New insight into the geochemical mechanism and behavior of heavy metals in soil and dust fall of a typical copper smelter

Geospatial analysis of trace metal pollution and ecological risks in river sediments from agrochemical sources in Morocco's Sebou basin

Sediments in agricultural ecosystems serve as critical indicators of environmental pollution, particularly in regions subjected to intensive agricultural practices. This research evaluates the environmental hazards and implications of heavy metal (HM) contamination in river sediments from the Sidi Allal Tazi area within Morocco's Sebou basin. Twenty sediment samples were extracted from strategically designated locations, and the contamination levels were analyzed using a multi-index integration approach, multi-statistical analyses (MSA), and Geographic Information Systems (GIS). The results revealed considerable spatial variability in HM concentrations, with Cd and As displaying the highest contamination levels. Statistical analysis, incorporating Principal Component Analysis (PCA), identified anthropogenic activities as the primary contributors to contamination. Hierarchical Cluster Analysis (HCA) categorized metals based on common pollution pathways, while GIS mapping revealed the spatial distribution of contamination across vulnerable areas. Pollution indicators like the Geo-accumulation Index (Igeo) as well as the Pollution Load Index (PLI). revealed that 75% of sites were categorized under "very high pollution", emphasizing the severity of contamination. Contamination Factor (CF) classified 90% of Cd samples and 100% of As samples as "very high contamination". Risk indices indicated significant ecological threats, with Cd contributing to an RI exceeding 600 in many areas, signifying "very high risk". These findings highlight the urgent need for targeted mitigation strategies and sustainable agricultural practices. The integration of multi-index and GIS methodologies provides a comprehensive framework for assessing and managing sediment contamination, offering critical insights for policymakers and environmental managers.

Comprehensive assessment of potential toxic elements in surface dust of community playgrounds in Xi'an, China

To identify the key factors for managing and controlling potential toxic elements (PTEs) in surface dust of urban community playgrounds, this study comprehensively analyzed the content, pollution characteristics, eco-health risks, and sources of commonly concerned PTEs in surface dust of Xi'an community playgrounds. The average levels of Cd, Hg, Cu, Cr, Ba, Zn and Pb in the dust were 2.2, 0.27, 1.4 × 102, 2.1 × 102, 1.7 × 103, 2.9 × 102, 1.5 × 102 mg kg-1, respectively, exceeding the soil background values. The main sources of PTEs in the dust were natural source, mixed source of construction and weathering of entertainment facilities, traffic source, and industrial source, accounting for 24.9%, 45.7%, 18.1%, and 11.3%, respectively. The contamination and ecological risk of PTEs in the dust were elevated, and Cd and industrial source were identified as the primary contributors. The non-carcinogenic risks for different age groups were within a safe range, but the cancer risk was high, especially for toddlers and the elderly. It is worth noting that the cancer risk based on the minimum values of key exposure parameters for toddlers, preschool children, children, and teenagers has exceeded the acceptable level. According to the results of source-oriented health risk assessment, the traffic source was identified as the main contributors of health risk, and Ni was a particularly concerned PTE. These findings can provide the scientific basis for controlling PTEs pollution in urban community playgrounds and the guidance for protecting residents' health.

Magnetic response and bioaccessibility of toxic metal pollution in outdoor dustfall in Shanghai, China

Toxic metal content testing, environmental magnetic monitoring and in vitro bioaccessibility experiments each have their own advantages and are often used independently for environmental monitoring, but there are few studies that combine the three to evaluate the hazards of toxic metals to humans. This paper investigated the total content, magnetic properties and bioaccessibility of nine potentially toxic metal elements (Zn, Sn, Pb, Cu, Fe, Ni, Cr, Sr, Mn) in dustfall from different functional zones in Shanghai, China, and systematically compared the related results. The results show that these nine metal elements have different degrees of contamination and enrichment in outdoor dustfall, and their content distribution shows the following trend: Zn > Sn > Pb > Cu > Fe > Ni > Cr > Sr > Mn. Magnetic characteristics χlf and SIRM are mostly positively correlated with the metal elements, indicating that the higher the content of magnetic minerals in the sample, the higher the concentration of metal elements. It was also found that χlf, SIRM, and χARM can well reflect the characteristics of dustfall pollution. The magnetic minerals have a certain degree of enrichment, and the particle size of the magnetic minerals is relatively coarse, mainly in the form of coarse multi-domain and pseudo-single-domain particles, which are largely derived from anthropogenic pollution. The χlf and PM10 concentrations in the precipitation show relatively similar spatial trends, so χlf, SIRM, and χARM can be used as air pollution indices to facilitate the evaluation of metal elements pollution in dustfall. The overall trend in gastric bioaccessibility is Pb > Zn > Mn > Cu > Cr. Due to the increase in the pH of digestive fluid, the bioavailability of toxic metals decreases significantly from the gastric stage to the intestinal stage. χlf, SIRM, and χARM/SIRM are all related to the bioaccessibility of toxic metals in the intestinal stage, so they can be used as toxicity indicators to evaluate the bioaccessibility of toxic metals in dustfall.

Pollution area identification, receptor model-oriented sources and probabilistic health hazards to prioritize control measures for heavy metal management in soil

Identifying the primary source of heavy metals (HMs) pollution and the key pollutants is crucial for safeguarding eco-health and managing risks in industrial vicinity. For this purpose, this investigation was carried out to investigate the pollution area identification with soil static environmental capacity (QI), receptor model-oriented critical sources, and Monte Carlo simulation (MCS) based probabilistic environmental and human health hazards associated with HMs in agricultural soils of Narayanganj, Bangladesh. The average concentration of Cr, Ni, Cu, Cd, Pb, Co, Zn, and Mn were 98.67, 63.41, 37.39, 1.28, 23.93, 14.48, 125.08, and 467.45 mg/kg, respectively. The geoaccumulation index identified Cd as the dominant metal, indicating heavy to extreme contamination in soils. The QI revealed that over 99% of the areas were polluted for Ni and Cd with less uncertain regions whereas Cr showed a significant portion of areas with uncertain pollution status. The positive matrix factorization (PMF) model identified three major sources: agricultural (29%), vehicular emissions (25%), and industrial (46%). The probabilistic assessment of health hazards indicated that both carcinogenic and non-carcinogenic risks for adult male, adult female, and children were deemed unacceptable. Moreover, children faced a higher health hazard compared to adults. For adult male, adult female, and children, industrial operations contributed 48.4%, 42.7%, and 71.2% of the carcinogenic risks, respectively and these risks were associated with Ni and Cr as the main pollutants of concern. The study emphasizes valuable scientific insights for environmental managers to tackle soil pollution from HMs by effectively managing anthropogenic sources. It could aid in devising strategies for environmental remediation engineering and refining industry standards.

Distinguishing the contributions of different smelting emissions to the spatial risk footprints of toxic elements in soil using PMF, Bayesian isotope mixing models, and distance-based regression

Toxic element pollution of soils emanating from smelting operations is an escalating global concern due to its severe impact on ecosystems and human health. In this study, soil samples were collected and analyzed to quantify the risk contributions and delineate the spatial risk footprints from smelting emissions for 8 toxic elements. A comprehensive health risk contribution and delineation framework was utilized, consisting of Positive matrix factorization (PMF), spatial interpolation, an advanced Bayesian isotope mixing model via Mixing Stable Isotope Analysis in R (MixSIAR), and distance-based regression. The results showed that the mean concentrations of As, Cd, Cu, Hg, Pb, and Zn exceeded the background levels, indicating substantial contamination. Three sources were identified using the PMF model and confirmed by spatial interpolation and MixSIAR, with contributions ranked as follows: industrial wastewater discharge and slag runoff from the smelter site (48.9 %) > natural geogenic inputs from soil parent materials (26.7 %) > atmospheric deposition of dust particles from smelting operations (24.5 %). Among the identified sources, smelter runoff posed the most significant risk, accounting for 97.9 % of the non-carcinogenic risk (NCR) and 59.9 % of the carcinogenic risk (CR). Runoff also drove NCR and CR exceedances at 7.8 % and 4.7 % of sites near the smelter, respectively. However, atmospheric deposition from smelting emissions affected soils across a larger 0.8 km radius. Although it posed lower risks, contributing just 1.1 % to NCR and 22.6 % to CR due to the limited elevation of toxic elements, deposition reached more distant soils. Spatial interpolation and distance-based regression delineated high NCR and CR exposure hotspots within 1.4 km for runoff and 0.8 km for deposition, with exponentially diminishing risks at further distances. These findings highlight the need for pathway-specific interventions that prioritize localized wastewater containment and drainage controls near the smelter while implementing broader regional air pollution mitigation measures.

Pollution and mobility of heavy metals in the soils of a typical agricultural zone in eastern China

The pollution of heavy metals (HMs) in agricultural soils profoundly threatens national food safety, and the mobility and environmental behaviors of HMs are closely implicated in crop safety. Here, we assessed the pollution level and mobility of ten HMs and explored their environmental behaviors in the soils of three different land uses from a main crop production zone in eastern China. The concentrations of HMs in the soils were higher in the farmland than the woodland and wasteland, and Cd showed a relatively higher pollution and ecological risk levels compared to other metals. Cadmium was dominated by the reducible (41%) and exchangeable (23%) fractions, and the rest of HMs were mainly in the residual fraction (> 60%). The significant correlation between the exchangeable and DGT-labile Cd indicates relatively higher mobility of Cd in the soils. Soil pH, organic matters and mineral elements had significant correlation with the exchangeable and reducible fractions of most of the HMs (e.g., Cd, Co, Mn, Ni, Pb and V; p < 0.05), indicating their good predictors of the HMs mobility. However, this was not the case for the DGT-labile fraction, which suggests a marked difference in the controlling mechanisms of the mobility versus potential bioavailability of HMs in the soils. The results of this study indicate that both the chemically extracted fractions and the bioavailable fractions of HMs need be considered when effectively assessing the safety of agricultural soils.

Exploring the accumulation capacity of dominant plants based on soil heavy metals forms and assessing heavy metals contamination characteristics near gold tailings ponds

Heavy metal contamination of soil commonly accompanies problems around gold mine tailings ponds. Fully investigating the distribution characteristics of heavy metals and the survival strategies of dominant plants in contaminated soils is crucial for effective pollution management and remediation. This study aims to investigate the contamination characteristics, sources of heavy metals (As, Cd, Pb, Hg, Cu, Zn, Cr, and Ni) in soils around gold mine tailings ponds areas (JHH and WZ) and to clarify the form distribution of heavy metals (As, Cd, Pb, Hg) in contaminated plots as well as their accumulation and translocation in native dominant plants. The results of the study showed that the concentrations of As, Pb, Cd, Cu, and Zn in soil exceeded the national limits at parts of the sampling sites in both study areas. The Nemerow pollution index showed that both study areas reached extreme high pollution levels. Spatial analysis showed that the main areas of contamination were concentrated around metallurgical plants and tailings ponds, with Cd exhibiting the most extensive area of contamination. In the JHH, As (74%), Cd (66%), Pb (77%), Zn (47%) were mainly from tailings releases, and Cu (52%) and Hg (51%) were mainly from gold ore smelting. In the WZ, As (42%), Cd (41%), Pb (73%), Cu (47%), and Zn (41%) were mainly from tailings releases. As, Cd, Pb, and Hg were mostly present in the residue state, and the proportion of water-soluble, ion-exchangeable, and carbonate-bound forms of Cd (19.93%) was significantly higher than that of other heavy metals. Artemisia L. and Amaranthus L. are the primary dominating plants, which exhibited superior accumulation of Cd compared to As, Pb, and Hg, and Artemisia L. demonstrated a robust translocation capacity for As, Pb, and Hg. Compared to the concentrations of other forms of soil heavy metals, the heavy metal content in Artemisia L correlates significantly better with the total soil heavy metal concentration. These results offer additional systematic data support and a deeper theoretical foundation to bolster pollution-control and ecological remediation efforts in mining areas.

The geochemical stability of typical arsenic-bearing sinter in the Tibetan plateau: Implications from quantitative mineralogy

High‑arsenic (As) sinter deposited from geothermal water is a potentially overlooked hazardous matrix and there remain substantial gaps in our comprehension of the stability of As sequestered within it. In this study, qualitative and quantitative analysis of the mineralogy of As-bearing sinter was conducted by Mineral Liberation Analyzer (MLA) in geothermal areas of the Tibetan Plateau to reveal the geochemical stability of As. Our results indicated that the contents of As in sinter were 3 orders of magnitude higher than the local soil. The dominant host minerals of As were calcite (40.9 %), thenardite (22.5 %), calcium silicate (13.0 %), and halite (8.1 %). Additionally, it was found that a relatively higher As bioavailability was extracted by ethylene diamine tetraacetic acid (EDTA), with a leaching rate of 41.2 %. Notably, the X-ray diffraction (XRD) showed that the thenardite and halite were decomposed after the leaching. The combination of mineralogy and geochemistry data suggested that calcite and calcium silicate were a crucial mechanism for As retention in sinter, while the dissolution of saline minerals (e.g., thenardite, halite, and calcium chloride) served as the primary sources for As release. This finding unveils the potential risks and mechanisms associated with high-As sinter, providing scientific guidance for risk management of sinter.

Heavy metals contamination, receptor model-based sources identification, sources-specific ecological and health risks in road dust of a highly developed city

The present study quantified Ni, Cu, Cr, Pb, Cd, As, Zn, and Fe levels in road dust collected from a variety of sites in Tangail, Bangladesh. The goal of this study was to use a matrix factorization model to identify the specific origin of these components and to evaluate the ecological and health hazards associated with each potential origin. The inductively coupled plasma mass spectrometry was used to determine the concentrations of Cu, Ni, Cr, Pb, As, Zn, Cd, and Fe. The average concentrations of these elements were found to be 30.77 ± 8.80, 25.17 ± 6.78, 39.49 ± 12.53, 28.74 ± 7.84, 1.90 ± 0.79, 158.30 ± 28.25, 2.42 ± 0.69, and 18,185.53 ± 4215.61 mg/kg, respectively. Compared to the top continental crust, the mean values of Cu, Pb, Zn, and Cd were 1.09, 1.69, 2.36, and 26.88 times higher, respectively. According to the Nemerow integrated pollution index (NIPI), pollution load index (PLI), Nemerow integrated risk index (NIRI), and potential ecological risk (PER), 84%, 42%, 30%, and 16% of sampling areas, respectively, which possessed severe contamination. PMF model revealed that Cu (43%), Fe (69.3%), and Cd (69.2%) were mainly released from mixed sources, natural sources, and traffic emission, respectively. Traffic emission posed high and moderate risks for modified NIRI and potential ecological risks. The calculated PMF model-based health hazards indicated that the cancer risk value for traffic emission, natural, and mixed sources had been greater than (1.0E-04), indicating probable cancer risks and that traffic emission posed 38% risk to adult males where 37% for both adult females and children.