Accumulation Of Potentially Toxic Elements Research Articles

Potentially Toxic Elements' Accumulation in Relation to Sediment Physicochemical Attributes and Microplastic Content in Zayandeh-Rood River, Iran.

Microplastics (MPs) are an emerging pollutant whose ability to adsorb potentially toxic elements (PTEs) poses a serious threat to aquatic ecosystems, including rivers. In highly developed basins, the abundance of MPs in river sediment is expected to be high, elevating the sedimentary accumulation of PTEs. This hypothesis was tested in the Zayandeh-Rood River, Central Iran, with 21 sediment sampling stations distributed along the entire river stretch. Results of sediment analysis showed significant variations in the abundance and size of MPs, with concentrations ranked as Ba (270.71mg/kg) > Li (21.29mg/kg) > Cs (2.50mg/kg) > Be (1.44mg/kg) > Sn (1.17mg/kg) > Mo (1.06mg/kg) > Ag (0.76mg/kg), along with sediment physicochemical attributes such as EC, TOC, pH and grain size. MPs were identified in all sediment samples with a mean of 588 items/kg dry weight. Except for Ag, all other PTEs were classified as uncontaminated but exhibited increased enrichment downstream. According to the results of the generalized additive model (maximum R-sq of 0.766), the sedimentary concentration of the majority of PTEs is nonlinearly and positively associated with smaller and more abundant MPs. This study acknowledges that MPs might influence sediment porosity, permeability and structure, thereby directly affecting the settling dynamics of other particles, especially PTEs.

Source Apportionment and Health Risk Assessment of Groundwater Potentially Toxic Elements (PTEs) Pollution Characteristics in an Accident Site in Zhangqiu, China

Source Apportionment and Health Risk Assessment of Groundwater Potentially Toxic Elements (PTEs) Pollution Characteristics in an Accident Site in Zhangqiu, China

ASSESSMENT OF THE POTENTIALLY TOXIC ELEMENTS CONTAMINATION AND THEIR UPTAKE BY AMBROSIA ARTEMISIIFOLIA L. IN SOILS IN THE NORTHERN PART OF BOSNIA AND HERZEGOVINA

This research focused on the determination of potentially toxic elements (PTEs) distribution in different agricultural soils and Ambrosia atremisiifolia L. (ragweed) at seven, different locations in the northern part of Bosnia and Herzegovina (BiH). Quantification of PTEs was done using atomic absorption spectrophotometry provided after acid digestion of the air-dried samples of soil and plant material. Determined content of elements in the soils increased as follows: Cd<Pb<Cu<Zn<Cr<Ni<Mn<Fe and were under the allowed maximum for unpolluted soils, except for Ni and Cr. However, transfer of Ni and Cr from the soil to the ragweed as well as their bioaccumulation was not intensive. Established metal contents ratio from plant tissues (root and shoot) to soil for both elements, represented their bioaccumulation factors (BAF), which were extremely low in the roots, as well as in the shoots, both in average less than 0.2. On the other hand, Zn showed a tendency to accumulate in ragweed shoots (BAF=2.07). The study showed that uptake and accumulation of PTEs in the ragweed was mainly influenced by their content in the soil, as well as specific characteristics and biological role of each element. Hence, content of PTEs in the ragweed tissue could be used as the soil contamination degree indicator.

Assessment of Nutrient Minerals and Potentially Toxic Elements in a Bangladesh-Origin Rice Cultivar (Oryza sativa cv. BR11) and Associated Health

Rice contributes significantly to both food security and livelihoods in Bangladesh. Despite challenges such as an immense population growth rate and decreased arable land since gaining independence, Bangladesh has attained self-sufficiency in rice production by adopting modern rice varieties (MRVs). However, not all introduced MRVs have gained widespread acceptance among farmers due to concerns about productivity and profitability. Notably, BR11, an MRV, stands out as a prominently adopted rice cultivar during the Aman rice-growing season. This study aims to assess the levels of essential nutrient minerals (Na, K, Ca and Mg) and potentially toxic elements (PTEs) (Cd, Cu, Pb, Ni, Co, Fe, Mn, Zn, Cr) in the BR11 rice cultivar and also to evaluate associated health risks. The concentrations of Na, K, Ca and Mg (mg 100 g–1) in the sampled BR11 rice cultivar were found to be 4.4 ± 2.4, 108.5 ± 24.9, 3.4 ± 0.4 and 4.5 ± 1.1, respectively. Among the PTEs, Cd, Pb, Ni, Co, or Cr contents were below the detection limit, while Fe, Mn, Zn and Cu contents (mg kg–1) were 12.0 ± 4.0, 9.2 ± 1.5, 18.7 ± 2.7 and 2.9 ± 1.0. Comparisons of PTE contents in BR11 rice cultivars exposed to industrial activities with those cultivated in non-industrial zones did not reveal any statistically significant variations (p < 0.05). The estimated daily intake of nutrient minerals through the consumption of BR11 rice was significantly below the daily recommended dietary reference intakes. Likewise, the accumulation of PTEs in the BR11 rice cultivar was well below the maximum allowable concentrations recommended by WHO or FAO. Health risk assessments, involving the computation of non-carcinogenic and carcinogenic risks, did not indicate any concerning risk scenarios associated with the consumption of the BR11 rice cultivar. The data suggests that BR11 is a safe MRV for daily consumption, affirming its suitability for inclusion in the daily diet.

Effect of freeze–thaw manipulation on phytostabilization of industrially contaminated soil with halloysite nanotubes

The latest trends in improving the performance properties of soils contaminated with potentially toxic elements (PTEs) relate to the possibility of using raw additives, including halloysite nanotubes (HNTs) due to eco-friendliness, and inexpensiveness. Lolium perenne L. was cultivated for 52 days in a greenhouse and then moved to a freezing–thawing chamber for 64 days. HNT addition into PTE-contaminated soil cultivated with grass under freezing–thawing conditions (FTC) was tested to demonstrate PTE immobilization during phytostabilization. The relative yields increased by 47% in HNT-enriched soil in a greenhouse, while under FTC decreased by 17% compared to the adequate greenhouse series. The higher PTE accumulation in roots in HNT presence was evident both in greenhouse and chamber conditions. (Cr/Cd and Cu)-relative contents were reduced in soil HNT-enriched-not-FTC-exposed, while (Cr and Cu) in HNT-enriched-FTC-exposed. PTE-immobilization was discernible by (Cd/Cr/Pb and Zn)-redistribution into the reducible fraction and (Cu/Ni and Zn) into the residual fraction in soil HNT-enriched-not-FTC-exposed. FTC and HNT facilitated transformation to the residual fraction mainly for Pb. Based on PTE-distribution patterns and redistribution indexes, HNT’s role in increasing PTE stability in soils not-FTC-exposed is more pronounced than in FTC-exposed compared to the adequate series. Sphingomonas, Acidobacterium, and Mycobacterium appeared in all soils. HNTs mitigated FTC’s negative effect on microbial diversity and increased Planctomycetia abundance.

Necrophagous flies as bioindicators in Cd and Zn co-contaminated areas of Tak Province, Thailand

Necrophagous flies may be effective bioindicators of chemical substances within polluted locations, as they are sensitive to environmental changes, have large populations, and thrive in a single location over their lifespan. Diversity and abundance of necrophagous flies were determined at livestock farms contaminated with potentially toxic elements (PTEs) in Tak Province and Nakhon Sawan Province, Thailand. Substantial soil zinc (Zn) concentrations (> 1100 mg kg−1) were detected at a cattle farm at Khaothong, Nakhon Sawan Province, and soil cadmium (Cd) values were significantly elevated (> 3 mg kg−1) at a cattle farm in Pha De, Tak Province. Anthropogenic inputs including Zn mining, domestic wastewater, and certain materials used in local agriculture were point sources of PTEs at the livestock farms in the Pha De and Khaothong subdistricts. Lower temperatures and humidity during the rainy season may have resulted in increased numbers of necrophagous flies, which was 1.5 times greater compared to the dry season. However, the dry season exhibited a higher PTE buildup in fly tissue. The order of important value index (IVI) values of the necrophagous flies were: Chrysomya megacephala (56.80), Musca domestica (27.21), C. rufifacies (25.40) and Sarcophaga spp. (17.54), respectively. These necrophagous flies may play a significant role in PTE-contaminated ecosystems based on their high IVI values, suggesting that they could be used as bioindicators of PTEs. Principal component analysis (PCA) results for necrophagous flies associated with each sampling site during the dry season were consistent with flies having substantial IVI values. Musca domestica and C. megacephala of both sexes displayed substantial correlations with Cr, Al, and Mn, while females of Sarcophaga spp. displayed strong associations with Cd. At the cattle farm in Khaothong, males of M. domestica showed a significant relationship with Zn, Cu, Pb, and Ni. When considering PTE accumulation capacity in flies commonly found at field sites, C. megacephala and M. domestica are the most suitable bioindicators of PTEs. This study confirms that necrophagous flies serve as reliable bioindicators of PTE pollution.

Soil enrichment of potentially toxic elements in relation to land‐use types in an alpine meadow of the Qinghai–Tibet Plateau

AbstractThe Qinghai–Tibet Plateau, a fragile ecosystem with unique biodiversity, is particularly susceptible to soil contamination from increasing anthropogenic activities like grazing and farming. However, research exploring the relationship between these factors remains limited. Our study examines soil changes and potentially toxic elements (PTEs) after converting alpine meadows, providing insight into the impact of land‐use in this area. We found significant differences in the concentrations of PTEs (Cd, Cr, Hg, and Pb) among the three land‐use types. Soil from Oat Field (OF) had lower levels of Cd, Cr, Hg, and Pb compared with Fence Enclosure (FE) and Winter Grazing (WG), indicating a potential uptake/phytoextraction of these elements by oats. Different profiles of soil physiochemical properties were also detected, particularly in the OF soil, which showed significantly lower available potassium, microbial carbon, and microbial nitrogen but higher soil bulk density and total and available phosphorus. Additionally, significant stratification was observed in soil concentrations of most studied PTEs and nutrients in FE and WG, but not in OF. Specifically, lower levels of As, Cr, and most nutrients were found in the top layer (0–10 cm) compared with the bottom layer (20–30 cm). By comparison, Cd and Hg showed higher concentrations in the top layer in FE. These contrasting trends suggest potential differences in the mobility or bioavailability of these elements in the soil of the alpine meadow. Furthermore, significantly negative correlations were found between most soil nutrients, and the concentrations of As, Cr, and Pb, whereas significantly positive associations were observed for soil nutrients with Cd and Hg. However, such relationships predominantly existed in soils of WG and FE, but not OF. Collectively, our results suggest the potentially disrupted PTE accumulation and nutrient distribution by anthropogenic activities, particularly agricultural practices within the studied land‐use types, and warrant further evaluation of the associated ecotoxicological risks.

Transfer of industrial contaminants from the inner to the outer region of Sepetiba Bay (SE Brazil) by dredge spoil dumping activities: a temporal record

A multiproxy approach involving grain size, geophysical (resistivity, magnetic susceptibility, and P-wave velocity), mineralogical (XRD), and geochemical (elemental, stable isotopes) data has been applied to core SP9 (128 cm long) to reconstruct natural and anthropogenic changes since ≈1850 AD (anno domine) (dating by 210Pb and 127Cs methods) in a distal region of Sepetiba Bay (SB), Rio de Janeiro State (SE Brazil). The analyzed core is a fine-grained sedimentary sequence (except its upper 20 cm). It comprises detrital particles derived from felsic and intermediate source rocks, as suggested by the fields defined by the biplot Zr vs TiO2 and the Al2O3/TiO2 ratios. Despite the increase in particle size at the top of the core, there was a progressive increase in the organic matter and potentially toxic elements (PTEs) contents and nutrients such as N and P. The geophysical data allowed us to identify the presence of subsurface (biogenic) gas, which suggests the occurrence of eutrophication processes in the study area despite its location in the outer region of the bay. Core SP9 records cyclical changes over the last ≈170 years in the mineralogical and elemental composition of the sediments and type of organic matter supplied to the bottom. These changes are associated with phases of more significant oceanic influence, salinity variations in the study area, and greater or lesser oxygen depletion in the sediment. These changes may have resulted from climatic oscillations or variations in the configuration and extension of the Ponta da Pombeba spit. The extent of this structure and the anthropic activities have contributed to the contamination of this area since 1975 AD. However, statistical analyses (Pearson correlations and principal components analysis) suggest that the transport and accumulation of PTEs (mainly Cd and Zn) did not strictly follow the general pattern of sedimentary dynamics prevailing in the studied area. Results indicate that this area became strongly polluted by Cd and Zn and with high ecological risk due to dredging and spoil disposal activities at sites close to the study area. It is noted that the environmental degradation reached higher levels here than in areas close to the primary source of the metals, the disabled Ingá Mercantil Company, in Madeira Island. This work demonstrates the temporal effect of dredge disposal activities in a distal region of Sepetiba Bay for the first time. It is a strong indicator that dredged spoil areas must be selected carefully, since healthy areas can become degraded due to the dumping of polluted waste.

Bioaccummulation and health risk assessment of some potentially toxic elements in crops from farms round granite quarry sites in ibadan southwestern nigeria

Potentially toxic elements (PTEs) in food crops have significant apprehension in the environment because of their impending human health risks. This study thus assessed PTEs concentrations in soils and crops from farmlands around quarry sites, quantifies their level of uptake by the crops and their potential health risks to human. Collection of Soil and crop (Dioscorea alata, Colocasia esculenta and Manihot esculenta ) samples were done and analysed for Fe, Mn, Pb, Zn, Cu, Cr, Co, Ni and Cd using suitable instrumentation methods Data were evaluated using accumulation factor (AF), calculated daily intakes (CDI), target hazard quotent (THQ) and hazard index (HI). Farmlands soils that are closer to studied sites had higher PTEs concentrations than those that are farther away. Mean PTEs concentrations in the crops were in the order of Dioscorea alata > Colocasia esculenta > Manihot esculenta. Mean values of AF are less than one indicating low potential PTEs accumulation in the crops. The mean CDI in mg/kg/day of PTEs in crops for children and adults were 0.0001 -0.060 while THQ values are in order Pb> Mn>Cu> Cd>Ni> Co>Fe >Zn>Cr. Hazard index (HI) is greater than one in all the crops from the farmlands closer to quarry sites, indicating risk upon consumption. Thus, necessary remediation methods should be taken to reduce the effect of these PTEs on the environment.

Assessment of land use effect, mapping of human health risks and chemometric analysis of potential toxic elements in topsoils of Aran-o-Bidgol, Iran.

This study examines topsoil contamination in Aran-o-Bidgol urban region of central Iran, with a focus on potentially toxic elements (PTEs). A total of 135 topsoil samples in different land types were characterized, ranging from areas with agricultural farms, desert, industrial and residential activity, and brick kilns. The average concentrations of Cd, Pb, Cu, Ni, Cr, Co, Fe, Zn, and Mn were 0.72, 11.41, 14.82, 29.87, 51.13, 106.69, 8741.87, 48.59, and 346.42mgkg-1, respectively, which all exceed the local background levels. The results reveal that land use significantly affected PTE concentrations. Cr, Co, Mn, and Fe concentrations in soils of residential and brick kiln areas were especially high. In contrast, concentrations of Cu, Ni, and Zn were higher in agricultural and residential areas. Risk assessment analysis showed that the sum of toxic units for PTEs for brick kilns (1.72), residential (1.82), and agricultural (1.79) areas exceeded those of other land types and that Ni and Cr contributed the most to the high toxic risk index values. Both carcinogenic and non-carcinogenic risk indices of PTEs in soils were within an acceptable limit, except for the cancer risk of Ni (3.52E-04) and Cr (3.00E-04) among children. The spatial hazard index and carcinogenic health risk of PTEs showed that samples from the southwestern parts of the study area might pose significant health problems to adults and children. This study demonstrates how combining different techniques can help spatially characterize PTE accumulation and protect populations at risk.

Effects of biochar on earthworms during remediation of potentially toxic elements contaminated soils

With the widespread use of biochar for soil remediation and improvement, its effects on soil organisms are receiving increased attention. The impacts of biochar on earthworms are still poorly understood. This study aimed to assess the potential ecotoxicity of rice husk biochar (RB) and sludge biochar (SB) on earthworms during potentially toxic elements (PTEs) contaminated soil remediation. The results showed that high rates of RB addition (5% and 10%) caused earthworm mortality, but SB addition did not affect earthworm survival. When added at non-lethal rates (3%), RB and SB addition did not affect survival, weight loss, and PTEs accumulation of earthworms, while resulting in apparent avoidance behavior and oxidative stress response. Among them, RB addition was more likely to cause avoidance behavior, while SB addition had a more pronounced stress effect on earthworms. Additionally, the bacterial communities in the earthworm gut were more sensitive to biochar addition than those in soil. SB addition had a greater impact on earthworm gut bacterial communities than RB addition. The addition of RB and SB increased the abundance of Bacillaceae while decreasing the abundance of Rhizobiaceae in the earthworm gut. This change in the composition of bacterial community may impact the nitrogen cycle and organic matter degradation functions of earthworms. The study suggests that RB and SB may have different effects on earthworms during PTEs-contaminated soil remediation, depending on their properties. It will assist us to understand the potential ecotoxicity of biochar and provide several guidance for its safe application.

Assessment of Potentially Toxic Elements Pollution and Human Health Risks in Polluted Farmland Soils around Distinct Mining Areas in China-A Case Study of Chengchao and Tonglushan.

This research study investigates the extent of heavy metal pollution and pollution trends in agricultural soil in mining areas during different time periods. A total of 125 soil samples were collected from two mining areas in China, the Chengchao iron mine and Tonglushan ancient copper mine. The samples were analyzed for various potentially toxic elements (PTEs). The index of geoaccumulation (Igeo), pollution index (Pi), potential ecological risk index (Eri), and hazard index (HI) were calculated to evaluate the pollution status of PTEs in the farmland around the two mining areas. The sources of PTEs were inferred by pollution distribution, and the pollution conditions of the two mining areas were compared. The results showed that the pollution of ancient copper mines was relatively severe. The main pollution elements were Cu, Cd, and As, and their average Pi values were 3.76, 4.12, and 1.84, respectively. These PTEs mainly came from mining and transportation. There are no particularly polluted elements in the Chengchao iron mine and the average Pi of all PTEs were classified as light pollution and had a wide range of sources. The findings suggest that the ancient copper mine, due to outdated mining techniques and insufficient mine restoration efforts, resulted in the spread and accumulation of PTEs in the soil over an extended period, making the farmland soil around the ancient copper mine more polluted compared to the Chengchao iron mine. In the two mining areas, there is no risk of cancer for adults and children. However, the RI values of Cr in adults and children are higher than 10-4, which indicates that the carcinogenic risk of Cr in these soils is very high. The non-carcinogenic effects of PTEs on the human body in the soil of ancient copper mine are also higher than that of the Chengchao iron mine.

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.

Potentially toxic elements in the environment- a review of sources, sinks, pathways and mitigation measures.

Pollution of ecosystems with potentially toxic elements (PTEs) has become a global problem with serious consequences for public health. The PTEs are hazardous to humans owing to their longevity, toxicity, and ability to accumulate in the biotic environment. As most PTEs cannot be degraded microbially or chemically, they can persist in soils for a long time. Besides posing a threat to landsphere, they may be transported to surrounding environmental spheres through movement of water, atmospheric circulation, and biological transmission. This can severely affect the ecological equilibrium. Accumulation of PTEs in soils pose serious health hazards to higher organisms leading to various diseases and disorders and significant relationships exist between the occurrence of PTEs and the toxic effects in humans. In natural soils, PTEs accumulate due to weathering of rocks and ores. Furthermore, locally or regionally significant accumulation of PTEs in soils may occur from industrial goods, pesticides and paints, municipal and industrial waste, fertilizer application, mining activities and atmospheric deposition. In response to the growing need to address PTE contamination, remediation methods have been developed employing mechanical, physico-chemical or biological based technologies. In this review, we discuss sources, sinks, pathways and mitigation measures related to natural and anthropogenic PTEs. We focus on As, Cd, Cr, Hg and Pb which are highly toxic and perform no physiological functions in biota. Further, these are the most widely studied PTEs.

Potential for the Accumulation of PTEs in the Biomass of Melilotus albus Med. Used for Biomethane Production

In this paper, a possible use of white sweet clover (Melilotus albus Med.) for phytoremediation was assessed. The plants were grown on soils with naturally occurring concentrations of potentially toxic elements (PTEs). First, the content of PTEs was determined in plant biomass and in soil samples using: (a) Optical emission spectrometry with inductively coupled plasma to determine Sb, As, Cd, Cu, Ni, Pb, and Se, and (b) thermal decomposition, amalgamation, and atomic absorption spectrometry to determine Hg. The effectiveness of Melilotus albus Med. (M. albus) for phytoremediation was evaluated using the bioconcentration factor (BCF). The phytoextraction potential of M. albus was determined using bioaccumulation factor (BAC) and translocation factor (TF) values. The highest concentration of PTEs in roots was detected for zinc (10.56 mg/kg of dry weight, DW) and copper (5.128 mg/kg of DW). Similarly, the highest concentration in above-ground parts of the plant was detected for zinc and copper (12.638 and 4.0 mg/kg of DW, respectively). Although the values were relatively high, the effectiveness of the absorption of these PTEs by plant biomass from the soil was relatively very low. BAC and BCF were always lower than 1. On the other hand, the results suggested that M. albus effectively transports PTEs (only for Zn, Pb and Hg) from roots to shoots, because TF was always higher than 1. However, the accumulation of PTEs from soils with a natural abundance of PTEs was not excessive in comparison to conventional maize silage. Therefore, there is no potential risk of biomethane production in biogas plants when biomass from M. albus is used.

The leaching behaviors of lead, zinc, and sulfate in pyrite ash contaminated soil: mineralogical assessments and environmental implications

Contaminated soil with high mobility of potentially toxic elements (PTEs) can threaten the environment and human health. Precisely quantifying trends in PTEs accumulation in the soil under changing pH conditions is essential to minimize potential exposure. However, this has long been a hard-to-monitor subject experimentally due to the relatively low content of PTEs and the lack of detailed knowledge of the minerals that control PTEs' leaching. Here we profoundly investigate the critical role of soil mineralogy in PTEs release and predict the leaching behavior of PTEs by exploiting the modeling approach. The investigated sample comes from a brownfield site devoted to fertilizers production. Hematite, jarosite, and gypsum are the major mineralogical phases, with zinc sulfate, anglesite, kintoreite, and Pb-bearing jarosite being identified as the dominant Pb and Zn phases. pH-dependent leaching tests in combination with geochemical modeling were used to reveal the potential leaching mechanisms and contaminants solubility-controlling phases at pH ranging from 1 to 12. The experimental and modeling results both demonstrated that Pb and Zn have an amphoteric leaching behavior, with the lowest leached concentrations at the neutral/alkaline region around pH values from 8.0 to 10.0. The calculated saturation indexes suggest that Pb retention is controlled by anglesite, cerussite, and hydrocerussite, while Zn retention is attributed to zinc carbonates and hydroxides. Further, jarosite and ferrihydrite may play a role in Pb and Zn retention. In comparison, the sulfate release increases with pH values, which is governed by the equilibrium of jarosite, gypsum, and anglesite. The overall results highlight the value of converging experimental-geochemical modeling approaches to gain a deeper understanding of PTEs' release and retention, which is difficult to reveal through experiments alone. These advances may be pivotal in the sustainable management and design of remediation strategies.

Phytoremediation Potential of Native Plant Species in Mine Soils Polluted by Metal(loid)s and Rare Earth Elements.

Mining activity has an adverse impact on the surrounding ecosystem, especially via the release of potentially toxic elements (PTEs); therefore, there is an urgent need to develop efficient technologies to remediate these ecosystems, especially soils. Phytoremediation can be potentially used to remediate contaminated areas by potentially toxic elements. However, in soils affected by polymetallic contamination, including metals, metalloids, and rare earth elements (REEs), it is necessary to evaluate the behavior of these toxic elements in the soil-plant system, which will allow the selection of the most appropriate native plants with phytoremediation potential to be used in phytoremediation programs. This study was conducted to evaluate the level of contamination of 29 metal(loid)s and REEs in two natural soils and four native plant species (Salsola oppositifolia, Stipa tenacissima, Piptatherum miliaceum, and Artemisia herba-alba) growing in the vicinity of a Pb-(Ag)-Zn mine and asses their phytoextraction and phytostabilization potential. The results indicated that very high soil contamination was found for Zn, Fe, Al, Pb, Cd, As, Se, and Th, considerable to moderate contamination for Cu, Sb, Cs, Ge Ni, Cr, and Co, and low contamination for Rb, V, Sr, Zr, Sn, Y, Bi and U in the study area, dependent of sampling place. Available fraction of PTEs and REEs in comparison to total concentration showed a wide range from 0% for Sn to more than 10% for Pb, Cd, and Mn. Soil properties such as pH, electrical conductivity, and clay content affect the total, available, and water-soluble concentrations of different PTEs and REEs. The results obtained from plant analysis showed that the concentration of PTEs in shoots could be at a toxicity level (Zn, Pb, and Cr), lower than toxic but more than sufficient or natural concentration accepted in plants (Cd, Ni, and Cu) or at an acceptable level (e.g., V, As, Co, and Mn). Accumulation of PTEs and REEs in plants and the translocation from root to shoot varied between plant species and sampling soils. A. herba-alba is the least efficient plant in the phytoremediation process; P. miliaceum was a good candidate for phytostabilization of Pb, Cd, Cu, V, and As, and S. oppositifolia for phytoextraction of Zn, Cd, Mn, and Mo. All plant species except A. herba-alba could be potential candidates for phytostabilization of REEs, while none of the plant species has the potential to be used in the phytoextraction of REEs.

Iron-modified phosphorus- and silicon-based biochars exhibited various influences on arsenic, cadmium, and lead accumulation in rice and enzyme activities in a paddy soil.

Contamination of paddy soils with potentially toxic elements (PTEs) has become a severe environmental issue. Application of functionalized biochar for rice cultivation has been proposed as an effective means to reduce environmental risks of these PTEs in paddy soils. This work was undertaken to seek the positive effects of a rice husk-derived silicon (Si)-rich biochar (Si-BC) and a pig carcass-derived phosphorus (P)-rich biochar (P-BC), as well as their Fe-modified biochars (Fe-Si-BC and Fe-P-BC) on the enzyme activity and PTE availability in an As-Cd-Pb-contaminated soil. A rice cultivation pot trial was conducted using these functionalized biochars as soil amendments for the alleviation of PTE accumulation in rice plants. Results showed that Si-BC decreased the concentrations of As in rice grain and straw by 59.4 % and 61.4 %, respectively, while Fe-Si-BC significantly (P<0.05) enhanced plant growth, increasing grain yield (by 38.6 %). Fe-Si-BC significantly (P<0.05) elevated Cd and Pb accumulation in rice plants. P-BC enhanced the activities of dehydrogenase, catalase, and urease, and reduced grain-Pb and straw-Pb by 49.3 % and 43.2 %, respectively. However, Fe-P-BC reduced plant-As in rice grain and straw by 12.2 % and 51.2 %, respectively, but increased plant-Cd and plant-Pb. Thus, Fe-modified Si- and P-rich biochars could remediate paddy soils contaminated with As, and enhance the yield and quality of rice. Application of pristine P-rich biochar could also be a promising strategy to remediate the Pb-contaminated paddy soils and limit Pb accumulation in rice.

Differential Response of Brassica Cultivars to Potentially Toxic Elements and Their Distribution in Different Plant Parts Irrigated with Metal-Contaminated Water

The increasing concentration of potentially toxic elements (PTEs) in agricultural soils has greatly disturbed the quality and productivity of soils. In this study, we investigated the uptake and distribution of cadmium (Cd), lead (Pb), and nickel (Ni) by two Brassica cultivars (Khanpur raya and Sandal canola) grown on soil irrigated with metal-contaminated water. Distilled water was spiked with salts to prepare irrigation water with various levels of metals (Ni application at 90, Cd at 20, Pb at 500, Ni + Pb at 20 + 500, Ni + Cd at 90 + 20, Cd + Pb at 20 + 500, and Ni + Cd + Pb at 90 + 20 + 500 mg L−1). These treatments were compared with water without the addition of any salt. The results indicated that compared to the control treatment, increasing metal concentrations decreased the shoot weight (44.25%, 29.03%), root length (33.33%, 12.74%), and shoot length (19.73%, 11.06%) in Khanpur raya and Sandal canola, respectively. Compared to the control treatment, irrigation with contaminated water decreased the photosynthesis rate (98.42%, 99.34%), chlorophyll content (18.27%, 13.73%), respiration rate (7.97%, 6.47%), and transpiration rate (9.90%, 33.33%) in both varieties, respectively. Notably, the concentrations of Ni (0.01 and 0.003), Cd (0.01 and 0.012), and Pb (0.03 and 0.05%) in the seeds were increased, as well as in Khanpur raya and Sandal canola, respectively, compared to the controls. Furthermore, the PTE accumulation in different components was recorded, with the order of soil &gt; root &gt; shoot &gt; seed. It was observed that brassica cultivars differed significantly in their response to the growth and accumulation of PTEs in edible parts. It was concluded that Khanpur raya did not exhibit a decline in growth due to PTEs in irrigation water and prevented the translocation of PTEs towards edible parts compared to Sandal canola and thus can be safely grown in soils receiving PTE-contaminated water.

Contamination levels and source apportionment of potentially toxic elements in size-fractionated road dust of Moscow.

The distributions of potentially toxic elements (PTEs) among PM1, PM1-10, PM10-50, and PM50-1000 fractions of the road dust were studied in the western and eastern parts of Moscow, impacted mainly by the road transport and the industrial sector, respectively. The partitioning of PTEs in road dust can provide more precise information on pollution sources and its further interpretation regarding human health risks. The concentrations of PTEs were analyzed by mass and atomic emission inductively coupled plasma spectrometry. Differences in the results between the western and eastern parts of the city were caused by the dissimilarity between traffic and industrial emissions. The source apportionment of the PTEs was carried out using absolute principal component analysis with multiple linear regressions (PCA/APCS-MLR). The contribution from anthropogenic sources was significant to PM1 and PM1-10 particles. In coarser fractions (PM10-50, PM50-1000), it decreased due to the input with the wind-induced resuspension of soil and rock particles. In the eastern part of the city, the accumulation of PTEs (especially Mo, Sb, Cd, Sn, Bi, Co, and As) is the most active in PM1-10, while in the western part, it is most pronounced in PM1 (especially Pb, Cu, Cr, and W) which is associated with differences in the size of particles coming from traffic and industrial sources. In the eastern part of Moscow, in comparison with the western part, the contribution from industrial sources to the accumulation of PTEs in all particle size fractions was higher by 10-30%. In the western part of Moscow, the finest particles PM1 and PM1-10 demonstrate the trend of rising pollution levels with the increase in road size, while in the eastern part of the city, only coarse particles PM50-1000 show the same trend. In the fractions PM1 and PM1-10 of road dust, a significant contribution was made by anthropogenic sources; however, its role decreased in the coarse fractions-PM10-50 and especially in PM50-1000-due to the influence of roadside soils and their parent material.