Assessment of heavy metal (HM) contamination in agricultural soil lands in northern Telangana, India: an approach of spatial distribution and multivariate statistical analysis

Effect of fertilization on the accumulation and health risk for heavy metals in native Andean potatoes in the highlands of Perú

Soil infertility is a global problem, amendments such as organic fertilizers and mineral fertilizers are used to improve crop yields. However, these fertilizers contain heavy metals as well as essential mineral elements. The objective of the study was to determine the effect of organic and inorganic fertilizer on the accumulation and health risk of heavy metals in tubers. The plants were cultivated at an altitude of 3970 m using four treatments (poultry manure, alpaca manure, island guano and inorganic fertilizer) and a control group. Soil contamination levels and the degree of metal accumulation in the tubers were also determined. As a result, it was found that the use of inorganic fertilizer and poultry manure increased the values of Cu and Zn in soils, exceeding the recommended standards. The accumulation of heavy metals in potato tubers did not exceed the maximum recommended limits with the exception of Pb, which exceeded the limit allowed by the FAO/WHO (0.1 mg kg-1). Poultry manure contributed to the highest accumulation of Zn, Cu and Pb in tubers with 11.62±1.30, 3.48±0.20 and 0.12 ±0.02 mg kg-1 respectively. The transfer of metals from the soil to the tubers was less than 1. Individual and total non-carcinogenic risk values were less than 1, indicating a safe level of consumption for children and adults. The cancer risk was found to be within an acceptable range. However, poultry manure and inorganic fertilizer treatments had the highest total cancer risk values in both age groups, suggesting a long-term carcinogenic risk.

Assessment of heavy metals and human health risk associated with the consumption of crops cultivated in industrial areas of Maputo, Mozambique

This study aimed to evaluate heavy metals concentrations in soils and vegetables (cabbage, lettuce, and cassava) cultivated at Matola and Beluluane Industrial Parks, and to assess health risks linked to their consumption through estimated daily intake, hazard index (HI), and incremental lifetime cancer risk. Concentrations of Al, As, Co, Cd, Cr, Ni, Pb, and Zn were determined in the two sites. Soil concentrations of As at Beluluane site and As, Cd, and Cr at Matola site exceeded reference limits of the Food and Agriculture Organization/World Health Organization, showing heavy metal contamination. At Beluluane site, all studied vegetables presented As and Pb levels higher than reference limits, Cd concentrations were higher than the reference limit in cabbage, lettuce, and cassava leaves. At Matola site crops concentrations of As, Cd, Cr, and Pb exceeded the reference limits. Zinc exceeded the reference limit in all crops except in cabbage. HIs for vegetables from Beluluane exceeded 1.0 in cabbage (2.66), lettuce (2.27), and cassava leaves (2.37). Likewise, at Matola, HIs exceeded 1.0 in lettuce (1.67), cassava leaves (1.65), and root tubers (13). We found that vegetables cultivated in industrial parks present high carcinogenic risk due to heavy metal contamination, rendering them unsuitable for human consumption.

Evaluation of pollution levels in sediments from Lake Edku, Egypt using laser ablation inductively coupled plasma mass spectrometry

The concentrations of 11 heavy metals in sediments from Lake Edku, Egypt were determined using LA-ICP-MS. The average concentrations of elements occurred in the order of Fe > V > Cr > Zn > Ni > Cu > Co > Pb > As > Sn > Mo with respective values of 4.67 %, 104.8, 77.9, 76.6, 59.2, 52, 27.8, 19.8, 4.14, 2.24, and 1.45 μg/g. Several pollution indices were used to evaluate individual and cumulative contamination levels. All HMs were found to be in the deficiency to minimal enrichment range based on the enrichment factor. The contamination factor indicated low contamination levels of Cr and As, low to moderate contamination levels of Fe, Ni, Zn, Mo, Sn, and Pb, and moderate contamination levels of Co and Cu. The pollution load index and contamination degree indicated the sediments to be polluted and moderately polluted, respectively.

Zinc oxide nanoparticles and Klebsiella sp. SBP-8 alleviates chromium toxicity in Brassica juncea by regulation of antioxidant capacity, osmolyte production, nutritional content and reduction in chromium adsorption

Heavy metals are one of the most damaging environmental toxins that hamper growth of plants. These noxious chemicals include lead (Pb), arsenic (As), nickel (Ni), cadmium (Cd) and chromium (Cr). Chromium is one of the toxic metal which induces various oxidative processes in plants. The emerging role of nanoparticles as pesticides, fertilizers and growth regulators have attracted the attention of various scientists. Current study was conducted to explore the potential of zinc oxide nanoparticles (ZnONPs) alone and in combination with plant growth promoting rhizobacteria (PGPR) Klebsiella sp. SBP-8 in Cr stress alleviation in Brassica juncea (L.). Chromium stress reduced shoot fresh weight (40%), root fresh weight (28%), shoot dry weight (28%) and root dry weight (34%) in B. juncea seedlings. Chromium stressed B. juncea plants showed enhanced levels of malondialdehyde (MDA), electrolyte leakage (EL), hydrogen peroxide (H2O2) and superoxide ion (O2• -). However, co-supplementation of ZnONPs and Klebsiella sp. SBP-8 escalated the activity of antioxidant enzymes i.e., superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) in B. juncea grown in normal and Cr-toxic soil. It is further proposed that combined treatment of ZnONPs and Klebsiella sp. SBP-8 may be useful for alleviation of other abiotic stresses in plants.

Analysis of soil fertility and toxic metal characteristics in open-pit mining areas in northern Shaanxi

The study specifically focused on the Hongliulin mining area, where a total of 40 soil samples were meticulously collected and analyzed from within a 1000 m radius extending from the tailings dam. The findings revealed that soil pH within the 0-1000 m range generally leaned towards the alkaline side. In terms of soil nutrient content, encompassing factors such as soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), total potassium (TK), alkali nitrogen (AK), available phosphorus (AP), and quick-acting potassium (AK), the variations fell within the following ranges: 2.23-13.58 g/kg, 0.12-0.73 g/kg, 0.18-1.15 g/kg, 9.54-35.82 g/kg, 2.89-6.76 mg/kg, 3.45-11.25 mg/kg, and 5.86-130.9 mg/kg. Collectively, these values indicate relatively low levels of soil nutrients. Within the 0-500 m range of soil samples, the average concentrations of Cd, Hg, Pb, and As were 0.778, 0.198, 24.87, and 17.92 mg/kg, respectively. These concentrations exceeded the established soil background values of Shaanxi Province and emerged as the primary pollutants in the study area. Within this same range, the mean values of eight toxic metals (Pi) were ranked in the following descending order: 1.726 (Hg), 1.400 (As), 1.129 (Cr), 1.109 (Pb), 0.623 (Zn), 0.536 (Cd), 0.309 (Cu), and 0.289 (Ni). With the exception of Hg, As, Cr, and Pb, which exhibited slight pollution, the other toxic metals were found to be within acceptable pollution limits for this sampling range, in line with the results obtained using the geo-accumulation index method. The average potential ecological risk index for the eight toxic metals in the study area stood at 185.0, indicating a moderate overall pollution level. When assessing individual elements, the proportions of ecological risk attributed to Hg, As, Pb, and Cd were 34.57%, 27.44%, 25.11%, and 23.11%, respectively. This suggests that the primary potential ecological risk elements in the study area are Hg and As, followed by Cd and Pb. Notably, toxic metals Hg and Pb, as well as As and Pb, exhibited significant positive correlations within the sampling area, suggesting a common source. An analysis of the relationship between soil physicochemical properties and toxic metals indicated that soil pH, SOM, TN, and TP were closely linked to toxic metal concentrations. The toxic metal elements in the research area's soil exhibit moderate variability (0.16 < CV < 0.36) to high variability (CV > 0.36). Within the range of 0-200 m, the CV values for Cd and Hg exceed 1, indicating a high level of variability. The coefficient of variation for SOM, TP, AP, AK and TK is relatively high with the of 2.93, 2.36, 2.36, 21.01, 7.54. The soil in the sampling area has undergone significant disturbances due to human activities, resulting in toxic metal pollution and nutrient deficiencies.

Evaluation of environmental and ecological risks caused by metals in agricultural areas: an example in the Amik Plain of South Turkey

The works of literature evaluating the eco-environmental risks posed by metals in agricultural areas in developing countries remains limited. This study sought to evaluate the environmental and ecological risks posed by metals in the intensively cultivated areas of the Amik Plain as well as to determine the origins of the metals. For this purpose, 137 soil samples were taken from agricultural production areas of the Amik Plain, and 11 metals (Al, Fe, Ni, Pb, Co, Cr, Cu, Mn, Zn, Cd and As) were examined in the samples. As Ni had the highest average enrichment factor (EF) value (8.04) when compared with the other metals, the soils were found to be significantly enriched with Ni. The Pearson correlation analysis and principal component analysis showed that the Zn concentration was controlled by lithogenic sources, while the Ni, Pb, Cd, Cr and Cu concentrations were controlled by both anthropogenic and lithogenic sources.

Determination of Soil Quality Index of agricultural land adjacent to industrial sites of Jamuria C.D.Block, Paschim Bardhaman District, West Bengal

A healthy soil is crucial for food security, but human activities, particularly industrialization, are degrading the soil's quality. This study aims to assess and compare the Soil Quality Index (SQI) at three industrial sites: the iron and steel industry, the open cast coal mining industry, and the brick kiln industry, along with a control field. To measure the SQI, the weighted additive method was applied to the nine selected physico-chemical properties of soil: soil temperature, soil moisture, Bulk Density, pH, N, P, K, OC, and EC. Principal Component Analysis coupled with multiple correlation methods was used to determine the Minimum Data Set. The most dominant factors near the iron and steel industrial site are soil temperature, N, K, and EC, while N, OC, soil moisture, P, K, and EC are the most significant factors near the open cast coal mine. In the case of the brick kiln industrial site, soil moisture, OC, K, soil temperature, and P have the highest loadings. The calculated SQI indicates that the quality of soil is in better condition in the control field (0.6475), while the soil adjacent to the coal mining industrial site (0.1426) is in the worst state, followed by the iron and steel industrial site (0.1611) and the brick kiln industrial site (0.289). To attain sustainable agricultural practices in industrial landscapes, efficient management of nutrient contents and phytoremediation can be helpful.

Alleviation of salinity stress in zinc oxide nanoparticle-treated Lagenaria siceraria L. by modulation of physiochemical attributes, enzymatic and non-enzymatic antioxidative system

Salt stress is a major abiotic stress that affects the world's agricultural soils and crop yield, the system that ensures food production. In the present study, three different concentrations of zinc oxide nanoparticles (250, 500 and 750ZnONPsmg L-1 ) were applied by soil drenching. The treatments aimed to improve the phytochemical characteristics of Lagenaria siceraria L. (bottle gourd) by lowering the oxidative stress brought on by salinity stress (200ppm NaF). Green synthesised ZnO NPs were prepared, having hexagonal and spherical shapes and sizes 16-35nm. Salt stress reduced fresh and dry biomass of plants and improved production of proline. ZnO NPs improved antioxidant response by enhancing catalase, ascorbate peroxidase, superoxide dismutase and peroxidase activities, and protecting cellular structures by eliminating free radicals and reactive oxygen species. The 500mg L-1 ZnO NPs treatment improved total chlorophyll (31%), total soluble sugars (23%) and maintained the gas exchange parameters under salt stress. This treatment also enhanced the biosynthesis of osmotic regulators (proline) by 19%, Na+ by 22% and Zn2+ by 17%, assisting mitigation of salt stress-mediated toxicity in plants. This study demonstrates that ZnO NP-treated seedlings show improved growth attributes, suggesting that ZnO NPs could be advantageous for L. siceraria cultivation in salt polluted areas and could be utilised in place of conventional Zn fertiliser for better crop yield.

Effects of long-term zinc smelting activities on the distribution and health risk of heavy metals in agricultural soils of Guizhou province, China

To assess the effect of zinc smelting on environment and human health, the concentration, distribution, sources and health risk of eight heavy metals (Pb, Cd, Cu, Zn, Cr, Ni, Mn, and As) were investigated from agricultural soils in a long-term Zn smelting area in Guizhou, China. Different health risk assessment methods and models were used to access health risks. The results show that the concentrations of all the eight heavy metals were significantly higher than their corresponding background values (p < 0.05). Pb, Cd, and As were the most contaminated elements, with 93.6%, 90.3% and 48.4% of agricultural soil samples higher than the risk screening values, respectively. Statistical analysis indicated that Pb, Cd, Cu, Zn, Mn, and As could be mainly accounted for Zn smelting activities, while Cr and Ni may be generally more controlled by natural sources. The geo-accumulation index (Igeo) suggested that the most seriously contaminating heavy metals were Pb, Cd, and Zn, with 96.8%, 90.3%, and 96.8%, respectively, of the soil samples classified as moderately to extremely contaminated. The non-carcinogenic health risk associated with Pb, Cd and As were observed for children, meanwhile, the carcinogenic risk due to As was found for both adults and children. Regardless of cancer risk or non-cancer risk, local children are at greater risk than adults. Therefore, Pb, Cd and As play the leading role to cause potential health risks in the study area, which need to be paid more attention and also effective control measures should be taken.

Urbanization-driven soil degradation; ecological risks and human health implications

Urban soils contaminated with heavy metals and pesticide residues are of great concern because of their adverse impact on human health. A total of 66 agricultural topsoil samples (15 cm) were collected to represent the study area and determine how anthropogenic activities adversely affect soil quality and human health. Sampling was conducted in the summer, when it was dry and hot, and in the winter, after atmospheric deposition. Seventeen potentially hazardous metals/metalloids (Ag, As, Al, B, Ba, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Mo, Pb, Se, Zn, and V) were measured in the soils. The mean concentrations of metals ranged between 0.05 and 8080 mg/kg, and their distribution was site-specific, with high pollution at the sampling sites owing to proximity to human activities. In agricultural areas, the greatest arsenic concentration was recorded at 48 mg/kg. The potential ecological risk index (PERI) and health hazard index (HI) were calculated, as well as metal contamination indices including contamination factor (Cf), geo-accumulation index (Igeo), and pollution load index (PLI). The mean PLI was calculated to be 4.89, indicating that the area is highly polluted. The potential ecological risk index showed remarkably high risks for As, Cd, and Hg, and moderate risks for Ni and Pb. The arsenic hazard index (HI) was greater than one (2.41) in children, indicating a risk of exposure through ingestion. Pesticide residue analyses were performed in areas where the metal intensity was high. Banned or restricted organochlorine pesticide (OCPs) residues, including, dieldrin, endrin ketone, endosulfan I, II, heptachlor, heptachlor epoxide, lindane (γ-HCH), PP-DDD, and methoxychlor, were detected between 0.002 and 1.45 mg/kg in the soil samples.

Heavy Metal and Rice in Gluten-Free Diets: Are They a Risk?

A gluten-free diet (GFD) is the treatment of choice for gluten-related disorders. It has been associated with macro- and micronutrient deficiencies. Recently, consumption of arsenic-contaminated rice has raised concern because of the potential greater risk that it may represent for people on GFDs, whose rice consumption is high, since it is a fundamental cereal in GFDs. We reviewed the data published over the last 20 years in Medline and Scielo, in English, French and Spanish, on four metals (As, Hg, Cd, and Pb), to assess whether the evidence suggests that celiac disease or consumption of a GFD is associated with increased levels of blood/urinary metal concentrations. The review revealed a few articles that were directly related to the four metals and their relationships with a GFD. The evidence supports that rice-based products are a relevant source of As and other metals. Clinical studies and evaluations based on NHANES have indicated that persons on GFDs have higher As and Hg blood/urinary levels, suggesting that the diet and not the disease is responsible for it. The levels described are statistically significant compared to those of persons on complete diets, but far from toxic levels. The question of whether higher exposure to heavy metals associated with a GFD is biologically relevant remains unanswered and deserves study.

Potentially toxic metals contamination, health risk, and source apportionment in the agricultural soils around industrial areas, Firozabad, Uttar Pradesh, India: a multivariate statistical approach

Potentially toxic metals (PTMs) contamination in the soil poses a serious danger to people's health by direct or indirect exposure, and generally it occurs by consuming food grown in these soils. The present study assessed the pollution levels and risk to human health upon sustained exposure to PTM concentrations in the area's centuries-old glass industry clusters of the city of Firozabad, Uttar Pradesh, India. Soil sampling (0-15 cm) was done in farmers' fields within a 1 km radius of six industrial clusters. Various environmental (geo-accumulation index, contamination factor, pollution load index, enrichment factor, and ecological risk index) and health risk indices (hazard quotient, carcinogenic risk) were computed to assess the extent of damage caused to the environment and the threat to human health. Results show that the mean concentrations of Cu (33 mg kg^-1), Zn (82.5 mg kg^-1), and Cr (15.3 mg kg^-1) were at safe levels, whereas the levels of Pb, Ni, and Cd exceeded their respective threshold limits. A majority of samples (88%) showed considerable ecological risk due to the co-contamination of these six PTMs. Health risk assessment indicated tolerable cancer and non-cancer risk in both adults and children for all PTMs, except Ni, where adults were exposed to potential threat of cancer. Pearson's correlation study revealed a significant positive correlation between all six metal pairs and conducting principal component analysis (PCA) confirmed the common source of metal pollution. The PC score ranked different sites from highest to lowest according to PTM loads that help to establish the location of the source. Hierarchical cluster analysis grouped different sites into the same cluster based on similarity in PTMs load, i.e., low, medium, and high.

Combination of enrichment factor and positive matrix factorization in the estimation of potentially toxic element source distribution in agricultural soil

The study intended to assess the level of pollution of potential toxic elements (PTEs) at different soil depths and to evaluate the source contribution in agricultural soil. One hundred and two soil samples were collected for both topsoil (51), and the subsoil (51) and the content of PTEs (Cr, Cu, Cd, Mn, Ni, Pb, As and Zn) were determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The concentrations of Zn and Cd in both soil horizons indicated that the current study levels were higher than the upper continental crust (UCC), world average value (WAV), and European average values (EAV). Nonetheless, the concentration values of PTEs such as Mn and Cu for EAV, As, Cu, Mn, and Pb for UCC, and Pb for WAV were lower than the average values of the corresponding PTEs in this study. The single pollution index, enrichment factor, and ecological risk revealed that the pollution level ranged from low to high. The pollution load index, Nemerow pollution index, and risk index all revealed that pollution levels ranged from low to high. The spatial distribution confirmed that pollution levels varied between the horizons; that is, the subsoil was considered slightly more enriched than the topsoil. Principal component analysis identified the PTE source as geogenic (i.e. for Mn, Cu, Ni, Cr) and anthropogenic (i.e. for Pb, Zn, Cd, and As). PTEs were attributed to various sources using enrichment factor-positive matrix factorization (EF-PMF) and positive matrix factorization (PMF), including geogenic (e.g. rock weathering), fertilizer application, steel industry, industrial sewage irrigation, agrochemicals, and metal works. Both receptor models allotted consistent sources for the PTEs. Multiple linear regression analysis was applied to the receptor models (EF-PMF and PMF), and their efficiency was tested and assessed using root-mean-square error (RMSE), mean absolute error (MAE), and R² accuracy indicators. The validation and accuracy assessment of the receptor models revealed that the EF-PMF receptor model output significantly reduces errors compared with the parent model PMF. Based on the marginal error levels in RMSE and MAE, 7 of the 8 PTEs (As, Cd, Cr, Cu, Ni, Mn, Pb, and Zn) analysed performed better under the EF-PMF receptor model. The EF-PMF receptor model optimizes the efficiency level in source apportionment, reducing errors in determining the proportion contribution of PTEs in each factor. The purpose of building a model is to maximize efficiency while minimizing inaccuracy. The marginal error limitation encountered in the parent model PMF was circumvented by EF-PMF. As a result, EF-PMF is feasible and useful for apparently polluted environments, whether farmland, urban land, or peri-urban land.

Heavy metal remediation using chelator-enhanced washing of municipal solid waste compost based on spectroscopic characterization

Due to high metal toxicity, mixed municipal solid waste (MSW) compost is difficult to use. This study detected the presence of heavy metals (Cd, Cu, Pb, Ni, and Zn) in MSW compost through mineralogical analysis using X-ray diffraction (XRD) and performed topographical imaging and elemental mapping using a scanning electron microscope and energy dispersive X-ray analysis (SEM-EDX). Ethylenediaminetetraacetic acid (EDTA), a typical chelator, is tested to remove heavy metals from Indian MSW compost (New Delhi and Mumbai). It deals with two novel aspects, viz., (i) investigating the influence of EDTA-washing conditions, molarity, dosage, MSW compost-sample size, speed, and contact time, on their metal removal efficiencies, and (ii) maximizing the percentage removal of heavy metals by determining the optimal process control process parameters. These parameters were optimized in a batch reactor utilizing Taguchi orthogonal (L₂₅) array. The optimization showed that the removal efficiencies were 96.71%, 47.37%, and 49.94% for Cd, Pb, and Zn in Delhi samples, whereas 45.55%, 79.52%, 59.63%, 82.31%, and 88.40% for Cd, Cu, Pb, Ni, and Zn in Mumbai samples. Results indicate that the removal efficiency of heavy metals was greatly influenced by EDTA-molarity. Fourier-transform infrared spectroscopy (FTIR) confirmed the presence of hydroxyl group, which aids heavy metal chelation. The results reveal the possibility of EDTA to reduce the hazardous properties of MSW compost.

A comprehensive method of source apportionment and ecological risk assessment of soil heavy metals: A case study in Qingyuan city, China

The study combined multiple models to provide a deeper understanding to soil heavy metal contamination and source information, which are essential for controlling pollution and reducing human health risks. In this study, the agricultural soils were collected from the Qingyuan City of China as an example. The multiple models (APCS/MLR, PMF, and GDM) were used to identify and quantitatively apportion the main sources of heavy metal pollution in the area. The results showed that Cu (56.4 %), Ni (70.9 %), B (44.5 %), and Cr (72.8 %) were associated with natural sources, such as soil parent material and soil-forming processes. However, Pb (41.2 %), Zn (61.8 %), Hg (67.0 %), and Cd (69.6 %) were associated with agricultural activities, atmospheric deposition, vehicle exhaust emissions, and vehicle tires, while Mo, Se, and Mn were possibly derived from natural sources, including rock weathering and soil parent materials. Additionally, the network of environmental analysis revealed that soil microbes are far more sensitive to soil heavy metal pollution than herbivores, vegetation, and carnivores. This study can serve as a guideline for reducing the ecological and health risks associated with heavy metals in soil by controlling their preferential sources. Environmental implication Combining multiple models is more effective approach to wide understanding of heavy metal contamination and source information, which is essential for controlling pollution and reducing human health risks. Based on multiple models (APCS/MLR, PMF, and GDM) and network environ analysis, a comprehensive method for apportioning soil heavy metal sources and assessing ecological risk had been provided. Further, the present study can be a guideline for reducing ecological and health risks by heavy metals in soil by controlling preferential sources.

Sequential extraction of selected metals to assess their mobility, pollution status and health risk in roadside soil

Assessment of the mobility and contamination of trace metals in the roadside soil is important to explore the environmental quality and potential risks to the public health. The contents of selected metals (Ca, Mg, Sr, K, Na, Li, Fe, Mn, Zn, Cu, Ag, Co, Ni, Cr, Cd and Pb) in the roadside soil collected from major highways/roadsides of Lahore, Pakistan were quantified employing mBCR sequential extraction. Among the metals, Ca, Sr and Na showed highest contribution in exchangeable fraction, Pb in the reducible fraction and K, Li, Fe, Ag, Ni, Cu and Cr in the residual fraction. However, Mg and Mn exhibited relatively higher contents in exchangeable and residual fractions while Cd, Co and Zn showed relatively higher concentration in all four fractions. Comparatively higher mobility and availability in the soil was shown by Ca followed by Sr, Pb, Na, Cd, Zn, Co, Mn, Cu, Ag and Ni. Principal component analysis demonstrated considerable anthropogenic contributions of the trace metals in the roadside soil. The pollution indices showed that the soil was heavily to extremely polluted by Cd and Ag, followed by significant to very high contamination for Co, Ni and Pb. The modified degree of contamination (4.60 and 3.99 in summer and winter, respectively) revealed an overall high degree of contamination. The health risk assessment revealed that the calculated risks were within the safe limit thereby indicating insignificant non-carcinogenic and carcinogenic heath risk to the populace.

Variation in pollution status, sources, and risks of soil heavy metals in regions with different levels of urbanization

Soil heavy metal (HM) pollution is an increasing threat to ecosystem integrity and human health with rapid urbanization. Nevertheless, how soil HMs vary with the process of urbanization remains unclear. Here we used index evaluation, spatial analysis, and a positive matrix factorization (PMF) model to determine the pollution characteristics and sources of eight soil HMs (Mn, Cr, Cu, Zn, As, Cd, Pb, and Ni) among regions with different urbanization levels (urban area, suburb, and ecoregion) in Baoding City, Northern China. We also assessed the risks posed to the ecosystem and human health using risk assessment models. The results indicated that the mean levels of Cu, Zn, As, Cd, and Pb in the study area exceeded the soil environmental quality standards by 10.7 %, 10.7 %, 12.5 %, 23.2 %, and 3.57 %, respectively. A pronounced regional spatial distribution was discovered with high levels in suburban areas. Both the geo-accumulation index and potential ecological risk index revealed significantly higher HM contamination in suburban areas than in urban or ecoregion areas. Source apportionment based on the PMF model and correlation analysis showed that soil HMs in suburban areas primarily originated from agricultural activity, industrial sources, and natural sources. Those in urban soils originated from industrial sources, urban traffic, and natural sources, whereas those in ecoregions derived from natural sources and agricultural activity. The complex sources of soil HMs in suburban areas resulted in the highest carcinogenic risks to children health, followed by the ecoregion, but not in urban areas. This study identified the differences in pollution levels, sources, and risks of soil HMs among regions with different urbanization levels and can guide future efforts to mitigate and manage soil HM pollution during urbanization.

Phytoremediation capability of Typha latifolia L. to uptake sediment toxic elements in the largest coastal wetland of the Persian Gulf

The present study evaluated the status of sediment toxicity and pollution, and the phytoremediation capability of Typha latifolia L. (TlL) within the largest coastal wetland in the southwest of Iran, the Shadegan International Wetland. In eight sampling sites, covering the entire wetland, the concentration of six toxic elements (As, Cr, Cu, Ni, Pb, and Zn) in the surface sediment, root, and stem of TlL were measured. The results indicated that mean concentrations of Cr, Cu, Pb, and Zn were found to be higher than those in the local background, which likely indicates anthropogenic sources of these elements. Due to the presence of a nearby landfill, the results of modified pollution index (MPI) and aggregate toxicity index (ATI) indicated a moderately-heavily polluted level and moderate to high toxic degree, respectively. However, the medium-low level of toxicity toward living of organisms (21 % probability) was detected based on the assessment of the Sediment Quality Guidelines (SGQ). The results of our study indicate that the root and stem tissues of TlL are capable of acting as an indicator of Cu/Pb/Zn and Zn pollution in sediment, respectively. Considering the potential of phytoremediation, TlL represented both phytostabilization and phytoextraction capabilities for Pb and Zn and a significant increase was observed in the phytoremediation capability by increasing the distance from the landfill area. According to the results of the metal accumulation index (MAI) and comprehensive bioconcentration index (CBCI), TlL grown in the study area showed an acceptable performance in the accumulation of multiple toxic elements compared to that in Turkey, India, and Poland. Overall, TlL is a good candidate for the phytoremediation of sediments contaminated by Pb and Zn.

Potentially Harmful Elements Associated with Dust of Mosques: Pollution Status, Sources, and Human Health Risks

Potentially harmful elements (PHEs) associated with dust generated from anthropogenic sources can be transported into mosques and deposited on the filters of the air-conditioners (AC); thereby, children and adults are exposed to such PHEs while visiting mosques. Data dealing with the assessment of PHEs pollution and its human health risk in mosques dust in Saudi Arabia are scarce. Therefore, this work aims to examine the levels and pollution status of PHEs in AC filter dust (ACFD) of mosques and their associated human health risk in three Saudi cities: Jubail, Jeddah, and Dammam metropolitan. A similar concentration pattern of PHEs is observed in three cities' mosques with noticeably higher concentrations than both global crustal and local background values for Zn, Cu, Pb, As, and Cd only. Except for Fe, Al, and Mn, the highest PHEs concentrations were found in Jeddah (1407 mg/kg), followed by Dammam (1239 mg/kg) and Jubail (1103 mg/kg). High PHEs' concentrations were also recorded in mosques located near workshops and suburban areas compared to urban areas. Based on the spatial pattern, enrichment factor, geo-accumulation index, pollution load index, and ecological risk values, Jubail, Jeddah, and Dammam have shown moderate pollution levels of Cd, As, Pb, and Zn. On the other hand, Cu. Zn, Cu, Cr, Pb, Ni, As, and Cd had degrees of enrichment levels that varied from significantly enriched to extremely highly enriched in the ACFD of the three cities. Heavy pollution is found in Jubail, which posed a higher potential ecological risk than in Jeddah and Dammam. Cd presents the highest ecological risk factors (ER) in the three cities. Carcinogenic and non-carcinogenic risks for children and adults follow the order: Jeddah > Dammam > Jubail, and the ingestion pathway was the main route for exposure. Carcinogenic and con-carcinogenic risks in the mosques of the various studied cities were generally within the acceptable range.

Evaluating heavy metal pollution risks and enzyme activity in soils with intensive hazelnut cultivation under humid ecological conditions

In order to promote sustainable agriculture and ensure food security, it has become more vital to identify the causes of soil pollution in agricultural areas. This study was carried out in order to determine the danger of heavy metal contamination in hazelnut production areas and to take the appropriate actions in accordance with the study's findings. In this context, the main objectives of this study were to (i) determine some physical, chemical, and biological properties and heavy metal concentrations of different soils in intensive hazelnut cultivation areas under humid ecological conditions; (ii) reveal the heavy metal pollution risks of these areas by their enrichment factor, contamination factor, geo-accumulation index, degree of contamination, pollution load index, and potential ecological risk index; (iii) analyze the quality of soils contaminated with heavy metals by their total enzyme activity index and the geometric mean of enzymatic activities; and (iv) explore the correlation between heavy metals and soil enzyme activity indices. According to our results, the average concentrations of heavy metals in the study area ranked as Fe > Mn > Zn > Cr > Ni > Cu > Co > Pb > Cd. Based on EF, the area was evaluated as between deficiency to low enrichment and moderate enrichment for all elements except for Cd. When the parameters used to assess the risk of heavy metal contamination were evaluated, it was determined that the risk of contamination of other elements in the study area, except Cd, was low. Finally, analyzing the heavy metals and soil enzyme activity indices shows that there is a negative correlation between Ni and GMea and TEI.

Quantitative Assessment and Spatial Analysis of Metals and Metalloids in Soil Using the Geo-Accumulation Index in the Capital Town of Romblon Province, Philippines

The municipality of Romblon in the Philippines is an island known for its marble industry. The subsurface of the Philippines is known for its limestone. The production of marble into slab, tiles, and novelty items requires heavy equipment to cut rocks and boulders. The finishing of marble requires polishing to smoothen the surface. During the manufacturing process, massive amounts of particulates and slurry are produced, and with a lack of technology and human expertise, the environment can be adversely affected. Hence, this study assessed and monitored the environmental conditions in the municipality of Romblon, particularly the soils and sediments, which were affected due to uncontrolled discharges and particulates deposition. A total of fifty-six soil and twenty-three sediment samples were collected and used to estimate the metal and metalloid (MM) concentrations in the whole area using a neural network-particle swarm optimization inverse distance weighting model (NN-PSO). There were nine MMs; e.g., As, Cr, Ni, Pb, Cu, Ba, Mn, Zn and Fe, with significant concentrations detected in the area in both soils and sediments. The geo-accumulation index was computed to assess the level of contamination in the area, and only the soil exhibited contamination with zinc, while others were still on a safe level. Nemerow's pollution index (NPI) was calculated for the samples collected, and soil was evaluated and seen to have a light pollution level, while sediment was considered as "clean". Furthermore, the single ecological risk (Er) index for both soil and sediment samples was considered to be a low pollution risk because all values of Er were less than 40.

Heavy Metal Pollution and Source Contributions in Agricultural Soils Developed from Karst Landform in the Southwestern Region of China

Heavy metal pollution of soil in agricultural areas is the most prominent environmental pollution problem in China, seriously affecting human health and food security. It has become one of the environmental problems to which all sectors of society attach great importance. Soil heavy metals in the weathering area of hazardous geological bodies in southwest China have naturally high background attributes. Therefore, ecological risk assessment and analysis of potential sources of soil heavy metals in southwest China is of great significance for soil health management, soil heavy metal pollution control and territorial spatial planning. In this study, we collected 787 soil samples (0-20 cm) in Xuanwei County in China and analyzed the concentrations of As, Cd, Cr, Cu, Hg, Ni, Pb and Zn in soils. Igeo, RI, HI and CR were used to calculate the pollution levels, ecological risks and human health risks. Additionally, the PMF model and one-way ANOVA were used to identify the potential sources and discuss the factors affecting the enrichment of heavy metals. The results showed that the mean contents of the surface soils were 1.190 (Cd), 139.4 (Cr), 96.74 (Cu), 0.081 (Hg), 56.97 (Ni), 46.66 (Pb) and 130.1 (Zn) mg/kg. All heavy metals exceeded the background values of the A layer soil in Yunnan Province. The I_geo showed that Cd was the most hazardous element in the study area, followed by Cu, Cr, As, Ni and Pb. The RI showed that low ecological risks, moderate ecological risks, considerable ecological risks and strong ecological risks accounted for 3.81%, 55.27%, 37.74% and 3.18%, respectively, of the total samples, and Cd was the main dominant element. The HI values of the As element in children were greater than 1, indicating a non-carcinogenic risk, and other elements' risks were acceptable. The CR values of Cr and Ni were higher than their limits (1 × 10^-4), and both had carcinogenic risks in children and adults, as did As in children. According to the PMF model, four heavy metals sources were identified: geological sources (32%), sources from mining activities (19.38%), atmospheric deposition sources (17.57%) and agricultural sources (31.05%). Thereinto, As and Pb were mainly derived from agricultural sources, Cd and Cr were mainly associated with geological sources, Cu was largely from mining activity sources, Hg was mainly from atmospheric deposition sources and Ni and Zn were mainly from geological sources, mining activities and agricultural activities. The parent material has a significant influence on the enrichment of heavy metals in the soil, and the heavy metals are significantly enriched in the carbonate parent material and quaternary parent material. Topography also plays a role in heavy metal accumulation; Cd, Cr, Cu, Ni and Zn gradually decreased with the increase in altitude, and As and Pb increased with the increase in altitude. Mn-oxide played a crucial part in the enrichment of Cu and Zn, while SOC, K₂O and pH had little influence on the accumulation of heavy metals.

Dynamics of Major and Trace Elements in Water-Soil-Tree Interaction: Translocation in Pyrus malus in Chihuahua, Mexico Using ICP-OES and Its Health Risk Implications

The transference of metals from water irrigation and soil to plants is a possible pathway of contamination for the trophic chain. This research is focused on the distribution of 16 analytes in the water-soil-tree (Pyrus malus) interaction in an agricultural region in the state of Chihuahua in Mexico from August 2019 (first sampling) to August 2020 (second sampling). The apple variety under investigation was Golden Delicious; it was found that the trace elements of As (0.18-0.34 mg·kg^-1) and Cd (0.11-0.14 mg·kg^-1) in the apple were above the corresponding permissible limit, according to FAO/WHO, and Cr (0.08-0.86 mg·kg^-1) was below the limit. Furthermore, the health risk implications were estimated by the Hazard Quotients (HQ) and carcinogenic risk (CR). For carcinogenic risk, As, Cd, and Cr exceeded the risk limit (CR > 10^-4). This investigation as well provides a link for similar research around the globe. Major and trace elements detection was performed with the Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) technique, along with a prior homogenization of samples and microwave acid digestion. To obtain the statistical behavior, an analysis of variance and correlation was performed.

An assessment of various potentially toxic elements and associated health risks in agricultural soil along the middle Gangetic basin, India

The present study analysed the levels of potentially toxic elements along with physico-chemical properties of agricultural soil samples (n = 59) collected from fields situated along the path of river Ganga in the middle Gangetic floodplain in two districts, Ballia and Ghazipur. Arsenic (As), chromium (Cr), copper (Cu), nickel (Ni), zinc (Zn), lead (Pb), iron (Fe) and manganese (Mn) levels were analysed by Wavelength Dispersive-X-Ray Fluorescence Spectroscopy (WD-XRF) and the associated health risks along with diverse indices were calculated. The mean concentrations of As, Cu, Cr, Pb, Zn and Ni were found to be 15, 42, 85, 18, 87 and 47 mg kg^-1, respectively in Ballia and 13, 31, 73, 22, 77 and 34 mg kg^-1, respectively in Ghazipur. Physico-chemical properties like pH, ORP and organic matter were found to be 7.91, 209 and 1.20, respectively in Ballia and 8.51, 155 and 1.25, respectively in Ghazipur. The calculated health quotient (HQ) for all the elements was observed to be within the threshold value of one, however with few exemptions. Therefore, the present study showcases the contamination of potentially toxic elements in agricultural fields and possible health hazards for people.

Environmental Assessment of Potentially Toxic Elements Using Pollution Indices and Data-Driven Modeling in Surface Sediment of the Littoral Shelf of the Mediterranean Sea Coast and Gamasa Estuary, Egypt

Coastal environmental assessment techniques have evolved into one of the most important fields for the long-term development and management of coastal zones. So, the overall aim of the present investigation was to provide effective approaches for making informed decisions about the Gamasa coast sediment quality. Over a two-year investigation, sediment samples were meticulously collected from the Gamasa estuary and littoral shelf. The inductively coupled plasma mass spectra (ICP-MS) was used to the total concentrations of Al, Fe, Ti, Mg, Mn, Cu, P, V, Ba, Cr, Sr, Co, Ni, Zn, Pb, Zr, and Ce. Single elements environmental pollution indices including the geoaccumulation index (Igeo), contamination factor (CF), and enrichment factor (EF), as well as multi-elements pollution indices comprising the potential ecological risk index (RI), degree of contamination (Dc), and pollution load index (PLI) were used to assess the sediment and the various geo-environmental variables affecting the Mediterranean coastal system. Furthermore, the Dc, PLI, and RI were estimated using the random forest (RF) and Back-Propagation Neural Network (BPNN) depending on the selected elements. According to the Dc results, all the investigated sediment samples categories were considerably contaminated. Cr, Co, Ni, Cu, Zr, V, Zn, P, and Mn showed remarkable enrichment in sediment samples and were originated from anthropogenic sources based on the CF, EF, and Igeo data. Moreover, the RI findings revealed that all the samples tested pose a low ecologically risk. Meanwhile, based on PLI, 70% of the Gamasa estuary samples were polluted, while 93.75% of littoral shelf sediment was unpolluted. The BPNNs -PCs-CD-17 model performed the best and demonstrated a better association between exceptional qualities and CD. With R2 values of 1.00 for calibration (Cal.) and 1.00 for validation (Val.). The BPNNs -PCs-PLI-17 models performed the best in terms of measuring PLI with respective R2 values of 1.00 and 0.98 for the Cal. and Val. datasets. The findings showed that the RF and BPNN models may be used to precisely quantify the pollution indices (Dc, PLI, and RI) in calibration (Cal.) and validation (Val.) datasets utilizing potentially toxic elements of surface sediment.

Source identification and health risk assessments of heavy metals in indoor dusts of Ilorin, North central Nigeria

BACKGROUND AND PURPOSE

Exposure to heavy metals (HMs) in indoor dusts is a serious public concern that is linked to a myriad of deleterious health outcomes. The objectives of this study are to estimate the contamination levels of HMs in indoor dusts of different residential areas in Ilorin, Nigeria; identify HMs sources in different residential areas; and evaluate human health risks of HMs in selected residential areas.

METHODS

Indoor dust sampling was conducted in ten randomly selected from low, medium and high population density residential areas of Ilorin, Nigeria. Ten HMs concentration levels, their health risk implication and the associated potential ecological risks were evaluated.

RESULTS

The mean concentration levels measured for Fe, Pb, Zn, As, Co, Cr, Cu, Cd, Mn and Ni were 38.99, 5.74, 3.99, 0.08, 2.82, 2.13, 0.47, 0.60, 6.45 and 1.09 mg/kg, respectively. Positive Matrix Factorization (PMF) model was applied to ascertain sources of HMs in sampled indoor dust. Percentage contribution from oil-based cooking (29.82%) and transportation (29.77%) represented the highest source to HM concentrations among the six factors identified. The results of the various pollution indices employed showed that Pb, Zn, As, Co, Cr, Cu, Mn and Ni contributed moderately to HMs concentration levels in the sampled dusts. Cd had highest potential ecological risk factor E r i of between 160 and 320. The average values of Enrichment Factors (EFs) obtained aside from Fe used as the reference metal, ranged between 8.46 (As) and 2521.61(Cd). Health risk assessment results revealed that children are the most susceptible to the risks associated with HMs bound indoor dust than the adults. The percentage risk contributions of Hazard Quotient via ingestion route (HQ_ing) in Hazard Index (HI) for non-cancer risk of indoor HMs were 93.17% and 69.87% in children and adults, respectively. Likewise, the percentage cancer risks contribution through ingestion pathway (CR_ing) were higher than cancer risks through inhalation and dermal pathways (CR_inh and CR_dermal), accounting for 99.84% and 97.04% of lifetime cancer risk in children and adults, respectively. The contamination level of Cd recorded is of great concern and signifies very strong contribution from anthropogenic sources.

CONCLUSION

This study has further revealed the levels of HMs in typical African residential settings that could be used by relevant stakeholders and policy makers in developing lasting control measures.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40201-021-00778-8.

Distribution and human health hazard appraisal with special reference to chromium in soils from Peenya industrial area, Bengaluru City, South India

Purpose

Presence of heavy metals in Peenya industries is considered a major environmental and human health risk. The purpose of this research is to determine the concentrations of trace elements in urban industrial soils in north Bengaluru in order to assess the degree of soil pollution and to evaluate environmental and human health risk.

Methods

Twelve soil samples during July-2016 were taken from Peenya industrial sites at different depth viz., 0-Hft., 1-3 ft., and 3-5 ft. heavy metals (As, Cd, Co, Cr⁺³, Cu, Fe, Mn, Pb, Sr, V, and Zn) were determined by inductively coupled plasma mass spectrometry (ICP-MS). Contamination Factor, Enrichment Factor, Pollution Index, Modified Pollution Index, indices of pollution, Toxic Unit (TU), Hazard Quotient (HQ), Hazard Index (HI), Total Hazard Index (THI), Cancer Risk (CR), and Lifetime Cancer Risk (LCR) were used to evaluate the environmental and potential health hazard risks of human beings.

Results

Results showed that Cr⁺³ concentration exceeded the threshold limit of 60 mg/kg and 66.66%, 50%, and 41.66% showing more than the threshold limit at 0-1 ft., 1-3 ft. and 3-5 ft. depth soil samples. Single pollution indices showed that the study site was contaminated with chromium concentration. Nemerow pollution index showed that majority of soil samples were in the very high level of pollution. THI values showing <1 indicating that there were non-carcinogenic risks for children and less risk for adults. Based on LCR for children, 100% of soil samples were at high risk. LCR for Cr⁺³ concentrations of the soils were found higher than the threshold value of 1.00E-04, indicating a significant carcinogenic risk.

Conclusions

The study area is polluted, mainly with Chromium, whereas environmental risk is limited to a small part of it. This study can be used as a reference point to develop future long-term risk assessment plans on the probable movement of heavy metals in urban soils to human beings.

Spatial distribution, risk estimation and source apportionment of potentially toxic metal(loid)s in resuspended megacity street dust

The levels of potentially toxic metal(loid)s (PTMs) As, Cu, Co, Cr, Hg, Mn, Ni, Pb, and Zn in resuspended street dust (<100 μm particles) from a megacity in north China were determined. The sources of PTMs in resuspended street dust were analyzed using multivariate statistical analysis and positive matrix factorization methods that combined the spatial distributions of PTMs. Average levels of Zn, As, Pb, Cu, Co, and Hg exceeded those found in local soil samples, while those of Cr, Mn, and Ni were less than their background levels found in local soil. The overall contamination of PTMs in resuspended street dust was characterized as moderately contaminated and as uncontaminated to moderately contaminated. The ecological risk associated with Hg was very high, while the ecological risks associated with Cu, Co, Cr, Mn, Ni, Pb, and Zn were low. The overall ecological risk of PTMs was defined as high, driven by Hg. The non-carcinogenic risks of PTMs to inhabitants fell within safety limits, and the carcinogenic risks of As, Co, Cr, and Ni were below receivable values. A comprehensive analysis of PTMs sources revealed that Co, Zn, Cu, and Pb were principally associated with traffic emissions, which accounted for about 38.3% of these PTMs' contents. Mn, Ni, and Cr were mainly generated by natural source, which contributed to about 41.5% of these PTMs' concentrations. Hg and As were primarily derived from coal-related industrial source, which accounted for 77.9% of Hg and 62.9% of As in resuspended street dust. This study demonstrates that coal-related industrial discharges and traffic emissions are the main anthropogenic sources of PTMs contamination in resuspended street dust in the study area.

Environmental Pollution Indices and Multivariate Modeling Approaches for Assessing the Potentially Harmful Elements in Bottom Sediments of Qaroun Lake, Egypt

This research intends to offer a scientific foundation for environmental monitoring and early warning which will aid in the environmental protection management of Qaroun Lake. Qaroun Lake is increasingly influenced by untreated wastewater discharge from many anthropogenic activities, making it vulnerable to pollution. For that, six environmental pollution indices, namely contamination factor (Cf), enrichment factor (EF), geo-accumulation index (Igeo), degree of contamination (Dc), pollution load index (PLI), and potential ecological risk index (RI), were utilized to assess the bottom sediment and to determine the different geo-environmental variables affecting the lake system. Cluster analysis (CA), and principal component analysis (PCA) were used to explore the potential pollution sources of heavy metal. Moreover, the efficiency of partial least-square regression (PLSR) and multiple linear regression (MLR) were tested to assess the Dc, PLI, and RI depending on the selected elements. The sediment samples were carefully collected from 16 locations of Qaroun Lake in two investigated years in 2018 and 2019. Total concentrations of Al, As, Ba, Cd, Co, Cr, Cu, Fe, Ga, Hf, Li, Mg, Mn, Mo, Ni, P, Pb, Sb, Se, Zn, and Zr were quantified using inductively coupled plasma mass spectra (ICP-MS). According to the Cf, EF, and Igeo results, As, Cd, Ga, Hf, P, Sb, Se, and Zr demonstrated significant enrichment in sediment and were derived from anthropogenic sources. According to Dc results, all collected samples were categorized under a very high degree of contamination. Further, the results of RI showed that the lake is at very high ecological risk. Meanwhile, the PLI data indicated 59% of lake was polluted and 41% had PLI < 1. The PLSR and MLR models based on studied elements presented the highest efficiency as alternative approaches to assess the Dc, PLI, and RI of sediments. For examples, the validation (Val.) models presented the best performance of these indices, with R2val = 0.948–0.989 and with model accuracy ACCv = 0.984–0.999 for PLSR, and with R2val = 0.760–0.979 and with ACCv = 0.867–0.984 for MLR. Both models for Dc, PLI, and RI showed that there was no clear overfitting or underfitting between measuring, calibrating, and validating datasets. Finally, the combinations of Cf, EF, Igeo, PLI, Dc, RI, CA, PCA, PLSR, and MLR approaches represent valuable and applicable methods for assessing the risk of potentially harmful elemental contamination in the sediment of Qaroun Lake.

Distribution, source identification, and health risk assessment of heavy metals in the soil-rice system of a farmland protection area in Hubei Province, Central China

Heavy metal contamination in farmland soil is of great concern due to the threat to food security arising from the bioaccumulation of heavy metals in crops planted in contaminated soil, such as rice, corn, and vegetables. Cd is the main contaminant in both paddy soils and rice. The purpose of this study was to reveal the spatial distribution of 8 heavy metals (Cd, Cr, Ni, Cu, Pb, Zn, As, and Hg) in the farmland protection areas in northwestern Hubei Province and to evaluate their pollution status, sources, and health risks. The total amounts of these 8 heavy metal elements in the samples were measured, and the health risk posed by their accumulation in rice was evaluated using the health risk evaluation model recommended by the US Environmental Protection Agency (US EPA). The mean contents of Cd, Ni, Cu, Zn, Hg, and As in soil exceeded the background levels (0.17, 37.3, 30.7, 83.6, 0.077, and 12.3 mg kg^-1, respectively) of Hubei Province, and Cd showed the highest enrichment coefficient. The concentration of Cd in 89.1% of samples exceeded the limit values stipulated in the Soil Environmental Quality Risk Control Standard for Soil Contamination of Agricultural Land (Trial) (GB15618-2018). The contents of heavy metals showed dissimilar geographical distribution patterns. The principal component analysis (PCA) results indicated that Cd, Zn, Ni, As, and Cu mainly originated from the application of pesticides and fertilizers; Cr mainly originated from soil texture and pedogenesis; exhaust gas generated during transportation was the point pollution source of Pb; livestock wastewater, manure irrigation, and atmospheric deposition were the main pollution source of Hg. The contents of Ni and Cd in 52.2% and 58.7% of the rice samples, respectively, exceeded the limit values stipulated in the Food Safety National Standards for Contaminants in Foods (GB2762-2017), and the average effective Cd content accounted for 81.9% of the total Cd. The average bioconcentration factor of each heavy metal in rice followed the order Cd >Zn >Hg >As >Ni >Cr >Pb. Cd and As were the main noncarcinogenic contributing factors, accounting for 80.8% of the total noncarcinogenic risk. The carcinogenic risk indexes of Cd, As, and Cr exceeded the risk index threshold of 10^-4, indicating a carcinogenic risk to the human body. The highest risks to local residents from heavy metals were found in rice. Cd and As were the main noncarcinogenic and carcinogenic factors and should receive greater attention in risk decision management.

Pollution Characteristics, Spatial Patterns, and Sources of Toxic Elements in Soils from a Typical Industrial City of Eastern China

Soil pollution due to toxic elements (TEs) has been a core environmental concern globally, particularly in areas with developed industries. In this study, we sampled 300 surface (0–0.2 m) soil samples from Yuyao City in eastern China. Initially, the geo-accumulation index, potential ecological risk index, single pollution index, and Nemerow composite pollution index were used to evaluate the soil contamination status in Yuyao City. Ordinary kriging was then deployed to map the distribution of the soil TEs. Subsequently, indicator kriging was utilized to identify regions with high risk of TE pollution. Finally, the positive matrix factorization model was used to apportion the sources of the different TEs. Our results indicated that the mean content of different TEs kept the order: Zn > Cr > Pb > Cu > Ni > As > Hg ≈ Cd. Soil pollution was mainly caused by Cd and Hg in the soil of Yuyao City, while the content of other TEs was maintained at a safe level. Regions with high TE content and high pollution risk of TEs are mainly located in the central part of Yuyao City. Four sources of soil TEs were apportioned in Yuyao City. The Pb, Hg, and Zn contents in soil were mainly derived from traffic activities, coal combustion, and smelting. Meanwhile, Cu was mainly sourced from industrial emissions and atmospheric deposition, Cr and Ni mainly originated from soil parental materials, and Cd and As were produced by industrial and agricultural activities. Our study provides important implications for improving the soil environment and contributes to the development of efficient strategies for TE pollution control and remediation.

Source-specific ecological and health risks of potentially toxic elements in agricultural soils in Southern Yunnan Province and associated uncertainty analysis

Source-specific risk apportionment is critical to prevent and control soil potentially toxic element (PTE) pollution. This study explored source-specific ecological and human health risks of soil PTEs in Southern Yunnan Province. Geochemical baseline values were determined to assess the pollution level of PTEs; then source-specific risk was apportioned combining positive matrix factorization (PMF) with ecological and human health risk assessment. Obvious accumulation of As, Cd, Pb, and Zn was observed in this area, especially Cd in 21.33% of the samples exhibited significant enrichment. Four sources were quantified based on PMF assisted with GIS-mapping: natural sources (41.49%), traffic emissions (24.70%), industrial activities (17.48%), and agricultural activities (16.33%). Industrial activities were the largest source (64.55%) to ecological risk. Agricultural activities were regarded as the major contributor to non-carcinogenic (adults: 75.93%, children: 62.33%) and carcinogenic risks (adults: 55.97%, children: 56.36%). Non-carcinogenic and carcinogenic risks for children were higher than adults, and their health risks showed similar trend. Thus, agricultural activities should be regarded as a priority to reduce health risk, whereas industrial activities should be given priority to control ecological risk. Although source-specific risk was quantified, combination with bioavailability and interactions of PTEs are necessary to obtain more accurate results in future.

Assessment of non-carcinogenic health risk of heavy metal pollution: evidences from coal mining region of eastern India

Various developmental projects and economic actions such as mining, industries, urban expansion, and agricultural activities contribute toxic heavy metals into the soils and it adversely affects to human health and broadly the environment. For the scientific study (coal mining region of Eastern India) around 120 soil samples were collected from top (0 - 20 cm) and subsurface soil (20 - 50 cm) of coal mining, semi mining and non mining type of land use sites to assess ten heavy metals applying standard methods and indices for the assessment of pollution load and human health risk. Statistical analysis clearly indicated that Fe, Mn, Zr are the most dominantly distributed in the study region. Coefficient of variance (CV)showed that there was very less variation in the metal values among samples of any particular landuse site. Correlation coefficient (0.05% level of significance) depicts that metals were very strongly correlated with each other in every site of Neturia block. Igeo (Geo- accumulation index) values of Fe and As indicated moderate to low pollution in the topsoil of study area. It is because of their regional background value. Enrichment Factor (EF) also showed thatcontamination of Fe ismainly supplied by natural factors (EF < 2)i.e., weathering of parent rock in all over the study area. All other heavy metals indicated their anthropogenic sources (EF > 2)on top and subsurface soil both of three landuse site. Degree of contamination (Cdeg), modified degree of contamination (mCdeg), contamination factor (CF) and pollution load index (PLI) clearly suggest that topsoil of coal mining sites is most polluted than two other sites. Subsurface soil of mining sites also indicated comparatively higher pollution load than subsoil of semi mining or non mining sites. PLI values have been classified into four groups i.e., high pollution (> 6), medium pollution (6 -3), low pollution (3 - 1) and no pollution (< 1) zone. There was no PLI value < 1 in topsoil of the study area. But subsurface soil of non mining site indicated no pollution to the soil. Spatial mapping using Inverse Distance Weightage (IDW) on Arc GIS 10.4 software showed clear variation of metal concentration and pollution load to the top and subsoil of the study area. Human health risk of non - carcinogenic typeisdue to heavy metals intake of topsoil through three exposure pathwaywhich indicates the health risk of HI _dermal> HI _ingestion> HI _inhalation for both the adult and children. Mean values of total HI showed that children are more prone to health risk in comparison with adult. There was no soil sample that exceeds its HI values > 1 for adults and thus no obvious health risk was found from soil heavy metals for adults.On the other hand, topsoil of mining sites indicated HI values >1;therefore, children are prone to health risk in this site. The present investigation suggests that coal mining region is highly polluted by their heavy metal burden on soil. Industrial and semi urban areas of semi mining region are also affected by heavy metal dust to its soil. Agricultural activities in non-mining region indicated lower pollution than other landuse sites. Remedial measures are highly needed to control heavy metal pollution of different landuse sites at colliery region to sustain environmental quality and human health as well. Modern scientific technologies and public awareness should be very useful on this way.

Appraisal of metallic pollution and ecological risks in agricultural soils of Alborz province, Iran, employing contamination indices and multivariate statistical analyses

The current study was done to evaluate the pH, electrical conductivity, bulk density, sand, silt, clay, available K and P, organic carbon, Zn, Cu, Mn, and Fe in agricultural soils of Alborz province, Iran. A total of 46 samples were collected as composite samples from 0-20 and 20-40 cm soil depths. The average values of Fe, Cu, Mn, and Zn were found lower than the European limits, Indian limits, and Earth's crust. Pearson's correlation analysis found that pH effects Zn retention and, Cu and Mn retention in soil samples. Cluster analysis and Principal component analysis established that HMs are originated from different sources. Contamination factor (CF) and ecological risk index (RI) results showed less contamination and ecological risk in soil samples. Enrichment factor (EF) and modified ecological risk index (MRI) results indicated high enrichment and ecological risk of Cu, Mn, and Zn in surface and sub-surface soil samples.

Activation of biochar through exoenzymes prompted by earthworms for vermibiochar production: A viable resource recovery option for heavy metal contaminated soils and water

The industrial revolution and indiscriminate usage of a wide spectrum of agrochemicals account for the dumping of heavy metals in the environment. In-situ/ex-situ physical, chemical, and bioremediation strategies with pros and cons have been adopted for recovering metal contaminated soils and water. Therefore, there is an urgent requirement for a cost-effective and environment-friendly technique to combat metal pollution. Biochar combined with earthworms and vermifiltration is a suitable emerging technique for the remediation of metal-polluted soils and water. The chemical substances (e.g., sodium hydroxide, zinc chloride, potassium hydroxide, and phosphoric acid) have been used to activate biochar, which also faces several shortcomings. Studies reveal that extracellular enzymes have been used to activate biochar which is produced by earthworms and microbes that can alter the surface of the biochar. The present review focuses on the global scenario of metal pollution and its remediation through biochar activation using earthworms. The earthworms and biochar can produce "vermibiochar" which is capable of reducing the metal ions from contaminated water and soils. The vermifiltration can be a suitable technology for metal removal from wastewater/effluent. Thus, the biochar has a trick of producing entirely new options at a time when vermifiltration and other technologies are least expected. Further attention to the biochar-assisted vermifiltration of different sources of wastewater is required to be explored for the large-scale utilization of the process.

Sources of and Control Measures for PTE Pollution in Soil at the Urban Fringe in Weinan, China

The environment of the urban fringe is complex and frangible. With the acceleration of industrialization and urbanization, the urban fringe has become the primary space for urban expansion, and the intense human activities create a high risk of potentially toxic element (PTE) pollution in the soil. In this study, 138 surface soil samples were collected from a region undergoing rapid urbanization and construction—Weinan, China. Concentrations of As, Pb, Cr, Cu, and Ni (Inductively Coupled Plasma Mass Spectrometry, ICP-MS) and Hg (Atomic Fluorescence Spectrometry, AFS) were measured. The Kriging interpolation method was used to create a visualization of the spatial distribution characteristics and to analyze the pollution sources of PTEs in the soil. The pollution status of PTEs in the soil was evaluated using the national environmental quality standards for soils in different types of land use. The results show that the content range of As fluctuated a small amount and the coefficient of variation is small and mainly comes from natural soil formation. The content of Cr, Cu, and Ni around the automobile repair factory, the prefabrication factory, and the building material factory increased due to the deposition of wear particles in the soil. A total of 13.99% of the land in the study area had Hg pollution, which was mainly distributed on category 1 development land and farmland. Chemical plants were the main pollution sources. The study area should strictly control the industrial pollution emissions, regulate the agricultural production, adjust the land use planning, and reduce the impact of pollution on human beings. Furthermore, we make targeted remediation suggestions for each specific land use type. These results are of theoretical significance, will be of practical value for the control of PTEs in soil, and will provide ecological environmental protection in the urban fringe throughout the urbanization process.

Spatial distribution, risk assessment, and source identification of pollutants around gold tailings ponds: a case study in Pinggu District, Beijing, China

This work investigated heavy metal and cyanide pollution in surface soils and edible plants around Yanzhuang gold tailings ponds in the region of Yanzhuang Village in Pinggu District, Beijing. Surface soil samples were collected from 33 sites around gold tailings ponds, and concentrations of seven heavy metals (i.e., Sb, As, Cd, Cu, Pb, Zn, and Hg) and cyanide were analyzed to determine their spatial distributions, pollution degrees, and sources. The potential ecological risks of As, Cd, Cu, Pb, Zn, and Hg were preliminarily assessed. The results showed that the mean cyanide, Sb, As, Cd, Cu, and Pb concentrations were higher than the standard values. The pollutant concentrations around the tailings ponds were high and decreased with increasing distance from the ponds. The single pollution index indicated that cyanide, As, and Cd were the main pollutants. The Nemerow pollution index revealed a large region and serious degree of heavy metal pollution in soils. The potential ecological risk level of the study area was moderate, with Cd and As posing the main risks. Multivariate statistical analysis suggested that the heavy metal and cyanide pollution present mainly derived from gold tailings, with agricultural pollution also had a certain effect. However, the 12 edible plants sampled were basically not polluted.

Determination of heavy metal content and pollution indices in the agricultural soils using laser ablation inductively coupled plasma mass spectrometry

In this study, we determined the concentrations of heavy metals in the agricultural soils of Kafr El-Zayat city using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The LA-ICP-MS performance was firstly evaluated by analyzing appropriate reference materials and comparing the concentration values found to those of the reference values. LA-ICP-MS was then applied to examine the content of 21 elements (Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Rb, Sr, Mo, Sn, Ba, Pb, Th, and U) in 16 collected agricultural soil samples from Egypt. The soil quality was assessed by calculating the contamination factor (CF), enrichment factor (EF), and the geo-accumulation index (I_geo) of the measured heavy metals. The average concentrations of V, Cr, Co, Ni, and Cu were higher than the average worldwide background concentrations and exceeded the Canadian soil quality guidelines with values of 162.8, 113.3, 42.2, 88.1, and 70.6 μg/g, respectively. Multivariate analysis was applied to investigate the correlation and sources of heavy metals in agricultural soils. Cluster analysis indicated the clustering of heavy metals into three groups: Cr and Mo; Fe and Mn; and V, Ni, Co, Cu, Zn, and Pb. The results of principal component analysis (PCA) agreed with those of the cluster analysis and yielded three components that explained 81.13% of the total variance. The contamination factor (CF) of soils from all sampling sites showed moderate contamination.

Spatial distribution and risk assessment of agricultural soil pollution by hazardous elements in a transboundary river basin

The present study aimed to evaluate the sources of pollution and the potential human and ecological risks of hazardous elements (HEs) in 40 hotspot sites of the agricultural soil around the Arvand River, Iran. The mean concentrations of As, Cd, Co, Cr, Ni, Pb, Zn, and Hg were measured to be 7.2, 0.8, 14.0, 67.9, 69.5, 63.0, 296, and 0.66 (mg kg^-1), respectively. With the exception of Ni, the mean concentrations of all the elements were found to be higher than those in the background. The spatial distribution of HEs in the study area indicated an increasing trend of contamination from the north to the south. Pb, Zn, and Hg were the most enriched elements, resulting in a high pollution load. Moreover, the agricultural soil of the study area was threatened by a very high ecological risk due to the contribution of Hg, Cd, and Pb. Multivariate statistical analyses determined that the pollution sources are specified by the oil refinery emissions and effluents, irrigation with polluted water, fertilizers, dust storms, and airport emissions. The carcinogenic risk of HEs in both adults and children revealed an acceptable level; however, children faced a great chance of non-carcinogenic risk. The results provide a scientific basis for monitoring HEs and managing health risks via effective methods in the agricultural areas of the Arvand River basin.

A meta-analysis of heavy metals pollution in farmland and urban soils in China over the past 20 years

A total of 713 research papers about field monitor experiments of heavy metals in farmland and urban soils in China, published from 2000 to 2019, were obtained. A meta-analysis was conducted to evaluate the level of China's heavy metal pollution in soils, mainly focusing on eight heavy metals. It was found that the average concentrations of cadmium (Cd), lead (Pb), zinc (Zn), copper (Cu), mercury (Hg), chromium (Cr), nickel (Ni), and arsenic (As) in China were 0.19, 30.74, 85.86, 25.81, 0.074, 67.37, 27.77 and 8.89 mg/kg, respectively. Compared with the background value (0.097 mg/kg), the Cd content showed a twofold (0.19 mg/kg) rise in farmland soils and a threefold (0.29 mg/kg) rise in urban soils. The decreasing order of the mean I_geo was Cd (1.77) > Pb (0.62) > Zn (0.60) > Cu (0.58) > Hg (0.57) > Cr (0.54) > Ni (0.47) > As (0.28). Nearly 33.54% and 44.65% of sites in farmland and urban soils were polluted with Cd. The average concentrations of eight heavy metals were not sensitive change in recent two decades in farmland and urban soils. The average P_n values for urban (2.52) and farmland (2.15) soils showed that heavy metal pollution in urban soils was more serious than that in farmland, and the middle Yangtze River regions, where industrial activity dominates, were the most polluted. The meta-analysis comprehensively evaluated the current pollution situation of soil heavy metal, and provided important basis for soil management and environment prevention in China.

Assessment of health and ecological risks of heavy metal contamination: a case study of agricultural soils in Thall, Dir-Kohistan

Heavy metal (HM) contamination in agricultural soils has been a significant health concern worldwide due to their persistent and non-biodegradable nature and biomagnification to higher trophic levels. The present study was conducted to assess Cd and Pb concentrations in soil samples collected from potato-growing areas in Thall, Dir-Kohistan, and to determine their associated health and ecological risks. The contamination factor calculated for Cd (0 to 1.74) and Pb (0 to 0.91) showed their moderate to low contamination in the study area. Geo-accumulation indices of Cd and Pb were less than 1, indicating moderate soil pollution of these HM in the study area. However, the ecological risk factor (Eri) of Cd was greater than 40 for only three soil samples, indicating the moderate potential of ecological risks of respective soils. The principal component analysis (PCA) and Pearson correlation suggested that the contamination in different soils was lithogenic followed by anthropogenic activities. The hazard quotient (HQ) in children and adults was found in the following order: dermal > ingestion > inhalation. Moreover, the values of HQ through various exposure routes were higher in children compared to adults, which showed that adults were at a lower level of risk associated with HM contamination. The results of the present study can serve as baseline data for government agencies related to environmental protection, which could devise policies to minimize Cd and Pb contamination in the agricultural soils.

Pollution assessment and health risk evaluation of eight (metalloid) heavy metals in farmland soil of 146 cities in China

Heavy metals are the most important indicator for farmland soil; however, in China, few provincial and national scales of studies have been done on heavy metals. Herein, by retrieving published studies, we calculated the spatial distribution characters and evaluated the health risks of Cu, Zn, Cd, Ni, Pb, Cr, As, and Hg in the farmland soil of 146 cities in China. Results showed that (1) the range (mean) values of eight (metalloid) heavy metals were as follows in mg/kg: Cu 0.236-251.015 (44.604), Zn 0.151-1547.060 (154.203), Cd 0.014-39.100 (1.497), Ni 0.709-554.420 (41.968), Pb 0.327-495.400 (55.143), Cr 0.078-333.510 (70.093), As 0.836-60.000 (12.207), and Hg 0.008-12.190 (0.371). The coefficient of variation values of Cu, Cr, and As displayed moderate variation, and Zn, Cd, Ni, Pb, and Hg displayed high variation (142.148-364.960%). (2) the I_geo values of As, Cu, Cd, Ni, Zn, Cr, Pb, and Hg were - 4.329 to 1.837, - 7.166 to 2.888, - 3.378 to 8.070, - 5.831 to 3.780, - 9.527 to 3.797, - 10.120 to 1.866, - 6.899 to 3.667, and - 3.681 to 6.966, respectively; in many cities, there was some degree of heavy metal pollution of the farmland soil such as Zn in Pingdu, Pb in Huludao, and Hg in Tongguan, Funshun, Huludao, and Qinglong (I_geo > 3); there were no obvious spatial patterns of Cr, Ni, and As, and Zn, Cu, but Cd, Ni, Pb, and Hg mainly located in some cities in the southwest, central or eastern parts of China. (3) Health risk assessment showed that with the exception of Cd, Cr, and As by the respiration route and Ni, Cr, and As through skin exposure, the average amount of daily exposure of the eight (metalloid) heavy metals all showed values for children > adults, and the HQ and HI values were all lower than 1.0, indicating noncarcinogenic risks; calculation of carcinogenic risks showed there were no carcinogenic risks for As, Cr, Ni, and Cd; however, the value for Cr was the maximum and contributed 98.505% of the total.

Potentially toxic elements (PTEs) pollution in surface soils in a typical urban region of south India: An application of health risk assessment and distribution pattern

The pollution level of potentially toxic elements (PTEs) in surface soils is detrimental to the ecosystem and human health. In this research, various indices such as an index of geo-accumulation (I_geo), contamination factor (CF), degree of contamination (DC), and principal component analysis (PCA) were implemented to identify and evaluate the soil PTEs pollution; and then human health risk assessment model used to establish the link between heavy metals pollution and human health in the urban region of south India. Results exhibited that the mean concentration of Cr, Cu, Ni and Zn were found to be 1.45-6.03 times greater than the geochemical background values. Cr and Cu were the most profuse PTEs measured in the soils. The pollution indices suggest that soil of the study region is mainly moderate to highly polluted. The non-carcinogenic health risk assessment proposed by the United States Environmental Protection Agency (USEPA) suggested the mean hazard indices (HIs) were below one which denotes no significant of non-carcinogenic risks to both children and adults. Furthermore, carcinogenic risk assessment results advised ~80% of cancer risk was caused by Cr contents, while other heavy metals indicate that neither children nor adults in the study region were of carcinogenic risks.

Health risk assessment of trace elements exposure through the soil-plant (maize)-human contamination pathway near a petrochemical industry complex, Northeast China

The trace elements contamination of agricultural soils near petrochemical industry complexes is a concern due to the risk of accumulating in food systems and subsequently affecting human health. We measured representative trace elements (Cu, Ni, Cr, Pb, Zn, Pb, Hg and As) through the soil-plant (maize)-human contamination pathway near a petrochemical industry complexes in an agricultural region from September 20 to 28, 2016. We found that the soil was mildly to moderately polluted by multiple trace elements, which was also confirmed by the contamination factor and enrichment factor values. Cd (enrichment factor = 2.28), Cu (2.75), Zn (1.85) and Pb (1.70) should be given more attention and prioritized over the other trace elements due to their higher potential risks. Furthermore, the trace elements contamination in maize grains was lower than the corresponding limits. The sequence of the transfer coefficient values was Zn > Cd > Cu > Hg > Ni > As > Cr > Pb. Maize grain safety was threatened mainly by Zn, Cd and Cu. There was no risk to humans through soil ingestion, while a potential health risk from maize grain consumption existed. Children were more sensitive than adults to the non-carcinogenic risks of maize grain consumption. Trace element As was found to be the priority metal for risk control. For carcinogenic risk, adults were more sensitive than children; As, Cr and Cd were the priority metals for risk control, with CR_maize values exceeding the risk threshold (1 × 10^-4). Overall, strict, intensive monitoring, especially of Cr and Cd, and soil protection measures are needed to prevent any furthertrace elements contamination and to ensure food safety. This study also provides a reference for similar studies worldwide.

Spatial characteristics of heavy metal contamination and potential human health risk assessment of urban soils: A case study from an urban region of South India

Due to the rapid development of urbanization, the contamination of heavy metals in urban soils has become one of the major concerns of environmental and risk to humans. The main objective was to determine the contamination of six heavy metals in 25 urban soils and also to evaluate the associated health risk via diverse indices for adults and children. The mean concentration of Pb (47.48 mg/kg), Cr (43.24 mg/kg), Cu (40.64 mg/kg), Zn (34.68 mg/kg), Co (16.54 mg/kg), and Ni (7.55 mg/kg) exceeded the geochemical background values. Pb and Zn were closely attributed to traffic sources. Geo-accumulation index (I_geo) showed that Pb and Co in the soils were at the moderately pollution level, while 4% of soil samples were moderately polluted to heavily pollution levels by Cu. Enrichment factor (EF) showed that soils presented minor to severe anthropogenic pollution levels in the investigated region. The heavy metals to the non-carcinogenic risk of humans in the investigated region are absolutely from Cr and Pb, while the carcinogenic risk is controlled by Cr, and the remaining metals pose no possible risk to the local people. Specially, children had larger health risks in terms of non-carcinogenic risks than adults which may be related to their behavioral and physiological characteristics.

Contamination and ecological risk assessment of the Red Sea coastal sediments, southwest Saudi Arabia

The level of heavy metals (HMs) in coastal sediments has attracted the environmental researchers due to their persistence, abundance, biomagnification and toxicity. The present study was conducted to assess the contamination and ecological risk assessment of HMs in Jazan coastal sediments, Red Sea, Saudi Arabia utilizing pollution indices and multivariate statistical analyses. A total of 32 surface samples were collected for Cu, Sb, Zn, Cr, Cd, Pb, Fe, Co, Ni, Al, and total organic matter analysis using an atomic absorption spectrophotometer. The results indicate the following descending order of metal concentrations: Al > Fe > Cr > Cu > Zn > Ni > Co > Pb > Cd > Sb. Average level of Cd is significantly higher than those from many neighboring and worldwide coastal sediments; and recorded very severe enrichment, severe contamination and very high risk in the investigated sediments. The pollution indices and statistical analyses revealed that proportion of Zn, Fe, Ni, Cr, Al, Cu, Sb and Pb were formed from lithogenic sources of weathering Quaternary units and atmospheric deposition. Most of the Cd, Sb, and Pb levels were derived from anthropogenic sources of industrial, agricultural, and fishing activities. The higher contribution of organic matter may be attributed to the mangrove roots and organic fertilizers; and played a key role in adsorbing, transferring and accumulating of elements.

Appraising drinking water quality in Ikem rural area (Nigeria) based on chemometrics and multiple indexical methods

The continuous deterioration of drinking water quality supplies by several anthropogenic activities is a serious global challenge in recent times. In this current study, the drinking water quality of Ikem rural agricultural area (southeastern Nigeria) was assessed using chemometrics and multiple indexical methods. Twenty-five groundwater samples were collected from hand-dug wells and analyzed for physicochemical parameters such as pH, major ions, and heavy metals. The pH of the samples (which ranged between 5.2 and 6.7) indicated that waters were slightly acidic. Cations and anions (except for phosphate) were within their respective standard limits. Except for Mn, heavy metals were also found to be below their maximum allowable limits. Factor analysis identified both geogenic processes and anthropogenic inputs as possible origins of the analyzed physicochemical parameters. Modified heavy metal index, geoaccumulation index, and overall index of pollution revealed that all the hand-dug wells were in excellent condition, and hence safe for drinking purposes. However, pollution load index, water quality index (WQI), and entropy-weighted water quality index (EWQI) revealed that some wells (about 8-12%) were slightly contaminated, and hence are placed in good water category. A hierarchical cluster analysis (HCA) was performed based on the integration of the WQI and EWQI results. The HCA revealed two major quality categories of the samples. While the first cluster comprises of samples classified as excellent drinking water by both WQI and EWQI models, the second cluster comprises of about 12% samples which were identified as good water by either the WQI or EWQI.

Pollution, Sources and Human Health Risk Assessment of Potentially Toxic Elements in Different Land Use Types under the Background of Industrial Cities

Residents in industrial cities may be exposed to potentially toxic elements (PTEs) in soil that increase chronic disease risks. In this study, six types of PTEs (Zn, As, Cr, Ni, Cu, and Pb) in 112 surface soil samples from three land use types—industrial land, residential land, and farmland—in Tonghua City, Jilin Province were measured. The geological accumulation index and pollution load index were calculated to assess the pollution level of metal. Meanwhile, the potential ecological risk index, hazard index, and carcinogenic risk were calculated to assess the environmental risks. The spatial distribution map was determined by the ordinary kriging method, and the sources of PTEs were identified by factor analysis and cluster analysis. The average concentrations of Zn, As, Cr, Ni, Cu, and Pb were 266.57, 15.72, 72.41, 15.04, 20.52, and 16.30 mg/kg, respectively. The results of the geological accumulation index demonstrated the following: Zn pollution was present in all three land use types, As pollution in industrial land cannot be neglected, Cr pollution in farmland was higher than that in the other two land use types. The pollution load index decreased in the order of industrial land > farmland > residential land. Multivariate statistical analysis divided the six PTEs into three groups by source: Zn and As both originated from industrial activities; vehicle emissions were the main source of Pb; and Ni and Cu were derived from natural parent materials. Meanwhile, Cr was found to come from a mixture of artificial and natural sources. The soil environment in the study area faced ecological risk from moderate pollution levels mainly contributed by As. PTEs did not pose a non-carcinogenic risk to humans; however, residents of the three land use types all faced estimated carcinogenic risks caused by Cr, and As in industrial land also posed high estimated carcinogenic risk to human health. The conclusion of this article provides corresponding data support to the government’s policy formulation of remediating different types of land and preventing exposure and related environmental risks.