No abstract

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.

No abstract

A fundamental requirement for the effective prevention and management of soil contamination involves the determination of heavy metal contamination levels and the assessment of associated health risks for human populations. In this study, an analysis was conducted to evaluate the pollution levels and health risks associated with heavy metals in urban soils, specifically focusing on four distinct soil types, namely Calcisols, Cambisols, Fluvisols, and Regosols. The mean values of five heavy metals (Zn, Cu, Cd, Pb, and Ni), some soil pollution indices, and human health risk indices were determined. Pollution indices including the integrated Newerow pollution index (PIN), single pollution index (PI), and pollution load index (PLI) showed a moderate pollution class in most soil samples. The non-carcinogen risk index of elements (HI) in each exposure pathway and the total of the exposure pathways (THI) was <1 for three different population groups (children, adult females, and adult males) and in all soils. This shows the lack of non-cancerous risk for local residents in the study site. The variations in HI and THI for the three population groups and three different exposure pathways was in the order of adult males > adult females > children and ingestion > dermal contact > inhalation. The carcinogenicity risk (CR) of Cd, Pb, and Ni through exposure by ingestion was >1 × 10−4 for children in all soils, meaning that soil ingestion is hazardous to children in the study region. For all three population groups and all soil types, Pb was most effective in HI and THI, whereas Cd had the highest carcinogenicity potential.