Heavy Metals Cr Research Articles

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

Visible-light-driven Z-scheme La-MOF/BiOBr heterojunction for the efficient removal of rhodamine B and hexavalent chromium from wastewater

Addressing the formidable challenge of treating significant quantities of organic dyes and heavy metal chromium in tannery wastewater, this study synthesized a novel Z-scheme La-MOF/BiOBr composite heterojunction photocatalyst via the hydrothermal method and established an efficient visible-light photocatalytic system. To comprehensively evaluate the photocatalytic redox activity, rhodamine B (RhB) and heavy metal Cr(VI) were selected as target pollutants. Kinetic analysis revealed that the optimal LM-BB-50 catalyst achieved over 99 % degradation of RhB and Cr(VI) within 15 min illumination, indicating the remarkable enhancement of Z-scheme heterojunction in photocatalytic oxidation and reduction efficiency. Based on various photoelectric analysis techniques, it was elucidated that the superior activity of the Z-scheme heterojunction originated from the modulation of the band structure upon La-MOF and BiOBr integration, significantly improving visible light absorption, electron-hole pair separation efficiency, and endowing the energy band with robust redox capabilities. Free radical capture and quenching experiments confirmed that photogenerated holes and superoxide radicals played a crucial role in RhB oxidation, while photogenerated electrons were the primary active species for Cr(VI) reduction.

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.

Physicochemical Analysis and Pollution Indices for Heavy Metal Assessment in Flooded and Non-flooded Soils of Obunagha, Bayelsa State, Nigeria

Soil samples from flood affected areas and non-affected areas of different farmlands in Obunagha, Bayelsa State, Nigeria; were collected for this study. The study was conducted to evaluate the physicochemical properties, and pollution indices of flooded and non-flooded farmlands to see if the flood had any effect in the fertility state of these soils. Atomic absorption spectroscopy (AAS) was used to identify and quantify the several heavy metals (Cd, Cr, Ni, and Zn) that were discovered in the collected soil samples. The findings indicated increased acidity since the pH of the soil varied between 4.8 and 5.7 in farmlands that were flooded and between 4.9 and 5.7 in farmlands that were not. In flooded areas, electrical conductivity ranged from 0.2x101 to 4x101 µS/cm, while in non-flooded areas, it was between 0.2x101 and 2x101 µS/cm. The cation exchange capacity in flooded farmlands was 0.16 to 0.24 meq/100 g, while in non-flooded farmlands it was 0.18 to 0.22 meq/100 g. Variations in metal contamination were found in different farming situations based on the contamination factor (CF) analysis. Chromium CF values ranged from 0.3 to 0.8 in both flooded and non-flooded farmlands, with certain non-flooded farmlands having slightly higher values. Cadmium contamination in flooded farmlands was much higher (25.5 to 43.7 CF) than in non-flooded farmlands (20.0 to 32.0 CF). Nickel contamination levels were from 0.7 to 1.1 in flooded farmlands and 0.5 to 0.8 in non-flooded farmlands, suggesting moderate pollution. Zinc contamination was consistently low throughout all circumstances, with CF values ranging from 0.2 to 0.4. According to the contamination factor average, Cd was followed by Ni, Cr, and Zn in decreasing order. The ecological pollution degree for the study area was low indicating no possible pollution by all the heavy metals. In conclusion, the study area is significantly contaminated with cadmium. Therefore, we urgently recommend monitoring the soil in the surrounding farmlands, particularly for cadmium, to prevent a potential environmental crisis.

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>Fe>Pb>Cd>Cr>Cu>Zn>Mn in premonsoon 2017, whereas in postmonsoon season, heavy metals values are shown as Fe>Pb>Ni>Mn>Cr> Cu>Zn>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.

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.

Assessment of Heavy Metals Concentrations in River Totowu: Implication for Environmental Health and Management

Heavy metals are metallic elements that have relatively high densities, atomic weights or atomic numbers. The rapid growth of industrialization and population is a leading cause of heavy metal pollution. In the present study, water, sediment and fish from Totowu River located at Ado-odo, Otta in Ogun State were analysed for concentration of five major heavy metals (Cu, Cr, Cd, Co and Pb) using Atomic Absorption spectroscopy (AAS). 0.016-0.030 mg/L, 0.00-0.123 mg/L and 0.078-0.269 mg/L for Cu, Cr and Pb were obtained respectively for water. Sediments gave concentrations of 0.057-0.137 mg/L, 0.00-0.191 mg/L and 0.102-0.578 mg/L for Cu, Cr and Pb respectively. The result for heavy metals analysis of fish gave concentrations of 0.025-0.103 mg/L, 0.00-0.189 mg/L and 0.111-0.602 mg/L for Cu, Cr and Pb respectively. Cadmium and Cobalt were not detected in all the samples. The obtained results showed that average value of Pb were high in sequence from Fish > sediment > water in the study area and are higher than allowed permissible concentration of WHO. The result confirms that Totowu River is contaminated and could be dangerous for human health. Regular monitoring and effective clean-up are therefore recommended.

Spatial distribution, sources and human health risk assessment of dissolved heavy metals and metalloids in Yalong River, China

The adverse effects of metal(loid) accumulation on ecological health and human health have attracted widespread attention from the society, and the reduction of species diversity in the whole Yalong River basin due to dam construction. In this study, we investigated the distribution characteristics of metal(loid)s in the whole Yalong River basin from the point of view of metal(loid)s, identified the pollution sources, assessed the risk level, and further evaluated the risk to human health. A total of 9 heavy metals (Cr, Mn, Fe, Ni, Ag, Cd, Pb, Cu and Zn) and 1 metalloid (As) were investigated and surface water samples were collected from 17 sites along the Yalong River, which were categorized into industrial and agricultural production zones (YL1–5), alpine canyon zones (YL6–12), and alpine meadow zones (YL13–17) based on altitude and habitat. The results indicated that the density of metal(loid) in the alpine meadow area was considerably highest compared to other areas. The Zn content ranged from 64.42 to 84.55 μg/L, the Mn concentration ranged from 7.47 to 20.03 μg/L, and the Pb value ranged from 0.63 to 3.44 μg/L. In other places, the concentrations for Zn ranged from 17.88 to 37.78 μg/L, for Mn they ranged from 2.84 to 12.86 μg/L, and for Pb they ranged from 0.16 to 0.50 μg/L. The main sources of the metal(loid)s were determined by correlation analysis (CA) and principal component analysis (PCA) to be from natural factors such as crustal movement, atmospheric deposition, and water-rock washout. The water quality of Yalong River was evaluated by HEI, NI and WQI indices, and the results showed that the overall water quality of Yalong River was "excellent", in which the water quality of the alpine meadow area was better than that of the industrial and agricultural production area and the alpine canyon area. HQdermal, HQingestion and HI values are calculated to expose the harm caused by metal(loid) elements. The results indicate that all of the aforementioned values are below 1, suggesting that the potential harm caused by these elements is minimal. The value of HQdermal tends to be higher than HQingestion. Consequently, skin contact is likely the primary mechanism of exposure. This study provides a reference basis for metal(loid) detection and ecological changes caused by the dam construction process, and provides an important basis for the use and protection of surface water in the Yalong River.

Advancements in Starch‐Based Aerogels and Hydrogels for Treatment of Water Containing Heavy Metals – A Short Review

AbstractRapid industrialization and profligate use of resources in the present era has led to increase in the concentration of toxic heavy metal ions in water bodies and has become a serious environmental concern. Starch hydrogels and aerogels with engineered functionality, porosity, regeneration characteristics, and high surface to volume ratio have rendered them potential candidates for the adsorption of heavy metal ions from wastewater streams. However, grafting, crosslinking, and composting of the starch aerogels and hydrogels to tailor them in response to various stimuli such as ionic strength, pH, and temperature has added an advantage in the treatment of wastewater containing heavy metal ions. This review critically analyses the various synthesis routes for the production of starch‐based aerogels and hydrogels with physico‐chemical characteristics (amylose content, gelatinization temperature, surface area, density, and porosity) and their applicability to adsorb heavy metal (Cd, Cu, Co, Ni, Cr, Pb, Zn, Fe, and Co) ions from wastewater. Future prospects in the development of economical and robust starch‐based aerogels and hydrogels in terms of their stability and reusability have also been discussed.

Effect of Lead and Chromium on the Toxicity of Glyphosate Herbicides to African Catfish Clarias Gariepinus (Burchell 1822)

There is a growing increase in pollution of the aquatic ecosystems with a wide range of chemicals including herbicides and heavy metals input through anthropogenic activities, leading to disruption of ecological balance. This study used a static toxicity bioassay to examine the interaction between heavy metals (Pb and Cr) and organophosphorus herbicides (analytical grade glyphosate, commercially formulated - Roundup and Forceup) on African catfish (Clarias gariepinus BURCHELL 1822). Lethal concentrations (LC50) for roundup (RU), forceup (FU), analytical grade glyphosate (AGG), chromium (Cr), and lead (Pb) were 17.23 mg/l, 4877 mg/l, 131.12 mg/l, 21.16 mg/l, and 74.82 mg/l respectively. In addition, fish exposed to varying concentration of chromium (5.0 mg/l and 7.5 mg/l) and lead (20 mg/l and 25 mg/l) with glyphosate (RU: 10 mg/l; FU: 4300 mg/l; and AGG: 100 mg/l) for 96 hours were examined for biochemical parameters. Blood plasma examined for liver and kidney profile indices showed that kidney functions’ parameters (protein, albumin, AST-aspartate aminotransferase, ALT-alanine aminotransferase and Bilirubin) and liver functions parameters (urea and creatinine) increased significantly (p<0.05) when glyphosates combined with lead and chromium treated groups compared with the control group. This study therefore, showed that low concentrations of combined toxicants of glyphosates and heavy metals (Cr and Pb) will synergistically induce deleterious effects on the liver and kidney of Clarias gariepinus.

Composition of heavy metals in sediment, water, and fish of the Ganga and Yamuna Rivers in two major cities of India.

The rapid industrial development in the Indian capital region has led to significant waste generation, which, despite undergoing treatment prior to disposal, contributes substantially to water body contamination. Given the diverse nature of these wastes and their potential repercussions across the food chain, a study was conducted to evaluate heavy metal contamination levels in the Ganga and Yamuna Rivers of two major cities. Six heavy metals (Pb, Cd, Hg, Cu, Cr, and Zn) were analyzed in fish, water, and sediment samples by utilizing flame atomic absorption spectrophotometry (Avanta Σ) from March 2019 to February 2020. Results revealed distinct heavy metal distribution patterns, with Cr > Zn > Pb > Cu > Cd > Hg in the Ganga River and Zn > Cr > Pb > Cu > Cd > Hg in the Yamuna River for fish samples. Additionally, levels of Hg in Cyprinus carpio and Sperata oar from the Ganga River, and Pb, Cd, Hg, and Cr in Salmophasia bacaila and Mystus cavasius from the Yamuna River exceeded WHO/FAO permissible limits. In water samples, the predominant heavy metal sequences were Pb > Cu > Zn > Cr > Cd > Hg for the Ganga River and Cr > Zn > Pb > Cu > Cd > Hg for the Yamuna River, with Pb, Cr, Zn, and Cd surpassing WHO standards. Sediment analysis revealed varying heavy metal compositions, with Zn > Cr > Pb > Cu > Cd > Hg in the Ganga River and Cr > Zn > Pb > Cu > Cd > Hg in the Yamuna River. While drinking water and fish from the Ganga River were deemed safe for consumption, those from the Yamuna River were not. Given the toxic nature of heavy metals and their detrimental health impacts, regular monitoring and effective management strategies are imperative.

Phytoremediation mechanism and role of plant growth promoting rhizobacteria in weed plants for eco-restoration of hazardous industrial waste polluted site: a review.

Plants have numerous strategies for phytoremediation depending upon the characteristic of pollutants. Plant growth promoting rhizobacteria (PGPR) are essential to the process of phytoremediation and play a key part in it. The mechanism of PGPR for phytoremediation is mediated by two methods; under the direct method there is phytohormone production, nitrogen fixation, nutrient mineral solubilization, and siderophore production while the indirect method includes quorum quenching, antibiosis, production of lytic enzyme, biofilm formation, and hydrogen cyanide production. Due to their economic and environmental viability, most researchers have recently concentrated on the potential of weed plants for phytoremediation. Although weed plants are considered unwanted and noxious, they have a high growth rate and adaptability which opens a high scope for its role in phytoremediation of contaminated site. The interaction of plant with rhizobacteria starts from root exudates containing various organic acids and peptides which act as nutrients essential for colonization and siderophore production by the rhizospheric bacteria. The rhizobacteria, while colonizing, tend to promote plant growth and health either directly by providing phytohormones and minerals or indirectly by suppressing growth of possible phytopathogens. Recently, several weed plants have been reported for phytoextraction of heavy metals (Ni, Pb, Zn, Hg, Cd, Cu, As, Fe, and Cr) contaminants from various agro-based industries. These potential native weed plants have high prospect of eco-restoration of polluted site with complex organo-metallic waste for sustainable development.

Porphyrin nanoparticles-based portable smartphone platform for visual monitoring heavy metal Cr (Ⅲ) in the environment

Chromium ions exist in various valence states in the environment, and their pollution poses serious harm to social ecology and human health. The existing detection is mostly focused on Cr6+, while the detection related to Cr3+ is often overlooked. Cr3+ has a certain impact on soil, water, and the growth of animals and plants and even disrupts ecological balance. Accordingly, it is necessary to explore sensitive, convenient, and fast detection devices for Cr3+ in the environment. Here, we have designed a ratio fluorescence probe with porphyrin nanoparticles formed by block copolymers as the sensing core for ultra sensitive detection of Cr3+. The porphyrin nanoparticles can effectively bind with Cr3+ to form metal complexes, leading to ligand metal charge transfer (LMCT), which will result in a significant color change of the probe from red to blue. Furthermore, we have developed two portable fluorescence sensors for Cr3+ in soil and water, respectively. These portable sensing platforms based on designed nanoprobes and smartphones can convert the color information of fluorescent photos into digital information for real-time analysis. Thus, the method reported in this article can provide a possibility for rapid on-site and visual inspection of Cr3+ in soil and water from different regions.

Source Apportionment and Health Risk Assessment of Heavy Metals in Dust Around Bus Stops in Kaifeng City Based on APCS-MLR Model

In order to reveal the influence of urban transportation systems on the quality of urban ecological environment, this study selected surface dust from bus stops, which is strongly disturbed by transportation, as the research object. The contents of eight heavy metals (V, Cr, Co, Ni, Cu, Zn, Cd, and Pb) in the dust were determined through inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectroscopy (ICP-ASE). The spatial distribution characteristics and pollution levels of the eight heavy metals in the dust were analyzed using the geo-accumulation index method. A combined qualitative (correlation analysis and principal component analysis) and quantitative (absolute principal component scores-multiple linear regression model (APCS-MLR)) method was used to explore the sources of heavy metals in surface dust near bus stops. The spatial distribution characteristics of heavy metals from different sources were elucidated using the Kriging interpolation method. The health risk assessment model proposed by the United States Environmental Protection Agency was used to evaluate the human health risks. The results showed that the average values of ω(V), ω(Cr), ω(Co), ω(Ni), ω(Cu), ω(Zn), ω(Cd), ω(Pb), and ω(As) in the bus stop surface dust were 68.36, 59.73, 5.81, 19.34, 40.10, 208.32, 1.01, and 49.46 mg·kg-1, respectively. The concentrations of heavy metals (Cd, Zn, Pb, Cu, and Cr) in the dust were all higher than the background values in the surrounding dust, exceeding them by 3.37, 2.70, 2.01, 1.95, and 1.28 times, respectively. The order of the geo-accumulation index for the eight heavy metals was Cd > Zn > Pb > Cu > Cr > V > Ni > Co, with Cd, Zn, Cu, and Pb in the dust indicating mild pollution levels and the others showing no pollution. The source analysis results showed that Cr, Co, and Ni were natural sources, whereas Cu, Zn, Pb, and Cd were traffic sources, and V was derived from a combination of industrial and natural sources. The APCS-MLR results indicated that the average contribution rates of the four sources were as follows:natural source (34.17 %), traffic source (29.84 %), industrial-natural mixed source (14.64 %), and unknown source (21.35 %). The spatial distribution map of the contribution rate of the traffic source was consistent with the trends of traffic volume and bus route density distribution. According to the health risk assessment, the cancer risk and non-cancer risk for children were both higher than those for adults. Cr was the main non-cancer factor, and Cd was the main cancer-causing factor. Natural and traffic sources contributed the most to non-cancer risk and cancer risk, respectively.

Removal of trivalent chromium ions in model contaminated groundwater using hexagonal boron nitride as an adsorbent

The feasibility of using hexagonal boron nitride (h-BN) to treat heavy metal Cr(III) from model contaminated groundwater was evaluated in this study by adsorption experiments and characterizations. To the best of our knowledge, this study is the first attempt to conduct the adsorption of Cr(III) by h-BN under various experimental conditions such as exposure time, ratio of adsorbates and adsorbents, solution pH, background ions with different ionic strength, and the presence of humic acids (HA) in model contaminated groundwater. The optimized h-BN showed excellent maximum adsorption capacity (i.e., 177 mg ∙ g−1) when the concentrations of Cr(III) and h-BN were 10 and 10 mg ∙ L−1, respectively. Subsequently, we confirmed there was a negligible change in the adsorption performance of Cr(III) by h-BN in the presence of co-ions (i.e., K and Mg) in concentrations in a range from 50 to 1000 mg ∙ L−1. Furthermore, the adsorption performance of Cr(III) gradually improved with HA concentrations from 2.5 to 25 mg ∙ L−1. Interestingly, the maximum adsorption performance of Cr(III) by both HA and h-BN increased until 500 mg ∙ g−1 in the presence of 25 mg ∙ L−1 HA. The adsorption mechanism was clarified by Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. Additionally, we successfully confirmed that h-BN could be reused until five cycles. On the basis of the adsorption performance results and characterizations, h-BN can be utilized as an efficient and practical adsorbent to treat Cr(III) in groundwater treatment.

Influence of vegetation on heavy metal Cr release process from bottom sediment under unidirectional flows and regular waves

As human activities become more intensive, a substantial number of heavy metals are discharged into estuarine or wetland environments. Due to the poor degradability, heavy metals are prone to adsorption and deposition on suspended particles in bottom sediments. Subsequently, under the influence of disturbances, there is a potential for their re-release, causing secondary pollution. To investigate the release process of the heavy metal Cr from sediment, laboratory experiments were conducted under both unidirectional flow and regular wave conditions. At the initial stage, the temporal trends of particulate (CrP) and dissolved (CrD) Chromium concentrations were both characterized by initial increments followed by stabilization and continuous escalation. Vertically, the stable concentrations of CrP and CrD increased with the presence of vegetation and the enhancement of hydrodynamics. The Elovich equation, pseudo-second-order kinetic equation, Double constant equation (Freundlich model), and parabolic diffusion equation were employed to predict the release process of CrD from bottom sediment. The Elovich equation proved most suitable for describing the release process of CrD, with an R2 exceeding 0.9. In order to assess the influence of vegetation on the Cr release process, the Stem-Reynolds were introduced to modify the Elovich equation. The final maximum error was 12 % (excluding the initial stage), which was much lower than that using the original Elovich equation (maximum error of 32 %). The study findings provide practical support for estuarine and wetland managers to formulate effective heavy metal management measures, which contribute to the conservation and sustainable management of aquatic ecosystems.

Estimation of heavy metals in sediments and aquatic plant species in two rivers of Punjab, Pakistan

This research highlights the distribution of heavy metals (Ni, Cu, Zn, Cr, Co and Mn) in Ravi and Chenab and assesses their effect on ecosystem health. Samples of plant species and sediments at eight sampling sites were collected and analysed by the PIXE technique. Heavy metal concentrations (µg/g) of Zn (7.98–411.23), Ni (12.59–209), Cu (3.74–38.77) and Mn (0–730.21) in river Ravi and concentrations of Zn (49.32–274.30), Ni (1.05–141.21) and Mn (41.66–519.47) in river Chenab were found to be high but Heavy metal concentration in the two compartments were in the following order plants > sediments. Heavy metals of sediments and plants depict that there are significant correlations between Cu (0.994), Zn (0.986) and Cr (0.978) in river Ravi and Ni (1.000), Zn (.990) and Cr (.978) in river Chenab. The results show the potential of heavy metals from plants in two rivers of Pakistan.

Pollution assessment and index properties of Okpulor soils, Rivers State, Nigeria: geochemical characterization, geotechnical and geoenvironmental implications

This study assessed soil pollution and index properties in Okpulor through geochemical, geotechnical, and geoenvironmental analyses. Twenty samples, comprising 14 surface and 6 shallow subsurface ones, underwent geochemical analysis for heavy metals (Fe, Cr, Cu, Zn, Ni, and Pb). Five geochemical indices, including the Geoaccumulation Index (Igeo), Enrichment Factor (EF), Contamination Factor (CF), Metal Pollution Index (MPI), and Potential Ecological Risk Index (PERI), were utilized. Simultaneously, six subsurface samples underwent geotechnical analysis for Natural Moisture, Grain Size, Specific Gravity, Bulk Density, and Atterberg Limits, following Unified Soil Classification System (USCS) and American Association of State Highway and Transportation Officials (AASHTO) guidelines. The Igeo highlighted significant heavy metal contamination in Okpulor soils, particularly Cd. EF values exceeding 1.5 underscored a strong anthropogenic influence, with CF indicating Cd's substantial contribution to overall contamination. PERI underscored the ecological risks associated with Cd contamination. Natural moisture content, ranging from 18.21% to 21.45%, indicated a notable presence of water in the soil during the dry season, potentially leading to increased leaching and migration of water-soluble contaminants. Bulk density values suggested moderate to lightly packed soils, impacting porosity and permeability, and influencing contaminant movement. Atterberg limits indicated low soil plasticity, impacting moisture retention and contaminant behaviour. Grain size analysis revealed poorly graded soils with a close sand-to-clay ratio, affecting water drainage. These geotechnical properties and heavy metal contamination reveal the intricate interplay between soil characteristics and contamination risks in the Okpulor area, emphasizing the need for targeted interventions to safeguard the environment.

Assessment of metals and metalloids agglutinated to airborne suspended particulate matter in selected plant species during the pre-and post-monsoon in the urban area

The elemental accumulation has emerged as a major environmental concern due to various anthropogenic sources such as vehicles, road dust, and industrial activities, contributing to the agglutination of elements to airborne Suspended Particulate Matter (SPM). SPM-bound elements accumulate on plant surfaces impact air quality and human health due to their noxiousness. Therefore, plants' ability to capture and mitigate air pollutants plays a crucial role in urban areas. This study aimed to investigate the levels and distribution of twenty-six elements, comprised of heavy metals (Cd, Pb, Cr, Cu Zn, Co, Ni, Fe, Mn, Ag, Mo, V, Ga, and Bi), light metals (B, As, Te, and Se), and metalloids (Al, Li, Sr, K, Mg, Na, Ca, and Ba) accumulated on the surface and inside the leaves of dominant plant species during the pre-and post-monsoon at six categorized (commercial, traffic-prone, residential, educational, greenbelt and industrial areas) locations in Delhi, India. In addition, the Metal Accumulation Index (MAI) was determined, and the statistical analysis was conducted using two-way ANOVA, Principal Component Analysis (PCA), and Hierarchical Cluster Analysis (HCA). In the pre-and post-monsoon, two-way ANOVA revealed significant differences (P < 0.05) in metal concentrations. During the pre-monsoon plants exhibited the highest metal accumulation (∼21%) at the Anand Vihar (commercial) in Delhi, with the maximum average concentrations of Cr (118.25 mg/kg), Cu (204.38 mg/kg), Zn (293.27 mg/kg), and Fe (2721.17 mg/kg). Ficus benghalensis L exhibited the maximum 213.73 MAI at the Anand Vihar in the pre-monsoon. Ni and Cr indicated the highest correlation (P < 0.05, r = 0.82) in the PCA test. HCA test revealed similarity (∼87.7%) at ITO (traffic-prone) and Okhla Phase-2 (industrial) in F. religiosa regarding metal concentration patterns. Findings highlighted seasonal elemental pollutants uptake dynamics of plant species and explored species-specific metal accumulation, revealing potential implications of metal-tolerant plants for urban greenbelt.