Variations In Heavy Metal Concentrations Research Articles

Using Enrichment Factor Approach for Source Identification of Potentially Toxic Heavy Metals along Benin-Ore-Sagamu Expressway in Nigeria

The variation in heavy metal concentration in different environment is dependent on the emission source. Source identification of heavy metal plays an important role in providing solution to its contamination in the atmosphere. Hence, the objective of this paper is to engage enrichment factor (EF) approach to evaluate the source identification of potentially toxic heavy metals along the Benin-Ore-Sagamu Expressway in Nigeria in four sampling locations (A, B, C and D) that are denoted with high traffic congestion. The source identification of Cu, Zn, Mn, Ni, Pd, Cd, Cr and Pb contamination in the study area were determined using appropriate standard methods. The EF values indicated for Cu ranged from (2.3-5.9), Zn (0.48-0.86), Mn (0.29-0.49), Ni (1.27-4.03), Pd (37012.18-59922.57), Cd (1909.11-2844.81), Cr (4.56-7.76) and Pb (0.77-4.64). The results suggest crustal source enrichment for Zn and Mn while Cu, Ni, Cr and Pb were enriched moderately. However, the EF values for Pd and Cd were found to be greater than 50, indicating extremely severe enrichment. The findings of this study provide evidence of anthropogenic impact on heavy metals pollution in the study area that is attributed to the intense vehicular traffic.

Impact of recurring irrigation with treated domestic wastewater on heavy metal accumulation in the soil

Water reuse for irrigation is a common practice globally, serving as an alternative to clean water. Wastewater contains traces of heavy metals that accumulate in the soil and food chain, posing an environmental and public risk. This study investigated the effect of irrigation with treated domestic wastewater (TDW) emanating from a homogenous community on heavy metal accumulation in the soil irrigated for three recurring farming cycles, namely R1, R2, and R3. A greenhouse experiment was conducted involving plots irrigated with TDW (PTw) and plots irrigated with fresh water (PFw) in triplicate. Soil samples were collected at depths of 0–20, 20–40, and 40–60 cm. Results revealed that heavy metals Pb, Cu, Cr, Zn, Cd, and Ni remained within the WHO permissible limits in the PTw and PFw, except Cd at 40–60 cm after the R3 in the TPw. Irrigation with TDW caused a decrease in Pb and Cd with respect to the baseline levels by 86–91% and 88–96% respectively. Other heavy metals increased in the soil in the order of Cr>Cu>Ni>Zn at 0–20 cm, Cr>Cu>Zn>Ni at 20–40 cm, and Cr>Cu>Ni>Zn at 40–60 cm. Variations in heavy metal concentrations were inconsistent with farming cycles except for Cu, which increased in the order of 3.2±0.75, 4.4±0.66, and 4.8±1.23 mg/kg at 0–20 cm for R1, R2, and R3, respectively, and 3.4±0.66, 3.7±0.62, and 6.0±0.44 mg/kg at 20–40 cm in the same order. Pollution index values revealed that irrigation with TDW for three recurring farming cycles caused slight soil contamination (1≤PI<2) with Zn and Ni, moderate soil contamination (2≤PI<3) with Cu, and high soil contamination (3<PI) with Cr at depths of 0–20 and 40–60 cm. The pollution load index indicated moderate soil pollution (1<PLI≤2) with heavy metals after the R3 at 40–60 cm. The findings suggest that irrigation with TDW proceed for at least three recurring farming cycles without causing significant soil heavy metal accumulation.

Investigation of Heavy Metals Contamination in Indian Aquaculture Shrimp -Litopenaeus vannamei

The expanding aquaculture industry in India has raised concerns about potential environmental contaminants, particularly heavy metals in seafood products. This study aims to assess the presence and levels of heavy metals in Indian aquaculture shrimp, focusing on the widely cultivated species Litopenaeus vannamei. Shrimp samples were collected from diverse aquaculture sites across India and rigorous analytical techniques were employed to quantify the concentrations of various heavy metals. Preliminary findings indicate the potential presence of mercury (Hg), lead (Pb), cadmium (Cd), arsenic (As), copper (Cu), zinc (Zn), chromium (Cr) and nickel (Ni) in the shrimp tissues. The study explores potential sources of contamination including water quality, sediments and feed to ascertain the pathways through which these heavy metals enter the shrimp cultivation environment.

Hazard Identification and Potential Risk Analysis of Toxic Metals in Redbelly Tilapia (Coptodon zillii) Consumed and Surface Water from the Niger Delta Estuary

Anthropogenic activities have caused toxic metals to escalate, polluting rivers, and accumulating in water, sediments, and fish. This harms aquatic ecosystems and has enduring impacts on humans and aquatic life. The study aimed to assess the accumulation of heavy metals (Pb, Cr, Cu, Fe, Ni, Cd, and Zn) in Redbelly tilapia (Coptodon zillii) and water obtained from three sampling stations along Atuka Creek which is a crude oil-contaminated site in a southern creek in Nigeria. The investigation further intends to evaluate potential health risks linked to the consumption of C. zillii and to analyze the pollution and productivity levels of the corresponding aquatic ecosystem. The results show significant variations in heavy metal concentrations across stations, with Station 1 exhibiting the highest contamination levels attributed to its proximity to pollution sources. The fish from Station 1 revealed elevated levels of contamination, surpassing recommended limits for Pb, Fe, Ni, and Zn. Calculations of chronic daily intake (CDI) values indicate potential health risks for both adults and children, particularly in Stations 1 and 2. The hazard quotient (HQ) and hazard index (HI) values surpassed safe limits in these stations, suggesting non-carcinogenic health risks linked to fish consumption and swimming. Moreover, lifetime cancer risk (ILCR and TLCR) assessments revealed an augmented risk of cancer, especially in Stations 1 and 2. These findings emphasize the need for stern pollution control measures, regulations, and remediation strategies to mitigate heavy metal contamination, ensure water quality, and safeguard public health in southern Nigerian communities.

Seasonal Variation of Fe, Mn, and Pb in Groundwater of Northwestern Bangladesh

Groundwater is one of the most significant natural resources on earth and also stands as the largest source of all-purpose water in Bangladesh. The higher concentrations of iron (Fe), manganese (Mn), and lead (Pb) in water constitute a threat to human health and the environment. The research aimed to assess the seasonal variations of heavy metal concentrations, including Fe, Mn, and Pb, and the water type controlling the geochemistry of groundwater. A total of sixty groundwater samples were collected over a year in three seasons and analyzed for several physicochemical parameters using the standard analysis methods The highest concentrations of Fe, Mn, and Pb in investigated groundwater samples were found to be 3.69, 2.50, and 0.17 mg/L, respectively. The study observed that the higher concentrations of Fe and Mn were in the pre-monsoon but Pb was in the post-monsoon. The contaminations of Fe, Mn, and Pb in the groundwater follows the order Fe &gt; Mn &gt; Pb in three seasons, and their concentrations of abundance follow the seasons: PRM &gt; POM &gt; MON. The groundwater samples showed the dominance of Ca++, Mg++, and HCO3-, indicating temporary hardness and the Ca-Mg-HCO3, hydrochemical facies, controlling the groundwater geochemistry in the study area. These findings would provide an in-depth understanding of water quality, potential risks to human health, and coping mechanisms for sustainable drinking water management.

Different “nongrain” activities affect the accumulation of heavy metals and their source-oriented health risks on cultivated lands

“Nongrain” production on cultivated land is one of the primary environmental issues in China. Different “nongrain” activities may introduce different pollution sources to the local environment, leading to variations in heavy metal contents in soil, which can profoundly impact national food security. In this study, three typical “nongrain” regions (Nanxun (NX), Xiaoshan (XS) and Lin'an (LA)) with intensive aquaculture, tea planting and flower (seedling) growth on cultivated land around the Hangzhou metropolitan area were selected to address the spatial heterogeneity of accumulation levels, sources and source-oriented health risks of heavy metals in soil. The results showed that Hg was the main pollutant in NX and XS, while Cd and As were the major contaminants in LA. Aquiculture and sericultural industries (37.43%), natural sources (23.59%) and industrial activities (38.99%) were the major sources in NX; atmospheric deposition (37.73%), flower and seedling planting (23.49%) and metal-related industries (35.16%) were the major sources in XS; and atmospheric deposition (28.06%), excessive application of fertilizers and pesticides during tea planting (43.47%) and natural sources (28.47%) were the major sources in LA. The major risk population, area, exposure route and hazardous elements were children, LA, ingestion and As and Cr, respectively. From the perspective of source-based health risk assessment, in addition to natural sources that are difficult to intervene in, industrial activities, especially leather and wood process industries, metal-related industries and excessive fertilizer and pesticide application during tea planting contributed the most to the total health risk, which explained 67%, 41% and 42%, respectively, of the total risk in NX, XS and LA. High health risks are present in sources with heavy loadings of hazardous heavy metals (As and Cr); thus, to protect human health, the corresponding high-risk anthropogenic pollution sources in different “nongrain” areas need to be controlled.

Recycling of municipal solid waste incineration bottom ash (MSWIBA) particles into natural fine sands for sustainable engineering cementitious composites

The manufacture of engineered cementitious composites (ECCs) consumes large amounts of natural fine aggregate. In this study, replacement of the natural fine aggregates in ECCs with municipal solid waste incineration bottom ash (MSWIBA) was found to reduce the consumption of natural river sand and the negative environmental impact of MSWIBA disposal. Previously, scholars have shown the potential of using MSWIBA particles as fine aggregates in concrete, but few scholars have evaluated ECCs with high percentages of MSWIBA powder in place of the natural fine aggregates. This study was conducted to design green ECCs by incorporating MSWIBA (BA–ECCs) to completely replace the natural silica sand with various fibers (PVA, PP and PE) and different fiber volume blends (0%, 0.5%, 1%, 1.5% and 2%) and to evaluate the BA–ECCs based on the fluidities, mechanical properties, microscopic morphologies, pore size distributions and heavy metal leaching capacities. The results showed that the addition of MSWIBA increased the porosities of the BA–ECCs. Compared with those of the control group, the maximum flexural strength of the BA–ECCs with 1.5% fiber doping were approximately 27.75% higher. There were relationships between the compressive strength and flexural strength and between the fiber volume content and strength. Moreover, microstructural observations revealed that the MSWIBA powder interacted strongly with both the matrix and the fibers, and the performance of the MSWIBA powder in the matrix was similar to that of a lightweight aggregate during internal curing. Additionally, fiber agglomeration (winding) at a 2% fiber content reduced the compressive and flexural strengths. The BA-ECCs showed lower heavy metal leaching contents than the MSWIBA, and the concentrations of various heavy metals were below the Chinese standards. Overall, this study could support research on the use of MSWIBA particles to prepare sustainable ECCs and recycle MSWIBA particles.

Investigation of heavy metals in tissues and habitats of three edible frogs from Türkiye.

The soil, water, and organisms have been contaminated by heavy metals due to human activities and industrialization, which has produced a major environmental problem that has a deleterious effect on human health and food quality. Frogs, one of the good bioindicators for environmental pollution, are also among the alternative essential protein sources for humans. In Türkiye, three of these frogs are edible: Pelophylax ridibundus, Pelophylax bedriagae, and Pelophylax caralitanus, also known as Anatolian water frogs. Hence, to assess the possible health risks that might result from consuming frog legs in addition aquatic habitat of Anatolian water frogs, the water, sediment, and frog tissue samples (muscle and liver) were obtained from 11 different provinces covering all regions of Türkiye and analyzed to determine Cd, Cu, Cr, Zn, Pb, and As concentrations. The results revealed considerable variations in heavy metal concentrations among frog tissues, influenced by the sampling sites and species (ANOVA: p < 0.05). The Estimated Daily Intake (EDI) values, calculated based on the average serving size, were also lower than the Provisional Tolerable Daily Intake (PTDI) levels for adult consumers. Furthermore, the study computed the Target Hazard Quotient (THQ) values for heavy metals, all of which were below the critical value of 1, indicating that consuming the hind leg muscles from these frog species would not pose an adverse health risk for humans.

Potential Health Hazards of Consuming Lutjanus Goreensis from Coastal Waters in the Niger Delta Contaminated with Toxic Metals

This study investigates the health risks associated with trace elements in Gorean snapper (Lutjanus goreensis) from Buguma Creek, Southern Nigeria. Fish samples were collected monthly from May to August 2023, and muscle tissues were analyzed for potential health risks posed by elevated levels of hazardous metals. The concentrations of various heavy metals (Fe, Zn, Pb, Cd, Cu, and As) in Gorean Snapper collected from different locations (Station 1, Station 2, and Station 3) were measured in milligrams per kilogram (mg/Kg) of fish tissue. Results revealed varying metal concentrations across stations, with notable differences in Fe, Zn, Pb, Cd, Cu, and As levels. The Estimated Daily Intake (EDI) values for Cadmium (Cd) were relatively low for both adults and children across all three stations. However, Lead (Pb) and Arsenic (As) exhibited low EDI values, while Zinc (Zn) showed significantly higher values, especially at Station 3. The Hazard Quotient (HQ) and Hazard Index (HI) results indicated potential health risks associated with Zinc exposure, particularly at Station 3, for both adults and children. Carcinogenic Risk (CR) analysis revealed potential health risks associated with long-term exposure to Cadmium for adults. The CR values for Lead and Arsenic fell within acceptable ranges. This study raises concerns about potential health risks associated with the consumption of L. goreensis from Buguma and recommends the continuous monitoring of heavy metal concentrations, public awareness programs, further research, collaboration among stakeholders, and the implementation of best practices in aquaculture and fisheries management to reduce heavy metal concentrations in fish.

Resource Disposal and Products of Fly Ash from Domestic Waste Incineration in Zhejiang Province, China: Migration and Change of Hazardous Heavy Metals

At present, domestic waste incineration fly ash is classified as hazardous waste. The technical hurdle of fly ash detoxification and resource usage must be overcome in order to effectively utilize fly ash resources. In this study, we investigate the migration and transformation of heavy metal contaminants in the course of utilizing domestic waste incineration fly ash resources through the technology pathway of low-temperature pyrolysis, cyclic rinsing, and evaporation crystallization. Firstly, a comparative analysis was conducted on the fly ash (FA), pyrolysis ash (PA), and water-washing ash (WA) resulting from domestic waste incineration, revealing 24 types of metals, 3 types of non-metals, and 8 types of oxides. We observed the variations in heavy metal concentrations as well as the acidity and alkalinity in three types of ash resulting from the regenerated salt (RS) and incineration processes. Moreover, we analyzed the changes in heavy metal levels and acidity and alkalinity of treated saline water (TSW) and industrial brine (IB), which originate from the fly ash treatment process. The study’s results have confirmed that the heavy metal content in RS was below the detection limit following resource treatment. In addition, the regenerated salt product is determined to be a CaO-SiO2-Al2O3-Fe2O3 system, which enables the utilization of fly ash as a valuable resource. Notably, there were significant changes observed in heavy metal content in TSW and IB. Continued attention needs to be paid to the potential risk of environmental contamination from heavy metals and dioxins in FA infiltration. This research will prove beneficial in assessing resource utilization potential of products subjected to environmentally sound incineration fly ash treatment.

Seasonal Variations in Heavy Metal Content of Periwinkle Samples obtained from Oil Producing Communities within Bayelsa State, Nigeria

The effects of seasonal variations on the heavy metal content of periwinkle (Littorina littorea) were investigated. Samples were obtained from five stations within the oil producing communities of Bayelsa State, Nigeria. The standard digestion method was used to determine the levels of zinc, lead, nickel, copper, cadmium and chromium with the aid of the atomic absorption spectrophotometer (AAS). (Cadmium (0.216 – 0.727 ppm) and chromium (0.003 – 0.110 ppm) were significantly higher. Zinc, lead, nickel and copper were below the minimum permissible limits. Results obtained for chromium was significant at p(0.05) for the Pearson correlation coefficient. Oil production increases the concentration of heavy metals in water causing harmful to living and non-living resources. Further studies within the study area will assist in effective monitoring of the environment for sustainable development.

Assessment of heavy metals concentrations in five marine organisms from Lianyungang in China and the corresponding health risk

This paper determined the concentrations of heavy metals (i.e. Cr, Ni, Cu, Zn, As, Cd, Hg and Pb) in the edible portions of five marine organisms (Larimichthys polyactis, Sphyraenus, Litopenaeus vannamei, Portunus trituberculatus, and Scapharca subcrenata) caught from Gaogong Island in the coast of Lianyungang, Jiangsu Province, between September 2022 and March 2023. Human health risks were evaluated by calculating non-carcinogenic risks (target hazard quotient (THQ), hazard index (HI)) and carcinogenic risk (cancer risk (CR)). The results revealed substantial variations in heavy metal concentrations among different sampling months and marine organisms. Notably, the mean concentrations of Zn (77579.07 μg/kg) and As (10326.77 μg/kg) in Portunus trituberculatu exceeded the Chinese standard limit in September 2022, while the mean concentrations of As exceeded the standard limit in Sphyraenus (1517.47 μg/kg), Portunus trituberculatu (8737.90 μg/kg) and Scapharca subcrenata (5612.25 μg/kg) in October 2022. Importantly, the estimated daily intake (EDI), THQ, HI, and CR values utilized to evaluate potential health risks were within acceptable thresholds for human consumption. In March 2023, HI for Scapharca subcrenata exhibited a value of 1.21 (>1), suggesting a need for vigilance. Furthermore, CR values for As in Larimichthys polyacti, Sphyraenus, Portunus trituberculatus, and Scapharca subcrenata exceeded 10−4 in some months, alongside Cd CR values in some months of Portunus trituberculatus and Scapharca subcrenata. Based on these results, continuous monitoring of heavy metal concentrations in Gaogong Island of Lianyungang is recommended to safeguard the health and well-being of individuals consuming marine organisms from this area.

A Comparative Study of Heavy Metal Pollution in Ambient Air and the Health Risks Assessment in Industrial, Urban and Semi-Urban Areas of West Bengal, India: An Evaluation of Carcinogenic, Non-Carcinogenic, and Additional Lifetime Cancer Cases

Air pollution is an immense problem due to its detrimental health effects on human populations. This study investigates the distribution of particle-bound heavy metals and associated health risks in three diverse areas (Durgapur as an industrial complex, Kolkata as an urban area, and Bolpur as a semi-urban region) in West Bengal, India. Twenty-one (84 samples) sampling sites were chosen, covering industrial, traffic, residential, and sensitive zones. The respirable suspended particulate matter (RSPM) samples were collected using a portable Mini-Vol Tactical Air Sampler, and heavy metal concentrations (Cd, Cr, Mn, Ni, Pb, and As) were analyzed using ICP-OES. The non-carcinogenic and carcinogenic health risks were assessed using exposure concentration (EC), hazard quotient (HQ), hazard index (HI), and additional lifetime cancer cases. The results highlight variations in heavy metal concentrations across the regions, with industrial areas exhibiting higher levels. Principal component analysis (PCA) unveiled distinct metal co-variation patterns, reflecting sources such as industrial emissions, traffic, and natural contributors. The sum of non-carcinogenic risks (HI) of all heavy metals exceeded the US EPA’s risk limit (HI&lt;1) in both Kolkata and Durgapur, except for Bolpur. Similarly, the sum of cancer risk in three distinct areas exceeded the USEPA limits (1.00E-06). The Monte Carlo simulation revealed the 5th and 95th percentile range of cancer risk was 9.12E-06 to 1.12E-05 in Bolpur, 3.72E-05 to 4.49E-05 in Durgapur and 2.13E-05 to 2.57E-05 in Kolkata. Kolkata had the highest additional lifetime cancer cases compared to Bolpur and Durgapur. This study provides information on the complex connections between heavy metal pollution and possible health risks in industrial, urban, and semi-urban regions.

ABOUT HEAVY METAL ACCUMULATION POTENTIAL OF SOME EVERGREEN TREES IN GREEN SPACES OF YEREVAN (ARMENIA)

This article presents the final research on the study the metal accumulation potential of two evergreen species Thuja occidentalis L. and Juniperus virginiana involved in the green infrastructure of Yerevan-Armenia’s capital city. We studied the condition of both evergreen species, seasonal variations of heavy metal contents in their needle at the end of summer and winter, and the bio concentration factor of plants. The decreased longevity shows that both studied evergreen species are inappropriate for planting in the streets with heavy traffic or close to industrial pollution sources.

Risk evaluation and remedial measures for heavy metal contamination in lagoonal sediments of the Negombo Lagoon, Sri Lanka after the X-Press Pearl maritime disaster

Negombo Lagoon is a vital ecological and socio-economic resource in Sri Lanka that has become susceptible to anthropogenic heavy metal contamination. Therefore, short-core sediment samples from the Negombo Lagoon were analyzed to quantify heavy metal contaminants including both metals (Cr, Ni, Co, Cu, Cd, and Pb) and metalloid As; assess their ecological risk; identify critically polluted regions; and to investigate temporal variation in heavy metal concentration. According to the results, Ni is the most abundant heavy metal in lagoonal sediments. Ni, As, and Cr have severely contaminated the sediments as confirmed by their higher geo-accumulation indices (Igeo) and contamination factors (CF). The degree of contamination (Cdeg) indicated an exceedingly high overall heavy metal contamination, and the pollution load index (PLI) exhibited a prominent site quality decline. Individual potential ecological risk factor (Er) values revealed that Ni, As, and Cd pose a substantial ecological risk. Similarly, the potential ecological risk index (PERI) displayed that heavy metal contamination is a significant peril to this ecosystem. Spatial distributions of the heavy metals are governed mainly by the sediment grain size and freshwater influx. Ni concentration in lagoonal sediments has remarkably increased during the last six years (2016–2022) predominantly due to anthropogenic Ni sources, including the recent X-Press Pearl ship accident. In light of the severe heavy metal contamination in lagoonal sediments, the current study recommends a phytoremediation approach for the Negombo Lagoon.

Heavy Metals and Microbial Diversity: A Comparative Analysis of Rivers Swat and Kabul

Water contamination with heavy metals seriously affects water and sediment quality and may affect the aquatic biota. This study assessed the impact of heavy metals on the morphological characteristics of aquatic microorganisms in potentially contaminated water. Different physicochemical parameters and heavy metals contents were analyzed for toxicological assessment along with microbial diversity in the rivers Swat and Kabul. The pH of River Swat water was neutral to slightly alkaline, while River Kabul was neutral to slightly acidic. The results showed substantial variations in heavy metal concentration across different sampling points. In both River Swat and River Kabul water samples, Cu and Zn concentrations were below the permissible limits for surface and drinking water qualities while the rest of the heavy metals exceeded the permissible limit with Cd being the most abundant heavy metal. Similarly, in sediment samples all the heavy metals were below the permissible limits except for Cd that exceeded the Environment Canada (EC) limits in River Swat and EC and NOVA limits in River Kabul. The rest of the heavy metals concentrations were within the permissible limits, with few exceptions. The results showed that in River Swat, most of the contamination was of geogenic origin, while the main source of contamination in River Kabul was anthropogenic. Results of microbial analysis showed that River Swat has more diversity than River Kabul, which may be due to the low contamination profile of River Swat. It was further observed that high heavy metal concentrations negatively impact the morphological characteristics of microorganisms. The heavy metals concentration and microbial diversity were closely related to each other.

Assessment of heavy metal accumulation in dust and leaves of Conocarpus erectus in urban areas: Implications for phytoremediation

This study investigated the spatio-temporal variation of heavy metal concentrations in roadside dust and its correlation with heavy metal content in roadside plant leaves. Sixty re-suspended dust samples were collected from six locations during two seasons (dry and wet). Simultaneously, leaf samples of Conocarpus erectus were collected from the same locations. The samples were analyzed using an atomic absorption spectrophotometer to determine the concentrations of As, Cu, Fe, Cd, Pb, and Ni. The pH and conductivity of the dust were also analyzed using a glass electrode. The mean concentrations (μg/g) of heavy metals in the dust ranged from 0.337 to 6.34 for As, 10.60–55.39 for Cu, 542.17–1453.45 for Fe, 0.193–1.026 for Cd, 11.82–52.56 for Pb, and 10.19–29.27 for Ni in different seasons. Similarly, the concentrations of heavy metals in the leaf samples ranged from 0.031 to 1.70 for As, 6.90–13.19 for Cu, 263.09–576.16 for Fe, 0.299–1.33 for Cd, 0.019–17.82 for Pb, and 2.09–7.015 for Ni in different seasons. The correlation between heavy metal concentrations in different seasons was examined using Pearson's and Spearman's correlation methods. To compare the bioaccumulation ability, bio-concentration factors (BCF), comprehensive bio-concentration index (CBCI), and metal accumulation index (MAI) were calculated. The Conocarpus erectus MAI was consistent across different locations and seasons (24.49 ± 0.149). Based on CBCI, the bioaccumulation capacity of heavy metals they were ranged from 6.57 to 12.83 in the dry season and from 5.84 to 10.24 in the wet season. These findings provide valuable insights into the distribution and accumulation of heavy metals in roadside dust and plant leaves, highlighting the potential of Conocarpus erectus as a bio-accumulator for heavy metal pollution in urban environments. The results can be utilized to develop appropriate strategies for environmental management and pollution control in areas affected by vehicular pollution.

Determining the factors controlling the chemical composition of groundwater using geochemical methods and groundwater health assessment in Qixing Town, southwest China

Abstract Studies on groundwater quality and possible hazards to human health are important for improved groundwater utilization. This study explored the chemistry of groundwater in Qixing Town and the influencing factors. Statistical evaluation, ion correlation, Entropy-Weighted Water Quality Index (EWQI) assessment, and human health risk evaluation were conducted on data derived from 25 groundwater samples. The main groundwater chemistry types were HCO3–Na and HCO3–Ca. The results of ion and geological modeling analysis indicated that major ion concentrations were mainly determined by cation exchange. The study on the variation of heavy metal concentration in groundwater with depth shows that the heavy metal content in groundwater decreases first and then increases with the increase of depth, and the EWQI suggested that groundwater was suitable for drinking. The total carcinogenic health risks for Cr and As for both adults and children were higher than the highest permissible hazard value suggested by the United States Environmental Protection Agency (USEPA). The categorization of hazardous ingestion (HI) by the USEPA indicated a negligible non-carcinogenic hazard to human health by toxic metals. The results suggest the need to increase Cr and As contamination monitoring in shallow groundwater. This study can facilitate the rational development of groundwater resources.

Anthropogenic increase of heavy metals in soil from a heavily contaminated area of China

ABSTRACT Evaluating the variation in heavy metal concentrations in soil caused by anthropogenic activities in heavily contaminated areas is of great significance. The degree of heavy metal pollution in soil is primarily assessed by different indices with different standards and reference elements. However, these methods cannot be used to evaluate the degree of heavy metal pollution caused by anthropogenic activities. In this study, Zhuzhou, China was selected as the contaminated area, and Yueyang, China was selected as the background area, where geological and climatic conditions are similar to those of Zhuzhou, China. The concentrations of As (6.6–23.6 mg/kg), Cd (0.125–0.757 mg/kg), Cu (33–75 mg/kg), Hg (0.032–0.202 mg/kg), Pb (17–108 mg/kg), and Zn (74–122 mg/kg) in the vertical soil profiles in the contaminated area were higher than those in the background area (ranging 1.7–20.7, 0.085–0.210, 21–47, 0.030–0.105, 17–38 and 32–88 mg/kg, respectively). K2O/Al2O3, SiO2/Al2O3, and the weathering leaching coefficient (ba) showed little difference, suggesting that the weathering degree of soil in these two areas was similar. The weathering degree of soil governs the geochemical behavior of heavy metals and reference elements. According to the prediction models for heavy metal concentrations and organic carbon, K2O/Al2O3, and SiO2/Al2O3 in the soil profiles from the background area, the increase in heavy metal concentrations in the topsoil in the contaminated area was depicted. The heavy metal concentrations in topsoil were obviously affected by anthropogenic activities. This study provides a case study for evaluating the impact of anthropogenic activities on heavy metals in soil.

Modelling heavy-metal phytoextraction capacities of Helianthus annuus L. and Brassica napus L.

Greenhouse experiments were conducted to test the phytoextraction potential of sunflower (Helianthus annuus L.) and rape (Brassica napus L.) during the initial growth in the heavy metal (i.e., Cd, Ni, Zn, and Pb) contaminated soil. The target plants were grown for 30 d in pots filled up with soil treated with various concentrations of heavy metals. The wet/dry weights of plants and heavy-metal concentrations were measured, and the bioaccumulation factors (BAFs) and Freundlich-type uptake model were then used to measure their capacities of phytoextracting accumulated heavy metals from the soil. It was observed that the wet/dry weights of sunflower and rapeseed decreased, and heavy-metal mass uptake increased in plants commensurate with the elevating heavy metal concentrations in the soil. The sunflower BAF for heavy metals was higher than that of rapeseed. The Freundlich-type uptake model suitably described the phytoextraction capacities of sunflower and rapeseed in a soil contaminated with a single heavy metal and can be used to compare the phytoextraction capacities of different plants for the same heavy metal or of the same plant with different heavy metals. Although this study is based on limited data from two species of plants and soils contaminated with one heavy metal, it provides a basis for evaluating the ability of plants to accumulate heavy metals during their initial growth stages. Additional studies utilizing diverse hyperaccumulator plants and soils polluted with multiple heavy metals are essential to enhance the suitability of the Freundlich-type uptake model for assessing the phytoextraction capacities of intricate systems.