Geogenic Sources Research Articles

Risk Analysis of Heavy Metals and Groundwater Quality Indices in Residential Areas: A Case Study in the Rajanpur District, Pakistan

Continuous monitoring of drinking water quality is essential in terms of the levels of heavy metals and toxic substances, especially in developing countries like Pakistan. Therefore, this study aimed to investigate groundwater quality in residential areas of the Rajanpur District, Pakistan. Groundwater samples (n = 200) were collected from various sites in the study area and analyzed by in situ tests (pH, EC, TDS, temperature, and turbidity), and the concentration of 32 dissolved elements and ions was also analyzed. The results showed that higher concentrations of dissolved elements are the primary reason for poor drinking water quality. A few measured parameters (TDS~992 mg L−1 and EC~1921.15 µS/cm) exceeded the permissible limits of the World Health Organization (WHO, Geneva, Switzerland) in most of the samples. Elements that had higher values than the allowable limits in most of the samples were calcium (Ca), sodium (Na), bicarbonates (HCO3), sulfate (SO4), chlorides (Cl), manganese (Mn), and strontium (Sr), with average values of 113 mg L−1, 223 mg L−1, 282 mg L−1, 367 mg L−1, 175 mg L−1, 69 mg L−1, and 1291 mg L−1, respectively. The measured parameters that had no significant issues in terms of drinking water quality were aluminum (Al), nitrite (NO2), phosphate (PO4), pH, and turbidity. The levels of potentially toxic elements such as arsenic (As), lead (Pb), chromium (Cr), and copper (Cu) (average ~2.179 mg L−1, 1.659 mg L−1, 0.092 mg L−1, and 1.032 mg L−1, respectively) were found to be lower than the drinking water guideline values of the WHO. The statistical analysis revealed weak correlations possibly due to multiple sources and localized variations. The physicochemical analysis-based WQI values for all groundwater samples were much lower at the residential sampling locations and in industrial settings, indicating poor water quality. The elevation model indicated that as water moves in the aquifer in the general direction of west to southeast, it gets concentrated by mineral dissolution, with geogenic sources having a major impact on the hydrochemistry. Hence, regular monitoring of water quality is required through advanced technology to overcome groundwater deterioration issues. The quality of water is poor for drinking purposes and the health of the residents of the Rajanpur District may be at risk.

Appraisal of groundwater quality for drinking and irrigation suitability using multivariate statistical approach in a rapidly developing urban area, Tirunelveli, India.

The quantitative and qualitative stress on groundwater resources has been witnessed across the globe. The current study assesses the groundwater quality of Tirunelveli district which faces the hazard of groundwater contamination through seepage of toxins, considering the open dumping ofhuge volumes of solid waste. The findings from this study confirmed the presence of more than 20% samples in the "poor to very poor" quality with high concentrations of TDS, Cl-, and NO3-, unfit for drinking, and other domestic purposes. The spatial distribution of TDS and NO3- highlighted the potentialimpact of solid waste dumping in the nearby landfill sites. K-means hierarchical clustering and multivariate analysis suggested that salinization and nitrate pollution was highly influenced by anthropogenic sources in comparison to geogenic sources. Rock water interaction and evaporation processes emerged as the two major dominant natural mechanisms controlling the groundwater chemistry. Four hydro-chemical facies were identified in the order of Ca-HCO3 > Ca-Mg-Cl > Na-Cl > mixed Ca-Na-HCO3. Thus, this study creates an urgent need of mitigation measures towards curbing and management of solid waste disposal and hence, the potential hazard ofcontaminant seepage into the groundwater.

Toxic elemental abundances in the sediment of the Jamuna River, Bangladesh: pollution status, sources, toxicity, and ecological risks assessment

ABSTRACT In this study, elemental abundances of As, Cd, Cr, Co, Cu, Pb, and Zn in the 30 composite sediment samples from Jamuna River, Bangladesh were measured by atomic absorption spectrophotometer to assess their contamination level, toxicity, and ecological risks in both summer and winter season. In the summer season, mean concentrations of As, Cd, Cr, Co, Cu, Pb, and Zn in sediment samples were 2.82, 1.13, 25.30, 8.63, 22.01, 4.58, and 68.82 mg/kg, respectively. In the winter season, mean concentrations of As, Cd, Cr, Co, Cu, Pb, and Zn were 3.83, 1.48, 43.22, 13.86, 35.63, 8.48, and 100.27 mg/kg, respectively. The mean concentrations of all elements were found lower than the sediment quality guidelines values of probable effect level (PEL), effect range medium (ERM), and toxic effect thresholds (TET) in both seasons. There was a significant variation in elemental concentrations between wet and dry seasons and also between upstream and downstream sites (P < 0.05). Principal component analysis showed Zn, Cr, and Pb; As and Cu; and Cd and Co might have originated from the same geogenic source. The pollution evaluation indices showed consistent outcomes of almost no pollution for As, Cr, Co, Cu, Pb, and Zn, but moderately to strongly polluted for Cd in all seasons. The contamination level of elements follows the decreasing order of Cd > Zn > Cu > As > Co > Cr > Pb for both seasons. The elemental toxicity in the sediments follows the order of Cd > Cr > Zn > As > Cu > Pb, with a very high risk for Cd while a minimal risk for other elements. The ecological threats of the toxic elements were found moderate to very high. Therefore, the findings of our study concluded that the ecological condition of the Jamuna River posed a considerable risk for human health and living organisms.

Distribution, sources, and pollution levels of toxic metal(loid)s in an urban river (Ichamati), Bangladesh using SOM and PMF modeling with GIS tool.

Indexical assessment coupled with a self-organizing map (SOM) and positive matrix factorization (PMF) modeling of toxic metal(loid)s in sediment and water of the aquatic environment provides valuable information from the environmental management perspective. However, in northwest Bangladesh, indexical and modeling assessments of toxic metal(loid)s in surface water and sediment are still rare. Toxic metal(loid)s were measured in sediment and surface water from an urban polluted river (Ichamati) in northwest Bangladesh using an atomic absorption spectrophotometer to assess distribution, pollution levels, sources, and potential environmental risks to the aquatic environment. The mean concentrations (mg/kg) of metal(loid)s in water are as follows: Fe (871) > Mn (382) > Cr (72.4) > Zn (34.2) > Co (20.8) > Pb (17.6) > Ni (16.7) > Ag (14.9) > As (9.0) > Cu (5.63) > Cd (2.65), while in sediment, the concentration follows the order, Fe (18,725) > Mn (551) > Zn (213) > Cu (47.6) > Cr (30.2) > Ni (24.2) > Pb (23.8) > Co (9.61) > As (8.23) > Cd (0.80) > Ag (0.60). All metal concentrations were within standard guideline values except for Cr and Pb for water and Cd, Zn, Cu, Pb, and As for sediment. The outcomes of eco-environmental indices, including contamination and enrichment factors and geo-accumulation index, differed spatially, indicating that most of the sediment sites were moderately to highly polluted by Cd, Zn, and As. Cd and Zn content can trigger ecological risks. The positive matrix factorization (PMF) model recognized three probable sources of sediment, i.e., natural source (49.39%), industrial pollution (19.72%), and agricultural source (30.92%), and three possible sources of water, i.e., geogenic source (45.41%), industrial pollution (22.88%), and industrial point source (31.72%), respectively. SOM analysis identified four spatial patterns, e.g., Fe-Mn-Ag, Cd-Cu, Cr-Pb-As-Ni, and Zn-Co in water and three patterns, e.g., Mn-Co-Ni-Cr, Cd-Cu-Pb-Zn, and As-Fe-Ag in sediment. The spatial distribution of entropy water quality index values shows that the southwestern area possesses "poor" quality water. Overall, the levels of metal(loid) pollution in the investigated river surpassed a critical threshold, which might have serious consequences for the river's aquatic biota and human health in the long run.

Geochemical accumulation and source tracing of heavy metals in arable soils from a black shale catchment, southwestern China

Heavy metal enrichment in soils has been linked to the weathering of lithologies with high geochemical backgrounds, such as black shale. Therefore, this study conducted a typical sampling of surface soils in a black shale catchment in southwestern China to characterize the accumulation and sources of the heavy metals As, Cd, Co, Cr, Cu, Ni, Pb, Zn, Mo and Tl. Elevated concentrations of most heavy metals in the soils underlain by black shale are determined to exceed the regional soil background values, even the risk screening values, especially for Mo, As and Cd. Sequential extraction analysis, together with previous results, reveals that most heavy metals in soils are mainly bound in the residual fraction (> 65 %) as a result of the fixation of stable aluminosilicates (e.g., clay minerals). In contrast, Cd mainly occurs in relatively labile proportions as exchangeable (24.42 %), carbonate (24.48 %) and Fe/Mn oxide fractions (26.60 %) due to the non-specific adsorption of soil colloids and the precipitation of carbonates and Fe/Mn oxides. Pb isotopic tracing and APCS/MLR receptor model suggest that heavy metals in the urban surface soils (SG1) have a mixed source of black shale weathering, vehicle exhaust and agricultural input, while heavy metals in the rural surface soils (SG2) are a geogenic source of black shale weathering. Overall, this study provides new insights into contamination management, land use planning and health risk assessment in regions with high geochemical backgrounds.

Ecological risk assessment of metals in the Arctic environment with emphasis on Kongsfjorden Fjord and freshwater lakes of Ny-Ålesund, Svalbard

The concentrations of five heavy metals (Cd, Cr, Cu, Pb, and Zn) in the sediments, water, phytoplankton, zooplankton, and macroalgae from Kongsfjorden Fjord and the freshwater lakes of Ny-Ålesund in the Svalbard archipelago were determined in order to describe the anthropogenic impacts related to the Ny-Ålesund town. Water samples from nine stations, sediment samples from 23 stations, plankton samples from five stations, and six species of macroalgae were collected and subjected to heavy metal analysis using atomic absorption spectrophotometry (AAS). Only Cu and Zn were detected in the water samples. The plankton samples had only Zn, Cu, and Cr. The average metal concentrations in macroalgae fell in the decreasing order of Cu > Zn > Cr > Cd > Pb. In sediment samples, the metal order was as follows: Zn > Cu > Cr > Pb > Cd. Multivariate statistical analyses including principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used to identify the source of the metal contamination. The metals were found to originate from a blend of both anthropogenic and geogenic sources. Pollution monitoring indices including geoaccumulation index (Igeo), contamination factor, contamination degree (Cdeg), pollution load index (PLI), and potential ecological risk (PER) were calculated using the metal data. In the study area, Igeo values of the metals showed pollution grades from 0 (uncontaminated) to 6 (extremely contaminated). Cdeg fell in classes from 1 (low contamination) to 4 (very high contamination). PLI values ranged between 0 and 5.68. PER values expressed that except for a few stations located at higher elevations in the glacial outwash plains, all other sites were highly polluted. The high level of pollution indices in the sites can be attributed to the anthropogenic activities persistent in the study area.

Levels, distribution characteristics, and sources of heavy metals in indoor dust in Shijiazhuang, China.

Heavy metals in indoor dust are associated with health risks in humans. However, in Shijiazhuang, a city in northern China with severe haze, no research has been published on this topic. To determine the content, distribution characteristics, and sources of heavy metals in indoor dust in the city of Shijiazhuang, indoor dust samples from 33 sampling points in the main urban area of Shijiazhuang were collected and tested. Concentrations of Cu, Ni, Cr, Zn, Cd, and Pb were 87.0, 35.1, 104.4, 568.0, 1.980, and 187.6mg·kg-1, respectively; their levels have been discussed statistically in comparison with the reported values in other cities in China. The sources of heavy metals were analyzed using enrichment factor, correlation coefficient, and principal component analysis. The results showed that the levels of all six elements in indoor dust in Shijiazhuang exceeded the background values of soil in Hebei Province. Among these, Cd, Pb, and Zn were significantly enriched. The enrichment factors of Cu, Ni, and Cr were below 10, and their levels at different sampling points were similar, indicating their geogenic source. The corresponding pollution levels of Cd, Pb, and Zn were relatively high, and their levels at different points were significantly different and correlated, indicating that they were derived mainly from transportation. Additionally, the level of Zn was significantly affected by the indoor environment. Our findings provide a basis for conducting health risk assessments in the future.

Occurrence, controlling factors and noncarcinogenic risk assessment based on Monte Carlo simulation of fluoride in mid-layer groundwater of Huaibei mining area, North China

Fluoride groundwater pollution is a major challenge to ensuring a safe groundwater supply for the global community. This study emphasized mid-layer groundwater (MG) as the main water supply source in the Huaibei mining area, North China. A total of 74 groundwater samples were taken to determine the hydrochemistry, source provenance, driving forces of high-fluoride groundwater, and associated probabilistic health risk using Monte Carlo simulation. The fluoride concentration in 55.56 % of the MG samples exceeded the Chinese drinking water permissible limit of 1 mg/L. In addition, MG is characterized by the hydrochemical faces of HCO3− type and Na+ type, lower Ca2+ and higher TDS concentration. Fluoride enrichment was predominantly controlled by the geogenic sources of fluorite dissolution, silicate weathering and lateral supply from the Carboniferous Taiyuan Formation limestone aquifer (CLA). In addition, the driving forces of high-fluoride groundwater were an alkaline environment, low Ca2+ concentration, high Na+ and HCO3− concentration, cation exchange between Ca2+ and Na+ on the surface of clay minerals, and competitive adsorption of HCO3−. The health risk assessment of F− for noncarcinogenic risk showed that the HQ values of 28.16 % of groundwater samples exceeded the safety limit of 1 for infants, followed by 2.1 % for children and 0 % for both adult females and males. Infants and children are more prone to the impact of excessive F−. The findings of this study will provide new insights into the geochemical behavior of F− and the safety of drinking water.

Assessment of the Ecological and Health Risks of Potentially Toxic Metals in Agricultural Soils from the Drosh-Shishi Valley, Pakistan

Soil pollution is a highlighted concern of modern society, particularly in developing countries. The Drosh-Shishi valley, which is a hilly region near Afghanistan with a land area of around 15,000 km2, is situated in the south of Chitral District (Pakistan) and has a population of approximately 450,000. Nowadays, this region is being explored for soil pollution, specifically heavy metals which pose a potential risk to human health. Therefore, our main goal was to investigate possible sources of heavy metals’ spread and to assess the content levels in soil and the associated risks for human. We collected 34 representative samples from transported sediments and 31 from agricultural crops. We analyzed the soil samples for the contents of Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn using ICP-OES analyzers. These values were used to obtain the contamination factor (CF) and to estimate the potential health risk caused by heavy metals according to the USEPA dose–response model. Our results suggest that the heavy metal pollution has a geogenic source, but it is also aggregated by chemical fertilizers used in farming. Regarding levels, most of the metals except Pb showed contents above the permissible level, with CF values from moderate to high. Overall, Cu and Ni showed a significant total cancer risk (TCR &gt; 1 × 10−4) in children. Therefore, we conclude that heavy metal pollution is causing a serious threat to humans in this area, and we recommend that authorities should make more efforts in monitoring the heavy metals content in soils to reduce potential health risks.

Machine learning can identify the sources of heavy metals in agricultural soil: A case study in northern Guangdong Province, China

Source tracing of heavy metals in agricultural soils is of critical importance for effective pollution control and targeting policies. It is a great challenge to identify and apportion the complex sources of soil heavy metal pollution. In this study, a traditional analysis method, positive matrix fraction (PMF), and three machine learning methodologies, including self-organizing map (SOM), conditional inference tree (CIT) and random forest (RF), were used to identify and apportion the sources of heavy metals in agricultural soils from Lianzhou, Guangdong Province, China. Based on PMF, the contribution of the total loadings of heavy metals in soil were 19.3% for atmospheric deposition, 65.5% for anthropogenic and geogenic sources, and 15.2% for soil parent materials. Based on SOM model, As, Cd, Hg, Pb and Zn were attributed to mining and geogenic sources; Cr, Cu and Ni were derived from geogenic sources. Based on CIT results, the influence of altitude on soil Cr, Cu, Hg, Ni and Zn, as well as soil pH on Cd indicated their primary origin from natural processes. Whereas As and Pb were related to agricultural practices and traffic emissions, respectively. RF model further quantified the importance of variables and identified potential control factors (altitude, soil pH, soil organic carbon) in heavy metal accumulation in soil. This study provides an integrated approach for heavy metals source apportionment with a clear potential for future application in other similar regions, as well as to provide the theoretical basis for undertaking management and assessment of soil heavy metal pollution.

Distribution, sources and toxicity of heavy metals in surface sediments of north western Karnataka, south India

This study presents spatial distribution, sources and toxicological risks of As, Cr, Cu, Hg, Ni, Pb, and Zn in the surface sediments from north-western Karnataka, southern India. Heavy metals (except Hg) are 1–5 times enriched than upper continental crust. High concentration of Cr, Ni, Cu, and Zn is in the central Kudalgaon, Devarayi, and Tavargatti and in the south-western Ganeshgudi area, whereas Arsenic is enriched in the north-eastern Alnavar, Kakkeri,Tavargatti and Pb, and Hg in the north-western Kapoli, Devarayi, Manjarpal villages. The ecological risk index, toxic risk index, and mean probable-effects-levels quotient of heavy metals suggest that ~ 40% of the area is prone to very high risk especially for Cr and As to the hydrological, biological, and ecological systems. Multivariate statistical analysis suggests possible geogenic sources for Ni, Cr, Cu, and Zn and anthropogenic sources such as emissions from vehicles and agricultural sectors for As, Hg, and Pb. This study is the first of its kind in the area, which will help, in better formulation of environmental pollution and risk related remedial measures to conserve the natural ecosystem and the well-being of humans.

The effects of colloidal Fe and Mn on P distribution in groundwater system of Jianghan Plain, China

Many studies have confirmed groundwater phosphorus (P) enrichment by anthropogenic and geogenic sources. However, the effects of colloidal iron (Fe) and manganese (Mn) on the groundwater P distribution remain poorly-understood. This study investigated the spatial distribution of three forms of Fe, Mn, and P (particulate, colloidal, and truly soluble) in aquifers based on groundwater monitoring data and sediment core samples for the Jianghan Plain. High proportions of colloidal Fe, Mn, and P of up to 52%, 58%, and 76%, respectively were found in the phreatic and confined aquifers. Particulate and truly soluble P dominated the phreatic aquifer and the confined aquifer, respectively. However, the truly soluble Fe and Mn were dominant among the three forms in both the phreatic and confined aquifers. The distributions of Fe, Mn, and P in colloids and sediments were also studied by X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). A comparison of the distributions of Fe, Mn, and P between site SD01 (riparian zones) and site SD02 (farmland) showed that both external inputs and the reduced release of Fe/Mn oxides/minerals from sediments contributed to the distributions of colloidal Fe, Mn, and P. Correlation analysis showed a strong relationship between colloidal Fe/Mn and P in both groundwater and sediment, implying that colloidal Fe/Mn play a role in regulating the distribution of P in the study area. This study provides a new understanding of the effects of colloidal Fe and Mn on the P distribution among the phreatic and confined aquifers.

Leaching behavior observation of arsenic-containing soil from geogenic sources insolubilized with magnesium oxide-based material and preserved for a long term.

Leaching behavior observation of arsenic-containing soil from geogenic sources insolubilized with magnesium oxide-based material and preserved for a long term.

Toxic metal pollution of aquatic ecosystems of European Union nature protection areas in a region of intensive agriculture (Lake Gopło, Poland)

The paper presents the results of research into toxic metal concentrations in the surface layer of bottom sediments in Lake Gopło. The research objectives were to identify the levels and spatial variability of Cu, Pb, Cd, Zn, Ni, Cr, As and Hg concentrations, their potential sources and the determinants of pollution levels. Metal contamination of the sediments was assessed using the geoaccumulation index (Igeo), pollution load index (PLI) and ecological risk index (RI). Chemometric methods (Pearson correlation, principal component analysis (PCA) and cluster analysis (CA) were used to determine the relationship between sampling sites and concentrations of toxic metals, thereby identifying the sources of contamination. The research found that grain-size composition, carbonate content and organic matter content in the bottom surface sediments of Lake Gopło are all characterised by low diversity. Therefore, the lithological features of the sediments are not a major factor in the concentrations and spatial variability of the metals. It was found that the metal concentrations in the great majority of samples were above regional geochemical background levels. The geochemical indices (Igeo, PLI, RI) indicate that the degree of toxic metal pollution in the sediments is slight in the central and southern parts of the lake and high in the northern part. The chemical analysis results showed that the samples in the central and southern parts of the lake differ little in their shares and concentrations of individual metals. This provides evidence that, as well as geogenic sources, their presence in sediments can be associated with non-point sources related to agricultural activities and with atmospheric sources (mainly the products of fossil fuel combustion). The higher concentrations of metals (especially Ni, Cd, Cr and Hg) in the northern part of the lake are influenced by the supply of industrial and communal pollutants from the lakeside town of Kruszwica. A factor limiting the migration of pollutants from the northern part of the lake towards the south is the lake’s morphology of the lake, which hinders water exchange between the northern part and the rest of the lake.

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.

Groundwater Quality Assessment in the Northern Part of Changchun City, Northeast China, Using PIG and Two Improved PIG Methods.

As a numerical indicator, the pollution index of groundwater (PIG) has gained a great deal of popularity in quantifying groundwater quality for drinking purposes. However, its weight-determination procedure is rather subjective due to the absolute dependence on experts’ experience. To make the evaluation results more accurate and convincing, two improved PIG models (CRITIC-PIG and Entropy-PIG) that integrate subjective weights and objective weights were designed, and they were employed to appraise groundwater suitability for drinking purposes in the northern part of Changchun City. A total of 48 water samples (34 unconfined water samples and 14 confined water samples) with abundances of Ca2+ and HCO3− were collected and tested to obtain the data for the analyses. The results showed that 60.4%, 47.9% and 60.4% of the water samples manifested insignificant pollution and were marginally potable based on the values of the PIG, CRITIC-PIG and Entropy-PIG, respectively. Though 48% of the water samples had different evaluation results, their level difference was mostly 1, which is relatively acceptable. The distribution maps of the three sets of PIG values demonstrated that the quality of groundwater was the best in Dehui City and the worst in Nongan County. Groundwater contamination in the study area was mainly caused by the high concentrations of TDS, TH, Fe3+, F− and NO3−, which not only came from geogenic sources but also anthropogenic sources.

From dust to the sources: The first quantitative assessment of the relative contributions of emissions sources to elements (toxic and non-toxic) in the urban roads of Tehran, Iran

This study represents the first quantitative assessment of the relative contributions of emissions sources to elements in the urban roads of Tehran, Iran. Road dusts (RDs) were collected in the nine districts of Tehran both during the warm and cold seasons (WS and CS) in 2018. Average concentrations of Cr, Cu, Ni, Pb, W, and Zn were remarkably higher in the WS than in the CS. Cu, Pb, and W during the WS and Cd during the CS showed the highest CV (coefficient of divergence). Scanning electron microscopy (SEM) analysis showed complex particle shapes with very irregular structures. Most of them had elongated shapes and contain multiple fine particles attached to the surface. The integrated pollution and risk indices indicated strongly integrated pollution and considerable ecological risk, respectively. The integrated hazard index (∑HI) indicated a higher non-carcinogenic risk in children than in adults. However, the integrated carcinogenic risks (∑CR) of adults were higher than children. Positive matrix factorization (PMF) model identified five sources of elements including: (1) local soils and geogenic sources (LS + GS) (28.2 %), (2) demolition and construction activities (D + CA) (20.2 %), (3) vehicle exhaust emissions (VEE) (16.2 %), (4) vehicle non-exhaust emissions (VNEE) (18 %), (5) industrial and metallic substances emissions (I + ME) (17.5 %). Among the apportioned sources, the highest ∑HI was associated with LS + GS, while the lowest ∑HI was related to VEE. Conversely, VEE contribute the most to the ecological risk (51 %), while LS + GS exhibited the lowest ecological risk contribution (1.25 %). The highest ∑CR from exposure to RD was associated with I + ME.

The assessment of the soil-plant-animal transport of the risk elements at the locations affected by brown coal mining.

The North Bohemian Brown Coal Basin (Czech Republic) is suggested as a source of significant pollution in the surrounding environment with various pollutants, including risk elements. A total of 53 sampling points were selected within the North Bohemian region. The selected sampling points represented either the basin areas (affected by the coal mining and related activities) or the mountain areas (an area unaffected by the coal mining but characterized by the geogenic sources of the risk elements). At each of the sampling points, soils and respective dominant indigenous plant samples were collected. A suite of ecological indices, namely, individual pollution index (Ii), Nemerow index (PN), bioaccumulation factor (BAF), translocation factor (TF), and hazard quotient (HQ), were applied to estimate the environmental risk of As, Be, Cd, and Zn levels in soils, potential soil-plant transfer, and soil-plant-animal transport of these stated elements. The results from Ii showed that the maximum values of As, Be, Cd, and Zn in the investigated soils exceeded the preventive values, where the Ii value was up to 58 for As in the mountain areas, indicating severe pollution. At the same time, mild pollution was recorded in the case of Cd. For Be in the researched soils, its Ii assessment result was a wide range, varying between a clean environment and severe pollution. Whereas As and Be uptake by plants was limited and these elements were retained in the plant's roots, relatively high mobility and soil to plant shoots transport ability of Cd were recorded and documented by the TF values. The HQs calculated for selected herbivorous mammals in the area showed that the potential health risk of As and Be was limited to only plant roots in the hotspots with extreme As and Be contents. In comparison, substantial health risk of Cd was observed in the aboveground biomass of plants. Therefore, the potential remediation of the coal mining areas should be focused on (i) identification of the As and Be hotspots and (ii) to reduce the mobility and plant availability of Cd in the whole investigated area.

Understanding the factors contributing to groundwater salinity in the coastal region of Andhra Pradesh, India

The present study focused on understanding the factors responsible for groundwater salinity in the coastal region, Prakasam district, Andhra Pradesh, India. Groundwater samples were collected and analysed for pH, EC, TDS, TA, TH, CH, NCH, EA, Ca2+, Mg2+, Na+, K+, HCO3−, Cl−, SO42−, NO3−, and F−. Groundwater quality was assessed using entropy weighted water quality index (EWQI), Chadha and Gibbs diagrams, ionic ratios, chloro-alkaline indices (CA), saturation indices (SI), principal component analysis (PCA), and hierarchical cluster analysis (HCA). TDS vs TH indicated that 86% of groundwater samples fall under brackish-cum-very hard water-quality type, while TA and TH relationship showed that 70% and 30% of groundwater samples fall under non‑carbonate hardness (NCH) and excess alkalinity (EA), respectively. EWQI classified groundwater samples into medium (22%), poor (40%), and exremely poor (38%) water quality types, indicating that most samples are not suitable for drinking purposes. Hydrogeochemical types in Chadha diagram showed saline water (Na+-Cl−) type in 92% of groundwater samples. Ionic ratios indicated that anthropogenic activities resulting from the leaching of surface water pollutants are the main source of groundwater pollution. Base ion exchange was indicated as the main process in CA indices. SI revealed precipitation of the calcite phase and dissolution of the gypsum and halite phases in groundwater. Evaporation appeared in Gibb's diagram as a primary process rather than a geogenic origin. PC1 (Na+, Cl−, SO42−, Mg2+, K+, and NO3−) and PC2 (HCO3− and F−) were considered salinity-process and alkalinity-process, respectively. The main sources of salinity in groundwater are brackish-water aquaculture and salt-making activities with household waste, septic tank spills, irrigation-return-flows, and chemical fertilizers being secondary sources. HCA classified groundwater samples into Group-I (46%), which represents domestic water, agricultural activities, etc., Group-II (30.24%), which shows the influence of both Group-I and Group-II, and Group-III (23.76%), which specifies brackish-water aquaculture and salt-making activities. Consequently, the present study obviously indicated that the groundwater quality of anthropogenic origin has largely overcome the influence of geogenic sources. The EWQI classification spatially delineated the study region into medium, high, and very high vulnerable zones, covering 28.69%, 32.75%, and 38.56%, respectively. Therefore, it is suggested to control the dumping of domestic waste and septic tank leaks, limit irrigation-return-flows and chemical fertilizers, ban brackish water aquaculture and salt production activities, and strictly implement an aquifer recharge management strategy to ensure human health. This study will assist decision-makers in addressing groundwater salinity issues in coastal regions.

Anomalous concentrations and environmental implications of rare earth elements in the rock-soil-moss system in the black shale area

Nowadays, rare earth elements (REEs) pollution caused by anthropogenic activities has aroused great attention, but the contribution of natural geological sources remains unclear. In this study, parent rocks, corresponding soil, and overlying moss (Pohlia flexuosa Harv. In Hook) were collected to identify the release, transportation, and environmental exposure of REEs in the black shale areas. The results showed that black shales had elevated REEs levels (245 ± 124 mg kg−1) and served as a geogenic source of REEs. The released REEs were temporarily enriched in the acidized soil (327 ± 91.8 mg kg−1, pH 4.87 ± 0.810) and were still highly bioavailable, thereby resulting in REEs accumulated up to a high level in moss P. flexuosa (86.2 ± 64.3 mg kg−1). Hence, the ecological risks of REEs in black shale areas were assuredly enhanced. The shale-normalized results of REEs concentrations in the parent rock - soil - moss system followed a remarkably identical pattern and were characterized by strong enrichment in HREEs (LaN/YbN 0.520 ± 0.274), indicating that geogenic input was responsible for the concentration and composition of REEs in mosses. Moreover, REEs were readily preserved and not easily fractionated in moss P. flexuosa due to its special morphological features, indicating the lithological signatures of REEs in black shales were readily inherited by moss P. flexuosa, and underwent only minor losses. Overall, moss P. flexuosa could be used as a powerful tool to reflect the content and composition of REEs in black shale areas.