhood definition, although spatial pattern was generally similar among the four. The hybrid approach based on the different neighborhood definition by urban and rural areas provided stable risk estimates. Higher risk districts in rural areas were found in more socioeconomically-deprived areas, whereas urban areas showed higher risk districts when their air pollution emissions were higher. Our approach and findings will help identify high risk areas and enhance understanding of geographic determinants.

Regional infectious risk prediction of COVID-19 based on geo-spatial data

After the first confirmed case of the novel coronavirus disease (COVID-19) was found, it is of considerable significance to divide the risk levels of various provinces or provincial municipalities in Mainland China and predict the spatial distribution characteristics of infectious diseases. In this paper, we predict the epidemic risk of each province based on geographical proximity information, spatial inverse distance information, economic distance and Baidu migration index. A simulation study revealed that the information based on geographical economy matrix and migration index could well predict the spatial spread of the epidemic. The results reveal that the accuracy rate of the prediction is over 87.10% with a rank difference of 3.1. The results based on prior information will guide government agencies and medical and health institutions to implement responses to major public health emergencies when facing the epidemic situation.