Pollution status, potential sources and health risk assessment of arsenic and trace metals in agricultural soils: A case study in Malatya province, Turkey

Sources apportionments of heavy metal(loid)s in the farmland soils close to industrial parks: Integrated application of positive matrix factorization (PMF) and cadmium isotopic fractionation

Understanding the source identification and distribution of heavy metal(loid)s in soil is essential for risk management. The sources of heavy metal(loid)s in farmland soil, especially in areas with rapid economic development, were complicated and need to be explored urgently. This study combined geographic information system (GIS) mapping, positive matrix factorization (PMF) model and cadmium (Cd) isotope fingerprinting methods to identify heavy metal(loid) sources in a typical town in the economically developed Yangtze River Delta region of China. Cd, As, Cu, Zn, Pb, Ni and Co in different samples were detected. The results showed that Cd was the most severely contaminated element, with an exceedance rate of 78.0 %. GIS mapping results indicated that the hotspot area was located in the northeastern area with prolonged operational histories of electroplating and non-ferrous metal smelting industries. The PMF model analysis also identified emissions from smelting and electroplating enterprises as the main sources of Cd in the soil, counted for 49.28 %, followed by traffic (25.66 %) and agricultural (25.06 %) sources. Through further isotopic analysis, it was found that in soil samples near the industrial park, the contribution of electroplating and non-ferrous metal smelting enterprises to cadmium pollution was significantly higher than other regions. The integrated use of various methodologies allows for precise analysis of sources and input pathways, offering valuable insights for future pollution control and soil remediation endeavors.

Determining priority control toxic metal for different protection targets based on source-oriented ecological and human health risk assessment around gold smelting area

Determining the priority control source and pollutant is the key for the eco-health protection and risk management around gold smelting area. To this end, a case study was conducted to explore the pollution characteristics, source apportionment, ecological risk and human health risk of toxic metals (TMs) in agricultural soils surrounding a gold smelting enterprise. Three effective receptor models, including positive matrix factorization model (PMF), ecological risk assessment (ERA), and probabilistic risk assessment (PRA) have been combined to apportion eco-human risks for different targets. More than 95.0% of samples had a Nemerow pollution index (NPI) > 2 (NPImean=4.27), indicating moderately or highly soil TMs contamination. Four pollution sources including gold smelting activity, mining source, agricultural activity and atmosphere deposition were identified as the major sources, with the contribution rate of 17.52%, 44.16%, 13.91%, and 24.41%, respectively. For ecological risk, atmosphere deposition accounting for 30.8% was the greatest contributor, which was mainly loaded on Hg of 51.35%. The probabilistic health risk assessment revealed that Carcinogenic risks and Non-carcinogenic risks of all population were unacceptable, and children suffered from a greater health risk than adults. Gold smelting activity (69.2%) and mining source (42.0%) were the largest contributors to Carcinogenic risks and Non-carcinogenic risks, respectively, corresponding to As and Cr as the target pollutants. The priority pollution sources and target pollutants were different for the eco-health protection. This work put forward a new perspective for soil risk control and management, which is very beneficial for appropriate soil remediation under limited resources and costs.

Bioavailability and health risk of pollutants around a controlled landfill in Morocco: Synergistic effects of landfilling and intensive agriculture

Toxic contamination of agricultural soils by trace metal(oid)s can pose detrimental effects on human health and agroecological systems. In this view, the current research explored total and available metal(oid)s in surface soils and assessed the associated hazards using pollution indices, PMF modeling, PCA, and Montecarlo probabilistic human risk assessment with 10,000 repetitions. The mean concentrations of Cd, Pb, As, Cr, Ni, Cu, Zn, and Fe were 0.89, 24.86, 1.81, 19.10, 25.44, 7.98, 49.12 and 6183.32 mg kg-1 dry weight, respectively. These findings highlighted that the concentration of pollutants exceeded the values measured in the geochemical background. Soil enrichment by heavy metal (oid)s was confirmed by analyzing available fractions using DTPA ,CaCl2 and enrichment factor (EF). Additionally, pollution indicators (Igeo, PLI, and PERI) displayed significant contamination levels, with a higher ecological risk. Matrix Factorization (PMF) receptor and multivariate statistical analysis reflected that anthropogenic activities, particularly landfilling and agricultural practices were the main causes of the contamination. Furthermore, probabilistic and deterministic human risk assessments showed that carcinogenic risks exceeded the threshold values (10-4) set by the USEPA. Consequently, it is crucial to implement continuous monitoring and supervision of landfill sites to prevent additional pollution. These measures should be integrated into the management plans for waste management.

Characterization of biofilm formation by Exiguobacterium strains in response to arsenic exposure

IMPORTANCE

In this work, we characterized the composition, structure, and functional potential for biofilm formation of Exiguobacterium strains isolated from the Salar de Huasco in Chile in the presence of arsenic, an abundant metalloid in the Salar that exists in different oxidation states. Our results showed that the Exiguobacterium strains tested exhibit a significant capacity to form biofilms when exposed to arsenic, which would contribute to their resistance to the metalloid. The results highlight the importance of biofilm formation and the presence of specific resistance mechanisms in the ability of microorganisms to survive and thrive under adverse conditions.

Evaluation of environmental and ecological risks caused by metals in agricultural areas: an example in the Amik Plain of South Turkey

The works of literature evaluating the eco-environmental risks posed by metals in agricultural areas in developing countries remains limited. This study sought to evaluate the environmental and ecological risks posed by metals in the intensively cultivated areas of the Amik Plain as well as to determine the origins of the metals. For this purpose, 137 soil samples were taken from agricultural production areas of the Amik Plain, and 11 metals (Al, Fe, Ni, Pb, Co, Cr, Cu, Mn, Zn, Cd and As) were examined in the samples. As Ni had the highest average enrichment factor (EF) value (8.04) when compared with the other metals, the soils were found to be significantly enriched with Ni. The Pearson correlation analysis and principal component analysis showed that the Zn concentration was controlled by lithogenic sources, while the Ni, Pb, Cd, Cr and Cu concentrations were controlled by both anthropogenic and lithogenic sources.

Boron contamination and related health risk assessment in the soils collected from olive groves in İzmir province, Türkiye

Although boron (B) is an essential element for plants, high levels are also toxic. In this respect, pollution of soils by B may pose a serious problem for ecosystem and human health. On the other hand, studies evaluating the ecological and human health risks that may arise due to B contamination in agricultural soils are limited. In this study, it was aimed to determine the B pollution degree of the soils taken from the olive groves of İzmir province, which is approximately 180 km away from the B deposits in the Bigadiç district. In addition, the factors affecting boron adsorption and availability were discussed and the ecological and health risks of boron were evaluated. For this, soil samples were collected at depths of 0-30 cm from 118 olive groves and their B, Al, Fe, pH and organic matter contents were determined. The mean B content (47.08 mg/kg) of the study area was comparable to world-soil average B concentration (42 mg/kg). Also, B had a "low potential ecological risk" in the study area according to the ecological risk index results. On the other hand, based on the results of contamination factor (Cf) and enrichment factor (EF), "moderate contamination" and "significant enrichment" were found in the study area for B. These findings indicated that the B content in the study area is mainly related to the soil parent material, but irrigation water also contributes slightly to B content. Correlation analysis results suggested that Al and Fe contents of the soils in the study area may have an effect on B adsorption. The results of health risk assessment indicated non-carcinogenic effects are not expected for adults and children exposed to soil B content by ingestion, dermal contact and inhalation.

Evaluation of radioactive and heavy metal pollution in agricultural soil surrounding the lignite-fired thermal power plant using pollution indices

Soil pollution caused by heavy metals negatively affects the environment and human health. However, the assessment of the environmental and ecological risks caused by heavy metals in agricultural soils in developing countries is limited. This study was carried out to determine heavy metal pollution and its possible sources in the agricultural lands surrounding the lignite-fired Afşin-Elbistan thermal power plant (TPP). A total of 52 soil samples were collected from the agricultural soils surrounding the TPP, and seven different heavy metal (U, Th, Ni, Fe, Cu, Cr and Zn) analyzes were performed on these samples. Soil samples were taken according to the prevailing wind direction. Nickel had a higher geoaccumulation index (1.40) and enrichment factor (5.09) values than the other metals. In addition, U posed a "moderate potential ecological risk" in the study area. Pearson correlation and principal component analyses showed that U, Ni, and Cr were controlled by anthropogenic sources.

Ecological and contamination assessment of soil in the region of coal-fired thermal power plant

This study was carried out to determine the heavy metal pollution and possible sources of agricultural soils in Tavşanlı district, Which energy power plant is located. Total 83 soil samples were taken and 8 (Cu, Cr, Pb, Co, Fe, Mn, Ni, and Zn) heavy metals were analyzed in soil samples The mean concentration of heavy metals were determined as Cu (32.89 mg kg-1), Cr (285.69 mg kg-1), Co (36.37 mg kg-1), Mn (860.20 mg kg-1), Ni (457.59 mg kg-1), Pb (22.14 mg kg-1), Fe (30,250 mg kg-1) and Zn (65.05 mg kg-1), were determined. The mean concentrations of Cu, Cr Co, Mn and Ni found to be higher than both the upper continental crust values and the European soil mean values. Contamination factor Co (2.1), Cr (3.10) and Ni (9.73), enrichment factor Co (2.73), Cr (3.75) and Ni (11.42) and geoaccumulation index Co (0.18), Cr (0.50) and Ni (1.98) values showed that the soils were polluted by Co, Cr, and Ni. In addition, it was determined that Ni (48.65) poses a "moderate ecological risk" in the study area. Pearson correlation anaysis and principal component analysis determined that Cr, Co and Ni have both lithogenic and anthropogenic origin.

Appraisal of contamination, source identification and health risk assessment of selected metals in the agricultural soil of Chakwal, Pakistan

Contamination of metals in agricultural soil is a serious global threat but there are limited reports related to their risks in major agronomic areas. The current study is aimed to assess the distribution of selected macroelements and essential/toxic trace metals (Ca, Mg, Na, K, Sr, Li, Ag, Fe, Zn, Co, Cu, Mn, Cd, Cr, Pb and Ni) in the agricultural soil of Chakwal, Pakistan, in order to appraise their contamination status, source identification and probable human health risks. Quantification of the metals was performed by AAS employing aqua regia digestion method. Among the selected metals, dominant mean concentrations were observed for Ca (48,285 mg/kg) and Fe (30,120 mg/kg), followed by Mg (9171 mg/kg), K (973.3 mg/kg), Mn (399.0 mg/kg) and Na (368.9 mg/kg). The correlation study indicated strong mutual relationships among the metals as well as physicochemical properties. Multivariate analysis (PCA/CA) of the metal levels revealed their diverse anthropogenic sources in the soil. Various pollution indices indicated extremely high contamination/enrichment of Cd, followed by moderate enrichment/contamination of Ag in the soil. The HQ values for most of the metals manifested insignificant non-cancer risks. The average CR value of Cr was exceeding the safe limit (1.0E-06) for both ingestion and inhalation exposure, indicating a considerable lifelong cancer risk for the population. The results of this study will provide a better understanding related to the contamination of agricultural soil and its effects on human health and to promote effective actions to reduce the soil pollution.

Ecological and health risk assessment associated with translocation of heavy metals in Lycopersicum esculentum from farmland soil treated with different composts

To meet the United Nations' Sustainable Development Goals, agricultural soil which is a non-renewable natural resource must be carefully managed. Heavy metals present in agricultural soil may imperil food security and instigate extreme risks to human health. Organic wastes have been long known for valuable amendments to soil thereby, improving overall soil health. In the present study, Echhornia crassipes, Hydrilla verticillata, and vegetable waste, was utilized to prepare compost amendments. Lycopersicum esculentum was used to metal uptake from compost amended soils. 5%, 10%, 15%, 25%, and 35% compost: soil (w/w) were studied to understand metal translocation in plants. Potential Ecological risk indices showed that while the degree of risk was medium for the natural soil, it reduced to slight for the soil amended with WHC and VWC for all compositions. The non-carcinogenic risks associated with the human health reduced on application of the composts, however, they still remained substantial for Fe, As, and Pb for WHC, HVC, and VWC composts at higher application ratios, especially among children. On the other hand, the carcinogenic health index values which were calculated to estimate the risk associated with ingestion of L. esculentum, showed a decrease in risk for all the metals studied, upon soil amendment. Soil amended with HVC compost showed an increase in carcinogenic risk for As, Pb, and Cr. Finally, we conclude that biological soil remediation is economical and a sustainable land management strategy that may lead to green and clean remediation solutions for metal contaminated soil.

Spatial distribution, sources, and risk assessment of potentially toxic elements in cultivated soils using isotopic tracing techniques and Monte Carlo simulation

Potentially toxic elements (PTEs) in cultivated lands pose serious threats to the environment and human health. Therefore, improving the understanding of their distinct sources and environmental risks by integrating various methods is necessary. This study investigated the distribution, sources, and environmental risks of eight PTEs in cultivated soils in Lishui City, eastern China, using digital soil mapping, positive matrix factorisation (PMF), isotopic tracing, and Monte Carlo simulation. The results showed that Pb and Cd are the main pollutants, which posed higher ecological risks in the study area than the other PTEs. Natural, mining, traffic, and agricultural sources were identified as the four determinants of PTE accumulation via a PMF model combined with Pearson correlation analysis, showing that their contribution rates were 22.6 %, 45.7 %, 15.2 %, and 16.5 %, respectively. Stable isotope analysis further confirmed that local mining activities affected the HM accumulation. Additionally, non-carcinogenic and carcinogenic risk values for children were 3.18 % and 3.75 %, respectively, exceeding their acceptable levels. We also identified that mining activities were the most important sources of human health risks (55.7 % for adults and 58.6 % for children) via Monte Carlo simulations coupled with the PMF model. Overall, this study provides insights into the PTE pollution management and health risk control in cultivated soils.

Environmental and human health risks of potentially harmful elements in mining-impacted soils: A case study of the Angouran Zn-Pb Mine, Iran

The soil pollution status, levels of exposure, and potential ecological and health risks to workers and residents by potentially harmful elements (PHEs) in the Angouran mining area (Iran), the biggest Zn-Pb mine in the Middle East, were studied. To this aim, topsoil (0-5 cm) samples (n = 63) from different land-uses were analyzed for their total PHEs concentrations. Mine worker's blood analysis and in vitro digestion extractions were applied in conjunction with human health risk assessment (HHRA) to assess the potential health impacts by exposure to PHEs. The maximum PHEs total concentrations were found in the soils near the waste rock dumps. HHRA indicated that ingestion of soils may induce a non-carcinogenic risk due to As and Pb (for both age groups of children and adults), while dermal contact for children may induce the same type of risk due to Cd, and Pb. The carcinogenic risks (CR_s) of As, Cd, Cr, and Ni through ingestion route were above the acceptable value of 1 × 10^-4, and children may face greater health risks. The average blood Zn, Pb, and Cd levels in the mine workers largely exceeded the safe concentration for adults, while 30% of the workers were tested positive for As in blood. In vitro digestion extractions indicated that the highest bioaccessible contents of As, Cd, Pb, Ni and Zn were found for the industrial-residential and mine soils in the area, while those of Cr and Cu were observed in the agricultural use soils. This study illustrates that a combination of techniques, including geochemical analysis, in vitro bioaccessibility extractions, HHRA, and blood analysis, is a workable integrated approach for evaluating pollution and health risks in mining districts.

Status, Sources and Assessment of Potentially Toxic Element (PTE) Contamination in Roadside Orchard Soils of Gaziantep (Türkiye)

To identify the sources of contamination with potentially toxic elements (PTEs) in roadside orchard soils and to evaluate the potential ecological and environmental impacts in Gaziantep, soil samples from 20 mixed pistachio and olive orchards on roadsides with different traffic densities and at different distances to the roads were analyzed. Concentrations were 23,407.36 ± 4183.76 mg·kg^-1 for Fe, 421.78 ± 100.26 mg·kg^-1 for Mn, 100.20 ± 41.92 mg·kg^-1 for Ni, 73.30 ± 25.58 mg·kg^-1 for Cr, 65.03 ± 12.19 mg·kg^-1 for Zn, 60.38± 7.91 mg·kg^-1 for Pb, 17.74 ± 3.35 mg·kg^-1 for Cu, 14.93 ± 4.94 mg·kg^-1 for Co, and 0.30 ± 0.12 mg·kg^-1 for Cd. It was found that the Ni content in 51% and the Cr content in 18% of orchard soils were above the legal limits for agricultural soils (pH > 6) in Türkiye. Factor analysis (FA) showed that Co, Cr, Cu, Fe, Mn, Ni, and Pb loaded on the first factor (FC1), while Cd and Zn loaded mostly on the second factor (FC2). It was found that Cr, Ni, and Pb were primarily enriched through pedogenic processes, whereas Cd most likely originated from agricultural activities, while the impact of road traffic as source of PTE contamination was insignificant. It has been revealed that the soils are of low quality for agricultural production due to PTE contamination (PIave ≥ 1). The SOPI values from environmental and ecological individual indices showed that the soil pollution level was moderate for Cd, Ni, and Pb, and low for Cr. The soil pollution index (SOPI) proved to be suitable for evaluating and comparing PTE pollution in regions with different soil properties.

Source Apportionment and Health Risk Assessment of Heavy Metals in Soils of Old Industrial Areas-A Case Study of Shanghai, China

Heavy metals in the soil of industrial areas pose severe health risks to humans after land-use properties are transformed into residential land. The public exposure time and frequency will soar significantly under residential land. However, much uncertainty still exists about the relationship between soil heavy metal pollution and-human health risks in an old industrial zone in Shanghai, China. Principal component analysis-(PCA) was used to explore the main sources of these heavy metals. Kriging interpolation was u-sed to identify their spatial distribution and high-risk areas, and the Human Health risk model was used to measure health risk. The results illustrate that the pollution levels of Cd, Hg, and Pb in industrial land are more serious than those in irrigation cropland. Meanwhile, the results of PCA showed that there were two main pollution sources under irrigated cropland, a natural source and a traffic source, accounting for 44.1% and 31.0%, respectively, and there were three main pollution sources under industrial land, with natural sources accounting for 28.5%, traffic sources accounting for 25.7%, and industrial sources accounting for 13.1%. In addition, the health risk assessment results indicated that the priority control pollutants of non-carcinogenic risk and carcinogenic risk were Zn and Cr, respectively. The high-risk area was mainly located in the middle of the study area. These results indicate that eliminating heavy metal pollution in the soil of the industrial area is so important to decrease health risks. The results of this study provide theoretical contributions to early warning of health risks related to heavy metal pollution in industrial area soil and serve as a practical reference for speeding up the formulation of industrial land pollution management policies.

Heavy metals and their sources, potential pollution situations and health risks for residents in Adıyaman province agricultural lands, Türkiye

In this study, the contents of heavy metals (HMs) such as Al, Cd, Co, Cr, Cu Fe, Mn, Ni, Pb and Zn in soil samples collected from 403 sampling locations of the agricultural lands of Adıyaman Province (Türkiye) were determined by Inductively Coupled Plasma‒Optical Emission Spectrometry (ICP‒OES). The mean concentrations of Al, Cd, Co Cr, Cu Fe, Mn, Ni, Pb and Zn HMs were detected 28,986, 3.60, 15, 127, 52.67, 45,830, 817, 62.40, 10.75 and 66.25 mg kg^-1, respectively. These results showed that the average concentrations of Cd, Cr, Cu, Fe, Mn and Ni exceeded the Upper continental crust average. To determine and to evaluate the contamination status and distribution of HMs in agricultural soils, metal pollution parameters such as enrichment factor (EF), geoaccumulation index (I_geo), contamination factor (Cf), pollution load index, potential ecological risk factor (Er), and potential ecological risk index (RI) were used. Factor analyses (FA) and principal component analyses (PCA) indicated that Cd, Cr and Ni levels were influenced by anthropogenic sources, Fe by both lithological and anthropogenic sources, and other HMs by lithogenic origins. For both children and adults, the hazard index (HI) and total hazard index (THI) values of HMs were < 1, suggesting that non-carcinogenic health risks to residents through ingestion, inhalation pathways, and dermal contact were currently absent. In addition, the cumulative carcinogenic risk (CCR) results were within the acceptable risk range (10^-4 to 10^-6). The results showed that children were more sensitive to the non-carcinogenic and carcinogenic effects of HMs.

Zinc in soil reflecting the intensive coal mining activities: Evidence from stable zinc isotopes analysis

In the mining area affected by coal mining activities for a long time, heavy metal Zn pollution poses a serious threat to soil quality and human health, and direct evidence showing the relationship between Zn accumulation mechanism in soils and mining activities is lacking. In this study, the Zn content and isotopes composition (δ⁶⁶Zn) from soil and environmental samples around mining area were determined and analyzed to clarify the Zn characteristics in soil. Moreover, the distribution and source of Zn content in soil of mining area were analyzed by mathematical statistics, correlation analysis and isotope mass mixing model. The results showed that: (1) the Zn content in soil ranged from 95 to 327 mg·kg^-1 (mean: 233 mg·kg^-1), exceeding the control point and the soil background value of Anhui Province; (2) the results of Zn isotope analysis showed that Zn in soil mainly derived from the wind dispersion input of fine particles in gangue and fly ash, followed by the natural weathering of parent material; (3) isotopic mass mixing model can be used to distinguish the contribution of anthropogenic and natural Zn sources. Mining input was the main contribution source of Zn in soil (mean: 67%), followed by natural background (mean: 33%). The employment of Zn isotopes can effectively evaluate the impact of anthropogenic and natural long-term processes on Zn in the soil of the mining area, and provide important information for the formulation of soil metal pollution control measures.

Metal Contents and Pollution Indices Assessment of Surface Water, Soil, and Sediment from the Arieș River Basin Mining Area, Romania

The current study was conducted to assess the level and spatial distribution of metal pollution in surface water, soil, and sediment samples from the Arieș River basin, located in central Romania, an area impacted by various mining and industrial operations. Several pollution indices, spatial distributions, cluster analyses, principal component analyses, and heat maps were applied for evaluating the contamination level with Ni, Cu, Zn, Cd, Pb, Mn, As, and Hg in the area. Based on the results of the Heavy-Metal Pollution Index and of the Heavy-Metal Evaluation Index of the surface-water samples, the middle part of the Arieș River basin, near and downstream of the gold mine impoundment, was characterized by high pollution levels. The metal concentration was higher near the tailing impoundment, with increased levels of Cu, Ni, Zn, and Pb in the soil samples and As, Cd, Pb, Na, K, Ca, Mn, and Al in the sediment samples. Ca (23.7–219 mg/L), Mg (2.55–18.30 mg/L), K (0.64–14.70 mg/L), Al (0.06–22.80 mg/L), and Mn (0.03–22.40 mg/L) had the most remarkable spatial variation among the surface-water samples, while various metal contents fluctuated strongly among the sampling locations. Al varied from 743 to 19.8 mg/kg, Fe from 529 to 11.4 mg/kg, Ca from 2316 to 11.8 mg/kg, and Mg from 967 to 2547 mg/kg in the soil samples, and Al varied from 3106 to 8022 mg/kg, Fe from 314 to 5982 mg/kg, Ca from 1367 to 8308 mg/kg, and Mg from 412 to 1913 mg/kg in the sediment samples. The Potential Ecological Risk Index values for soil and sediments were in the orders Cu > Ni > Pb > Hg > Cr > As > Mn > Zn > Cd and As > Cu > Cr > Cd > Pb > Ni > Hg > Mn > Zn, respectively, and the highest values were found around the gold mine impoundment.

Bibliometric Analysis of the Influencing Factors, Derivation, and Application of Heavy Metal Thresholds in Soil

The study of threshold levels of heavy metals in soil is essential for the assessment and management of soil environmental quality. This study reviewed the influencing factors, the derivation, and application aspects of heavy metals' threshold values comprehensively by a combination of bibliometric analysis and scientific knowledge mapping. A total of 1106 related studies were comprehensively extracted from the Web of Science database during the period from 2001 to 2020. The results showed that the publication output has been growing strongly. An analysis on the subject, journal, country, and institution was carried out to demonstrate the development and evolution of this research branch during the two decades. According to high-frequency keywords analysis, external factors (e.g., soil physicochemical properties) and internal factors (e.g., crop genotype) can affect heavy metal threshold values in the soil-crop system. The current methods mainly include the Point model (e.g., evaluation factor method), the Probability model (e.g., species sensitivity distribution method), and the Empirical model (e.g., ecological environment effect method). A threshold study can be applicable to the risk assessment for soil heavy metal contamination in order to determinate the soil pollution degree and its spatial and temporal distribution characteristics. Moreover, challenges and prospects of the study of heavy metal threshold values are proposed, indicating that research should focus on the relationships between human health risks and the established threshold values of heavy metals in the soil, long-term field trials and bioavailability of heavy metals for the derivation of the thresholds, and the establishment of more scientific and rational soil environmental benchmarks.

Adverse Effects of Arsenic Uptake in Rice Metabolome and Lipidome Revealed by Untargeted Liquid Chromatography Coupled to Mass Spectrometry (LC-MS) and Regions of Interest Multivariate Curve Resolution

Rice crops are especially vulnerable to arsenic exposure compared to other cereal crops because flooding growing conditions facilitates its uptake. Besides, there are still many unknown questions about arsenic’s mode of action in rice. Here, we apply two untargeted approaches using liquid chromatography coupled to mass spectrometry (LC-MS) to unravel the effects on rice lipidome and metabolome in the early stages of growth. The exposure is evaluated through two different treatments, watering with arsenic-contaminated water and soil containing arsenic. The combination of regions of interest (ROI) and multivariate curve resolution (MCR) strategies in the ROIMCR data analyses workflow is proposed and complemented with other multivariate analyses such as partial least square discriminant analysis (PLS-DA) for the identification of potential markers of arsenic exposure and toxicity effects. The results of this study showed that rice metabolome (and lipidome) in root tissues seemed to be more affected by the watering and soil treatment. In contrast, aerial tissues alterations were accentuated by the arsenic dose, rather than with the watering and soil treatment itself. Up to a hundred lipids and 40 metabolites were significantly altered due to arsenic exposure. Major metabolic alterations were found in glycerophospholipids, glycerolipids, and amino acid-related pathways.

Enhanced remediation of Cd-contaminated soil using electrokinetic assisted by permeable reactive barrier with lanthanum-based biochar composite filling materials

Electrokinetic remediation (EK) combined with a permeable reactive barrier (PRB) is a relatively new technique for efficiently remediating Cd-contaminated soil in situ. Eupatorium adenophorum, which is a malignant invasive plant, was used to synthesise biochar and a novel lanthanum-based biochar composite (LaC). The biochar and LaC were used as cheap and environmentally benign PRB filling materials to remediate simulated and real Cd-contaminated soils. The pH and residual Cd concentration in the simulated contaminated soil during remediation gradually increased from the anode to the cathode used to apply an electric field to the EK-PRB system. However, the soil conductivity changed in the opposite way, and the current density first increased and then decreased. For simulated contaminated soils with initial Cd concentrations of 34.9 and 100.6 mg kg^-1, the mean Cd removal rates achieved using LaC were 90.6% and 89.3%, respectively, which were significantly higher than those of biochar (P < 0.05). Similar results were achieved using natural soils from mining area and polluted farmland, and the Cd removal rates were 66.9% and 72.0%, respectively. Fourier-transform infrared and X-ray photoelectron spectroscopy indicated that there were many functional groups on the LaC surfaces. The removal mechanism of EK-PRB for Cd in contaminated soil includes electromigration, electroosmotic flow, surface adsorption, and ion exchange. The results indicated that the LaC could be used in the EK-PRB technique as a cheap and 'green' material to efficiently decontaminate soil polluted with heavy metals.

An integrated multidisciplinary-based framework for characterizing environmental risks of heavy metals and their effects on antibiotic resistomes in agricultural soils

In this study, a new integrated multidisciplinary-based framework has been proposed to better understand the environmental risks of heavy metals (HMs) in agricultural soils. The source apportionment results revealed by a multilinear engine model were incorporated into the geochemical indexes and the probabilistic health risk assessment models for identifying the source-oriented risks of HMs in the environment. High-throughput sequencing-based metagenomic assembly analysis was used for characterizing the prevalence and dissemination risk of antibiotic resistomes and their associations with the geochemical enrichment of HMs in the soils. Results showed agricultural and industrial activities were the main sources of HMs in the environment. Although the soils were contaminated moderately by HMs and the health risks posed by soil metals were negligible for both adult and children, source-oriented risk evaluation suggested agricultural activities contributed relatively higher contamination and health risks than the other sources. Notably, abundant and diverse antibiotic resistant genes, mobile gene elements, virulence factors, and antibiotic-resistant bacterial pathogens were identified in the agricultural soils, as well as their co-occurrences on the same contigs, implying a non-negligible resistome risk. Further, statistical and network analyses showed the geochemical enrichment of HMs exerted significant effects on the antibiotic resistomes in the environment.

A comprehensive analysis on source-distribution-bioaccumulation-exposure risk of metal(loid)s in various vegetables in peri-urban areas of Shenzhen, China

The health risk induced by metal(loid)s in crops are becoming increasingly serious. In this study, eight major vegetables and rhizosphere soils were collected in a peri-urban area with intense electronic information manufacturing activities. The source, distribution and bioaccumulation of six typical metal(loid)s in different vegetable species were analyzed, and exposure risk through vegetable ingestion was estimated. Results showed that vegetables and agricultural soils in the study area suffered from serious metal(loid)s pollution, especially for Cd and Pb. The bioaccumulation capacity differed greatly among individual metal(loid)s and vegetable categories. In general, the highest transfer factors (TF) for Cd, Pb, and As were found in leafy vegetables, while leguminous vegetables had the highest TF of Cu and Zn and root vegetables had the highest TF for Cr. Significant correlations were found between concentrations in vegetables and rhizosphere soils for most metal(loid)s, the exceptions being Pb and Zn. The enrichment of Pb, Cd, Cr and As was mainly attributed to electronic information manufacturing activities, while the enrichment of Zn, Cu and Cd was associated with the application of commercial fertilizers and pesticides. The health risk associated with vegetable intake decreased in the order of leafy > fruit > leguminous > root vegetables. Leafy vegetables were identified as the category with the highest risk, with the mean risk value of 1.26. Cd was the major risk element for leafy vegetables. The non-carcinogenic risks estimated for leguminous and root vegetables were under the acceptable level. In conclusion, special attention should be paid to the health risks of toxic metal(loid)s in leafy vegetables in peri-urban areas with intense electronic information manufacturing activities. In order to minimize health risk, it is necessary to identify low-risk crops based on a comprehensive consideration of the metal(loid)s' pollution characteristics, transfer factors and local people's consumption behaviors.

Monitoring Potentially Toxic Element Pollution in Three Wheat-Grown Areas with a Long History of Industrial Activity and Assessment of Their Effect on Human Health in Central Greece

Agricultural lands, especially those where wheat is cultivated, in the vicinity of intense anthropogenic activities may be laden with potentially toxic elements (PTEs), resulting in increased risk for human health. In this study we monitored three regions located in central Greece, currently cultivated with wheat: Domokos and Eretria, two areas with abandoned chromium mines, but never studied before, and the industrial area of Volos, near a major steel factory. All soils were alkaline with medium CaCO₃ content. As expected, Cr was extremely high in the first two areas (705.2 in Eretria and 777.5 mg kg⁻¹ in Domokos); Ni was also found elevated (1227 in Eretria, 1315 in Domokos and 257.6 mg kg⁻¹ in the steel factory), while other harmful metals (Cd, Cu, Pb and Zn) were rather low. As a result, pollution load index, a cumulative index showing the contamination level of an area, was higher than 1.0 in all three areas (Eretria = 2.20, Domokos = 2.28, and steel factory = 1.61), indicating high contamination and anthropogenic inputs. As for the wheat parts (shoots and grains), they were found to have no elevated concentrations of any of the measured metals in all three study areas, probably due to the alkaline soil pH that decelerates metal mobility. This was also confirmed by the very low soil-to-plant transfer coefficient values for all metals. In assessing the possible risk concerning human health, we found that the soil-to-human pathway would induce no significant risk (exhibited by hazard index of less than 1.0), while the risk from grain-to-human resulted in considerable risk for human health in the steel factory of Volos (where HI > 1.0). Our findings suggest that rural areas never studied before with a history in some offensive anthropogenic activity can prove to be a contamination hotspot; we regard this study as a pivotal for similarly never-visited-before areas casually cultivated with wheat (or other important crops for human nutrition). We further recognize the need for a more in-depth study that would acknowledge the geochemical speciation of the studied metals and also monitor other important crops and their possible uptake of PTEs.