Heavy Metals Pb Research Articles

Statistical modeling and optimization of heavy metals (Pb and Cd) adsorption from aqueous solution by synthesis of Fe3O4/SiO2/PAM: isotherm, kinetics, and thermodynamic

In this study, magnetic material was synthesized using iron salts, then silicon-specific material was used to gain porosity, straight-chain polyacrylamide (PAM) was modified to give the surface functional properties, and the final product synthesized Fe3O4/SiO2/PAM nanocomposite material. Heavy metal (Pb and Cd) removal studies were carried out with the synthesized composite material, considering the central composite design and response surface methodology (CCD-RSM) optimization model. The effects of various parameters, for example, the initial concentration, pH, adsorbent dose, temperature and contact time, were investigated as a part of this study. To optimize these parameters, the CCD-RSM model was applied to design the experiments. Analysis of variance (ANOVA) was applied to evaluate statistical parameters and investigate interactions of variables. In the designed experimental set, the amount of adsorbent (30 mg), pH 7.0 value, temperature (40 °C), initial concentration of Pb (80 mg/L) and Cd (20 mg/L) and 90 min contact time were determined as the optimum conditions. The high coefficient of determination of both metals showed good agreement between experimental results and predicted values (R2 0.99; 0.95). TEM, SEM, XRD, FTIR, BET and Zeta potential analyses were performed to characterize the structure and morphology of the adsorbent. In Pb2+ and Cd2+ heavy metal removal studies, maximum adsorption capacities were determined as 66.54 and 13.22 mg/g, respectively. Additionally, adsorption isotherms, adsorption kinetics and thermodynamic modeling studies were conducted. Features such as large surface area and high adsorption capacity of the synthesized nanoparticles were observed. In this study, Fe3O4/SiO2/PAM demonstrated its potential as an effective adsorbent for the removal of heavy metal ions present in simulated wastewater samples. In particular, we can say that the material has a strong selectivity, as well as a high affinity for Pb(II) ions.

Ecological risk assessment of heavy metals (Pb, Cd, Cr, Ni, Zn, Fe) and metalloid (As) in surface sediment of Anzali International Wetland, Iran

ABSTRACT This study aimed to assess the metal concentration, mobility, bioavailability, ecological risk, and toxicity in the surface sediment of Anzali International Wetland. Contamination and ecological risk were evaluated using parameters such as Global Contamination Factors (GCF), Risk Assessment Code (RAC), Toxic Unit (TU), sum of Toxic Units (ΣTUs), Toxic Risk Index (TRI), ecological risk (ER), Risk Index (RI), and modified Hazard Quotients (MHQ). Heavy metal mean concentrations (mean ± SD) ranked as follows: Zn (95.46 ± 20.71) > Cr (19.79 ± 2.79) > Ni (18.49 ± 5.23) > Pb (13.97 ± 3.20) > As (6.45 ± 1.87) > Cd (0.90 ± 0.34). Cd exhibited high mobility and bioavailability, while Cr, Pb, Zn, Ni, and As mainly existed in residual fractions, indicating low bioavailability and minimal ecological risk. Ecological risk assessment identified “moderate” to “considerable” risk potential for Cd at specific sites. The Risk Index categorized Anzali sediment as having “low” to “moderate” risk potential (150 < RI < 300). Values of RI, ΣTUs, and MHQ suggested low to moderate risk potential and low toxicity in the sediment. Global Contamination Factor (GCF) values indicated high contamination (12.53 to 79.11). Recommendations include installing effective sewage treatment plants and promoting proper agricultural practices to mitigate metal toxicity in Anzali Wetland and also protect human and environmental health.

Heavy Metal Concentrations in Water, Sediment, and Fish Species in Chashma Barrage, Indus River: A Comprehensive Health Risk Assessment.

The increasing levels of heavy metals in aquatic environments, driven by human activities, pose a critical threat to ecosystems' overall health and sustainability. This study investigates the bioaccumulation of heavy metals (Pb, Cu, Cr, and Cd) in water, sediment, and three fish species (Catla catla, Labeo rohita, Cirrhinus mrigala) of different feeding zones within Chashma Barrage, located in the Mianwali district of Punjab, Pakistan, on the Indus River. A comprehensive analysis, including an assessment of associated human health risks, was conducted. Thirty samples from all three sites for each fish species, with an average body weight of 160 ± 32g, were collected from Chashma Barrage. Water quality parameters indicated suitability for fish growth and health. Heavy metal concentrations were determined using an atomic absorption spectrometer. Results indicated elevated levels of Cd, Cr, and Cu in sediment and Pb and Cd in water, surpassing WHO standard limits. Among the fish species, bottom feeder (C. mrigala) exhibited significantly (P < 0.05) higher heavy metal levels in its tissues (gills, liver, and muscle) compared to column feeder (L. rohita) and surface feeder (C. catla). Liver tissues across all species showed higher heavy metal bioaccumulation, followed by gills. Principal component analysis (PCA) revealed strong correlations among heavy metals in sediment, gills, muscle, and water in every fish species. However, the vector direction suggests that Cr was not correlated with other heavy metals in the system, indicating a different source. The human health risk analysis revealed lower EDI, THQ, and HI values (< 1) for the fish species, indicating no adverse health effects for the exposed population. The study emphasizes the bioaccumulation differences among fish species, underscoring the higher heavy metal concentrations in bottom feeder fish within Chashma Barrage.

Combining biochar with sediment in the treatment for the effectiveness of sulfate and heavy metal Pb reduction of acid mine drainage

The increasing mining activities have led to the problem of acid mine drainage (AMD) pollution. A method that combines biochar treatment as an adsorbent with wetland sediment treatment as a source of sulfate-reducing bacteria is used to address AMD effectively. This research aimed to determine the ability of biochar in combination with wetland sediment treatment to reduce sulfate and heavy metal content in acid mine drainage wastewater. This research was conducted on a laboratory scale in an AMD wastewater treatment reactor with the following treatments of biochar mixed with wetland sediment. Observations included sulfate content, pH, and heavy metal content. Scanning electron microscope (SEM) analysis was also performed on the biochar. SEM observations revealed the presence of small, dense, and irregularly shaped pores on the surface of the biochar. The results on day 30 showed that biochar mixed with wetland sediment was able to reduce sulfate concentration by 74.19% and reduced Pb by 73.79%, compared with treatment sediment only to 64.81% sulfate concentration and reduced Pb by 53.85%, treatment biochar only had reduced sulfate of 46.90% and reduced Pb by 58.67% and control 1.79% sulfate concentration and reduced Pb by 1.87%.

Heavy metals concentrations of traditional herbs consumed in Northwestern zone of Nigeria and associated health risks on humans

Herbal drugs have gained much popularity as alternative medicine among residents of the northern part of Nigeria, taking advantage of abundant medicinal plants in the region. This study therefore investigated the levels of some selected heavy metals (Cd, Hg, Ni, Pb and Zn) in five identified herbal drugs sold in Andaza town, Kiyawa local Government area of Jigawa State. Preparation of the samples was done using a wet digestion method with HNO3 and HCl as digestion acids and the metals were determined using an atomic absorption spectrophotometer (AAS). The health risk assessment (HRA) for adults and children was done by using the estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI) and target cancer risk (TCR). The concentrations of heavy metals on dry weight (dw) basis in this study fell within the range (mg/kg dw, mean±SD)): Cd (0.156-0.312, 0.221±0.065), Hg (8.58-16.7, 12.7±3.78), Ni (0.960-2.74, 1.67±0.698), Zn (4.26-10.1, 6.17±2.34) and Pb (0.876-1.91). Pb was not detected in two out of the five samples and therefore the mean±SD of Pb was not computed. A comparison of the results with the World Health Organisation (WHO) maximum permissible limit showed that Hg levels were far above the permissible limit in all the samples; two samples had Cd values above the maximum limit. The concentrations of Ni, Zn and Pb in all the samples were within the recommended levels of WHO. Results of HRA showed that THQ were less than 1 in the analyzed metals except for Hg with relatively high values in both adults (70 kg body weight) and children (24 kg body weight) categories and this may pose a potential health risk to consumers. Results of the percentage non-carcinogenic risk (NCR) of each metal showed that Hg contributed more than 95% to HI (the overall NCR) in each sample. TCR of Pb indicates moderate to high cancer risk whereas, that of CD showed high to very high cancer risk if the samples are consumed for a long period of time. It is therefore important that consumption of these medicines should be monitored and regulated in order for consumers to avoid future health challenges.

Pengaruh Cangkang Pomacea canaliculata L Terhadap Sifat Fisika dan Kimia Air Sungai Cisadane

The Cisadane River is a very important ecosystem for the people of the city of Tangerang. Its utilization has the potential to produce waste that can damage aquatic life so that it becomes one of the sources of the problem of decreasing water quality both physically and chemically. One of the efforts made to overcome the problem of Cisadane river water is to use water purifiers derived from natural materials so that they do not endanger health and can bind heavy metals. The purpose of this study was to determine the effect of adding snail shells to the water quality of the Cisadane river in industrial areas, urban areas and slums in terms pH value, TDS value and Pb heavy metal. The experimental procedures in this study were snail shell preparation, Cisadane river water sampling, sample analysis before application, snail shell powder application, and sample analysis after application. The results of analys show that the clarity level of Cisadane river water ranges from 19 NTU to 59 NTU, the pH value ranges from 7.2 to 7.9, the TDS value ranges from 60 mg/l to 170 mg/l and the heavy metal content is 0.0047 mg /l. The conclusion of this research is that there is an increase in the level of clarity with the addition of snail shells by 45%, there is not visible effect of the snail shells addition’s on the pH value and content of Pb heavy metal. And there is an increase in the TDS value after adding snail shells.

THE SALINITY ORIGIN OF THE SURFACE WATER IN THE WATERSHED DAM ZARDEZAS, EASTERN ALGERIA

: The deterioration of the physico-chemical quality of surface waters in the Algerian Northeast is caused by several factors. Our study aims to fill the knowledge gap on the control of hydro-chemical evolution of surface waters in wetlands. The main focus is on major elements in surface waters of the Skikda region in northeastern Algeria. To address this issue, we received 45 samples during the 09 campaigns conducted during the period of low and high water of the year 2015-2016, distributed over five points, namely the tributary Oued Khemakhem, Oued Bouadjeb, Oued Safsaf, reservoir of the Zerdazas dam and the downstream of the Zerdazas dam. First, we studied the variation of physical elements such as pH and EC. Then, using PCA and FA, we characterized the physicochemical properties of the water to demonstrate the relationship between the elements and the factors controlling the distribution of the major elements and the heavy metals Pb2+, Fe2+ and Sr2+. The specific formula of the dominance of the different concentrations in the surface waters of the study area followed the sequence: Ca-Mg-Na-K and Cl-SO4-HCO3 from which a predominant specific facies emerges on 67% of the samples, is of the chloride and sulfate-calcoMagnesian facies.

Contribution of Hair Care Products in Heavy Metals Exposure in Pakistan

Products used for hair care by humans are essential for cleaning, protection, perfuming, and beautification. These are applied directly on the skin and can be a potential factor for dermal exposure to toxic metals. The present research deals with the assessment of heavy metals in the hair care products available in the local markets of Karachi, Pakistan. A total of 20 brands of shampoo and 05 brands of conditioners were collected in triplicate and analyzed for 10 heavy metals (Fe, Mn, Cr, Ni, Cu, Co, Pb, Cd, Zn, and Hg) by atomic absorption spectrophotometer. Toxic metals were found to be higher in conditioner than in shampoo of respective color and brand. Ni and Zn concentrations have exceeded the maximum permissible limits. Consumers belonging to the lower class are more vulnerable to heavy metals exposure because of the high metal content in low-cost products. These results suggested that hair care products should also be considered as one of the sources of heavy metals exposure.

Concentrations, Dietary Intake, and Risk Assessment of Heavy Metals (Pb, Cr, and Ni) from Some Brands of Biscuits Sold in Kathmandu, Nepal

Concentrations, Dietary Intake, and Risk Assessment of Heavy Metals (Pb, Cr, and Ni) from Some Brands of Biscuits Sold in Kathmandu, Nepal

Deteksi Konsentrasi Fe, Cu, Zn dan Pb Air Sungai dan Ikan yang Tercemar Air Lindi di Bandar Lampung Dengan Menggunakan SSA

Leachate is a pollutant produced by landfills which can pollute the aquatic environment. This will have an impact on fish that live in waters contaminated with leachate and if consumed by the public it will harm health. The toxic effects of leachate are caused by the content of toxic chemicals, one of which is heavy metals. The aim of this research was to determine the concentrations of Fe, Cu, Zn and Pb in Bakung landfill leachate, Sukamaju river water and fish meat. Bakung landfill leachate samples were taken from two outlet points. The fish sampling location was carried out in the Sukamaju River. The physical factors of water measured are temperature, pH, salinity, turbidity, DO, COD and BOD. Fe, Cu, Zn and Pb concentrations were measured using the Atomic Absorption Spectrophotometry (AAS) method. The results show that the physicochemical parameters in leachate and river water exceed the threshold. The contents of Zn, Cu, Fe and Pb in the leachate at both outlet points exceeded the threshold value with values of 2.48 mg/L and 2.80 mg/L; 16.55 mg/L and 17 mg/L; 0.078 mg/L and 0.113 mg/L; 3.26 mg/L and 3.01 mg/L. The concentration of heavy metals Pb and Fe in river water is 0.083-0.162 mg/L and 2.68-2.97 mg/L which are above the quality standard value, while the heavy metal Fe content in fish meat exceeds the specified threshold value, namely 0.557 mg/100 g and 0.564 mg/100 g.

Deciphering the Environmental Code: SEM-EDX Analysis of Lead and Mercury Distribution in Enhalus Acoroides From Kayeli Bay, Indonesia

Background: Illegal gold mining activities around Kayeli Bay have led to increased heavy metal contamination that has the potential to impair water quality and growth of Enhalus acoroides, an important seaweed species. This study aimed to investigate the distribution and concentration of heavy metals Pb and Hg in Enhalus acoroides organs (roots, rhizomes, and leaves) using SEM-EDX techniques and evaluate the impact of mining activities on the surface microstructure of these organs. Methods: Enhalus acoroides samples were collected from ten sampling points in Kayeli Bay, which were selected based on potential heavy metal contamination. SEM-EDX analysis was performed to assess the surface microstructure and distribution of heavy metals in the seaweed samples. Results: Results showed significant differences in Pb and Hg concentrations among samples from different locations, with Hg content consistently higher than Pb. Surface microstructure analysis showed morphological changes in roots, rhizomes, and leaves exposed to heavy metals, indicating environmental stress in Enhalus acoroides. Conclusion: This study confirmed the negative impact of heavy metal contamination on Enhalus acoroides in Kayeli Bay due to illegal gold mining activities. High concentrations of heavy metals, especially Hg, in seaweed organs indicate potential risks to marine ecosystem health and the sustainability of fisheries resources. These findings emphasize the need for stricter environmental monitoring and management to protect this important marine habitat from heavy metal pollution.

Alleviation of heavy metals chromium, cadmium and lead and plant growth promotion in Vigna radiata L. plant using isolated Pseudomonas geniculata.

Plants exposed to heavy metals (HMs) stress negatively affect their development and production capacity. Chromium (Cr), Cadmium (Cd), and Lead (Pb) are the most common hazardous trace metals in agriculture. The physiological, biochemical, and molecular characteristics of crops are being affected. Phytoremediation is a method to alleviate heavy metals from the contaminated soil. The study aims to evaluate the phytoremediation ability of Vigna radiata L. (mung bean) in the absence and the presence of multi-metal tolerant and plant growth promoting Pseudomonas geniculata strain TIU16A3 isolated from soil of tannery industrial estate, Kolkata, West Bengal, India. The strain was further assessed with increasing concentrations of Cr, Cd, and Pb (10, 20, 40, and 80µg/mL) when the mung bean plant was a test crop. The strain significantly increased plant growth, chlorophyll content, increased level of antioxidant enzymes such as superoxide dismutase, peroxidase, and catalase, and decreased oxidative stress indicators like H2O2 and electrolyte leakage in the presence of Cr, Cd, and Pb as compared to plants grown in the absence of Pseudomonas geniculata strain. Shoot length responsive gene (Aux/IAA) in the presence of heavy metal alone and Pseudomonas geniculata treated Cd and Cr showed higher relative expression of (Aux/IAA) compared to Pb. Due to these intrinsic abilities, Pseudomonas geniculata strain TIU16A3 can be a plant growth promoter and thus can help in the remediation of heavy metal (Cr, Cd, and Pb) contaminated soil.

Prevailing parasitic diseases affecting Oreochromis aureus in Lake Burullus.

Lake Burullus is an important source of fish production in Egypt; it produces 20.5% of the Egyptian fisheries' production. There is intense controversy about the heavy metal pollution in Burullus water and its effects on fish health and safety for human consumption. Heavy metals represent a major concern for aquatic life and could negatively affect fish health. Agricultural and industrial water drainage represents a considerable part of the lake water supply. The present work was conducted to determine heavy metal concentrations in lake water and blue tilapia Oreochromis aureus musculature. Water samples were collected from six locations to determine cadmium, copper, lead, zinc and iron. Sixty O. aureus fish samples were also collected from the same sampling points to assess the prevalent parasites infesting fish and to determine the heavy metal (Cd, Cu, Pb, Zn and Fe) concentrations in fish musculature then study the relationship between heavy metals concentration and prevailing fish parasites. Results indicated that 53.34% of the examined fish were infested with encysted metacercaria. Centrocestus formosanus, Prohemistomum vivax, and Euclinostomum heterostomum were retrieved from gills, musculature, hepatopancreas and the posterior kidney. The parasitic intensity in fish tissues was between 1 and 9 cystg-1. Centrocestus formosanus was identified using the polymerase chain reaction in the gill tissues of 16 fish. The gill parasitic copepod Lamproglena monodi was identified in one fish. Degenerative changes such as thickening, corrugation, and destruction of gill filament are the most dominant pathological changes in infested fish gills. Heavy metal concentrations in water samples were at normal levels, except for copper and iron in the southern part of the lake. All heavy metals in fish musculature were below the permissible limits. The parasitic infestation was more dominant in the northern part of the lake than in the southern region; this could be due to elevated copper concentration in the southern part of the lake that could negatively affect the survival of the first intermediate host and parasite cercaria. In conclusion, captured fish from Lake Burullus were safe for human consumption, and heavy metal pollution in lake water does not represent a severe risk.

Human health and ecological risk assessment of heavy metals in topsoil of different peatland use types

Peatlands, known for their ability to retain and immobilize heavy metals due to unique waterlogged conditions and organic matter, face challenges when subjected to disturbances such as land use changes. These disruptions alter the organic matter, redox potential, and pH of the peatsoil, potentially influencing the migration, mobilization, and increased availability of stored heavy metals. Peatsoil samples from various peatland use types (improved and semi-natural grassland, forest, industrial cutaway bog) were collected to assess the human health and ecological risk associated with heavy metals (Cd, Cu, Hg, Pb, and Zn) in Co-Offaly, Ireland. Results reveal variations in heavy metal concentrations across peatland use types, with Cd, Hg, and Pb in improved and semi-natural grassland peatsoils exceeding the World Health Organization (WHO) permissible safety limits. Contamination factors (CF) were higher in improved grassland, especially for Cd and Pb, exceeding one. Hakanson potential ecological risk assessment indicates acceptable overall risk levels, though variations exist between improved grassland, unimproved grassland, forest, and industrial cutaway bog. Combined exposure routes (dermal, ingestion and inhalation routes) to all heavy metals do not exceed safe exposure levels (indicating low non-carcinogenic risks. However, the cancer risk (CR) exceeds acceptable thresholds across all use types, with higher CR in improved grassland, especially for children. Overall, the findings emphasize the need for careful consideration of heavy metal risks associated with land use changes in peatlands, particularly in the improved grassland areas.

Оценка химического состава сапропелей различных месторождений

Complex chemical composition and wide mining opportunities determine the use of sapropels and sapropel-based products in various sectors of national economy. The fullest potential of sapropel is revealed in agriculture, where it is used as fertilizer, a component of soils, raw materials for humic preparations production etc. The aim was to study the sapropels’ suitability for the production of humic fertilizers. Using validated methods we analyze chemical composition of sapropel sediments from 4 freshwater lakes located within the latitudinal section of 53–56° N in the temperate climate. Microbiological parameters of all studied samples are within the normal range. Dry matter content in the range of 46.1–51.3% corresponds to the normative indicators. The mass fraction of organic matter varies in the range of 31.8–39.9% DM. This allows classifying all samples as organo-clay, and determines the possibility of their use for soils of light granulometric composition. The relatively high content of humic (18.3–22.9% DM) and fulvic acids (3.7–6.4% DM) makes it possible to use the studied sapropel samples for the manufacture of humic preparations (especially, a sapropel sample of the lake Chervonoe, Belarus). Low P and K content (0.24–0.36% DM and 0.32–0.42% DM, respectively) can negatively affect the efficiency of fertilizers from these sapropel species; this can be avoided by mixing sapropel with manure or enrichment with mineral fertilizers. Indicators of heavy metal (Cu, Mn, Zn, Co, Pb and Cd) content in all studied samples meet the safety requirements. Samples from deeper layers of the Rusaki Lake (Altai Territory) and the Beloe Lake (Novosibirsk Region) refer to the 1st class of suitability, the rest (according to a number of indicators) – to the 2nd class. The content of trace elements in the studied sapropels is within the established norms and makes it possible to use them for replenishing the deficit of trace elements in soils. In general, all the studied samples can be used as environmentally friendly organomineral fertilizers, as well as production of humic preparations to increase in the biological and energy capacity of agrocenoses and to reproduce the soil fertility.

Groundwater Quality Assessment with Respect to Heavy Metal Content by using Heavy Metal Pollution Index (HPI) of Moradabad District, Uttar Pradesh, India

Heavy metal pollution index (HPI), is a rating method to assess the water quality and to categorize the groundwater pollution with respect to heavy metals content. The aims of the present study are to look over the current status of heavy metals pollution in and around Moradabad city. Heavy metal pollution in water has gained universal consciousness due to its tenacity, accumulation in the food chain and negative effects on ecological as well as human health. Its variation in concentration can cause deterioration of water. The study focuses on examining the content of heavy metal (Zn, Fe, Cd, Mn, Pb, Ni, Cu, and Cr) in the 30 water samples from the surrounding areas of Moradabad city. The concentrations of Cd, Mn, Fe, Cu, Pb, Zn, Ni, and Cr in water samples were recorded in the pre- and post-monsoon season of 2017. The examined samples reveal that the contamination level of heavy metal is in the following sequence Ni&gt;Fe&gt;Pb&gt;Cd&gt;Cr&gt;Cu&gt;Zn&gt;Mn in premonsoon 2017, whereas in postmonsoon season, heavy metals values are shown as Fe&gt;Pb&gt;Ni&gt;Mn&gt;Cr&gt; Cu&gt;Zn&gt;Cd. The HPI average value in pre-monsoon 2017 is 13.07, which recommended that the groundwater quality is good. While in post-monsoon season HPI average values has been 159.26 suggesting that the water quality is poor to inferior. The correlation matrix has been evaluated and shows a positive correlation with the elements. The immense production of industrial solid waste in Moradabad city and its improper disposal in the form of heap piled outside the city area generates leachate. Heavy metal leaching from these disposal points may contaminate the groundwater as well as surface water resources. The study shows that heavy metal concentration has a noticeable rise in water due to different anthropogenic and various natural sources of contamination.

Sustainable bioleaching of heavy metals from coal tailings using Bacillus inaquosorum B.4: Mechanistic insights and environmental implications

Coal tailings are byproducts of the coal washing process and pose significant environmental pollution issues due to the release of heavy metal elements. In this study, a sustainable bioleaching method was proposed, and a Bacillus inaquosorum B.4 strain with high Extracellular Polymeric Substances(EPS) production characteristics was isolated through mutagenesis. The importance of EPS in the adsorption of free heavy metals was validated, as EPS-covered (EPS-C) cells exhibited significantly higher removal rates of Cu (71.30 ± 1.10 %), Pb (79.90 ± 1.02 %), and Zn (64.90 ± 1.00 %) compared to EPS-removed (EPS-R) cells. The adsorption kinetics followed pseudo-second-order kinetics models. The significant bioleaching efficiency of this strain for heavy metals Pb, Zn, and Cu in coal tailings was investigated. Through shake flask experiments under conditions of a particle size of 45–74 μm, pH of 7, and a bacterial concentration of 15.00 %, the bioleaching rates of Pb, Zn, and Cu were found to be 91.88 mg/kg、23.21 mg/kg、8.06 mg/kg, respectively. The B.4 strain's mechanism of action was determined using techniques like SEM, XRD, FT-IR, and LA-ICP-MS. It involves absorbing organic compounds, disrupting the lattice structure of heavy metal minerals, and releasing metal ions. These metal ions are then immobilized by forming complexes with functional groups on the bacterial surface. The bioleaching process was primarily subject to a combination of chemical reaction and diffusion control. This research offers a practical bioremediation strategy to manage heavy metals in coal tailings and has important implications for environmental protection and sustainable resource utilization.

Chemical Speciation, Contamination, Human Health Risk Assessment, and Source Identification of Heavy Metals in Soils Composted with Swine Manure

ABSTRACT Heavy metal accumulation in the swine manure composting vegetable soil continues to attract attention for the reason that heavy metals are often added to animal feeds as growth promoters. The seven heavy metals (Cr, Ni, Cu, Zn, As, Cd, and Pb) concentration and chemical speciation in soil samples from 15 swine manure composting vegetable fields of Jiangxi Province were analyzed. The results showed that the average concentration of Cr, Ni Cu, Zn, As, Cd, and Pb was 48.46 ± 5.58 mg/kg, 29.06 ± 1.80 mg/kg, 48.16 ± 9.69 mg/kg, 142.32 ± 38.71 mg/kg, 10.62 ± 2.76 mg/kg, 0.13 ± 0.04 mg/kg, and 15.75 ± 2.36 mg/kg, respectively. The average concentration of Ni, Cu, Zn, and Cd was 1.12, 1.89, 1.77, and 1.17 times greater than their background values, whereas the average concentration of Cr, As, and Pb was lower than their background values. The chemical speciation analysis indicated that these heavy metals were dominated by residual fractions and have low mobility and bioavailability. The Geo-accumulation index (I geo) indicated that the soils were unpolluted with Cr, Ni, As, Cd, and Pb, while unpolluted to moderately polluted with Cu and Zn. The Nemerow comprehensive pollution index suggested that the soils were lightly polluted with heavy metals. They posed a considerable potential ecological risk to the soils. Based on the risk assessment code (RAC), these heavy metals exhibited no to medium risks. There was little non-carcinogenic risk and acceptable carcinogenic risk to humans from the heavy metals. Principal component analysis (PCA) indicated that Ni, Cu, Zn, and Cd originated from the use of a large quantity of swine manure; Pb and As mainly derived from atmospheric deposition; Cr was mainly from natural sources.

Heavy Metal Accumulation Trends for Tsunga, Tomatoes and Rape in Soils from Two Provinces of Zimbabwe

Tomatoes, tsunga (mustard) and rape were sampled from Mashonaland East and Central provinces of Zimbabwe. Aim was to assess hyper accumulative tendency of these towards heavy metals (Cd, Cu, Co, Cr, Ni, and Pb). Most of these heavy metals were noted to be of anthropogenic origin. Co, Mn and Cr were noted to be naturally inherent in Mushimbo, Mutoko soils. Heavy metal levels in irrigation water were within internationally acceptable ranges according to ATSDR. There was no direct reflection of level dependency between the water and plants studied. Bioaccumulation of cadmium and lead levels occurred in all vegetables despite low levels in the soil environment. High heavy metal levels in arable land as compared to virgin land proves contamination at play and also the anthropogenic origin. It was concluded that different vegetables accrue different heavy metals at different rates under the same environment. It was recommended to do more investigations on factors that determine absorption and hyper accumulation tendency of heavy metals in plants. This data could be used as a basis for recommending what crops to grow and in specific areas hence promote food safety in addition to food security for the nation.

Overexpression of histone demethylase gene SlJMJ18 and SlJMJ23 from tomato confers cadmium tolerance by regulating metal transport and hormone content in Arabidopsis

A lower concentration of cadmium (Cd), a hazardous and non-essential element for plant growth, will have deleterious effects on plants and endanger human health. Histone demethylase (JHDM) is important for plants' ability to withstand abiotic stress, according to an increasing number of studies. The degree of expression of the SlJMJ18 and SlJMJ23 genes in different tomato tissues was confirmed by this study. These two genes were responsive to the heavy metals Cd, Hg, Pb, and Cu stress, according to fluorescence quantification and GUS staining. Interestingly, the overexpression transgenic Arabidopsis plants of two genes have different responses to Cd stress. While SlJMJ18-OE lines consistently display Cd resistance but an early-flowering phenotype, SlJMJ23-OE plants have sensitivity during the post-germination stage and then greater tolerance to Cd stress. It was discovered that these two genes may affect cadmium tolerance of plants by regulating the expression of hormone synthesis related genes and hormone contents (BRs and ABA). Moreover, SlJMJ23 may resist cadmium stress by increasing the total phenol content in plants. The functional significance of JMJs is better understood in this study, which also offers a theoretical foundation for the use of molecular technology to develop plants resistant to Cd and an experimental basis for the efficient use of land resources.