Toxic and heavy metals contamination assessment in soil and water to evaluate human health risk

Lead toxicity in plants: mechanistic insights into toxicity, physiological responses of plants and mitigation strategies

Soil toxicity is a major environmental issue that leads to numerous harmful effects on plants and human beings. Every year a huge amount of Pb is dumped into the environment either from natural sources or anthropogenically. Being a heavy metal it is highly toxic and non-biodegradable but remains in the environment for a long time. It is considered a neurotoxic and exerts harmful effects on living beings. In the present review article, investigators have emphasized the side effects of Pb on the plants. Further, the authors have focused on the various sources of Pb in the environment. Investigators have emphasized the various responses including molecular, biochemical, and morphological of plants to the toxic levels of Pb. Further emphasis was given to the effect of elevated levels of Pb on the microbial population in the rhizospheres. Further, emphasized the various remediation strategies for the Pb removal from the soil and water sources.

Improved microbial-plant soil bioremediation of PAHs and heavy metal through in silico methods

The combined pollution of polycyclic aromatic hydrocarbons (PAHs) and organic cadmium (Cd) in farmland soils, and the field controlling strategy need to be studied urgently. In this study, 5 PAHs, 5 Cd and 11 soil conditioners were selected to explore the co-exposure risk and remediation efficiency. Firstly, a significant combination Fl-alkylalkoxy cadmium was obtained using forward and reverse methods coupling variation coefficient methods (the combined pollution value was 0.173). Secondly, the interaction energy of microbial degradation / plant absorption of Fl under Cd stress, and microbial mineralization / plant absorption of alkylalkoxy cadmium under PAHs stress were characterized using factorial experimental design, molecular docking and molecular dynamics simulation. The combined pollution of alkylalkoxy cadmium and dialkyl cadmium, phenanthrene and Benzo [a] pyrene was significant (synergistic contribution rates were 17.58 % and 19.22 %, respectively). In addition, 6 soil conditioners with significant efficiency were selected to design Taguchi orthogonal experimental schemes, indicating the microbial degradation / mineralization and plant absorption were significantly effective (the maximum increase of remediation efficiency was 93.81 %) under the combinations (i.e., trratone, coumarol, fulvamic acid, potassium fertilizer and others, etc.). Finally, it was found that the soil conditioners affected the hydrophobic groups and forces, and the efficiency was proportional to the highest peak value and minimum distance in the RDF curve. This study identifies the risk characteristics of co-exposure of PAHs and Cd and screens effective soil conditioners, providing theoretical guidance for risk controlling.

Heavy metals in urban soil: Contamination levels, spatial distribution and human health risk assessment (the case of Ufa city, Russia)

The article examines the concentration of 9 heavy metals (Hg, Pb, Zn, Cr, Co, Ni, Cu, Ba and V) and As in the soil cover of the urban area in one of the largest cities in Russia, Ufa (the Republic of Bashkortostan). It is compared with aggregated data of concentrations on urbanized areas in surface soils throughout the world. For elements exceeding the average background values in soils of the urban area (Cr, Ni, Cu and Co), the average concentrations in the city soils were 346, 101, 51 and 18 ppm, respectively. Using enrichment factor (EF), geoaccumulation index (Igeo), and concentration coefficients (CC), Cr and Ni were identified as elements entering the soil cover as a result of anthropogenic pollution. Although the level of their enrichment and contamination of soils in the most territory of the city corresponds to the moderate class, there are sites with critical threshold values. Spatial analysis of heavy metals distribution was carried out based on the results of pollution load index (PLI) and ecological risk factor (Er) calculations with the use of graphical presentation of results, which allowed specific and detailed description of sites calling for special attention. The use of cluster analysis allowed dividing the sample of chemical elements into groups with probably similar sources of entry into the environment. Monte Carlo modeling of risk calculation showed negligible non-cancer risks for both adult and child populations in most of the city. While children's exposure to Cr was of concern in the more residential part of the city, free of large industrial plants, As posed a threat with respect to cancer risks in the southern part of the city, with elevated concentrations and other HMs in vicinity of the oil refineries.

Carbon quantum dots from hemicucur[6]bit and the application for the detection of Pb2

A macrocyclic compound, hemicucurbit[6]uril (HemiQ[6]), is employed as the carbon source to produce a novel sort of carbon quantum dots (CQDs) with blue fluorescence in aqueous solution. The CQDs are fully identified by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Nuclear Magnetic Resonance (NMR), zeta potential, ultraviolet/visible (UV-vis) and photoluminescence spectroscopy (PL). The nanomaterial is developed for the analysis of Pb2+ in the light of the Resonance Rayleigh scattering (RRS) changes with the increasing Pb2+ concentration. The proposed probe emerges a high selectivity to Pb2+ and excellent sensitivity in the linear concentration range of 0-6 μM with a detection limit low to 0.42 μM, which is superior to the previous values of Pb2+ sensors, as well as the good anti-interference ability is confirmed by the specifical response to Pb2+ in the presence of other metal cations. Therefore, the proposed analysis of Pb2+ is explored for the application in real samples of tap water and lake water, in satisfied results of acceptable recoveries.

Comprehensive monitoring of contamination and ecological-health risk assessment of potentially harmful elements in surface water of Maroon-Jarahi sub-basin of the Persian Gulf, Iran

The increase in heavy metal concentration in water bodies due to rapid industrial and socio-economic development significantly threatens ecological and human health. This study evaluated metal pollution and related risks to ecology and human health in the Maroon-Jarahi river sub-basin in the Persian Gulf and Oman Sea basin, southwest Iran, using various indicators. A total of 70 water samples were taken from the sampling sites in the Maroon, Allah, and Jarahi sub-basins and analyzed for nine heavy metals. According to the results, the mean concentration of metals in the sampling locations across the entire sub-basin of Maroon-Jarahi was observed as follows Iron (528.22 µg/L), zinc (292.62 µg/L), manganese (56.47 µg/L), copper (36.23 µg/L), chromium (11.78 µg/L), arsenic (7.09 µg/L), lead (3.43 µg/L), nickel (3.23 µg/L), and cadmium (1.38 µg/L). Most of the metals were detected at the highest concentration in the sub-basin of the Jarahi River. The Water Quality Index (WQI) index in the basin varied from 18.74 to 22.88, indicating well to excellent quality. However, the investigation of the pollution status at the monitoring stations, based on the classification of Degree of Contamination (CD) and Heavy Metal Pollution Index (HPI) indices, revealed that they are in the category of relatively high pollution (16 < CD < 32) to very high (32 ≤ CD), and in the low pollution category (HPI < 15) to high pollution (HPI < 30), respectively. According to the three sub-basins, the highest amount of WQI, HPI, and Cd was observed in the stations located in the sub-basins of the Jarahi River. The calculation of Heavy Metal Evaluation Index (HEI) also indicated that only 10% of the monitoring stations are in moderate pollution (10 < HEI < 20), while in other monitoring stations the HEI level is less than 10. The Potential ecological risk factors ( E r i ) of an individual metal was obtained as follows: Cd (173.70) > As (131.99) > Zn (57.52) > Cu (55.39) > Ni (48.98) > Cr (21.57) > Pb (0.71), revealing that Cd and As are the main elements responsible for creating ecological risk in the studied area. The Maroon-Jarahi watershed included areas with ecological risks that ranged from low (PERI ≤ 150) to very high (PERI ≥ 600). HI and ILCR health indicators indicated that consumption and long-term contact with river water in the study area can cause potential risks to human health, especially children. Moreover, the findings, the highest level of pollution and health risk for both children and adults, considering both exposure routes, occurred in the Jarahi River sub-basin, suggesting that those who live in the vicinity of the Jarahi River are likely to face more adverse health effects. In addition, the findings of the evaluation of the relationship between land use patterns and water quality in the studied basin showed that agricultural lands acts as a main source of pollutants, but forest lands play an important role in the deposition of pollutants and the protection of water quality at the basin scale. In general, the results of pollution indicators, risk assessment, and statistical techniques suggest that the lower sub-basin, the Jarahi area, and the Shadegan wetland are the most polluted areas in the investigated sub-basin due to excessive discharge of agricultural runoff, industrialization, and rapid urbanization. Thus, special measures should be considered to reduce the risks of HMs pollution in the sub-basin of the Maroon-Jarahi watershed, especially its downstream and the impact of agricultural land use on water quality should be taken into consideration in basin management plans.

Study on the migration behaviour of heavy metals at the improved mine soil-plant rhizosphere interface

With the increasing shortage of land resources and the aggravation of soil pollution in mining areas, the remediation of soil in abandoned mining areas has gradually attracted people's attention. The remediation of heavy metal contaminated soil in mining areas is the key to reduce the harm of heavy metals to the environment and human health. In this study, municipal sludge and phytoremediation technology were combined to investigate the migration and transformation of heavy metals at the soil-plant interface in improved mining areas through indoor pot experiments. The results showed that heavy metals in non-rhizosphere soil entered the rhizosphere environment with the growth of plants, leading to the increase of heavy metal content in rhizosphere soil. The cumulative amounts of Cu, Zn, Pb and Cd were 1299.32, 832.10, 347.89 and 71.34 mg/kg, respectively. The content of oxidized Cu and Zn decreased with increasing planting days, while the oxidized Pb and Cd showed an increasing trend. Under acidic conditions, H+ is easy to compete with heavy metal ions for exchangeable positions in the clay mineral layer, so that the reducible heavy metals are easy to be converted into exchangeable states. In this paper, the effects of various factors on the distribution of heavy metals were discussed by adjusting soil pH, adding humic acid and root exudates, so as to analyse the migration and transformation mechanism of heavy metals at the soil-plant interface, and provide a reliable theoretical basis for soil remediation in mining areas.

Soil pollution identification and human health risk assessment of soil heavy metals in an abandoned mine area in the Republic of Korea

In this study, the Geo-accumulation index (Igeo), Human Health Risk Assessment (HRA), and Ecological Risk Index (ERI) were utilized to examine the risks associated with the soils at the DaeyangYeongseong mine. Brassica juncea and Raphanus sativus were employed in the ecological toxicity test. In all soil samples, the mean Igeo value of arsenic measured 3.15, and cadmium measured 6.63, indicating a very high level of heavy metal contamination. The carcinogenic risk of cadmium and arsenic for adults was 4.30×10-3 and 1.43×10-5, respectively. For children, these values were 3.92 × 10-2 and 1.33 ×10-4, exceeding the acceptable level (1×10-6). In all soils, cadmium showed extremely high ecological risk levels, and arsenic had extremely high risk levels in 34.8% of the total area. This was also confirmed in toxicity assessments using plants. Therefore, arsenic and cadmium were found to be the main causes of soil contamination and ecological risk.

Dimercaprol-modified mesoporous silica nanoparticles for efficient removal of toxic mercury ions from aqueous solution

A surface-modified mesoporous silica nanoparticle containing dimercaprol monomers was created utilizing the sol-gel condensation process, using tetraethyl orthosilicate (TEOS) as the silica source and poloxamer as the structure directing agent. To accomplish this synthesis, 3-glycidoxypropyl triethoxysilane (GPTS, 20 mol%) was incorporated into the silica walls during the sol-gel condensation process, along with TEOS. Furthermore, dimercaprol (DM) monomers were incorporated onto silica surfaces by a ring-opening reaction between GPTS epoxy groups, and dimercaprol hydroxyl groups. The prepared dimercaprol-modified silica adsorbent (MSN-DT NPs) material has been studied using a variety of instruments, including XRD, FT-IR, N2 adsorption-desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric (TG) analysis, and zeta potential analysis. The MSN-DT NPs material selectively adsorbs mercury ions, with a high adsorption amount of 125 mg/g and a removal capability of roughly ~ 90% from the original metal ion mixture comprising other competing metals such as Pb2+, Ni2+, Fe2+, and Zn2+. The MSN-DT NPs adsorbent shows recyclable qualities for up to five cycles when treated with an acidic aqueous solution (0.1 M HCl). As a result, the MSN-DT NPs adsorbent may be regenerated and reused up to five times without losing its adsorption effectiveness. The experimental findings showed that the MSN-DT NPs adsorbent may be employed to selectively remove hazardous Hg2+ ions from an aqueous solution.

Informal E -waste recycling in nine cities of Pakistan reveals significant impacts on local air and soil quality and associated health risks

The global increase in electronic waste (e-waste) has led to a rise in informal recycling, emitting hazardous heavy metals (HMs) that threaten human health and ecosystems. This study presents the first comprehensive assessment of HM levels in dry deposition and soils at proximity of forty (40) informal e-waste recycling sites across Pakistan, between September 2020 to December 2021. Findings reveal that Zn (1410), Pb (410) and Mn (231) exhibited the higher mean deposition fluxes (μg/m2.day), derived from air samples, particularly in Karachi. Similarly, soils showed higher mean concentrations (μg/g dw) of Mn (477), Cu (514) and Pb (172) in Faisalabad, Lahore, and Karachi, respectively. HMs concentrations were found higher in winter or autumn and lower in summer. In addition, HM levels were significantly (p = 0.05) higher at recycling sites compared to background sites year-round, highlighting the e-waste recycling operations as the major source of their emissions. The Igeo index indicated moderate to extremely contaminated levels of Cu, Pb, Cd, and Ni in Karachi, Lahore and Gujranwala. Ingestion was found as a leading human exposure route, followed by dermal and inhalation exposure, with Pb posing the greatest health risk. The Cumulative Incremental Lifetime Cancer Risk (ILCR) model suggested moderate to low cancer risks for workers. Strategic interventions recommend mitigating health and environmental risks, prioritizing human health and ecosystem integrity in Pakistan's e-waste management.

Health-risk assessment of mercury in main market-sold foods in the Pingliang region of Gansu province, China, from 2013 to 2021

In the present study, we analyzed mercury concentrations in 742 samples across five main food categories from 2013 to 2021 using direct mercury analysis (DMA) to understand mercury pollution in major market-sold foods in the Pingliang region of Gansu Province and assess the health risks of mercury dietary exposure in adults. Health risks of adult dietary exposure were assessed through deterministic evaluation. Total mercury content ranged from non-detectable (ND) to 0.13 mg/kg, with a detection rate of 90.70% (673/742), the highest detection rates being in fresh edible mushrooms and nuts. The overall exceedance rate was 0.13% (1/742), with one sample of fresh edible mushrooms exceeding the regulatory limit for total mercury content. Additionally, we incorporated the average mercury content and consumption levels of meat and seafood from regions geographically close to Pingliang, as reported in the Fifth National Total Diet Study, to calculate the Estimated Daily Intake (EDI) by a deterministic evaluation. For adult males, the exposure was 0.120 μg/(kg BW), while for adult females, it was 0.141 μg/(kg BW). Both values are significantly lower than the provisional tolerable weekly intake (PTWI) of 4 μg/(kg BW) established by JECFA in 2010, indicating that the total mercury concentration from food intake does not pose a significant health risk to the residents of the Pingliang area. These findings offer valuable scientific data to inform food safety regulations in the region and can serve as a benchmark for future mercury pollution risk assessments in other locations.

Assessment of potential environmental and human risks for Bisphenol AF contaminant

Bisphenol AF (BPAF) is found in high concentrations in aquatic environments due to the increased use of thermal paper and food packaging. However, there have been relatively few toxicological studies and potential risk assessments of BPAF. In this study, the risk quotient (RQ) and hazard quotient (HQ) of BPAF were derived to present the safety standards for environmental risk management and protection in lakes, rivers, bays, and Italian regions. We applied the species sensitivity distribution (SSD) method based on the previous ecotoxicological data and the results of supplementary toxicity tests on BPAF. From the SSD curves, the hazardous concentration for 5 % of the species (HC5) values for the acute and chronic toxicity data were 464.75 µg/L and 3.59 µg/L, respectively, and the acute- and chronic-based predicted no-effect concentration were derived as 154.92 µg/L and 1.20 µg/L, respectively. The acute-based RQ (RQA)values of BPAF in all regions were negligible (RQ < 0.1). The chronic-based RQ (RQC) in the Xitang River (XR) and the Central Italy (CI) showed a considerably high ecological risk (12.77 and 1.29) and the Hangzhou Bay (0.21), the South and North Italy (0.79 and 0.27), and the Tamagawa River (0.13) had a medium ecological risk (0.1 < RQ < 1.0). However, the HQ values based on the tolerable daily intake for BPAF over all age groups in these regions was < 0.1, indicating the low health risk. Nonetheless, the result of this study indicates that BPAF contamination is serious in XR and CI, and their use and emissions require continuous monitoring.

Natural mercury exposure of European insectivorous bats may exceed a recognized toxicity threshold

Heavy metals are an important group of toxic substances harmful for many organisms. Of these, mercury is one of the most monitored in the environment. Several matrices are used for the monitoring of environmental load, including a range of organisms; bats, however, have only been examined rarely. Insectivorous bats are apex predators threatened by several human interventions in their natural environment, including heavy metal pollution. The aim of this study was to analyze the content of total mercury in the fur, flight membrane, and pectoral muscle of greater mouse-eared bats (Myotis myotis). Total mercury concentrations were also measured in carabid beetles from the catch locality Zastávka u Brna. Samples were obtained from 43 bat carcasses at two different localities in the Czech Republic (Zastávka u Brna, Malá Morávka). Total mercury content varied between 1.76-72.20 µg/g in fur, 0.04-0.14 µg/g in skin, and 0.05-0.20 µg/g in muscle. Total mercury values in the fur of some individuals from Malá Morávka exceeded the recognized toxicity limit. Furthermore, there was a significant difference (p < 0.001) in content of total mercury in fur between localities, and there was a clear effect of age on concentrations in fur, skin, and muscle, the concentrations being significantly correlated (fur and skin rs = 0.783; fur and muscle rs = 0.716; skin and muscle rs = 0.884). These findings confirm the usefulness of fur samples from living bats for biomonitoring mercury burden in the environment.

Multi-element Contamination and Health Risks in Green Leafy Vegetables from Ambagarh Chowki, Chhattisgarh, India

Leafy plants are commonly consumed as vegetables in India due to their high nutrient and vitamin content. This study, conducted in Ambagarh Chowki (India), investigated the accumulation potential of 52 elements (including Al, As, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Ho, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, P, Pb, Pr, Rb, Sb, Sc, Se, Sm, Sn, Sr, Tb, Te, Th, Ti, Tl, Tm, U, V, W, Y, Yb, and Zn) in seven leafy vegetable species, namely Amaranthus tricolor L., Corchorus olitorius L., Cordia myxa L., Hibiscus sabdariffa L., Ipomoea batatas (L.) Lam., Moringa oleifera Lam., and Spinacia oleracea L. Technique: Inductively coupled plasma mass spectrometry (ICP-MS) was employed for analysis. The maximum concentrations of elements such as Al, Ba, Be, Bi, Cd, Co, Cr, Fe, Ga, Ge, Li, Mn, Ni, Pb, Sb, Th, Tl, U, V, W, and REEs were observed in S. oleracea leaves, indicating their highest accumulation potential. In contrast, the maximum concentrations of As were found in H. sabdariffa leaves; Ca and Si in M. oleifera leaves; Mg, Sr, and Mo in A. tricolor leaves; and P, K, Cu, and Zn in C. myxa leaves, respectively. Twenty-one elements (Cr, Cd, Pb, Ni, Co, V, Cu, Zn, Fe, Mn, Th, Sb, Ba, Be, Li, Sr, Tl, U, Se, Sn, and REEs) exceeded permissible limits set by the WHO. The elevated hazard index values indicated significant non-carcinogenic effects. The sources of these elements could be attributed to a combination of geological factors and agricultural practices. This study highlights the need for further investigation into the potential health implications of consuming these vegetables in the aforementioned region.

Ecological and human health risk associated with heavy metals (HMs) contaminant sourced from petroleum refinery oily sludge

The environmental and human health risk of heavy metals (HMs) in petroleum based oily sludge (OS) varies depending upon the source of origin of the crude oil and treatment processes practiced at the refineries. Consequently, the present study explores the potential risk associated with HMs of OS obtained from different refinery sites to the environment and human health. The results showed that HMs (Cu, Ni, Zn, Mn) present in OS surpasses the permissible limit of WHO guidelines except for Cr. Additionally, the Igeo value (grade 3-6), Ef (2.48-121.4), PLI (5.12-22.65), Cd (32.48-204.76) and PERI (grade 1-5) confirmed the high level of HMs contamination into the OS and its risk to the environment. Besides, the hazard index (HI) and the total carcinogenic risk (TCR) for HMs show substantial risk to both adult and children health. Likewise, the G-mean enzyme index and potential soil enzyme risk index (PSERI) of the OS showed a high risk to soil biological properties. Furthermore, statistical analysis confirmed the heterogeneity in properties of the OS and its potential impact on the soil ecosystem arising from different sites. Finally, the study unveils a novel perspective on the environmental and human health consequences associated with the OS.

Analysis of nationwide soil pesticide pollution: Insights from China

China is a typical agricultural country that heavily relies on pesticides. Some pesticides can remain in the soil after application and thus pose a significant threat to human health. In order to characterize the status and hazards of nationwide soil contamination, this study extracted concentration data from published literature and analyzed them by a scoring approach, standard comparison and health risk assessment. For the soil pollution score, northern regions got the highest values, such as Henan (0.63), Liaoning (0.55), Heilongjiang (0.54) and Jilin (0.53), which implies high soil pesticide residues in these provinces. In contrast, Qinghai (-0.77), Guizhou (-0.64) and Tibet (-0.63) had lower scores. China's soil pesticide standards cover only 16 pesticides, and these pesticide concentrations were all below the corresponding standards. Direct exposure to soil pesticides in this study generally posed a negligible risk to children. Furthermore, pesticide dissipation and usage intensity in each province were analyzed as they were possible influences on pollution. The result showed that soil in the northern regions could accumulate more pesticides than those in the southern regions, and this geographic pattern was basically consistent with the distribution of soil pollution. However, the relationship between agricultural activities and soil pollution was less well characterized. It is recommended to establish a long-term monitoring database for pesticides and include more pesticides in regulatory frameworks. Additionally, efforts to accelerate pesticide degradation and shift the planting structure to reduce pesticide usage can help alleviate the pressure on soil from pesticides. This study can serve as a critical reference for policymakers and stakeholders in the field of agriculture.

Assessment of carcinogenic and non-carcinogenic risk of exposure to potentially toxic elements in tea infusions: Determination by ICP-OES and multivariate statistical data analysis

BACKGROUND

The perennial evergreen tea (Camellia sinensis) plant is one of the most popular nonalcoholic drinks in the world. Fertilizers and industrial, agricultural, and municipal activities are the usual drivers of soil contamination, contaminating tea plants with potentially toxic elements (PTEs). These elements might potentially accumulate to larger amounts in the leaves of plants after being taken up from the soil. Thus, frequent monitoring of these elements is critically important.

METHODS

The present study intended to determine PTEs (Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb) in both tea leaves and infusions using ICP-OES. Various multivariate data analysis methods such as principal component analysis (PCA) and hierarchical cluster analysis (HCA) were employed to elucidate the potential sources of PTEs contamination, whether from anthropogenic activities or natural origins. Additionally, Pearson's correlation coefficient (PCC) was calculated to assess the relationships between the variables under study.

RESULTS

The mean contents (mg/L) of all studied elements in tea infusions decreased in order Mn (150.59 ± 1.66) > Fe (11.39 ± 0.99) > Zn (6.62 ± 0.89) > Cu (5.86 ± 0.62) > Co (3.25 ± 0.64) > Ni (1.69 ± 0.23) > Pb (1.08 ± 0.16) > Cr (0.57 ± 0.09) > Cd (0.46 ± 0.09) > Al (0.05 ± 0.008), indicating that Mn exhibits the highest abundance. The mean concentration trend in tea leaf samples mirrored that of infusions, albeit with higher concentrations of PTEs in the former. The tolerable dietary intake (TDI) value for Ni and provisional tolerable monthly intake (PTMI) value for Cd surpassed the standards set by the WHO and EFSA. Calculated hazard index (HI < 1) and cumulative cancer risk (CCR) values suggest negligible exposure risk.

CONCLUSION

Elevated levels of PTEs in commonly consumed tea products concern the public and regulatory agencies.

Assessing the impacts and contamination potentials of landfill leachate on adjacent groundwater systems

Landfilling is a globally prevalent method for managing municipal solid waste disposal. Nonetheless, the potential for serious contamination and the significant regional disparities in the leachate produced pose varying degrees of risks to groundwater quality. Previous studies have focused on a single landfill or the same geo-climatic conditions, with a limited number of samples having resulted in a narrow distribution of landfill age and scale, which prevents the description of the pattern of change in landfill age and scale. As well as the effect of this change on the contaminants in the landfill leachate and surrounding groundwater is still unclear. Therefore, we sampled and analyzed leachate and surrounding groundwater from 62 landfills with different landfill ages, scales, and operating conditions in a region with dense and varied topography and climate. Aim to explore the effects of different landfill ages, scales, and operating conditions on contaminants in leachate and surrounding groundwater. Findings indicate that pollutant profiles in different media are influenced by the age, scale, and operational status of the landfill, and the impact of leachate on pollutant types and concentrations in groundwater is limited. A significant correlation exists between the concentration of contaminants in the groundwater affected by leaching from the impermeable layer and the age and scale of the landfill when compared to the leachate. The contamination potentials posed by different pollutants vary across environmental media. Total dissolved solids and NH4+-N in leachate presented high contamination potentials, whereas elemental metalloids (Mn, Al, Ba, and Fe) in the surrounding groundwater posed high environmental concerns. These insights furnish new avenues for monitoring, identification, and safeguarding against pollutants in landfills and proximate groundwater, which is imperative for the sustainable management of municipal waste.

Biostimulation of sulfate reduction for in-situ metal(loid) precipitation at an industrial site in Flanders, Belgium

A 30-month pilot study was conducted to evaluate the potential of in-situ metal(loid) removal through biostimulation of sulfate-reducing processes. The study took place at an industrial site in Flanders, Belgium, known for metal(loid) contamination in soil and groundwater. Biostimulation involved two incorporations of an organic substrate (emulsified vegetable oil) as electron donor and potassium bicarbonate to raise the pH of the groundwater by 1-1.5 units. The study focused on the most impacted permeable fine sand aquifer (8-9 m below groundwater level) confined by layers of non-permeable clay. The fine sands exhibited initially oxic conditions (50-200 mV), an acidic pH of 4.5 and sulfate concentrations ranging from 600 to 800 mg/L. At the central monitoring well, anoxic conditions (-200 to -400 mV) and a pH of 5.9 established shortly after the second substrate and reagent injection. Over the course of 12 months, there was a significant decrease in the concentration of arsenic (from 2500 to 12 μg/L), nickel (from 360 to <2 μg/L), zinc (from 78,000 to <2 μg/L), and sulfate (from 930 to 450 mg/L). Low levels of metal(loid)s were still present after 34 months (end of study). Mineralogical analysis indicated that the precipitates formed were amorphous in nature. Evidence for biologically driven metal(loid) precipitation was provided by compound specific stable isotope analysis of sulfate. In addition, changes in microbial populations were assessed using next-generation sequencing, revealing stimulation of native sulfate-reducing bacteria. These results highlight the potential of biostimulation for long-term in situ metal(loid) plume treatment/containment.

Isotopic insights and integrated analysis for heavy metal levels, ecological risks, and source apportionment in river sediments of the Qinghai-Tibet Plateau

The research was carried out to examine the pollution characteristics, ecological risk, and origins of seven heavy metals (Hg, As, Pb, Cu, Cd, Zn, and Ni) in 51 sediment samples gathered from 8 rivers located on the Qinghai-Tibet Plateau (QTP) in China. The contents of Hg and Cd were 5.0 and 1.1 times higher than their background values, respectively. The mean levels of other measured heavy metals were below those found naturally in the local soil. The enrichment factor showed that the study area exhibited significantly enriched Hg with 70.6% sampling sites. The Cd contents at 19.6% of sampling sites were moderately enriched. The other sampling sites were at a less enriched level. The sediments of all the rivers had a medium level of potential ecological risk. Hg was the major ecological risk factor in all sampling sites, followed by Cd. The findings from the positive matrix factorization (PMF) analysis shown agricultural activities, industrial activities, traffic emissions, and parent material were the major sources. The upper, middle, and low reaches of the Quanji river had different Hg isotope compositions, while sediments near the middle reaches were similar to the δ202Hg of the industrial source. At the upstream sampling sites, the Hg isotope content was very close to the background level. The results of this research can establish a strong scientific sound to improve the safety of the natural circumstances of rivers on the QTP.

Arsenic uptake by Agrostis capillaris, as related to its genotypic diversity in the area of historical ore mining and processing

Common bentgrass Agrostis capillaris L. is known as tolerant to toxic elements. A hypothesis was examined that its ecotypes growing in historically polluted sites show a limited arsenic uptake and have genetic features that distinguish them from commercially available cultivars. The study was conducted in Złoty Stok, a historical area of arsenic mining. Additionally, two commercial cultivars were grown in pots with arsenic-rich soils. Based on arsenic concentrations in plant roots and shoots, bioconcentration and translocation factors BCF and TF were calculated. Commercial cultivars indicated many times higher BCF shoots and TF values compared to field plants. DNA analysis of leaf blades showed a clear distinction between the plants growing in some sites and patches in the field, and also a gene overlap between the plants in the field and commercial forms. The research did not allow for identification of ecotypes with exceptionally limited arsenic uptake. Moreover, there were no significant differences between the genotypic characteristics of plants growing in polluted sites and those poorly tolerant grown from commercially available seeds. Apparently, other factors, and not genetically determined features, are responsible for A. capillaris tolerance to arsenic in Złoty Stok.

Conversion of char from pyrolysis of plastic wastes into alternative activated carbons for heavy metal removal

The valorization of post-consumer mixed plastics in pyrolysis processes represents an abundant reservoir of carbon that can be effectively converted into useful chars. This process not only holds appeal in terms of improving plastic waste concerns but also contributes to the reduction of greenhouse gas emissions, thus aligning with the principles of a circular economy paradigm. In this study, the char produced from the pyrolysis of post-consumer mixed plastic waste has been activated with Na2CO3, KOH, NaOH, and K2CO3 to improve the textural, structural, and composition characteristics, leading to improved adsorption capability. These characteristics were studied by N2 adsorption-desorption isotherms, scanning electron microscopy, elemental and immediate analysis, and X-ray photoelectron spectroscopy. The developed surface area (SBET) was 573, 939, 704 and 592 m2 g-1 for Na2CO3, KOH, NaOH and K2CO3 activated carbons, respectively. These activated chars (ACs) were tested for the adsorption of heavy metals in both synthetic waters containing Pb, Cd, and Cu and industrial wastewater collected at an agrochemical production plant. Na2CO3-AC was the best performing material. The metal uptake in synthetic waters using a batch set-up was 40, 13 and 12 mg g-1 for Pb, Cd and Cu. Experiments in a column set-up using Na2CO3-AC resulted in a saturation time of 290, 16, and 80 min for Pb, Cd, and Cu synthetic waters, respectively, and metal uptakes of 26.8, 4.1, and 7.9 mg g-1, respectively. The agrochemical effluents, containing mainly Cr, Cu, Mn, and Zn were tested in a plug-flow column. The metal uptake notably decreased compared to synthetic water due to a competition effect for active sites.

Geochemical fractionation of iron in paper industry and municipal landfill soils: Ecological and health risks insights

Industrial processes and municipal wastes largely contribute to the fluctuations in iron (Fe) content in soils. Fe, when present in unfavorable amount, causes harmful effects on human, flora, and fauna. The present study is an attempt to evaluate the composition of Fe in surface soils from paper mill and municipal landfill sites and assess their potential ecological and human health risks. Geochemical fractionation was conducted to explore the chemical bonding of Fe across different fractions, i.e., water-soluble (F1) to residual (F6). Different contamination factors and pollution indices were evaluated to comprehend Fe contamination extent across the study area. Results indicated the preference for less mobile forms in the paper mill and landfill, with 26.66% and 43.46% of Fe associated with the Fe-Mn oxide bound fraction (F4), and 57.22% and 24.78% in the residual fraction (F6). Maximum mobility factor (MF) of 30.65% was observed in the paper mill, and 80.37% in the landfill. The enrichment factor (EF) varied within the range of 20 < EF < 40, signifying a high level of enrichment in the soil. The individual contamination factor (ICF) ranged from 0 to >6, highlighting low to high contamination. Adults were found to be more vulnerable towards Fe associated health risks compared to children. The Hazard Quotient (HQ) index showed the highest risk potential pathways as dermal contact > ingestion > inhalation. The study offers insights into potential Fe contamination risks in comparable environments, underscoring the crucial role of thorough soil assessments in shaping land use and waste management policies.

Spatial distribution of heavy metal abundance at distance gradients of roadside agricultural soil from the busiest highway in Bangladesh: A multi-index integration approach

Bangladesh is currently experiencing significant infrastructural development in road networking system through the construction or reconstruction of multiple roads and highways. Consequently, there is a rise in traffic intensity on roads and highways, along with a significant contamination of adjacent agricultural soils with heavy metals. The purpose of this study was to evaluate the ecological risk, health risk and the abundance of seven heavy metals (Cu, Mn, Pb, Cd, Cr, As, and Ni) in three distance gradients (0, 300, and 500 m) of agricultural soil along the Dhaka-Chattogram highway. The concentration of heavy metals was measured with an Atomic Absorption Spectrophotometer (AAS) on a total of 36 soil samples that were taken from 12 different sampling sites. Based on the findings, Cd had a high contamination factor for all distance gradients, whereas Cr had a moderate contamination factor in 67% of the study areas. According to the Pollution Load Index (PLI), Cd, Cr, and Pb were the predominant pollutants. Principal component analysis (PCA) result shows these metals mainly came from anthropogenic sources. The considerable positive correlations between Cu-Pb, Cu-Cd, Pb-Cd, and Cr-Ni all pointed to shared anthropogenic origins. As per Potential Ecological Risk Assessment (PERI) analysis, Pb, Cd, Cr, and Ni each contribute significantly and pose a moderate threat. The Target Hazard Quotient (THQ) values for all pathways of exposure to Pb and Cr in soils were more than 1, which would pose a significant risk to human health in the following order: THQadult female > THQadult male > THQchildren. This study will help to evaluate the human health risk and develop a better understanding of the heavy metal abundance scenario in the agricultural fields adjacent to this highway.

Evaluating the human health risks of heavy metal contamination in copper and steel factory effluents in Nnewi, Anambra State, Nigeria

Heavy metal (HM) contamination above permissible limits poses a risk to human health. The study evaluated the health risk (cancer and non-cancer) of exposure to copper (Cu) and steel factory wastes on water samples near the factory based on the hazard quotient (HQ) derived from the HM concentrations. Triplicate water samples were collected by purposive sampling and their concentrations of selected HMs [Pb, Zn, Cu, Mn, Mg, Fe, Cd] were analyzed by Atomic Absorption Spectrometry. The health risks were determined from the concentrations of HMs in water samples ingested orally. The range concentrations were [Fe, 0.074-0.178], [Pb, 0.011-0.013], [Cd, 0.005-0.02], and [Mn, 0.023-0.045] which were above the reference values set by World Health Organization. The contribution of the individual metal to the chronic daily intake (CDI) in the three samples are Mg>Fe>Mn>Zn>Cd>Pb>Cu. In the three different samples, the CDI for Mg was highest in the factory borehole [0.15523]. Comparing the CDI values from the three different collection points, Cu, Pb, Zn and Fe were highest from the factory effluent. Mg contributed the highest HQ [5.46307] in all the water samples, followed by Pb [3.87618] and then Cd[2.64009], which reflect their significantly high hazard indices observed. The incremental life cancer risk [ILCR] via ingestion showed that the cancer risk resulting from Cd in the different sources demands attention. The factory effluent recorded the highest mean levels of the metals analyzed, which were higher than the permissible limits. Magnesium contributed the highest non-cancer risk, while Cd had the highest cancer risk.

Potentially toxic elements (PTEs) and ecological risk at waste disposal sites: An analysis of sanitary landfills

This study presents an analysis of soil contamination caused by Ni, Zn, Cd, Cu, and Pb at municipal solid waste (MSW) landfills, with a focus on ecological risk assessment. The approach aims to assess how different landfill practices and environmental conditions affect soil contamination with potentially toxic elements (PTEs) and associated environmental risks. Soil samples were collected from MSW landfills in Poland and the Czech Republic. The research included a comprehensive assessment of PTEs in soils in the context of global environmental regulations. The degree of soil contamination by PTEs was assessed using indices: Geoaccumulation Index (Igeo), Single Pollution Index (Pi), Nemerow Pollution Index (PN), and Load Capacity of a Pollutant (PLI). The ecological risk was determined using the Risk of PTEs (ERi) and Sum of Individual Potential Risk Factors (ERI). The maximum values of the indicators observed for the Radiowo landfill were as follows: Igeo = 4.04 for Cd, Pi = 24.80 for Cd, PN = 18.22 for Cd, PLI = 2.66, ERi = 744 for Cd, ERI = 771.80. The maximum values of the indicators observed for the Zdounky landfill were as follows: Igeo = 1.04 for Cu, Pi = 3.10 for Cu, PN = 2.52 for Cu, PLI = 0.27, ERi = 25 for Cd, ERI = 41.86. The soils of the tested landfills were considered to be non-saline, with electrical conductivity (EC) values less than 2,000 μS/cm. Varying levels of PTEs were observed, and geostatistical analysis highlighted hotspots indicating pollution sources. Elevated concentrations of Cd in the soil indicated potential ecological risks. Concentrations of Cu and lead Pb were well below the thresholds set by the environmental legislation in several countries. In addition, Ni concentrations in the soils of both landfills indicated that the average levels were within acceptable limits. Principal Component Analysis (PCA) revealed common sources of PTEs. The identification of specific risk points at the Radiowo and Zdounky sites contributes to a better understanding of potential hazards in landfill environments. By establishing buffer zones and implementing regular maintenance programs, emerging environmental problems can be addressed in a timely manner.

Mapping soil trace metal distribution using remote sensing and multivariate analysis

Trace metal soil contamination poses significant risks to human health and ecosystems, necessitating thorough investigation and management strategies. Researchers have increasingly utilized advanced techniques like remote sensing (RS), geographic information systems (GIS), geostatistical analysis, and multivariate analysis to address this issue. RS tools play a crucial role in collecting spectral data aiding in the analysis of trace metal distribution in soil. Spectroscopy offers an effective understanding of environmental contamination by analyzing trace metal distribution in soil. The spatial distribution of trace metals in soil has been a key focus of these studies, with factors influencing this distribution identified as soil type, pH levels, organic matter content, land use patterns, and concentrations of trace metals. While progress has been made, further research is needed to fully recognize the potential of integrated geospatial imaging spectroscopy and multivariate statistical analysis for assessing trace metal distribution in soils. Future directions include mapping multivariate results in GIS, identifying specific anthropogenic sources, analyzing temporal trends, and exploring alternative multivariate analysis tools. In conclusion, this review highlights the significance of integrated GIS and multivariate analysis in addressing trace metal contamination in soils, advocating for continued research to enhance assessment and management strategies.

Comparative effectiveness of carbon nanoparticles and biochar in alleviating copper stress in corn (Zea mays L.)

The application of carbon nanoparticles (CNPs) and biochar in agriculture for improving plant health and soil quality and alleviating metal stress offers alternative approaches to meet the ever-increasing demand for food. However, poor understanding of their roles in improving crop production under Cu stress represents a significant obstacle to their wide application in agriculture. To clarify how CNPs and biochar affect corn (Zea mays L.) seed germination, seedling growth, plant health, and nutrient uptake under different Cu stress levels, soil-less Petri-dish and greenhouse soil-based bioassays were conducted. The results revealed that CNPs and biochar stimulated corn seed germination and seedling growth. Besides, they were effective in immobilizing Cu2+ sorption in sandy soil and alleviating Cu stress for plant growth, as shown by the increased plant height and dry biomass. The plant nutrient uptake efficiency (NUE) was significantly increased by CNPs, with a maximum increase of 63.1% for N and 63.3% for K at the highest Cu2+ stress level (400 mg Cu2+ L-1). In contrast, non-significant effects on NUE were observed with biochar treatments regardless of Cu stress levels. Interestingly, CNPs significantly increased plant uptake of Cu in the Petri dish test, while biochar inhibited plant uptake of Cu under both experimental conditions. Principle component analysis (PCA) and Pearson correlation analysis indicated that CNPs mitigated Cu stress mainly by elevating antioxidant enzyme activities, enhancing plant photochemical efficiency, and increasing plant uptake of N and K, while biochar was more likely to reduce bioavailability and uptake of Cu in the plant. These findings have great implications for the application of CNPs and biochar as plant growth stimulators and de-toxicity agents in agriculture.

Soil pollution indices and health risk assessment of metal(loid)s in the agricultural soil of pistachio orchards

Elevated levels of metal(loid)s in soil may pose potential threats to the ecosystem and can be harmful for human health. The concentrations of As, Cd, Pb, Cr and Ni were determined in agricultural soil collected from 45 pistachio orchards around Feizabad city, Khorasan Razavi province, Iran using ICP-OES. Also, soil pollution indices including contamination factor (CF), pollution load index (PLI) and geo-accumulation index (Igeo) were evaluated. In addition, non-carcinogenic and carcinogenic risk indices were estimated. The mean concentrations of metal(loid)s were in the order of Ni = 466.256 > Cr = 120.848 > Pb = 12.009 > As = 5.486 > Cd = 0.394 mg/kg. Concentrations of As, Cd and Pb in the soil samples were within their respective permissible limits set by World Health Organization (WHO). But concentrations of Cr and Ni in 84.4 and 100% of the samples, respectively exceeded the WHO allowable limits. The CF, PLI and Igeo showed that soil of some of the pistachio orchards was contaminated with some metals. The possible sources of the metals in the soil are application of pesticides, chemical fertilizers, manures as well as irrigation water. Hazard quotient (HQ) ad Hazard index (HI) values from soil of all the orchards were found to be well below the respective threshold limit (1), suggesting that there is no immediate non-cancer threat arising from the contamination at all the orchards with metal(loid)s for children and adults. The highest cancer risk values (1.13E-02 for children and 1.25E-03 for adults) were estimated for Ni in the soil. Collectively, this study provides valuable information to improve the soil in the pistachio orchards to reduce metal(loid)s contamination and minimize the associated health risks to the population in the area.

Errors in agricultural practices increase the toxicity of heavy metals in the food chain at Ishwardi Upazila in Bangladesh

Due to the potential harm to human health, heavy metal deposition in agricultural products has gained importance throughout the world. Excessive use of agrochemicals and poultry wastes dramatically increased during the cultivation processes of rapidly growing vegetables without maintaining authorized guidelines. It happens due to the availability and low cost of these materials and higher production of the vegetables. Higher levels of heavy metals, especially Arsenic (As), Lead (Pb), Chromium (Cr), and Cadmium (Cd) contamination in food have detrimental effects on human health as well as the environmental ecosystems. This study revealed the profile of the heavy metals in the fast-growing vegetable called red amaranth (Amaranthus cruentus) due to the frequent use of poultry manure. We collected a total of 75 samples of red amaranth, water, and soil from five villages of five different unions at Ishwardi upazila in Bangladesh, and we analyzed the contamination levels of As, Pb, Cr, and Cd in them. Except for the As, we found that the accumulation levels of Pb, Cr, and Cd in samples crossed the highest permissive limit compared to FAO/WHO standards. Results suggested that daily intake of red amaranth in this area is alarming to human health due to the detrimental effects of these heavy metals.

Elemental composition and potential health risk of vegetable cultivated in residential area situated close to abandoned gold mine dump: Characteristics of soil quality on the vegetables

The presence of toxic metals in residential areas near abandoned gold mine tailings is a major environmental issue. This study mainly aimed to investigate the elemental distribution of both toxic and essential elements in soils and leafy vegetables (Brassica oleracea) collected from eight different sites around the Davidsonville residential area, located closer to the abandoned Princess gold mine dump, Johannesburg, South Africa. The nutritional value of vegetables in the human diet was determined to assess their value to their health. The vegetables contained metals in the following descending order: Ca > Mg > Ca > Sb > Pb > Fe > Mo > Cr > Se > As > V > Ni > Co > Cd. The bioaccumulation factor (BAF) revealed that vegetables tend to accumulate most metals even (toxic) during the transfer and translocation process. Based on the recommended daily allowance (%RDA) the vegetables showed to contribute 152%, 84% and 75% toward RDA for Se, V and Ca, respectively for most adults and these play a role in human metabolic activities. The vegetables were found to be a good source of essential elements (Ca, Mg, Ni, Na, Fe) but with some traces of toxic metals such as Pb, As and Sb. Based on the health risk assessment, the vegetable posed an adverse health hazard for human consumption due to metals with high HRI >1.

Using L. minor and C. elegans to assess the ecotoxicity of real-life contaminated soil samples and their remediation by clay- and carbon-based sorbents

Toxic substances, such as polycyclic aromatic hydrocarbons (PAHs) and heavy metals, can accumulate in soil, posing a risk to human health and the environment. To reduce the risk of exposure, rapid identification and remediation of potentially hazardous soils is necessary. Adsorption of contaminants by activated carbons and clay materials is commonly utilized to decrease the bioavailability of chemicals in soil and environmental toxicity in vitro, and this study aims to determine their efficacy in real-life soil samples. Two ecotoxicological models (Lemna minor and Caenorhabditis elegans) were used to test residential soil samples, known to contain an average of 5.3, 262, and 9.6 ppm of PAHs, lead, and mercury, for potential toxicity. Toxicity testing of these soils indicated that 86% and 58% of soils caused ≤50% inhibition of growth and survival of L. minor and C. elegans, respectively. Importantly, 3 soil samples caused ≥90% inhibition of growth in both models, and the toxicity was positively correlated with levels of heavy metals. These toxic soil samples were prioritized for remediation using activated carbon and SM-Tyrosine sorbents, which have been shown to immobilize PAHs and heavy metals, respectively. The inclusion of low levels of SM-Tyrosine protected the growth and survival of L. minor and C. elegans by 83% and 78%, respectively from the polluted soil samples while activated carbon offered no significant protection. These results also indicated that heavy metals were the driver of toxicity in the samples. Results from this study demonstrate that adsorption technologies are effective strategies for remediating complex, real-life soil samples contaminated with hazardous pollutants and protecting natural soil and groundwater resources and habitats. The results highlight the applicability of these ecotoxicological models as rapid screening tools for monitoring soil quality and verifying the efficacy of remediation practices.

Evaluation on quality and health risk of groundwater in a highly urbanized watershed, China

Urbanizations and industrializations may accelerate the contamination and deterioration of groundwater quality. This study aimed to evaluate the quality and potential human health risks associated with shallow groundwater in Shenzhen, China, a city characterized by high levels of urbanization and industrialization. The hydrochemistry characteristics, water quality levels, and human health risks of main ions, nutrient elements, and metals in 220 samples collected from Maozhou River Basin (MRB) located in the northwest of Shenzhen were investigated. It showed that chemical constituents of the groundwater were further complicated by seawater intrusion and urbanization expansion. Water quality evaluated by fuzzy comprehensive method showed that 21.05% of samples distributed around reservoirs were classified into grade II or better. Nearly 79% of samples distributed in the densely populated urban land were classified into grade III or worse, indicating pollution from anthropogenic factors cannot be ignored. For the river tidal reach where river stage fluctuated about 0.5 to 1.5 m within a tidal cycle, the chemical composition of groundwater was influenced by frequent water exchange with the river. The carcinogenic and non-carcinogenic health risks for different age groups, from the high to the low, were children, adult women, adult men, adolescent women, and adolescent men, respectively. Approximately 39% of groundwater samples distributed around the densely populations area with health risk larger than 5 × 10-5 were unacceptable for children. This investigation would be helpful for improving groundwater management and as a practical reference for sustainable groundwater exploitation in the MRB.

Exploring the fluorescence properties of tellurium-containing molecules and their advanced applications

This review article explores the fascinating realm of fluorescence using organochalcogen molecules, with a particular emphasis on tellurium (Te). The discussion encompasses the underlying mechanisms, structural motifs influencing fluorescence, and the applications of these intriguing phenomena. This review not only elucidates the current state of knowledge but also identifies avenues for future research, thereby serving as a valuable resource for researchers and enthusiasts in the field of fluorescence chemistry with a focus on Te-based molecules. By highlighting challenges and prospects, this review sparks a conversation on the transformative potential of Te-containing compounds across different fields, ranging from environmental solutions to healthcare and materials science applications. This review aims to provide a comprehensive understanding of the distinct fluorescence behaviors exhibited by Te-containing compounds, contributing valuable insights to the evolving landscape of chalcogen-based fluorescence research.

Risk assessment for the long-term stability of fly ash-based cementitious material containing arsenic: Dynamic and semidynamic leaching

Fly ash from municipal solid waste incineration (MSWIFA) contains leachable heavy metals (HMs), and the environmental risk of contained HMs is an important concern for its safe treatment and disposal. This paper presents a dynamic leaching test of fly ash-based cementitious materials containing arsenic (FCAC) in three particle sizes based on an innovative simulation of two acid rainfall conditions to investigate the long-term stability of FCAC under acid rain conditions. As well as semi-dynamic leaching test by simulating FCAC in three scenarios. Furthermore, the long-term stability risk of FCAC is evaluated using a sequential extraction procedure (SEP) and the potential risk assessment index. Results showed that the Al3+ in the FCAC dissolved and reacted with the OH- in solution to form Al(OH)3 colloids as the leaching time increased. Moreover, the oxidation of sulfide minerals in the slag produced oxidants, such as H2SO4 and Fe2(SO4)3, which further aggravated the oxidative dissolution of sulfides, thereby resulting in an overall decreasing pH value of the leachate. In addition, due to the varying particle sizes of the FCAC, surface area size, and adsorption site changes, the arsenic leaching process showed three stages of leaching characteristics, namely, initial, rapid, and slow release, with a maximum leaching concentration of 2.42 mg/L, the cumulative release of 133.78 mg/kg, and the cumulative release rate of 2.32%. The SEP test revealed that the reduced state of HMs in the raw slag was lowered substantially, and the acid extractable state and residual state of HMs were increased, which was conducive to lessening the risk of FCAC. Overall, the geological polymerization reaction of MSWIFA is a viable and promising solution to stabilize mining and industrial wastes and repurpose the wastes into construction materials.

Biochar reduces the cadmium content of Panax quinquefolium L. by improving rhizosphere microecology

Cadmium (Cd) accumulation in American ginseng (Panax quinquefolium L.) can negatively impact its yield and safety. Our previous study found that biochar could reduce cadmium content of P. quinquefolius, however, the mechanism was yet to be elucidated. In the present study, we tested four treatments in order to reveal the mechanism by which this phenomenon occurs: control, Cd, Cd + biochar and biochar. The results showed that the following responses were induced by the addition of biochar under Cd stress. Firstly, the soil physicochemical properties were improved, this is especially true for the soil pH value and soil organic matter content, which were increased by 20.42 % and 15.57 %, respectively. Secondly, the relative abundances of several beneficial microorganism phyla; such as Proteobacteria, Bacteroidota and Actinobacteria; were increased by 10.69 %, 20.11 % and 60.86 %, respectively. Thirdly, treatment with biochar reduced the Cd content by increasing cadmium-chelated metabolites within the soil (e.g., naringenin, caffeic acid, and valine) and increasing detoxification substances in plants (e.g., malic acid, flavonoids, and fumaric acid). Changes in these metabolites were significantly correlated with rhizosphere microecology. In summary, biochar treatment reduced the Cd content in seedlings by improving the soil properties, rhizosphere community, soil metabolites, and plant metabolites.

Assessment of health risks associated with prediction of vegetable inorganic arsenic concentrations given different soil properties

Inorganic arsenic (iAs) is a carcinogen. Vegetables such as water spinach (Ipomoea aquatica Forssk.) and amaranth (Amaranthus mangostanus L.) are recognized as high-risk sources of iAs exposure because they can accumulate significant amounts of iAs and are widely consumed. To ensure safe cultivation conditions, this study aimed to establish prediction models for iAs concentration in the edible parts of water spinach and amaranth based on soil properties. Subsequently, health risk assessments associated with iAs exposure through the consumption of these vegetables were conducted using prediction models. Soil samples were collected from agricultural fields in Taiwan and used in the pot experiments. Pearson correlation and partial correlation analyses were used to explore the relationship between soil properties, including total As, clay, organic matter, iron oxides and available phosphates, and iAs concentration in edible parts of water spinach and amaranth. Prediction models based on soil properties were developed by stepwise multiple linear regression. Health risk assessments were conducted using the Monte Carlo algorithm. The results indicate that total As and organic matter contents in soil were major predictors of iAs concentration in water spinach, whereas those in amaranth were total As and clay contents. Therefore, higher health risks for consuming water spinach and amaranth are associated with higher levels of organic matter and clay contents in soil, respectively, and these are crucial factors to consider to ensure food safety. This study suggested that As-elevated soils enriched with organic matter and clay contents should be avoided when growing water spinach and amaranth, respectively.

Assessment of human health risk from potentially toxic elements and predicting groundwater contamination using machine learning approaches

The Rooppur Nuclear Power Plant (RNPP) at Ishwardi, Bangladesh is planning to go into operation within 2024 and therefore, adjacent areas of RNPP is gaining adequate attention from the scientific community for environmental monitoring purposes especially for water resources management. However, there is a substantial lack of literature as well as environmental datasets for earlier years since very little was done at the beginning of the RNPP's construction phase. Therefore, this study was conducted to assess the potential toxic elements (PTEs) contamination in the groundwater and its associated health risk for residents at the adjacent part of the RNPP during the year of 2014-2015. For the purposes of achieving the aim of the study, groundwater samples were collected seasonally (dry and wet season) from nine sampling sites and afterwards analyzed for water quality indicators such as temperature (Temp.), pH, electrical conductivity (EC), total dissolved solid (TDS), total hardness (TH) and for PTEs including Iron (Fe), Manganese (Mn), Copper (Cu), Lead (Pb), Chromium (Cr), Cadmium (Cd) and Arsenic (As). This study adopted the newly developed Root Mean Square water quality index (RMS-WQI) model to assess the scenario of contamination from PTEs in groundwater whereas the human health risk assessment model was utilized to quantify the risk of toxicity from PTEs. In most of the sampling sites, PTEs concentration was found higher during the wet season than the dry season and Fe, Mn, Cd and As exceeded the guideline limit for drinking water. The RMS score mostly classified the groundwater in terms of PTEs contamination into "Fair" condition. The non-carcinogenic risks (expressed as Hazard Index-HI) revealed that around 44% and 89% of samples for adults and 67% and 100% of samples for children exceeded the threshold limit set by USEPA (HI > 1) and possessed risks through the oral pathway during dry and wet season, respectively. Furthermore, the calculated cumulative HI score was found higher for children than the adults throughout the study period. In terms of carcinogenic risk (CR) from PTEs, the magnitude of risk decreased following the pattern of Cr > As > Cd. Although the current study is based on old dataset, the findings might serve as a baseline for monitoring purposes to reduce future hazardous impact from the power plant.

Copper stress shapes the dynamic behavior of amoebae and their associated bacteria

Amoeba-bacteria interactions are prevalent in both natural ecosystems and engineered environments. Amoebae, as essential consumers, hold significant ecological importance within ecosystems. Besides, they can establish stable symbiotic associations with bacteria. Copper plays a critical role in amoeba predation by either killing or restricting the growth of ingested bacteria in phagosomes. However, certain symbiotic bacteria have evolved mechanisms to persist within the phagosomal vacuole, evading antimicrobial defenses. Despite these insights, the impact of copper on the symbiotic relationships between amoebae and bacteria remains poorly understood. In this study, we investigated the effects of copper stress on amoebae and their symbiotic relationships with bacteria. Our findings revealed that elevated copper concentration adversely affected amoeba growth and altered cellular fate. Symbiont type significantly influenced the responses of the symbiotic relationships to copper stress. Beneficial symbionts maintained stability under copper stress, but parasitic symbionts exhibited enhanced colonization of amoebae. Furthermore, copper stress favored the transition of symbiotic relationships between amoebae and beneficial symbionts toward the host's benefit. Conversely, the pathogenic effects of parasitic symbionts on hosts were exacerbated under copper stress. This study sheds light on the intricate response mechanisms of soil amoebae and amoeba-bacteria symbiotic systems to copper stress, providing new insights into symbiotic dynamics under abiotic factors. Additionally, the results underscore the potential risks of copper accumulation in the environment for pathogen transmission and biosafety.

Assessing the ecological and health risks associated with heavy metal pollution levels in sediments of Big Giftun and Abu Minqar Islands, East Hurghada, Red Sea, Egypt

This study assessed pollution levels, ecological and health risk, and spatial distribution of eight heavy metals in sediments of Big Giftun and Abu Minqar Islands, Red Sea, Egypt. Iron (Fe) and manganese (Mn) had the highest contents in both island sediments, while cobalt (Co) in Big Giftun and cadmium (Cd) in Abu Mingar had the lowest values. The obtained PCA data exhibited positively significant loadings of Cd, Co, copper (Cu), nickel (Ni), and zinc (Zn) with 51.03 % of data variance in Big Giftun, and lead (Pb), Cu, Mn, Ni, Zn, and Fe (37.7 %) in Abu Minqar sediments. The contamination factor (CF) showed low contamination for all metals, except cadmium; Cd (moderate). The geo-accumulation index (Igeo) values showed uncontaminated (Cd, Co), moderately (Cu), extremely contaminated (Fe, Mn) (Igeo > 5) in Big Giftun, and uncontaminated (Cd), moderately to strongly contaminated (Cu, Ni), and extremely contaminated (Fe, Mn, and Zn) in Abu Minqar sediments. The pollution load index (PLI) values indicated baseline level of contamination (PLI <1), and degree of contamination (DC) indicated low degree of contamination (DC < n) in all sediments. Nemerow pollution index (NPI) showed unpolluted sediments in Abu Minqar (NPI ≤1) and slight pollution (1 < NPI ≤2) in Big Giftun. Cd showed moderate potential ecological risk (40 ≤ Eri < 80) in Big Giftun sediments. Potential ecological risk index (PERI) indicated low risk sediments (PERI <150). Mean effects range median quotient (MERMQ) indicated low-priority risk of toxicity (MERMQ ≤0.1), and toxic risk index (TRI) showed no toxic risk in all sediments (TRI <5). The modified hazard quotient (mHQ) indicated very low severity of contamination (mHQ <0.5). The hazard quotient (HQ) levels of all metals were below the safe value (HQ <1). The hazard index (HI) levels indicated that no chronic risks occur (HI <1). The total cancer risk (TCR) for all metals were below the safe level (1 × 10-4) of the United States Environmental Protection Agency (U.S. EPA) guidelines.

Environmental health risk assessment and source apportion of heavy metals using chemometrics and pollution indices in the upper Yamuna river basin, India

River Yamuna is the largest tributary of the Ganges with great economic importance, and provides water for about 57 million people and accounts for more than 70% of Delhi's water supply. Various pollution indices and chemometric methods were used to investigate heavy metal pollution, associated risks, and probable sources in the upper Yamuna river water. A total of 56 river water samples, 28 each in pre and post-monsoon season were collected and analysed for 15 heavy metals. The findings reveal that Al (38.66 ± 21.14 μg/L), As (16.52 ± 15.81 μg/L), and Mn (41.06 ± 89.25 μg/L) in pre-monsoon and Al (45.77 ± 29.46 μg/L), As (10.30 ± 12.15 μg/L), Fe (48.03 ± 81.11 μg/L), and Mn (31.02 ± 70.13 μg/L) in post-monsoon exceeded the Bureau of Indian Standards (BIS) acceptable limits. The pollution indices (HPI, NPI, HEI, and Cd) indicate that most locations are low to moderately polluted, except for the lower catchment. Health indices, i.e., hazard Index (HI) and incremental lifetime cancer risk (ILCR), suggest that the prolonged consumption of river water may cause potential human health hazards. In contrast, the water is suitable for domestic and other uses as the dermal risk is less prominent. The ecological risk index (ERI) of pre (0.22-58.75) and post-monsoon (0.12-44.21) were in the low-risk category (<110), indicating no ecological risk associated with heavy metals. In pre and post-monsoon, four principal components (PCs) described 73.97% and 76.18% of the total variance respectively, suggesting the mixed impact of numerous geogenic and anthropogenic sources in the region's water chemistry. Cluster analysis demonstrates that the lower catchment samples (National Capital Region, Delhi) significantly vary from each other due to wastewater discharge, industrialisation, and rapid urbanization, while the upper and mid-catchment samples are less distinct. Hence, more than 90% of the Yamuna water is extracted from the upper region; present findings may aid in developing an effective catchment scale management strategy.

Ecological and health risk assessment of heavy metals in agricultural soils from northern China

Soil pollution by heavy metals can cause continuing damage to ecosystems and the human body. In this study, we collected nine fresh topsoil samples and 18 maize samples (including nine leaf samples and nine corn samples) from agricultural soils in the Baiyin mining areas. The results showed that the order of heavy metal concentrations (mg/kg) in agricultural soils was as follows: Zn (377.40) > Pb (125.06) > Cu (75.06) > Ni (28.29) > Cd (5.46) > Hg (0.37). Cd, Cu, Zn, and Pb exceeded the Chinese risk limit for agricultural soil pollution. The average the pollution load index (4.39) was greater than 3, indicating a heavy contamination level. The element that contributed the most to contamination and high ecological risk in soil was Cd. Principal component analysis (PCA) and Pearson's correlation analysis indicated that the sources of Ni, Cd, Cu, and Zn in the soil were primarily mixed, involving both industrial and agricultural activities, whereas the sources of Hg and Pb included both industrial and transportation activities. Adults and children are not likely to experience non-carcinogenic impacts from the soil in this region. Nonetheless, it was important to be aware of the elevated cancer risk presented by Cd, Pb, and especially Ni. The exceedance rates of Cd and Pb in corn were 66.67% and 33.3%, respectively. The results of this research provide data to improve soil protection, human health monitoring, and crop management in the Baiyin district.

Emerging Trends in nanostructured materials-coated screen printed electrodes for the electrochemical detection of hazardous heavy metals in environmental matrices

Heavy metal ions (HMIs) have become a significant contaminant in recent years. The increase in heavy metal pollution is a serious situation, requiring progressively robust, fast sensing, highly sensitive, and suitable techniques for heavy metal detection. Compared to other classical analytical methods, electroanalytical techniques, especially stripping voltammetric techniques with modified screen-printed electrodes (SPEs), have several advantages, such as fast sensing, great sensitivity, specificity, and long-time stability. Therefore, these techniques are more suitable for HMI detection. In this review, the nanostructured materials used to coat SPEs for the electrochemical determination of HMI are summarized. Additionally, the electrode fabrication method, modification steps, and electroanalytical study of these materials are systematically discussed. Hence, this review will support the researchers in precisely evaluating the electrochemical HMIs detection through highly sensitive stripping voltammetric techniques using SPE modified with nanostructured carbon and their allotropes, metal, metal oxides and their nanocomposites as sensor materials. Moreover, modified electrodes real time detection of HMIs in different food and environmental samples were briefly discussed.

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 346.42 mg kg-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.

Human health risk assessment of potentially toxic elements and microplastics accumulation in products from the Danube River Basin fish market

The present study aimed to quantify the concentration levels of potentially toxic elements (PTEs) such as aluminum, arsenic, cadmium, chromium, copper, nickel, lead, zinc, and mercury, as well as microplastics occurrence in various tissues of fish and seafood species, commercialized in the Lower Danube River Basin. A health risk assessment analysis was performed based on the PTEs concentration levels in the muscle tissue. Estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI), and target cancer risk (TR) of PTEs were calculated. It was observed that the species within the seafood category registered the highest levels of PTEs. For instance, in the muscle tissue of bivalve Mytilus galloprovincialis (from the Black Sea), the highest value was observed in the case of Zn (37.693 mg/kg), and the presence of polystyrene polymer was identified. The values associated with EDI, THQ, HI, and TR of PTE exposure were significantly lower than 1.

Exposure Assessment of Essential and Potentially Toxic Metals in Wheat-Based Sweets for Human Consumption: Multivariate Analysis and Risk Evaluation Studies

In recent years, there has been a growing concern about the negative impact of unforeseen contaminants such as metals in commonly consumed food items, which pose a threat to human well-being. Therefore, it is of utmost importance to evaluate the levels of these contaminants to guarantee the safe consumption of these food items. The goal of the current research is to determine the levels of essential (EMs: Mg, Ca, Mn, Fe, Co, Cu, and Zn) and potentially toxic metals (PTMs: Al, Cr, Ni, As, Cd, and Pb) in various brands of wheat-based sweets. One hundred samples were collected and analysed via flame atomic absorption spectrometry (FAAS) and inductively coupled plasma-optical emission spectrometry (ICP-OES). Also, the current study was to investigate the distribution, correlation, and multivariate analysis of 13 metals (Mg, Ca, Mn, Fe, Co, Cu, Zn, Al, Cr, Ni, As, Cd, and Pb). Hierarchical cluster analysis (HCA) and principal component analysis (PCA) were used to interpret the metals' association. The concentration (mg/kg) ranges of EMs were, in order, Mg (12.70-65.67), Ca (24.02-209.12), Mn (1.32-9.61), Fe (4.55-111.23), Co (0.32-8.94), Cu (2.12-8.61), and Zn (2.60-19.36), while the concentration (mg/kg) ranges of PTMs were, in order, Al (0.32-0.87), Cr (0.17-5.74), Ni (0.36-1.54), Cd (0.16-0.56), and Pb (0.14-0.92), and As was not detected in any sample under investigation. The HCA data revealed that Co, Al, and Ni form clusters with other metals. Sweets are prepared at high temperatures, and the elevated temperatures can increase the likelihood of Ni and Al leaching from stainless steel. Tolerable dietary intake (TDI) values for Ni were higher than the values established by the European Food Safety Authority (EFSA). The CR value found for the Ni and Cr was at the threshold level of cancer risk, if an amount of 25 g were to be used over a lifetime. In a nutshell, this study highlights the monitoring of EM and PTM levels in wheat-based sweets, and from a food safety perspective, the study is important for consumers of wheat-based sweets.

Ecological and human health risk assessment of potentially toxic elements in water and soils within a crude oil waste management facility, Southwestern Ghana

Crude oil waste management is challenging due to the diverse constituents of the waste and its consequent impact on valued environmental receptors (water and soil). Characterization of the potentially toxic elements (PTEs) in soils and water within the surroundings of crude oil waste management facility is imperative, to aid evaluation of potential risks. The study assessed the potential environmental and human health risks posed by PTEs in soil and water from surroundings and adjoining settlement communities. A total of forty-four (44) samples were analyzed for PTEs (Cr, Pb, Zn, Co, Mn, Ni, Hg, Fe, As, Cu, Hg, and Cd) and physicochemical properties in both matrices. The total carcinogenic risk (TCR) for adults and children in the neighbouring community was 4.73 × 10-6 and 1.2 × 10-4, respectively, which was due to the high carcinogenic slope factor of arsenic. A strong correlation was observed between the PTEs and physicochemical properties, and their health risk was attributed to both geogenic and anthropogenic factors. The study indicated that the human health and ecological risk values obtained were within acceptable limits, with the waste management facility posing a higher risk in comparison to the nearby community. These risks may be attributed to the specific nature and intensity of the activities conducted at the facility. Hence, there is the need for continuous promotion of occupational and public awareness on the health and environmental impact of crude oil waste management.

Metal tolerance and biosorption capacities of bacterial strains isolated from an urban watershed

Rapid industrialization and urbanization have led to widespread metal contamination in aquatic ecosystems. This study explores the metal tolerance and biosorption characteristics of four bacterial strains (Serratia sp. L2, Raoultella sp. L30, Klebsiella sp. R3, and Klebsiella sp. R19) isolated from Saint Clair River sediments. These strains effectively removed various metal cations (As3+, Pb2+, Cu2+, Mn2+, Zn2+, Cd2+, Cr6+, and Ni2+) in single and multi-metal solutions. Minimum inhibitory concentration (MIC) assays revealed strain-specific variations in metal tolerance, with L2 and L30 exhibiting higher tolerance. Surprisingly, R3 and R19, despite lower tolerance, demonstrated superior metal removal efficiency, challenging the notion that tolerance dictates removal efficacy. In single-metal solutions, R3 and R19 excelled at extracting various metal ions, while competitive binding in multi-metal solutions hindered removal. However, R3 and R19 retained higher removal efficiencies, possibly due to enhanced flocculation activities facilitating metal-ion contact. Comprehensive Fourier-transform infrared (FTIR) analysis highlighted the strains' metal-binding capabilities, with novel peaks emerging after metal exposure, indicative of extracellular polymeric substance (EPS) production. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed metal accumulation on bacterial surfaces and within cytoplasmic regions and revealed morphological changes and metal adsorption patterns, emphasizing the strains' ability to adapt to metal stress. Scanning transmission microscopy (STEM) and EDX analysis uncovered metal accumulation within bacterial cells, underscoring the complexity of microbial-metal interactions. This study also confirms that the simultaneous presence of an aqueous solution may cause a mutual inhibition in the adsorption of each metal to the EPS resulting in reduced metal uptake, which emphasizes the need to select specific bacterial strains for a given metal-containing effluent. The differences in metal distribution patterns between Klebsiella sp. R19 and Raoultella sp. L30 suggest species-specific metal accumulation strategies driven by environmental conditions and metal availability. The heavy metal-removing capabilities and the ability to grow over a wide range of metal concentrations of the strains used in this study may offer an advantage to employ these organisms for metal remediation in bioreactors or in situ.

Open acid dissolution-Ammonia solution extraction-ICP OES rapid determination of 7 trace metal elements in soil

To overcome the corrosion of hydrofluoric acid on the ICP OES injection system in the acid dissolution system, this paper makes some improvements based on the traditional open digestion. The improved method does not require the complete removal of hydrofluoric acid. After appropriate digestion of the sample with a mixed acid, the solution can be transferred to a colorimetric tube containing ammonium hydroxide solution to give the final volume for analysis. In this paper, two-point standard curves are plotted using soil standards and process blanks, which is not only convenient but also overcomes the interference of the matrix effect. Through continuous experiments, the preferred ratio of mixed acid is 3 mL nitric acid + 5 mL hydrofluoric acid, and the concentration of ammonia solution is 0.5%. The spectral lines of the measured elements V (292.4), Cr (283.5), Co (228.6), Ni (231.6), Cu (324.7), Zn (213.8) and Pb (220.3) were determined. The method quantification limits of the seven measured elements V, Cr, Co, Ni, Cu, Zn and Pb were 0.909, 4.32, 0.269, 0.261, 0.968, 3.69 and 2.64 μg g-1, respectively, and the precision was 3.5%, 5.2%, 4.8%, 2.4%, 6.1% and 4.5%, respectively. After processing six national standard materials according to the experimental method, the measured values of each measured element were basically in agreement with the certified values, indicating that this method is fully feasible for the measurement of V, Cr, Co, Ni, Cu, Zn and Pb in soil. This method greatly improves the efficiency of pretreatment and is particularly suitable for analysing large batches of samples.

Development of a certified reference material for accurate determination of the leaching of Pb and Zn in solid waste

Certified reference materials (CRMs) with high accuracy and traceability play a significant role in the calibration of equipment and validation of analytical methods. However, there is still a lack of suitable solid waste CRMs for quality assurance and quality control. Thus, a CRM (GBW(E)085538) was developed for accurate determination and reliable measurement of the leaching of Pb and Zn in solid waste according to the requirements of ISO 17034 and the recommendations of ISO Guide 35. This study describes the steps performed for the development of the CRM. These steps include material preparation, homogeneity, and stability during transport and storage, assignment of certified values, and their uncertainties. The material was dried, ground, sieved and well-mixed, and the final bulk material was bottled in 1 kg portions. Analytical techniques like inductively coupled plasma-mass spectrometry (ICP-MS), inductively coupled plasma-optical emission spectrometry (ICP-OES), and flame atomic absorption spectrometry (AAS) have been used for the characterization of property values. Concurrently, an inter-laboratory comparison study involving 9 qualified laboratories was implemented to support the certification study. The certified values of Pb and Zn were (4.66 ± 0.21) mg/L and (2.95 ± 0.14) mg/L with 7-month stability.