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

Environmental and human health risk assessment of soils in areas of ore mineralization and past gold-mining activity

The patterns of the potentially toxic elements (PTEs: Cr, Fe, Ni, Cu, Zn, As, Mo, Pb, Hg) distribution in soils were studied together with the health risk assessment in the area of ore mineralization, past gold activity, and tailing effects of the Sarala gold-ore group located in the Republic of Khakassia, Russia. High PTE concentrations were found in soils with the presence of potential negative impact on human health based on the following: local background investigation, according to statistics; geochemical, environmental, and human health risk calculations; and comparative analysis using international and local reference, such as continental crust, clarke, and permissible concentrations. Sources of PTE soil enrichment and pollution were statistically identified in ascending order of degree: geogenic (local background) < geogenic-technogenic (sites with geological exploration traces - trenches) < technogenic (waste tailings). The main pollutants are Hg and As which showed moderate to significant ecological risk. Negative impact of Cr on soils was found. The pollution degree and toxicity (moderate to significant) of other PTEs increase in the location of ore mineralization zone with exploration trenches and waste tailings. Arsenic poses a carcinogenic risk to adults and children upon contact with polluted soils and non-carcinogenic effect on children in areas affected by tailings and ore mineralization zone. The non-carcinogenic effect of Fe on children was found in soils of all sites. The results provide useful information regarding the studied PTEs and their impact on the environment and human health. Such information can be helpful for the state-level decision-making process when addressing solutions for contaminated areas.

Current situation and prospects for the clean utilization of gold tailings

Gold tailings are characterized by low-grade, complex composition, fine embedded particle size, environmental pollution, and large land occupation. This paper describes the mineralogical properties of gold tailings, including chemical composition, phase composition, particle size distribution, and microstructure; summarizes the recycling and utilization of components such as mica, feldspar, and valuable metals in gold tailings; reviews harmless treatment measures for harmful elements in gold tailings; and adumbrated the research progress of gold tailings in the application fields of building materials, ceramics, and glass materials. Based on these discussions, a new technology roadmap that combines multistage magnetic separation and cemented filling is proposed for the clean utilization of all components of gold tailings.

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.

Assessment of the Levels of Potentially Toxic Elements Contained in Natural Bentonites Collected from Quarries in Turkey

Potentially toxic elements (PTEs) are an important type of pollutant, causing constant and far-reaching concerns around the world due to their increase in the mining process. Bentonite formed by the alteration of glass-rich volcanic rocks is a smectite clay consisting mostly of montmorillonite. Bentonite is an important mineral used in a wide range of applications in many fields such as oil and gas, agriculture, food, pharmacological, cosmetic, and construction industries due to its unique qualities. Given the widespread distribution of bentonite in nature and its use in a wide variety of consumer products, it is inevitable that the general population will be exposed to PTEs contained in bentonites. In this study, concentrations of PTEs in 69 bentonite samples collected from quarries located in different geographical regions of Turkey were analyzed by an energy-dispersive X-ray fluorescence spectrometric method. The average concentrations of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Zr, and Pb in bentonite samples were found to be 3510, 95, 129, 741, 30,569, 67, 168, 25, 62, 9, 173, and 28 mg/kg dry weight, respectively. Results of the enrichment factor relating to Earth's crust average indicated moderate enrichment with Cr, Ni, and Pb and significant enrichment with Co and As.

Assessment of native plants for their potential to remove trace metals around Legadembi tailings dam, Southern Ethiopia

Native plant species growing on metal contaminated soil at the foot of the Legadembi tailings dam were selected to evaluate their phytoremediation potential. For this purpose, soil, aboveground tissues, and roots of plant samples were analyzed for the concentrations of Zn, Cu, Ni, Pb, and Cd. The bioaccumulation and transfer of metals were evaluated in terms of translocation factor (TF), bioconcentration factor (BCF), and biological accumulation coefficient (BAC). The results showed that most of the species were efficient to take up and translocate more than one trace element (TE) from roots to shoots. Argemone mexicana L., Rumex nepalensis Spreng., Cyperus alopecuroides Rottb., and Schoenoplectu sconfusus (N.E.Br.) Lye showed potential for phytoextraction of Cu, while R. nepalensis and C. alopecuroides can accumulate in their above-ground parts and are suitable for phytoextraction of Ni. Rumex nepalensis, C. alopecuroides, and Typha latifolia L. have the ability for phytostabilization of Zn metal. Findings suggest concentrations of some metals in plants' tissue showed above the normal range which suggests their potential use in phytoremediation.

Potential Risk, Spatial Distribution, and Soil Identification of Potentially Toxic Elements in Lycium barbarum L. (Wolfberry) Fruits and Soil System in Ningxia, China

Eight potentially toxic elements (PTEs, including nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), lead (Pb), chromium (Cr), and mercury (Hg)) in Lycium barbarum L. (wolfberries) and the associated root soil from a genuine producing area were analyzed. The potential ecological risk of PTEs in the soil and the health risk of PTEs through wolfberry consumption were determined. Geostatistical methods were used to predict the PTE concentrations in the wolfberries and soil. Positive matrix factorization (PMF) was applied to identify the source of PTEs in the soil. The PTE concentrations in the soils were within the standard limits, and Cd in the wolfberries exceeded the standard limit at only one site. The bioconcentration factors (BCF) order for the different PTEs was Cd > Cu > 1 > Zn > Cr > As > Ni > Pb, indicating that Cd and Cu were highly accumulated in wolfberries. The multiple regression models for Ni, Cu, Zn, As, Pb, and Cr concentrations in the wolfberries exhibited good correlations (p < 0.1). The ecological risk for Hg in the soil was high, whereas the risks for the remaining PTEs were mostly medium or low. Health risks for inhabitants through wolfberry consumption were not obvious. The spatial distributions of the PTEs in the soil differed from the PTE concentrations in the wolfberries. Source identification results were in the order of natural source (48.2%) > industrial activity source (27.8%) > agricultural activity source (14.5%) > transportation source (9.5%). The present study can guide the site selection of wolfberry cultivation and ensure the safety of wolfberry products when considering PTE contamination.

An Integrated Gray DEMATEL and ANP Method for Evaluating the Green Mining Performance of Underground Gold Mines

Green mining (GM) can achieve the harmonious development of mineral resource exploitation and environmental protection. Performance evaluation is the key to promoting GM. This research explores favorable methods to evaluate the green mining performance (GMP) of underground gold mines. First, according to the specific characteristics of underground gold mines, an evaluation criteria system for GM is formulated. Meanwhile, the weights are calculated using an integrated gray DEMATEL and ANP technique, which considers the correlation between indicators. Subsequently, the solution methodology for performance evaluation is proposed based on normalization of indicators. Finally, six underground gold mines are utilized as case studies to verify the methodological feasibility. The results of the empirical study show that there is a significant gap between ordinary mines and pilot green mines, and this study, via comparison analysis and cause–effect analysis, gives direction for mines improvement. Not only will the work provide technical and theoretical support for the evaluation and construction of similar green mines, it will also serve as a reference for government policy implementation.

Assessment of the Heavy Metal Contamination of Roadside Soils Alongside Buddha Nullah, Ludhiana, (Punjab) India

The present study was carried out to determine the physico-chemical characteristics and heavy metal contents in roadside soil samples collected during 2 sampling periods (September 2018 and April 2019) from 8 different roadside sites lying parallel to the Buddha Nullah, an old rivulet, flowing through Ludhiana, (Punjab) India. The contents (mg/kg) of seven metals (cadmium, chromium, cobalt, copper, lead, nickel and zinc) were estimated using a flame atomic absorption spectrophotometer. Among the metals analyzed, the contents of Cd, Co, Cu, Pb and Zn were found above the permissible limits. The results of the index of geoaccumulation (Igeo), contamination factor (CF), contamination degree (Cdeg), modified contamination degree (mCdeg), the Nemerow pollution index (PI) and pollution load index (PLI) indicate a moderate to high heavy metal contamination of the analyzed soil samples. The results of the potential ecological risk factor (ERi) and potential ecological risk index (RI) indicate a low to moderate risk of heavy metals in the studied soil samples. The Pearson correlation analysis revealed that most of the variables exhibited a statistically significant correlation with one or more variables during the two samplings. Multivariate analysis demonstrates that contents of heavy metals in the study area are influenced by anthropogenic and geogenic factors.