Potentially Toxic Elements Concentrations Research Articles

Trace metals enrichment and potential ecological risk in sediments of the Sepetiba Bay (Rio de Janeiro, SE Brazil)

The Sepetiba Bay (SB; SE Brazil) has been severely affected by growing of urbanization and industrial activity. This work aims to analyze the evolution of contamination by metals of sediments in SB. The results show a marked increasing trend in the concentrations of potentially toxic elements (PTEs), which is consistent with the rapid populational and industrial growth, mostly since 1970 CE. The remobilization and redistribution of sediments by currents have contributed to the dispersion of metals from the main source of pollutants to relatively distant regions. “Moderately to strongly polluted” sediments are also recorded in some sites in deeper sedimentary layers (namely in preindustrial periods), probably due to lithologic sources of the sediments. The concentrations of PTEs in SB are relatively high when compared with those found globally and in other Brazilian water bodies. Samples of high-resolution sediment cores confirmed that potential ecological risk to the coastal system is influenced not only through human actions but also by natural causes.

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.

Bioaccumulation and human health risks of potentially toxic elements in fish species from the southeastern Carajás Mineral Province, Brazil.

Anthropogenic activities may have increased the concentrations of potentially toxic elements (PTEs) in fish from the southeastern Carajás Mineral Province in Brazil, which has not yet been studied. The objectives were to determine the quality parameters of surface water and bottom sediments, and to assess the bioaccumulation and risks of Al, Fe, Ba, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Ti, V and Zn in fish species from the southeastern Carajás Mineral Province. Water, sediments and fish species (Colossoma macropomum, Curimata cyprinoides, Geophagussp., Leporinus trifasciatus, and Serrasalmus eigenmanni) were collected in 14 areas in the municipalities of Parauapebas, Marabá and Canaã dos Carajás, contemplating the Gelado Stream and the Parauapebas, Tapirapé and Itacaiúnas Rivers. Water samples were subjected to physicochemical analysis using a multiparameter meter. Concentrations of PTEs in all samples were quantified by inductively coupled plasma-optical emission spectrometry. Enrichment factor (EF) and geoaccumulation index (Igeo) were calculated to study the sediment enrichment and contamination. Ecological and human health risk assessments were performed to determine the risks to the environment and population's health. EF and Igeo revealed that the sediments from the Parauapebas River and Gelado Stream are respectively enriched by Ba, Co, Cu, Cr, Mn, Pb, and Ba, Co, Cr, Ni, Pb and V. The concentrations of Fe (1.67mg L-1) and Mn (0.11mgL-1) in water and the concentrations of Cr (>0.1mgkg-1) and Pb (>2mgkg-1) in fish were above the Brazilian legislation thresholds. The ecological risk assessment revealed considerable risk from Ni and moderate risk from multiple PTEs in sediments from the Gelado Stream. Human health risks were detected for Pb in all fish species and for Mo in L.trifasciatus. These results indicate that techniques for monitoring and controlling contamination must be implemented by the environmental agencies.

Phytoremediation of Soils Contaminated with Heavy Metals from Gold Mining Activities Using Clidemia sericea D. Don.

Soils contaminated by potentially toxic elements (PTEs) as a result of anthropogenic activities such as mining are a problem due to the adverse effects on human and environmental health, making it necessary to seek sustainable strategies to remediate contaminated areas. The objective of this study was to evaluate the species Clidemia sericea D. Don for the phytoremediation of soils contaminated with PTEs (Hg, Pb, and Cd) from gold mining activities. The study was conducted for three months, with soils from a gold mining area in northern Colombia, and seeds of C. sericea, under a completely randomized experimental design with one factor (concentration of PTEs in soil) and four levels (control (T0), low (T1), medium (T2), and high (T3)), each treatment in triplicate, for a total of twelve experimental units. Phytotoxic effects on plants, bioconcentration (BCF), and translocation (TF) factors were determined. The results obtained for the tissues differed in order of metal accumulation, with the root showing the highest concentration of metals. The highest values of bioconcentration (BCF > 1) were presented for Hg at T3 and Cd in the four treatments; and of translocation (TF > 1) for Hg and Pb at T0 and T1; however, for Pb, the TF indicates that it is transferable, but it is not considered for phytoextraction. Thus, C. sericea demonstrated its potential as a phytostabilizer of Hg and Cd in mining soils, strengthening as a wild species with results of resistance to the stress of the PTEs evaluated, presenting similar behavior and little phytotoxic affectation on the growth and development of each of the plants in the different treatments.

Assessment of Potentially Toxic Elements’ Contamination in the Soil of Greater Cairo, Egypt Using Geochemical and Magnetic Attributes

Enhanced soil’s magnetic susceptibility reflects particles of anthropogenic/natural origin; therefore, it can be utilized as an indication of soil contamination. A total of 51 different land-use soil samples collected from Greater Cairo, Egypt, were assessed integrally using potentially toxic elements content (PTEs), magnetic susceptibility, and statistical and spatial analysis. PTE concentrations were compared to the world average, threshold, and screening values set by literature. Various environmental indices were estimated to assess soil contamination with these elements. Spatial distribution maps of PTEs and environmental indices were constructed to provide decision makers with a certain identification of riskier areas. In general, the concentrations of the analyzed PTEs showed variation with land-use types and follows a pattern of: Industrial > Agricultural > Urban. The distribution of PTEs in Greater Cairo was influenced by several anthropogenic sources, including traffic emission, industrial activity, and agricultural practices. The measured magnetic susceptibility values indicate magnetically enhanced soil signals dominated by multi-domain or pseudo-single-domain superparamagnetic particles of anthropogenic origin. A significant association was observed between magnetic susceptibility values and Co, Cr, Cu, Ni, and V, and the calculated environmental indices. It can be concluded that magnetic susceptibility is of proven effectivity in the assessment of soil contamination.

Prediction of nickel concentration in peri-urban and urban soils using hybridized empirical bayesian kriging and support vector machine regression

Soil pollution is a big issue caused by anthropogenic activities. The spatial distribution of potentially toxic elements (PTEs) varies in most urban and peri-urban areas. As a result, spatially predicting the PTEs content in such soil is difficult. A total number of 115 samples were obtained from Frydek Mistek in the Czech Republic. Calcium (Ca), magnesium (Mg), potassium (K), and nickel (Ni) concentrations were determined using Inductively Coupled Plasma Optical Emission Spectroscopy. The response variable was Ni, while the predictors were Ca, Mg, and K. The correlation matrix between the response variable and the predictors revealed a satisfactory correlation between the elements. The prediction results indicated that support vector machine regression (SVMR) performed well, although its estimated root mean square error (RMSE) (235.974 mg/kg) and mean absolute error (MAE) (166.946 mg/kg) were higher when compared with the other methods applied. The hybridized model of empirical bayesian kriging-multiple linear regression (EBK-MLR) performed poorly, as evidenced by a coefficient of determination value of less than 0.1. The empirical bayesian kriging-support vector machine regression (EBK-SVMR) model was the optimal model, with low RMSE (95.479 mg/kg) and MAE (77.368 mg/kg) values and a high coefficient of determination (R2 = 0.637). EBK-SVMR modelling technique output was visualized using a self-organizing map. The clustered neurons of the hybridized model CakMg-EBK-SVMR component plane showed a diverse colour pattern predicting the concentration of Ni in the urban and peri-urban soil. The results proved that combining EBK and SVMR is an effective technique for predicting Ni concentrations in urban and peri-urban soil.

Comparative study on the characteristics and environmental risk of potentially toxic elements in biochar obtained via pyrolysis of swine manure at lab and pilot scales

Pyrolysis is considered as a promising method to immobilize potentially toxic elements (PTEs) in animal manures. However, comparative study on characteristics and environmental risk of PTEs in biochar obtained by pyrolysis of animal manure at different reactors are lacking. In this study, swine manure was pyrolyzed at 300–600 °C in a lab-scale or pilot-scale reactor with the aim to investigate their effects on characteristics and environmental risk of As, Cd, Cu, Ni, Pb, and Zn in swine manure biochar. Results showed that biochars produced from pilot scale had lower pH and carbon (C) content but higher oxygen (O) content than those from lab scale. Biochars from pilot scale had higher total PTEs (except Cd) concentrations and releasable PTEs (except Pb) but lower CaCl2-extractable PTEs and phytotoxicity germination index (GI) to radish seedings than those from lab scale. Chemical speciation analysis indicated that PTEs in biochar produced from pilot-scale fast pyrolysis at 400 °C had higher percentage of more stable fraction (F5 fraction) and lower potential ecological risk index (RI) than those from lab-scale slow pyrolysis. These findings demonstrated that bioavailability and potential ecological risk of PTE in swine manure biochar were greatly decrease in the pilot-scale pyrolysis reactor and the optimum temperature was 400 °C considering the lowest potential ecological risk index.

Assessment of Potentially Toxic Element Concentrations in Soil And Vegetables and Impact on Human Health Through TF, EDI, and HRI Indicators: Case Study Anadrinia Region (Kosovo).

Vegetable cultivation areas in the Anadrinia region may have higher than background concentrations of potentially toxic elements (PTEs) from contaminated sources including anthropogenic activity and lithologic composition. The purpose of the present study was to assess PTEs concentrations in soil and vegetables and their impact on human health. In this study, 50 soils and 5 vegetables were sampled from the studied area. PTEs (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn) were measured by inductively coupled plasma optical emission spectroscopy (ICP-OES) after digestion in microwave system. PTEs in soil and vegetables were assessed and compared to international data (Dutch List and WHO/FAO 2011), and their toxicological risk was estimated using transfer factor (TF), estimated daily intake (EDI), and hazard quotients (HQ). The average values of As, Cd, Co, Fe, and Mn in soil were 44.96, 0.324, 16.34, 13,172, and 765.1 mg/kg, and Cr, Ni, and Pb in vegetables were 21.02, 17.11, and 4.982 mg/kg. TF values were less than 1, suggesting low bioaccumulation. EDI values of Cu, Ni, Pb, and Zn were 6.29, 6.23, 2.09, and 16.6 mg/kg, higher than international guidelines. HQ values of Pb, Ni, and Cu were 6.22, 3.66, and 1.72, higher than maximum tolerable value 1 indicating significant health risk. Some of the analyzed elements in soil and vegetable exceeded permissible limits to Dutch List and WHO/FAO 2011, respectively. From a health point of view, this study revealed vegetable contamination, recommends periodic monitoring.

Dissolved Potentially Toxic Elements (PTEs) in Relation to Depuration Plant Outflows in Adriatic Coastal Waters: A Two Year Monitoring Survey

The Adriatic Sea is vulnerable to pollution due to its low bathymetry, intense industrial activity, and tourism. In this context, a good depuration plant activity could play a key role for the maintenance of a good environmental quality. In the framework of the AdSWiM project, “Managed use of treated urban wastewater for the quality of the Adriatic Sea”, a study on dissolved potentially toxic element (PTE) levels was carried out to assess the impact of treated urban wastewaters on the quality of the bathing waters in the Adriatic Sea during the 2019 and 2020 summer period. In the present study, three areas along the Italian–Croatian coastline (Gulf of Trieste, Zadar, and Split) were identified for the monitoring of five depuration plant (DP) outflows. Water samples were collected after the treatment inside the DPs, and coastal seawater was sampled in the proximity of the discharging pipelines. Dissolved Hg, Cd, and As levels were determined with an atomic fluorescence spectrometer. Results did not show statistically significant differences between treated wastewater and seawater samples (Hg 10 ± 6 and 10 ± 4, Cd 14 ± 6 and 21 ± 8, As 610 ± 176 and 687 ± 140 ng L−1, respectively), while the geographical area and the seasonality affected the PTE concentration. Furthermore, the levels detected were lower than the European and national limits, indicating a good environmental status of the northern Adriatic Sea waters. The determination of further parameters (nutrients, microbiological indicators) must be investigated to identify possible synergistic effects. However, our results demonstrate the efficiency of DPs investigated, underlining the importance of the wastewater treatment for the protection of the Adriatic Sea.

Contamination Levels and the Ecological and Human Health Risks of Potentially Toxic Elements (PTEs) in Soil of Baoshan Area, Southwest China

The primary goals of this study were to reveal the environmental status of potentially toxic elements (PTEs) and their ecological risks, as well as their associated health risks in the Baoshan area, southwest China, which has been surveyed with the scale of 1:250,000 geochemical mapping. Based on a comparison of the PTE concentrations with the soil environmental quality of China and the enrichment factor (EF), geo-accumulation index (Igeo), contamination factor (Cf), and potential ecological risk indexes (Eri and PERI), as well as the potential non-carcinogenic hazard indices (HI and CHI) and carcinogenic risks indices (TCR and CTCR), the following conclusions were drawn: The PTE concentrations in the surface soil samples that were collected from the investigated area (1.65% sites) exceeded the risk intervention values (RIV) for soil contamination of agricultural land of China. Cadmium (Cd) and mercury (Hg) posed higher ecological risks than other PTEs (arsenic (As), chromium (Cr), lead (Pb), copper (Cu), nickel (Ni), and zinc (Zn)), which was highlighted by their toxic response factor. Arsenic was the main PTE with a non-carcinogenic risk (19.57% sites for children and 0.25% sites for adults) and the only PTE that carries a carcinogenic risk (2.67% sites for Children and 0.76% sites for adults) to humans in the research area. Children are more vulnerable to health risks when compared to adults because of their behavioral and physiological traits. Geological genesis was responsible for the high concentrations, ecological risk, and health risk distribution patterns of the examined PTEs. Even though the present research highlights several important aspects related to PTE pollution in the research area, further investigations are needed, especially in mining areas.

SPATIAL DISTRIBUTION AND ECOLOGICAL RISK OF POTENTIALLY TOXIC ELEMENTS IN MAROS REGENCY, INDONESIA

Air pollution is a major environmental problem in Indonesia. Potentially toxic elements (PTEs) which bounded to particulate matter (PM) samples were collected from Maros karst area, the second largest karst in the world. The seasonal levels of PTEs and ecological risk assessment were used to investigate the pollution levels near the residential areas using pollution load index (PLI) and potential ecological risk index (PERI). Spatial distributions of ecological risks based on the PTEs concentration have been explored with Empirical Bayesian Kriging method. The result indicated the mean concentration of PTEs (Cr, Pb, Cu, As and Zn) were significantly higher in dry season than wet season. Based on the PERI and PLI values, the PTEs accumulation are more severe near industrial activities and traffic roads. Hotspots of the PTEs were located in the East and Southeast area. The implications of this study could be used to optimize the management strategies in controlling the PTEs pollution and become a scientific reference for taking environmental protection policies

Effects of mining on the potentially toxic elements in the surrounding soils in China: A meta-analysis

Previous studies about the effects of mining on the potentially toxic elements (PTEs) in the surrounding soils mainly focused on single or few mining areas. However, these studies couldn't comprehensively quantify the mining-induced variations of soil PTE concentrations at the national scale. Moreover, the quantitative relationships between the effects of mining on soil PTEs and some related factors remained unclear at the national scale. This study first conducted a literature survey for soil PTE data affected by mining in China. Then, the random-effects model in the meta-analysis was used to quantify mining-induced variations of soil PTE concentrations in the surrounding areas. Last, the single meta-regression was used to explore the relationships between the effects of mining on soil PTEs and the related factors at the national scale. Results showed that: (i) mining-induced increases of soil PTE concentrations followed the order: Cd (1017%) > Hg (319%) > Pb (291%) > Zn (176%) > Cu (129%) > As (92%) > Ni (23%); (ii) mining-induced increases of soil PTE concentrations in clay (531%), non-ferrous mine (188%), paddy field (212%), and Central South China (290%) were more than those in other soil textures, mine types, land-use types, and geographical divisions, respectively; (iii) the effects of mining on soil PTEs were negatively correlated with soil pH (QM = 29.76, p < 0.01) and positively correlated with soil organic carbon (QM = 28.54, p < 0.01) and mean annual precipitation (QM = 91.75, p < 0.01); (iv) the effects of mining overall decreased with the sampling year (QM = 35.01, p < 0.01) and showed latitudinal zonality (QM = 180.39, p < 0.01). The above results provided valuable information for soil PTE mitigation in the areas affected by mining in China.

Integrated assessment of the impact of land use types on soil pollution by potentially toxic elements and the associated ecological and human health risk

The impact of land use type on the content of potentially toxic elements (PTEs) in the soils of the Qinghai-Tibet Plateau (QTP) and the associated ecological and human health risks has drawn great attention. Consequently, in this study, top- and subsurface soil samples were collected from areas with four different land uses (i.e., cropland, forest, grassland, and developed area) and the total contents of Cr, Cd, Cu, Pb and Zn were determined. Geostatistical analysis, self-organizing map (SOM), and positive matrix factorization (PMF), ecological risk assessment (ERA) and human health risk assessment (HRA) were applied and used to classify and identify the contamination sources and assess the potential risk. Partial least squares path modeling (PLS-PM) was applied to clarify the relationship of land use with PTE contents and risk. The PTE contents in all topsoil samples surpassed the respective background concentrations of China and corresponding subsurface concentrations. However, the ecological risk of all soil samples remained at a moderate or considerable level across the four land use types. Developed area and cropland showed a higher ecological risk than the other two land use types. Industrial discharges (32.8%), agricultural inputs (22.6%), natural sources (23.7%), and traffic emissions (20.9%) were the primary PTE sources in the tested soils, which indicate that anthropogenic activities have significantly affected soil PTE contents to a greater extent than other sources. Industrial discharge was the most prominent source of non-carcinogenic health risk, contributing 37.7% for adults and 35.2% for children of the total risk. The results of PLS-PM revealed that land use change associated with intensive human activities such as industrial activities and agricultural practices distinctly affected the PTE contents in soils of the Qinghai-Tibet Plateau.

Non-Lethal Assessment of Potentially Toxic Elements Across Mammalian Trophic Levels in African Savannahs

South Africa is one of the most diverse countries in the world but the increase in agricultural, industrial and technological development to meet the needs of the growing human population has led to increased amounts of potentially toxic elements (PTEs) and other chemicals in the environment. As regional and global environmental processes influence local conditions to differing degrees, all organisms within a specific environment are exposed to highly complex, ill-defined PTE and chemical mixtures. Differences in feeding strategies within and between vertebrate trophic levels are likely to influence the degree to which individuals may be exposed to and affected by PTE presence. Using vertebrate faeces as a biological matrix, we investigate and compare quantitative differences in PTE concentrations in herbivorous, omnivorous and carnivorous terrestrial vertebrates from two protected areas in South African savannah. Of the eleven PTEs assessed [aluminium (Al), arsenic (As), barium (Ba), cadmium (Cd), chromium (Cr), mercury (Hg), lead (Pb), antimony (Sb), tin (Sn), strontium (Sr), and vanadium (V)], the highest concentrations of Al, As, Cr, Pb, Sn, and V were found in carnivores. General patterns were evident between groups at each site for specific elements, but absolute values for the same elements were site-specific. This is the first study to non-invasively examine and compare PTE concentrations in a variety of free-ranging mammalian wildlife occupying different trophic levels within South African protected areas. Our results confirm that all individuals across trophic levels within these sites are exposed to multiple and varied PTE mixtures on a continuous basis. Whether PTEs at these concentrations cause synergistic or antagonistic disruption of physiological and biological systems alone or in combination in free-ranging African wildlife species is still unclear and requires further investigation.

New Eco-Sustainable Feed in Aquaculture: Influence of Insect-Based Diets on the Content of Potentially Toxic Elements in the Experimental Model Zebrafish (Danio rerio).

According to the concept of circular economy, insects represent good candidates as aquafeed ingredients. Nevertheless, there are some potential chemical risks linked with insect consumption. In this study, we reared the teleost Danio rerio, used as an experimental model, with five experimental diets characterized by increasing levels (0%, 25%, 50%, 75%, and 100%) of full-fat Hermetia illucens (Hi) prepupae, substituting for fish meal (FM) and fish oil (FO). We investigated the presence of potentially toxic elements (PTEs) Cd, Pb, Ni, As, and Hg in larval (20 days), juvenile (2 months), and adult (6 months) fish. Quantitative determinations of Cd, Pb, Ni, and As were made with an atomic absorption spectrometer; the total mercury content was determined by a direct mercury analyzer. The substitution of FM and FO with Hermetia illucens meal led to a reduction in the content of some PTEs, such as Pb, As, and Ni, in fishfeed, leading to concentrations below the legal limit of undesirable substances in animal feed. By increasing the Hi meal dietary content, we observed in the Danio rerio specimens an increase in Cd, Pb, and Ni content and a reduction in As content for all life stages. Moreover, a general increase in the content of Cd, Pb, Hg, and Ni from larvae to juvenile was measured, while the shift of Danio rerio from the juvenile to the adult stage involved a significant increase in the content of Pb, Hg, and Ni. Larvae had a reduced ability to bioaccumulate metal(loid)s compared to juveniles and adults. In conclusion, the content of PTEs in Danio rerio is influenced both by the type of diet administered and by the life stage of the animal itself. This research demonstrates the possibility of using Hi prepupae as an aquafeed ingredient without exposing fish to a chemical risk and, in perspective, allows applying these eco-sustainable diets for the breeding of edible fish species, without endangering human health.

Phytoremediator Potential of Ipomea asarifolia in Gold Mine Waste Treated with Iron Impregnated Biochar

Growing environmental pollution in recent decades has been generating potentially toxic elements (PTE) which pose an ongoing threat to terrestrial and aquatic ecosystems and human health, especially in mining areas. Biochar and PTE-tolerant species have been used in soil remediation as they are environmentally friendly alternatives. This study aimed to assess the influence of açaí seed biochar (Euterpe oleracea Mart), impregnated with iron (BFe) or not (BC), on the bioavailability of PTEs, in a multi-contaminated soil from a gold (Au) mining area in the Amazon, using Ipomea asarifolia as a plant test since it was naturally growing on the tailings. BC increased the soil pH while BFe reduced. Biochars increased PTEs in the oxidizable fraction (linked to soil organic matter). The use of BC and BFe improved the immobilization of PTEs and BC increased arsenic (As) in the easily soluble fraction in the soil. Moreover, plants grown with biochars showed lower dry matter yield, higher concentrations of PTEs and lower nutrient content than the control treatment. According to the phytoextraction and translocation factors, Ipomea asarifolia can be classified as a species with potential for phytostabilization of Zn and tolerant to other PTEs, mainly As.

Potentially toxic elements in cascade dams-influenced river originated from Tibetan Plateau

Rivers originated from Tibetan Plateau are of great significance due to their environmental sensibility and fragility. However, the pollution of suspended particulate matter (SPM) in these rivers is rarely reported, in particular, the potentially toxic elements (PTEs) contamination. To clarify the status, sources, behavior, and risks of PTEs in SPM, a full investigation was conducted in dams-influenced Lancangjiang River basin. The findings revealed that the PTEs content (mg kg−1) ranked Mn (766) > V (151.7) > Zn (131.0) > Cr (94.6) > Ni (44.2) > Pb (36.7) > Cu (29.4) > Co (14.6) > Sb (2.6) > Mo (1.6) > Tl (0.78) > Cd (0.48). The multi-index assessment suggested that Sb and Cd were moderately severe to severe enriched PTEs with the enrichment factor values of 10.0 and 8.8 and the geo-accumulation index values of 2.2 and 2.0, respectively, while the rest of PTEs were minor/no enrichment. In contrast, Cr and Ni were major toxic elements in SPM which contributed 25 ± 10%, 24 ± 8% to the total toxic risk index. The high partition coefficients (e.g., 6.1 for Cr) were observed in most PTEs and resulted in the 96.3% of Cr, 85.2% of Zn, 83.6% of Pb, 77.8% of Ni, and 63.2% of Cu transportation in the SPM form. Natural inputs (e.g., soil erosion) are the main source (53.6%∼61.9%) of V, Cr, Mn, Co, Ni, and Tl, while fuel burning contributed 40.9% of Zn, 32.5% of Pb, and 37.3% of Cd. Moreover, 51.2% of Sb was attributed to industrial waste source, while porphyry copper/molybdenum deposits related milltailings were the co-source of Mo (54.4%) and Cu (34.8%). Overall, the PTEs geochemistry of SPM showed the potential in tracing regional environmental change.

Predictive modeling of contents of potentially toxic elements using morphometric data, proximal sensing, and chemical and physical properties of soils under mining influence

Several anthropic activities, especially mining, have contributed to the exacerbation of contents of potentially toxic elements in soils around the world. Mines can release a large amount of direct sources of contaminants into the environment, and even after the mines are no longer being exploited, the environmental liabilities generated may continue to provide contamination risks. Potentially toxic elements (PTEs), when present in the environment, can enter the food chain, promoting serious risks to human health and the ecosystem. Several methods have been used to determine the contents of PTEs in soils, but most are laborious, costly and generate waste. In this study, we use a methodological framework to optimize the prediction of levels of PTEs in soils.We used a total set of 120 soil samples, collected at a depth of 0–10 cm. The covariate database is composed of variables measured by proximal sensors, physical and chemical soil characteristics, and morphometric data derived from a DEM with a spatial resolution of 30 m. Five machine learning algorithms were tested: Random Forests, Cubist, Linear Model, Support Vector Machine and K Nearest Neighbor. In general, the Cubist algorithm produced better results in predicting the contents of Pb, Zn, Ba and Fe compared to the other tested models. For the Al contents, the Support Vector Machine produced the best prediction. For the Cr contents, all models showed low predictive power. The most important covariates in predicting the contents of PTEs varied according to the studied element. However, x-ray fluorescence measurements, textural and morphometric variables stood out for all elements. The methodology structure reported in this study represents an alternative for fast, low-cost prediction of PTEs in soils, in addition to being efficient and economical for monitoring potentially contaminated areas and obtaining quality reference values for soils.

Potentially toxic elements in invasive fish species Prussian carp (Carassius gibelio) from different freshwater ecosystems and human exposure assessment.

Concentrations of Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Sn, and Zn were detected in the muscle and gills of Prussian carp from three different freshwater ecosystems: isolated ponds and the South Morava River in Serbia, and Kopačko Lake in complex wetland ecosystem of the Kopački Rit Nature Reserve in Croatia. The main goals of the present research were to assess the concentrations of potentially toxic elements (PTEs) in the muscle and gills of Prussian carp (Carassius gibelio), to examine whether abiotic factors from three different freshwater ecosystems affect the accumulation of PTEs in fish tissues, and to estimate the human health risk resulting from fish consumption. There were only six concentrations of PTEs in the gill tissue (Cr, Hg, Mn, Pb, Sn, and Zn) that were not significantly different among the different freshwater ecosystems. In the muscles, the differences were much less visible. Kopačko Lake distinguished with the highest values of metal pollution index (MPI) for muscles (0.24) and isolated ponds with the highest values of MPI for gills (0.8). The redundancy analysis (RDA) showed that concentrations of Al, Mn, Zn, Cu, and Fe in the gill tissue were significantly correlated with the environmental variables. In contrast, the RDA based on element concentrations in the fish muscles indicated no significant relationship with the environment. Isolated ponds, with no inflow of freshwater, stand out as the most polluted, followed by Kopačko Lake with occasional floods. Flowing freshwater ecosystem South Morava River can be single out as at least polluted with PTEs. The target hazard quotients (THQ) and hazard index (HI) suggested there were no significant noncarcinogenic health risks. The target carcinogenic risk factor (TR) for As and Pb confirmed there were no cancer risks related to human fish consumption. Since the elevated concentrations of toxic Cd and As in Prussian carp were estimated, an early warning should be assumed, especially for fishing activities in these areas.

J. curcas and Manihot esculenta are potential super plants for phytoremediation in multi-contaminated mine spoils

Phytoremediation approaches have increasingly been applied in environmental remediation projects. In this study, the potentials of Manihot esculenta (M. esculenta), Vigna unguiculata (V. unguiculata) and J. curcas curcas (J. curcas) in remediating multi-contaminated mine spoils was evaluated. The target potentially toxic elements (PTEs) are Cd, As, Zn, Pb, and Hg. The test plants were grown and monitored under growth stress conditions for 270 days. Using inductively Coupled Plasma- Mass Spectrometry and EPA method 200.8, the total elemental contents in the shoot and root parts of the plants were determined. Significant differences (p&lt; 0.01) were observed in the uptake performance of the test plants. For example, M. esculenta and J. curcas, bioaccumulated 50- 80 % of the various baseline PTE contents in their root parts at 270 days after planting. In contrast, &lt; 27 % of PTEs were found in the root parts of V. unguiculata, except Zn at 70 %. Growth stressors and soil PTEs were factors that reduced biomass production in respective plants by 25 %. Cummulatively, the performance order M. esculenta&gt; J. curcas&gt; V. unguiculata was observed for multi-contaminant removal in soils. Techniques for enhancing the easy cultivation of the test plants are recommended to enhance their applicabilities in phytoremediation projects.