Potentially Toxic Elements Contamination Research Articles

Coronilla juncea, a native candidate for phytostabilization of potentially toxic elements and restoration of Mediterranean soils

Soil contamination pattern due to industrial activities often leads to high concentrations of potentially toxic elements (PTE) decreasing with depth. This spatial heterogeneity of the soil contamination may have significant consequences on the soil properties and soil living communities. We evaluated the effects of both surface and solum soil contamination heterogeneity on Coronilla juncea L. (Fabaceae) functional traits in field conditions and the phytostabilization potential of this species. Plant and soil samples were collected on 3 sites along a PTE contamination gradient. The correlations between PTE concentration in plant and soil samples at 2 depths, physico-chemical properties of soil, plant biomass and soil microbial activity were tested. Field measurements highlight a decreasing PTE concentration with soil depth in addition to an important surface heterogeneity of As, Cu, Pb, Sb and Zn soil concentrations. Root PTE concentrations in C. juncea did not follow soil PTE concentrations. Concentrations of PTE in the root parts were higher than those of the aerial parts. Low PTE translocation and root symbioses with microorganisms suggest that this native plant species may play a role as engineer species with positive implications for the phytostabilization of Mediterranean PTE contaminated soils and their ecological restoration.

Ecotoxicological assessment of toxic elements contamination in mangrove ecosystem along the Red Sea coast, Egypt

Identifying biochemical aspects of the potentially toxic elements (PTEs) is of particular concern in mangrove ecosystems, Avicennia marina (Forssk.) Vierh., due to their importance as natural buffers in coastal areas. Nonetheless, the microbial community dynamics and potential scavenging responses of mangrove ecosystems to the phytotoxicity of PTEs remain questionable. This study assesses the ecological risk benchmarks of some PTEs, including aluminum (Al), boron (B), barium (Ba), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn), and their microbial responses in the bottom sediments of mangrove ecosystems along Egypt's Red Sea coast. In particular, we assessed the role of microbial metabolites in biochemical cycling of nutrients and scavenging against phytotoxicity hazards. We quantified a spectrum of ecological risk assessment indices, which suggested elevated levels of PTEs in sediment, particularly Cr, Hg, and Pb. Canonical correspondence analysis and generalized linear mixed effects models indicate that the spatial biodiversity of microbial taxa is impacted significantly by the physicochemical characteristics of sediments and concentrations of PTEs. Results demonstrate that the microbial communities and their metabolites exert a significant influence on organic matter (OM) decomposition and the biochemical cycling of phytoavailable nutrients including nitrogen (N), phosphorus (P), and potassium (K). Spatially, nitrogenase activities were higher (411.5 μmoL h−1 mL−1) in the southern sites of the Red Sea coast relative to the northern locations (93.8 μmoL h−1 mL−1). In contrast, higher concentrations of phytohormones, including indole-3-acetic acid (IAA) (61.5 mg mL−1) and gibberellins (534.2 mg mL−1), were more evident in northern sites. Siderophores correlated positively with Fe concentration in sediments and averaged 307.4 mg mL−1. Overall, these findings provide insights into the biochemical signals of PTEs contamination in hostile environments, contributing to a better understanding of the future prospects of PTEs bioremediation in contaminated coastal environments.

Integrated approaches to mitigate threats from emerging potentially toxic elements: A way forward for sustainable environmental management

Potentially toxic elements (PTEs) such as toxic metal (loid)s and other emerging hazardous contaminants, exist in the environment and poses a serious threat. A large amount of wastewater containing PTEs such as cadmium, chromium, copper, nickel, arsenic, lead, zinc, etc. Release from industries during production process. Besides these, chemical-based fertilizers used in soils during crop production have become one of the crucial sources of PTEs. Various techniques are being employed for the mitigation of PTEs like chemical precipitation, ion exchange, coagulation, activated carbon, adsorption, membrane filtration, and bioremediation. Among these mitigation strategies, biological processes such as bioremediation, phytoremediation etc. Are extensively used, as they are economic have high-efficiency rate and are eco-friendly. This review intends to provide information on PTEs contamination through various sources; along with the toxicity of metal (loid)s with respect to their patterns of transmission and risks in the changing environment. Various remediation methods for the management of these pollutants along with their techno-economic perspective are also summarized in this review.

Pollution characteristics and health risk assessment of potentially toxic elements in soils around China's gold mines: a meta-analysis.

Since toxic element pollution is widespread in soils near gold mines due to increasing mining activities, the adverse effects of potentially toxic elements (PTEs) in the soils on ecological systems and human health cannot be ignored. However, assessments of PTE pollution in soils and their ecological-health risks on a national scale are still limited. Here, the concentrations of eight PTEs in soils near gold mines throughout China were obtained from published articles. Based on these data, the pollution levels and ecological-health risks of the eight PTEs in soils were comprehensively estimated. The results showed that the average contents of As, Cr, Cd, Pb, Hg, Cu, Ni, and Zn were 81.62, 79.82, 1.04, 206.03, 2.05, 40.82, 71.82, and 130.42mgkg-1, respectively, which exceeded the corresponding background values for soils. Most of the examined soils were heavily polluted by Hg and Cd, and higher pollution levels were found in the Henan and Shaanxi Provinces than in other regions. The average potential ecological risk value of all PTEs was 2534.71, indicating the presence of very high risks. Contribution of Hg to the potential ecological risk was more than 80%. For adults, all hazard index (HI) values of noncarcinogenic risks were below the safe level of 1.00. For children, none of the HI values exceeded the safe level, with the exception of As (HI = 1.81); nevertheless, four PTEs (As, Cr, Cu, and Ni) presented unacceptable carcinogenic risks. This study provides scientific basis for controlling PTE contamination and reducing the health risks in soils near gold mines worldwide.

Toxicidade aguda de elementos potencialmente tóxicos em protozoários ciliados do Lago de Maracaibo (Venezuela)

Abstract: Aim In this article the acute ecotoxicological effects of Cr(III), Cr(VI), Cd(II) and V(V) on ciliated protozoa isolated from Lake Maracaibo were evaluated, by estimating of the LC50 for an exposure time of 1-h and observations every 5 min. Methods Isolations and cultures of ciliated protozoa were made from surface water samples to then carry out toxicity essays under static and controlled conditions, identifying cell immobility (death) as the endpoint. Results The response of the ciliated protozoa made it possible to unequivocally determine the acute toxicity in presence of potentially toxic elements (PTE), with variable mortalities depending on the gender, the element tested and its concentration. The results obtained with Euplotes sp. indicate that protozoan is a sensitive biomonitor indicated for the biomonitoring of PTE contamination in Lake Maracaibo. Conclusions The use of shorter exposure periods offers opportunities to show early toxicity effects on natural populations and to act in a timely manner (early warning systems) in contamination events by PTEs, as well as the development of sensitive and rapid biomonitoring methods for detection of these elements in the environment.

Pollution impact on microbial communities composition in natural and anthropogenically modified soils of Southern Russia

Metagenomic studies of soil microbocenoses are extremely relevant nowadays. The study of pollution impact on soil microbiomes is of particular interest. The structure of microbial communities in soils with different levels of pollution by polycyclic aromatic hydrocarbons (PAHs) and potentially toxic elements (PTEs) was studied. High bacterial biodiversity was found in all the studied soil samples, but its lowest values are found in soil samples taken on the territory of technogenically polluted Lake Atamanskoye. Assessment of soil pollution showed the highest content of polycyclic aromatic hydrocarbons (PAHs) and potentially toxic elements (PTEs) for the soils Lake Atamanskoye. The high content of pollutants negatively affects the abundance of representatives of the phyla Actinobacteria, Planctomycetes, Verrucomicrobia, and Nitrospirae. Such phyla as Proteobacteria, Candidate Divisions TM7, OD1, WPS-2, Chlamydiae, Cyanobacteria are characterized by positive direct correlation with the content of pollutants, especially with PAHs. A cooperative effect of decrease in the number of Actinobacteria and Proteobacteria with an increase in Armatimonadetes probably corresponds to PTEs contamination. The proportion of Candidate Division OD1, Chlamydiae, Cyanobacteria, and Candidate Division WPS-2 was increased in the soil microbiome under the influence of severe combined pollution. Pollutants negatively affect the abundance of dominant unclassified_o__Gaiellales and unclassified_o__WD2101 genera. Iamia, Salinibacterium, Arthrobacter, Kaistobacter, Thiobacillus genera are characterized by a low abundance, but they are presumably the most resistant to soil pollution. It was revealed that the level of soil pollution largely determines the composition and diversity of bacterial communities in the soils of the studied territories. Operating taxonomic units have been established that have prognostic value for assessing the state, level of soil pollution, and their biological safety.

The content and health risk assessment of selected elements in bee pollen and propolis from Turkey

This study aimed to determine the concentrations of potentially toxic elements (PTEs), including Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Sn, V, and Zn, in pollen and propolis samples collected from migratory beekeeping areas in Turkey. A health risk assessment was performed to identify the potential risk of these PTEs to consumers in terms of public health. Concentrations of the elements were analyzed by inductively coupled plasma optical emission spectroscopy. The most abundant element in the bee pollen and propolis samples was Fe, with average concentrations of 47.3 and 390 mg kg−1, respectively, followed by Al, Zn, Mn and Sn. Concentrations of all elements except Cu, Mn and Sn were higher in propolis than in pollen. The concentrations of Fe, Al, and Zn in the propolis samples were over eight, seven, and two times higher than in the bee pollen samples, respectively. Se, Cd, and Hg in pollen and Se and Cd in propolis were below the detection limits. Pb, Co, and Cr were detected below 0.62, 0.06, and 0.91 mg kg−1, in pollen samples, respectively. Co and Hg were detected below 0.68, and 0.18 mg kg−1, in propolis samples, respectively. Detection of the PTEs contamination level and assessment of the health risks in pollen and propolis is necessary to ascertain quality and safety before consumption. In this study, we concluded that bee pollen and propolis may be good indicators for the screening of environmental pollution with PTEs and standards regulating acceptable concentrations of these pollutants in bee products should be established. In addition, it has been determined that consumption at the specified rates does not pose a risk. This study suggests the determination of admissible concentrations of PTEs in bee pollen and propolis.

Risk assessment of potentially toxic elements in stream sediments around granite quarries, barite mines, and cultivation areas, Southeastern Nigeria.

This study assessed the contamination of streams with potentially toxic elements (PTEs) in sediments around mining, quarrying, and cultivation areas in Akamkpa and environs Southeastern Nigeria. Analysis done using ICP MS technique shows that barium (Ba) and lead (Pb) recorded mean concentrations above their average shale content (ASC) in stream sediments. Chromium (Cr) exceeded Canadian Interim Sediment Quality Guideline (ISQG) and US Environmental Protection Agency (USEPA) screening benchmark value. Pb exceeded Canadian ISQG value but tallies with USEPA benchmark value. Pearson's correlation exhibited significant correlation (p < 0.01) of molybdenum (Mo) with copper (Cu) and Pb; Cu with Pb, vanadium (V), and Ba; V with Cu, Pb, iron (Fe), Ba, and beryllium (Be); and Fe with Be and V. Principal component (PC 1) consists of Pb, Mo, cobalt (Co), Cu, arsenic (As), Cr, V, and nickel (Ni) and showed significant correlation. Geo accumulation index (I-geo) values for Mo, Cu, V, Pb, Zn, Ni, Co, Mn, and Ba fall under unpolluted (0) to moderately polluted (1-2) classes. Maximum enrichment factor (EF) values show extremely high and significant enrichment of Ba and Pb in few locations. Co, Cr, Cu, Mn, and Zn possess maximum EF values classified as moderate enrichment. Ni, Mo, As, and V obtained maximum EF values classified as depleted to minimal enrichment. Modified pollution index (MPI) values showed high PTEs contamination in mostly cultivation locations. Single element potential ecological risk (EiR) mean values trend EiR (As) > EiR (Pb) > EiR (Co) > EiR (Cr) > EiR (Cu) > EiR (V) > EiR (Ni) > EiR (Zn). Comprehensive potential ecological risk (RI) shows medium risk "B" and strong risk "C" levels in few locations. The use of multiple pollution indices such as I-geo, EF, EiR, and RI in pollution assessment indicated similar trend of PTEs contamination of stream sediments. Levels of PTEs contamination are elevated in cultivation areas more than in granite quarrying and mining areas. This study serves as a benchmark for conducting suitable environmental management strategies to scientists in Nigeria and other parts of the world.

Exploring distribution of potentially toxic elements in soil profiles to assess the geochemical background and contamination extent in soils of a metallurgical and industrial area in Kosovo

This geochemical study explored the distribution of potentially toxic elements (PTEs), such as As, Cd, Co, Cr, Cu, Ni, Pb, Sb, Tl, U, and Zn, along soil profiles of a metallurgical and industrial area in Kosovo, with the aim of assessing geochemical background and contamination threshold of PTEs in soil, and defining surface and vertical level and extent of soil contamination by PTEs. The geochemical background was assessed by exploratory data analysis of PTE concentrations in soil profiles. The upper limit of geochemical background (contamination threshold) was used as reference value to calculate the single pollution index and establish the PTE contamination level. Cadmium, Pb, Sb, Zn were the primary soil contaminants and As, Cu, Tl the secondary ones. The main sources of soil contaminants were the Zvecan smelter for Pb, Sb, As, Cu, Tl, and the Trepca industrial complex for Cd and Zn. The highest levels of Pb and Sb contamination were found up to depths between 30 and 60 cm in soil profiles within 5 km north and south-east of the Zvecan smelter. Contamination by Pb and Sb decreased with depth and affected the whole thickness of soil profiles closer the smelter. Cadmium and Zn contamination declined with distance from the Trepca industrial complex and decreased with depth, extending down to depths of 40–90 cm and 30–70 cm, respectively. Anomalous natural concentrations of Co, Cr, and Ni were found in soils collected in the northern part of the study area, where the geology consists mainly of ultrabasic and basic magmatic rocks.

Pollution Assessment of Potentially Toxic Elements (PTEs) in Soils around the Yanzhuang Gold Mine Tailings Pond, Pinggu County, Beijing, China.

The accumulation of tailings from gold mining and smelting may result in PTE pollution. We investigated PTE contamination from a large amalgamated gold mine tailings pond in Pinggu County, Beijing. In November 2017, 30 soil samples were collected around the tailings pond. The concentrations and pollution degree of PTEs in the samples and the sources of Sb, As, Cd, Cu, Pb, Zn and Hg were analyzed. The average concentration of these elements in soil samples near the tailings pond (16.24, 28.29, 0.99, 171.04, 263.25, 99.73, 0.72 mg/kg, respectively) were higher than their corresponding standard values and background values of the study area. The geoaccumulation index showed that the pollution degree of As, Pb and Hg was moderate, while Sb and Cu present non-pollution to moderate pollution. The average EF values of the elements were Sb (38.31), As (4.23), Cd (0.71), Cu (3.68), Pb (21.24), Zn (0.82) and Hg (5.29), respectively. The environmental risk assessment developed throughout the PERI method indicated that Sb, As, Hg and Pb were the main pollutants in the study area. The three quantitative risk indicators (RI, Igeo and EF) were positively correlated, and all of them indicated that PTEs had significant pollution to the local area. Thus, Sb, As, Pb, Cu, and Hg pollution should be highly concerning. Multivariate statistical analysis shows that the pollution of PTEs was mainly caused by the accumulation of tailings ponds after gold mining and smelting. The research result is of great significance for the prevention and control of soil pollution of PTEs near the tailings pond.

Screening of Pioneer Metallophyte Plant Species with Phytoremediation Potential at a Severely Contaminated Hg and As Mining Site

Phytoremediation of mine soils contaminated by potentially toxic elements (PTEs) requires the use of tolerant plants given the specific conditions of toxicity in the altered soil ecosystems. In this sense, a survey was conducted in an ancient Hg-mining area named “El Terronal” (Asturias, Spain) which is severely affected by PTE contamination (As, Hg, Pb) to obtain an inventory of the spontaneous natural vegetation. A detailed habitat classification was performed and a specific index of coverage was applied after a one-year quadrat study in various sampling stations; seven species were finally selected (Agrostis tenuis, Betula celtiberica, Calluna vulgaris, Dactylis glomerata, Plantago lanceolata, Salix atrocinerea and Trifolium repens). A total of 21 samples (3 per plant) of the soil–plant system were collected and analyzed for the available and total concentrations of contaminants in soil and plants (roots and aerial parts). Most of the studied plant species were classified as non-accumulating plants, with particular exceptions as Calluna vulgaris for Pb and Dactylis glomerata for As. Overall, the results revealed interest for phytoremediation treatments, especially phytostabilization, as most of the plants studied were classified as excluder metallophytes.

Occurrence, distribution, and pollution indices of potentially toxic elements within the bed sediments of the riverine system in Pakistan.

Potentially toxic elements (PTEs) are a major source of pollution due to their toxicity, persistence, and bio-accumulating nature in riverine bed sediments. The sediment, as the largest storage and source of PTEs, plays an important role in transformation of mercury (Hg), lead (Pb), nickel (Ni), chromium (Cr), copper (Cu), zinc (Zn), and other toxic PTEs. Several important industrial hubs that contain a large population along the banks of different rivers, such as Kabul, Sutlej, Ravi, Jhelum, and Chenab in Pakistan, are acting as major sources of PTEs. In this study, 150 bed sediment samples (n=30 from each river) were collected from different sites. Total (acid extracted) PTE (Hg, Cu, Cr, Ni, Zn, and Pb) concentrations in bed sediments were determined using inductively coupled plasma mass spectrometry (ICP-MS). Sediment pollution indices were calculated in the major rivers of Pakistan. The results demonstrated high levels of Hg and Ni concentrations which exceeded the guideline standards of river authorities in the world. The contamination factor (CF) and contamination degree (CD) indices for Hg, Ni, and Pb showed a moderate to high (CF≥6 and CD≥24) contamination level in all the selected rivers. The values of geo-accumulation index (Igeo) were also high (Igeo≥5) for Hg and Pb and heavily polluted for Ni, while Cr, Cu, and Zn showed low to unpolluted (Igeo) values. Similarly, the enrichment factor (EF) values were moderately severe (5≤EF≤10) for Hg, Pb, and Ni in Sutlej, Ravi, and Jhelum, and severe (10≤EF≤25) in Kabul and Jhelum. Moreover, Hg and Ni showed severe to very severe enrichment in all the sampling sites. The ecological risk index (ERI) values represented considerable, moderate, and low risks, respectively, for Hg (The ERI value should not be bold. Please unbold the ERI in the whole paper. It should be same like RI, CD and EF.[Formula: see text]≥160), Pb and Ni (40≤[Formula: see text]≤80), and Cr, Cu, and Zn ([Formula: see text]≤40). Similarly, potential ecological risk index (PERI) values posed considerable (300≤RI≤600) risk in Ravi and moderate (150≤RI≤300) in Kabul and Jhelum, but low (RI≤150) risk in Ravi and Chenab. On the basis of the abovementioned results, it is concluded that bed sediment pollution can be dangerous for both ecological resources and human beings. Therefore, PTE contamination should be regularly monitored and a cost-effective and environmentally friendly wastewater treatment plant should be installed to ensure removal of PTEs before the discharge of effluents into the freshwater ecosystems.

Modelling the dynamics of the cancer risk due to potentially toxic elements in agricultural soils, in the upper Crocodile River catchment, North-West province, South Africa

Contaminated agricultural soil with potentially toxic elements (PTEs) poses a threat to food safety and can adversely affect human health. This study evaluates the potential health risk caused by PTEs contamination in cultivated soils and the possible related health effect. Sixty-four (64) soil samples from cultivated soils before crop cultivation and post-crop were harvested and twenty-four (24) soil samples from a natural game reserve park were collected and. The PTEs were analysed using the inductively coupled plasma-mass spectrometry (ICP-MS) for the following elements As, Cd, Cr, Cu, Ni, Pb, Zn, Mn, Al, and Fe. The contamination factor (CF), pollution load index (PLI), hazard quotient (HQ), and hazard index (HI) was calculated to assess the human health risks for the different pathways to the exposed population. A carcinogenic probabilistic risk model based on the mathematical derivation and PTEs transmission pathways is presented. The mean concentrations of the PTEs in the cultivated soil varied in order of Al > Fe > Mn > Cr > Ni > Zn > Cu > Pb > As > Cd. Cr and Ni concentrations in all the cultivated soils were found to be higher than the Canadian guidelines and the Finnish permissible threshold guidelines for agricultural. The CF in the soil indicates extreme contamination suggestion an ecotoxicological effect. The PLI value also suggests that the soils have undergone some form of deterioration, particularly with Cr and Ni. The ingestion seems to be the major pathway followed by dermal to children. The HQ and HI values for the children were > 1 indicating an adverse health effect for the children residing around the cultivated fields. The simulated results indicate that the percentage of the affected humans that may be consuming crop derived from the contaminated soil increases by a factor of 2 as the contamination factor increases. The transmission compartments can be used as an effective measure in which mitigation can be effectively used.

Microbial diversity and activity assessment in a 100-year-old lead mine

Mining activities frequently leave a legacy of residues that remain in the area for long periods causing the pollution of surroundings. We studied on a 100 year-old mine, the behavior of potentially toxic elements (PTEs) and their ecotoxicological impact on activity and diversity of microorganisms. The PTEs contamination assessment allowed the classification of the materials as highly (reference- and contaminated-samples) and very highly polluted (illegal spill of olive mill wastes (OMW), tailings, and dumps). OMW presented the lowest enzymatic activities while tailings and dumps had low dehydrogenase and arylsulfatase activities. All the α-diversity indices studied were negatively impacted in dumps. Tailings had lower Chao1 and PD whole tree values as compared to those of reference-samples. β-diversity analysis showed similar bacterial community composition for reference- and contaminated-samples, significantly differing from that of tailings and dumps. The relative abundance of Gemmatimonadetes, Bacteroidetes, and Verrucomicrobia was lower in OMW, tailings, and dumps as compared to reference-samples. Fifty-seven operational taxonomic units were selected as responsible for the changes observed between samples. This study highlights that assessing the relationship between physicochemical properties and microbial diversity and activity gives clues about ongoing regulating processes that can be helpful for stakeholders to define an appropriate management strategy.

Assessment of the impact of 2019 Karun River flood on river sediment in Ahvaz city area, Iran.

Following the 2019 Karun River's flood, this study was conducted to evaluate the impact on the physicochemical characteristics and potentially toxic elements (PTEs) concentrations in the sediments as compared to 2015 pre-flood study. Surficial and core samples were collected from the river bed stretching through Ahvaz city for analysis and evaluation. The physicochemical properties of the sediments and the concentrations of PTEs (Mn, Fe, Cr, Ni, As, Zn, Pb, and Cu) in samples were determined by standard methodology. The PTEs contamination in sediments was assessed by calculating the contamination factor and the contamination degree. The potential ecological risk index (RI) was used to assess the contamination degree and ecological effects of PTEs in sediments. The comparative results showed that the flood reduced the concentration of PTEs and organic carbon in the sediments. The flood also decreased the silt and clay content and increased the acidity and sand content compared to pre-flood samples. The post-flood ecological risk assessment revealed that the sediments remained as low risk as compared to pre-flood state. Reduction of post flood PTEs concentration in the sediments as compared to pre-flood concentrations is probably due to long-term exposure to pollutants in the pre-flood sediments. It appears the reduction in the amount of clay particles and organic carbon (as important adsorbents for pollutants) has resulted in reduction of pollutants in the sediments. Statistical analysis of PTEs in the post-flood sediments showed that the major source of metals is geogenic. It seems that despite being destructive for the inhabitants, the flood, has reduced the amount of pollutants and the ecological risk, in the study area, at least for a while.

The potential of elm trees (Ulmus glabra Huds.) for the phytostabilisation of potentially toxic elements in the riparian zone of the Sava River.

The use of trees to immobilise potentially toxic elements (PTEs) is a low-cost and effective method of soil remediation. Thus, the objective of this study was to assess the content of total and bioavailable As, Cd, Cr, Cu, Ni, Pb and Zn in soil samples, as well as their levels in the roots and leaves of elm (Ulmus glabra Huds.) in order to evaluate its potential for the phytostabilisation of PTEs in the riparian zone of the Sava River. Analysis of soils showed that the availability of PTEs ranged from low to medium, while the pollution load index (PLI) and potential ecological risk index (RI) showed that the examined soil fell into the category of uncontaminated to moderately contaminated, as well as into the category of low risk of PTEs contamination. However, the levels of Cr, Cu and Ni in soils were above the critical range for plants. The content of As and Cr measured in roots and leaves was in the toxic range for plants, while the content of Cd and Ni was elevated but not in the toxic range. Bioaccumulation (BCF) and translocation (TF) factors indicated that U. glabra is suitable for the phytostabilisation of As, Cu, Cr, Ni and Pb. Additionally, this species displayed the ability to transport most of the acquired Cu and Zn to the leaves. Correlation analysis showed that PTE content in U. glabra roots was significantly positively correlated to their respective levels in soil (total and DTPA-extractable), except for Cu, indicating that PTE levels in soil strongly influence those in plants. This research into a successful phytoremediating species provides new possibilities when selecting PTE-tolerant native trees in riparian zones of large regional rivers such as the Sava.

Spatial distribution of potentially toxic elements in urban soils of Abbottabad city, (N Pakistan): Evaluation for potential risk

Potentially toxic elements (PTE) are one of the main sources of soil toxicity with detrimental impacts on the environment due to their persistence, perseverance, and potential health risks. This study investigated the PTE such as nickel (Ni), lead (Pb), cadmium (Cd), cobalt (Co), iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn) contaminations in urban soils of Abbottabad city, (N Pakistan). For this purpose, soils from different land types were collected and assayed for PTE level using atomic absorption spectrometry. Results showed relatively higher Fe and lower Cd contamination. The contamination factor (Cf), pollution load index (PLI) and ecological risk index (ERI) of pollution quantification factors were determined for PTE contamination. Results showed the relatively high Cf values for Ni and low for Pb. The PLI crossed the threshold of 1 in 40% of sampling sites, indicating significant PTE contamination at those sites. The ERI indicated low to considerable risk of PTE contamination across all sampling sites. The PTE were evaluated for carcinogenic and non-carcinogenic risks via ingestion, inhalation and dermal pathways. Health index (HI) values of 1.48E-02 and 1.18E-02 and cancer risk (CR) values of 9.39E-09 and 2.03E-04 were found for adults and children, respectively. Potential sources of PTE were quantitatively allocated by principal component analysis (PCA) along with geo-spatial analysis, indicating natural and anthropogenic inputs.

Identification of the sources and influencing factors of potentially toxic elements accumulation in the soil from a typical karst region in Guangxi, Southwest China

Southwestern China contains the largest and most well-developed karst region in the world, and the potentially toxic elements (PTEs) content in the soils of the region is remarkably high. To explore the internal and external control factors and sources of soil PTEs enrichment in this area and to provide a basis for the treatment of PTE pollution, 113 soil samples were collected from Hengxian County, a karst region in Guangxi Province, southwestern China. The importance of eighteen influencing factors including parent material, weathering, physicochemical properties, topography and human activities were quantitatively analyzed by (partial) redundancy analysis. The sources of PTEs were identified using the Pb isotope ratio and absolute principal component score/multiple linear regression (APCS-MLR) model. The contents of all soil PTEs were higher than the corresponding background values of Guangxi soils. The contents in Cu, Zn, Cd, Hg and Pb were the highest in the soil from carbonate rock. The factor group of geological background and weathering explained 26.5% for the accumulation and distribution of soil PTEs and the influence of physicochemical properties was less than 2% but increased to 25.6% through interaction with weathering. Fe (47.1%), Al (42.1%), Mn (22%), chemical index of alteration (12.8%) and clay (11.9%) were the key factors affecting the soil PTEs, while the influence of human activities was weak. Pb isotope ratio and APCS-MLR classified 62.8–74% of soil PTEs as derived from natural sources, whereas 18.23% and 18.95% were derived from industrial activities and agricultural practice/traffic emissions, respectively. The Pb isotope ratio showed that the natural sources account for up to 90% of the Pb in the soil from carbonate rock, the highest contribution among the studied soils. The results of the study can provide background information on the soil PTEs contamination in the karst areas of China and other areas worldwide.

Enrichment of potentially toxic elements in the fine fraction of soils from Iraq and Kuwait

The fine fraction of soils in arid and semi-arid regions can be readily suspended into the atmosphere by winds and transported long distances, carrying potentially toxic elements (PTEs) associated with these source materials. In this study, environmentally available PTE loadings for As, Cd, Cr, Cu, Ni, Pb, V, and Zn were measured in the fine fraction (< 75 μm) of 19 bulk soil samples collected in 2007 from 4 sites in Iraq and 15 sites in Kuwait. Soil samples were mechanically sieved and particle size distribution in the fine fraction was measured using laser diffraction particle sizing. Major and minor element composition was determined in the soil fine fraction using energy-dispersive X-ray fluorescence. Sub-samples were digested using strong acids and analyzed using high-resolution inductively coupled mass spectrometry to assess the maximum environmental availability of PTEs in each fine fraction of each soil sample. Measured environmentally available PTE loadings were normalized to soluble iron to allow for an assessment of soil contamination at and between sites that included weathering effects and was more focused on the mobile fraction of the total PTE load. Physiologically based fluid extractions were also performed on select samples to assess potential bioavailability of PTEs through ingestion and inhalation. Results show significant PTE loadings and anthropogenic contamination in the fine fraction of soils from Iraq and Kuwait. All sites showed moderate-to-high Ni contamination but loadings and contamination levels for all PTEs varied among sites in Iraq and Kuwait as a function of weathering, local geology, and inputs from non-local and/or anthropogenic sources. PTE contamination tended to be higher in the fine fraction of soil collected at the sites in Iraq, and the lowest overall PTE loadings were found at sites in northern Kuwait where the mean measured particle diameter was largest. Potential bioavailability of PTEs via inhalation was generally low (< 10% of loading) but a significant portion of the PTE load for As, Cu, and Pb (and V and Zn at select sites) was available via ingestion. The fine fraction of soils collected from Iraq and Kuwait in this study had significant environmentally available PTE contamination. Sites from Lower Mesopotamia in Iraq were the most impacted. PTE loadings and contamination were strongly influenced by local-scale weathering and geology, proximity to urban PTE sources, and inputs from non-local and/or anthropogenic sources. Sites with a smaller mean particle diameter had the greatest levels of PTE contamination. Potential bioavailability of PTEs was generally low.

Associations of potentially toxic elements (PTEs) in drinking water and human biomarkers: a case study from five districts of Pakistan.

Potentially toxic elements (PTEs) are hazardous contaminants with great global environmental/ecological concerns due to their toxic, persistence, and bio-accumulative nature. This study investigates the concentrations of PTEs (Cd, Co, Cu, Fe, Ni, Mn, Pb, and Zn) in drinking water sources and consumers' biomarkers such as hair, nails, urine, and blood. For this purpose, drinking water (n = 190) and consumer biomarker (n = 60) samples were collected from five districts of the Southern Khyber Pakhtunkhwa, Pakistan. Samples were extracted and analyzed for selected PTEs concentrations using an inductively coupled plasma mass spectrometer (ICP-MS, PerkinElmer Optima 7000 DV, USA). The concentrations of PTEs were observed within the drinking water guidelines set by the World Health Organization (WHO), except for Fe, Mn, and Pb. The determined concentrations of PTEs were used to evaluate the health risk through exposure, particularly hazard quotient (HQ) and hazard index (HI). The PTEs contamination of drinking water has led to the highest mean ADI values (39.0 and 91.8μg/kg/day) and HQ values (0.306 and 0.130) for Zn in adults and children, respectively. The mean values of HQ and HI for selected PTEs were observed within the safe health limits (< 1). Among studied biomarkers, hair showed the highest concentrations for Mn, Zn, Cd, and Pb, plasma for Co and Cu, nails for Ni, and red blood cells (RBCs) for Fe only. This study concluded that chronic exposure of PTEs through drinking water consumption has led to their bioaccumulation in human biomarkers.