Heavy Metal Pollution Research Articles

Heavy metal characteristics and ecological threat assessment in water and sediments of Eniong Creek, Niger Delta, Nigeria

Heavy metal characteristics and ecological threat assessment in water and sediments of Eniong Creek, Nigeria was studied between August 2022 and January 2023 in 3 stations. Seven heavy metals were analyzed with standard methods and compared with quality Standard. Ecological threat was assessed in water using two metal pollution indices while six sediment quality assessment indices were used to access the sediment quality. Results showed that the mean concentrations of nickel, copper, cadmium and zinc in water sample exceeded the permissible limits set by National environmental (surface and groundwater) quality regulations for aquatic life, while copper and cadmium exceeded the permissible limits set by Canadian sediment standards quality for the protection of aquatic life in sediments in all the stations. The heavy metal pollution index (HPI) values exceeded the threshold (100) across the stations, ranging between 469.53 and 686.74 while comprehensive pollution index (CPI) ranged between 1.405 and 1.854, indicating moderate contaminated water. The sediment indices indicated that cadmium and copper were the major metallic pollutants. The indices indicated the following –contamination factor: copper (moderate) and cadmium (very high), degree of contamination (very high); ecological risk: cadmium and copper (high) while lead and zinc were moderate; potential ecological risk (high); quantification of contamination: cadmium and copper (anthropogenic); geo-accumulation index: cadmium (very highly polluted). The study revealed that the water body and sediments were polluted, attributed to anthropogenic activities.Keywords: Eniong Creek; Heavy Metals, Nigeria; Sediment; Water

Are Microplastics Always Toxic? --Certain Concentrations of Polystyrene Are Promoters of Marine Algae Growth and Heavy Metal Bioremediation

The influence of microplastics on the bioremediation capabilities of algae in aquatic environments is an area of growing concern, particularly when these tiny plastic particles interact with heavy metals like cadmium (Cd). Such interactions could alter the algae's natural ability to detoxify and purify water, posing significant challenges to maintaining the health and stability of aquatic ecosystems. This study investigated the effects of different types (including Polystyrene (PS), Polyvinyl Chloride (PVC), and Polyethylene Terephthalate (PET)) and concentrations (1-100 mg/L) of microplastics on the ability of algae to absorb Cd, focusing on whether the simultaneous presence of microplastics and heavy metals can affect both algal growth and heavy metal bio-uptake. The study results indicated that Cd or different types of microplastics individually inhibit algal growth. However, when algae are co-exposed to Cd and microplastics, a PS concentration of 1 mg/L combined with Cd significantly promotes algal growth, demonstrating an antagonistic effect, whereas the other two types of microplastics exhibit a synergistic effect with Cd. Additionally, regardless of exposure duration, when PS is present at 1 mg/L, it enhances the bio-uptake of Cd in algae compared to treatments with Cd alone. Among the various types and concentrations of microplastics studied, the combination of 1 mg/L PS and Cd was found to not only promote algal growth in aquatic environments but also enhance heavy metal bio-uptake, thereby mitigating heavy metal pollution. Consequently, the presence of microplastics at certain concentrations (such as 1 mg/L PS) may not necessarily be considered "pollutants" in aquatic environments. These findings provide a new perspective for re-evaluating the role of microplastics in aquatic ecosystems and suggest a strategy for leveraging microplastics to enhance algal bioremediation of heavy metals.

A comprehensive study on native plant species for phytoremediation of heavy metals contamination in soil

Phytoremediation refers to the use of plants to remove or stabilize environmental contaminants in an environment. It is regarded as a highly effective and inexpensive method in countering heavy metal pollution. This paper examines the feasibility of using native plants in phytoremediation through the demonstration of their sensitivity, survivability, and tolerance towards the local environmental condition and their capability to accumulate and tolerate contaminants such as lead, cadmium, and arsenic. Native species have various advantages that include lesser upkeep requirements, improved ecosystem incorporation, and least invasive danger. The mechanisms involved in phytoremediation range from phytoextraction, Phyto stabilization, and rhizofiltration to the specific roles played by native plants in remediation processes of soil and water. Case studies are presented to demonstrate the successful use of native species at various contaminated sites. Challenges related to scalability and ecological risks are addressed. Emerging trends, including biochar amendments, genetic modification, and expanded applications into urban areas, suggest promising future directions.

Heavy metals concentration and human health risk assessment in selected shrimp species of Pakistan

ABSTRACT Heavy metal pollution in marine organisms poses a significant threat to both ecosystems and human health. Dumping untreated sewage into the sea pollutes coastal waters with toxic metals. This study examined the levels of chromium (Cr), lead (Pb), nickel (Ni), mercury (Hg), arsenic (As) and copper (Cu) in three shrimp species of genus Penaeus i.e. Penaeus merguiensis, Penaeus monodon, and Penaeus indicus. The findings revealed that the average levels of arsenic, lead, and mercury were considerably higher than the legislative limits. Furthermore, chromium and lead levels remained consistent across shrimp species, while other metals exhibited significant variation. Additionally, THQ and HI values were below the limit of 1, indicating low health risks from consuming shrimp species from this area. However, sustained monitoring and research are essential to protect consumer health and ensure long-term sustainability of seafood resources.

Metal Content of the Yellowtail Fish (Caesio cuning) Consumed by the Community in Boedingi, North Konawe, Indonesia: An Environmental Health Risk Assessment in the Mining Area

The rapid development of mining activities, the shipping industry, and public transportation across the land and water areas of Boedingi Village can have both positive and negative impacts on the water quality of this area. This study aimed to determine the heavy metal content in yellowtail fish (Caesio cuning), a type of fish that is generally consumed by Boedingi villagers in North Konawe, Indonesia. A descriptive method with an environmental health risk assessment (EHRA) was employed to measure metal profiles (Pb, Cd, and Hg). The results showed that the metal levels in the water exceeded the thresholds, indicating significant heavy metal pollution. In addition, the Cd levels of the fish surpassed the food safety standard according to the USA Food and Drug Administration (FDA). Since Indonesia began its large-scale shift from conventional to electrical transportation, global and government collaboration have become critical in managing the environmental and health impacts of the related industries. This is especially important because this area is one of the largest nickel producers (the raw material of electrical transportation) both nationally and globally.

Analysis of Trace Heavy Metal in Solution Using Liquid Cathode Glow Discharge Spectroscopy.

Heavy metal pollution, particularly from cadmium (Cd) and copper (Cu), poses significant environmental and health risks. To address the need for efficient, portable, and sensitive detection methods, this study introduces an improved atmospheric pressure glow discharge atomic emission spectrometry (APGD-AES) technique for quantifying Cd and Cu in water samples. The APGD-AES method offers key advantages, including low energy consumption (<33 W), high excitation energy, and compact design. The system was optimized for a discharge voltage of 550 V (Cd) and 570 V (Cu), a flow rate of 3.6 mL/min, and a solution pH of 1.0. Under these conditions, detection limits reached 16 µg/L for Cd and 1.3 µg/L for Cu. APGD-AES was tested on real water samples, including sewage and tap water, demonstrating compliance with national safety standards and comparable performance to graphite furnace atomic absorption spectrometry (GFAAS). This technique shows promise for real-time, on-site monitoring of trace heavy metals due to its portability, precision, and cost-efficiency.

Uncovering the Relationship Between Soil Bacterial Community and Heavy Metals in a Copper Waste Pile

In the present study, the relationship between the microbial community and heavy metal content of soil was analyzed based on 16S rRNA gene high-throughput sequencing, in order to screen the corresponding heavy metal-resistant bacteria in a copper mine waste dump and adjacent shrubbery. Approximately 22 phyla, 57 classes, 128 orders, 173 families, 263 genera, 433 species, and 954 OUTs obtained from soil sample species annotation indicated the Spearman relevance analysis at the phylum level. Specifically, Gemmatimonadota is positively correlated with arsenic (As); Patescibacteria is positively correlated with arsenic (As), copper (Cu), and cadmium (Cd); Proteobacteria is positively correlated with chromium (Cr); and Acidobacteriota is positively correlated with cadmium (Cd), respectively. Meanwhile, at the genus level, Acidibacter is positively correlated with arsenic (As); norank_f__LWQ8, norank_f__Gemmataceae, and Bryobacter are positively correlated with cadmium (Cd); Acidiphilium and Conexiactor are positively correlated with Zinc (Zn); norank_f__norank_o__IMCC26256 is positively correlated with nickel (Ni); norank_f__norank_o__norank_c__AD3 is positively correlated with manganese (Mn), and nickel (Ni); and Alicyclobacillus and unclassified_f__Acidiferobactereae are positively correlated with chromium (Cr). These bacterial flora are significantly and positively related to the resistance of heavy metals, which provides a promising reference for the development of in situ remediation of heavy metal pollution in mines.

A Comprehensive Study of Heavy Metals in Centralized Drinking Water Sources of the Yangtze River Basin: Levels, Sources, and Probabilistic Health Risk

The water quality of centralized drinking water sources (CDWSs) in the Yangtze River Basin (YRB) has received widespread public attention. Regrettably, due to the lack of large-scale and high-frequency monitoring data, the trends, sources, and risks of heavy metals (HMs) in the water of CDWSs in the YRB are still unclear. In addition, the correlation between HMs and water quality parameters in natural water has not been established, which greatly affects the efficiency of water management. Herein, we collected data for eight HMs and twelve water quality physical–chemical parameters from 114 CDWSs in 71 prefecture-level cities in the YRB region. An unprecedented spatial distribution map of HMs in the YRB region was drawn, and the response of HMs to water quality and nutrient levels was studied. Overall, the level of HM pollution was low, but the threat of chloride, nitrogen, and phosphorus still exists. The detection rates of the eight HMs ranged from 60.00% (Ti) to 99.82% (Fe), and the mean concentrations were ranked as follows: Fe (36.576 ± 36.784 μg/L) &gt; Mn (7.362 ± 7.347 μg/L) &gt; Ti (3.832 ± 6.344 μg/L) &gt; Co (2.283 ± 3.423 μg/L) &gt; Se (0.247 ± 0.116 μg/L) &gt; Cd (0.089 ± 0.286 μg/L) &gt; Be (0.054 ± 0.067 μg/L) &gt; Tl (0.015 ± 0.012 μg/L). In the large geographic area, the total concentrations of the eight HMs exhibited a fluctuating decay trend over time from 2018 to 2022. Geographically, industrial and agricultural production and geological coupling factors led to significant spatial heterogeneity in HM concentrations in the following order: midstream &gt; downstream &gt; upstream. Importantly, this study proved that Cl−, SO42−, nitrogen, and phosphorus may drive the absorption and transfer of HMs in natural water. Fortunately, exposure to the eight HMs does not cause adverse health effects in humans.

Novel Genomic Regions and Gene Models Controlling Copper and Cadmium Stress Tolerance in Wheat Seedlings

Heavy metal pollution is a global issue that affects plant growth and human health. Copper and cadmium are two significant heavy metals that have become more concentrated in many soils. These metals are taken up by many plants, including wheat, and can cause various diseases in humans. The most effective way to mitigate the harmful effects of heavy metals is to grow tolerant wheat genotypes. In the current study, two different pot experiments were conducted to understand the genetic control of copper and cadmium tolerance in wheat seedlings. Two populations were used in this study, consisting of 92 genotypes for the copper experiment and 73 genotypes for the cadmium experiment. In both experiments, a replicated complete block design with three replications was used. Highly significant differences were found between the tested genotypes for all studied traits in both metals, except for root weight and the ratio between shoot weight and root weight under cadmium contamination. Single-marker analysis was performed for all significant traits, and a total of 265 and 381 markers were found to be significantly associated with seedling traits under copper and cadmium conditions, respectively. Of these markers, only eight were commonly associated with the tolerance to both metals. These markers were located within five different gene models that were functionally annotated to control heavy metal tolerance. Gene enrichment of the five identified genes revealed two key genes that significantly influenced eight biological processes, six molecular functions, and three Kyoto Ecyclopedia of Genes and Genomes (KEGG) pathways involved in heavy metal tolerance. The sources of the eight markers and their associated genes were identified in twelve genotypes, including one Egyptian and one Kazakhstani genotype, which showed superior responses to copper and cadmium, respectively. These genes and the genotypes carrying them are crucial for future breeding programs aimed at enhancing heavy metal tolerance in wheat.

Considering the bioavailability and bioaccessibility of heavy metals for risk assessment of street dust by typical transportation cities in China

Heavy metals (HMs) pollution from dust was prevalent in cities worldwide. In order to quantify the risk-releasing capacity of HMs to the environment and human body, 54 road dust samples from Zhengzhou were selected for this study to analyze 9 different HMs among them. The risk-releasing capacity of HMs in the environment was determined using the sequential extraction method developed by the European Community Bureau of Reference, and the risk-releasing capacity of HMs in the human body was assessed using the bioaccessibility method. The results showed that elements such as Zn, Cd and Pb were significantly enriched, and Cd was the priority control pollutant. The positive matrix factorization results indicated that industrial activities (28.5%), oil combustion (20.7%), transportation activities (31.6%) and natural sources (19.2%) were the main sources of HMs in dust. The percentage of different speciation of HMs was determined, which showed that Cd had the strongest risk-releasing capacity in the environment. Cu, Zn, Cd, and Pb were highly bioaccessible in the gastrointestinal tract. The bioaccessibility of HMs in artificial lysosomal fluid solution was two orders of magnitude higher than that in Gamble’s solution. When considering the bioaccessibility of HMs, the non-carcinogenic and carcinogenic risk indices were significantly lower. This study provides new insights into the determination of the risk-releasing capacity of HMs.

Effect of heavy metals contamination due to leachate migration from uncontrolled dumpsites: A comprehensive analysis on soil and groundwater

In the contemporary era, the widespread practice of open dumping persists as a major method for municipal solid waste (MSW) disposal, contributing significantly to global environmental degradation and posing severe health risks. Deficient waste management systems result in over 90% of waste being openly discarded or burned at numerous unregulated dumpsites, particularly in developing nations like India. This research focuses on the active waste dumping site, Bhandewadi Dumpsite in Nagpur, Maharashtra, India, aiming to assess soil and groundwater contamination caused by the release of toxic elements into the surrounding region. Various parameters, such as the index of geoaccumulation, contamination factor, potential ecological risk, heavy metal pollution index, and water metal index were employed to evaluate the impact of the dumpsite. Results indicated heavy contamination in soil and groundwater samples, particularly from Bidgoan Road and Pardi, with elevated levels of metals, such as Cr, Ni, and Pb within 2 km radius of Bhandewadi dumpsite, Nagpur (India). The principal component analysis confirmed these locations as highly polluted, emphasizing the influence of leachate migration from the uncontrolled dumpsite. The findings underscore the urgent need to improve waste management strategies at municipal landfills and highlight the importance of policy measures to control environmental pollution and the introduction of scientific methods to curb the migration of metals into the environment.

Contamination characteristics of heavy metals and enrichment capacity of native plants in soils around typical coal mining areas in Gansu, China

Exploitation of mineral resources is a vital backbone of a country’s socio-economic development. However, the coal exploration would cause ecological and environmental problems such as pollutions of water, soils and atmosphere. Especially, the pollution of heavy metals of soil has become increasingly severity. Plant enrichment and tolerance to heavy metals are crucial for the phytoremediation of coal gangue mountain. In phytoremediation, phytostabilization which can reduce the metal contamination of soil by uptake and burn-off of heavy metals with highly accumulating plants, is one of the most effective techniques of eco-remediation treatment. In present work, heavy metals contamination of soil and plants in the Yaojie mining which located in arid and semi-arid area of northwest China were investigated through field investigation. To identify the suitable plants for the remediation and ecological reclamation of heavy metal contaminated soil in typical mining area, the contamination characteristics of heavy metals in the above-ground parts of 27 native plants and their surrounding non-rhizosphere soils were analyzed. After eliminated by wet digestion and high-pressure closed digestion, the mass fractions of Zinc (Zn), cadmium (Cd), chromium (Cr) and copper (Cu) were determined with inductively coupled plasma emission spectrometer, and the contents of Hydrargyrum (Hg) and Arsenic (As) were analyzed with atomic fluorescence spectrophotometer. The Nemerow pollution index showed that in the surrounding soil, the pollution index of heavy metal was 6.32, which reached the extreme severe pollution level. Among the 6 heavy metals, the most severe contamination being Hg (Pi = 8.50) and had particularly strong Coefficient of variation (CV = 105.8%), which is more likely to be caused by anthropogenic activities. In the aboveground parts of 27 plants, except for Zn, other metals exceeded the standard level, and the exceedance rates in descending order were As, Hg, Cr, Cd, and Cu. The most severe exceedance of As was found in C. virgata, which was as high as 19.20, and the average exceedance rate of As in all plants was 2.79. Bioconcentration Factor (BCF) was utilized as an indicator of the enrichments of various metals in 27 plants. The maximum value of BCF for As and Hg in C. virgata were 1.52 and 2.50, Cr and Cu in X. sibiricum were 0.72 and 2.32, Cd and Zn in S. glauca were 3.33 and 1.82. As revealed, except Cr, all the BCF of other metals are greater than 1, indicating that the three plants exhibited a strong accumulation capacity of heavy metal and are potential candidate pioneer species for the removal of heavy metals from the contaminated soil in the Yaojie mining area. This study provides a basis for plant selection for ecological restoration of contaminated soils in arid and semi-arid regions.

Mapping of heavy metal pollution density and source distribution of campus soil using geographical information system

In this study, the pollution intensity, spatial distribution, and index-based risk distribution in campuses, which are a small prototype of cities, were mapped and the sources of heavy metals in the soil were investigated. Soil samples were taken from 9 different points from the Aksaray University Central campus, which was determined as the study area. It has been determined that the pH value in the collected soil samples varies between 8.7 and 11.0. This situation created an effect on reducing the accumulation and mobility of heavy metals in the soil. When the study area was evaluated based on the geo-accumulation index, Pb heavy metal was much denser in the places indicated as circulation areas and where students were actively present. Based on the pollution load index, it was concluded that 75% of the study area was moderately/highly polluted, and the rest consisted of unpolluted soils. Pearson correlation analysis and APCS-MLR analyses conducted to determine the source distribution showed that the contributions of natural sources, mixed sources of industrial and traffic activities, agricultural activity-based sources, and other sources were 57.49%, 21.44%, 12.67%, and 8.40%, respectively. Pb is mainly related to the mixed sources of industrial and traffic activities. Therefore, to clear up its long-term impact on the accumulation of heavy metals in the soil, it is important to conduct continuous heavy metal monitoring in the soil throughout the campus.

Elemental composition and health risks of indoor PM2.5 in Taiyuan, China: Associations with fractional exhaled nitric oxide (FeNO) in preschoolers

The adverse health effects of indoor PM2.5 are considerably influenced by its elemental composition. Here, we evaluated indoor PM2.5 elements in preschools in Taiyuan, China, and assessed the lifetime carcinogenic and non-carcinogenic risks of 11 selected elements in children. Additionally, we assessed the association between these elements and fractional exhaled nitric oxide (FeNO), a non-invasive biomarker of respiratory symptoms. We randomly selected 10 preschools in Taiyuan and measured FeNO levels in 507 5-year-old children. Elemental analysis of the PM2.5 samples was conducted using inductively coupled plasma-mass spectrometry. Associations between PM2.5-bound elements and FeNO were calculated using linear mixed models. Health risk assessments revealed that Cr and Mn have hazard quotient > 1, indicating they pose a non-carcinogenic risk in the study area. Meanwhile, Cr, Ni, As, Cd, and Co presented carcinogenic health risks with Ri > 10−6. The risks of other toxic heavy metals were within acceptable limits. The indoor levels of most elements in PM2.5 correlated with elevated FeNO levels. This study provides novel insights into the associations between PM2.5-bound elements in classrooms and FeNO among children. It is crucial to implement strategies controlling heavy-metal pollution in preschools and ensuring the protection of children who may be exposed.

Heavy metal pollution and evaluation of health risk of amaranth around Don Bosco wastewater treatment plant, Iringa, Tanzania

One of the world’s most significant sources of environmental pollution is heavy metals contamination of soil, water, and agricultural products. Liver cancer, kidney damage, anaemia, coma, hypertension and sporadic fever are among the illnesses that might result from consuming plants contaminated with heavy metals. This study assesses heavy metals (Cu, Mn, Cd, Cr, Ni and Pb) contamination and associated human health risks in amaranth (Amaranthus hybridus) grown near Don Bosco wastewater treatment plant in Iringa municipal, Tanzania. The study measured the concentration of heavy metals in amaranth vegetables using AAS. The level of Mn in the vegetables ranged between 67.90 and 493.44 mg/kg. The mean concentration of Mn obtained was 280.67 mg/kg, lower than the permissible levels set by FAO/WHO but above the limit as set by TBS. The Cu levels in amaranth ranged between 6.37 and 7.90 mg/kg, with a mean concentration of 7.24 mg/kg lower than the permissible limits set by FAO/WHO and TBS. The Cd levels in amaranth ranged between 0.05 and 0.35 mg/kg, and the mean concentration was 0.20 mg/kg below the permissible limit set by FAO/WHO and TBS. The calculated daily intake consumption fell in the following sequence: Mn>Cu>Cd. The hazard quotient (HQ) for Mn and Cd is 261.66 and 6.45, respectively, higher than the allowed limit (HQ <1), and the hazard index (HI) for all samples was HI>1, which indicates the consumption of these veggies could pose a harm to one’s health. Additionally, the assessment of cancer risks revealed that Mn and Cd levels exceeded the USEPA recommended threshold of 1E-04, indicating a risk of one additional cancer case for every 10,000 individuals consuming amaranth vegetables. Thus, regularly checking for heavy metal contamination in vegetables is critical to minimize health hazards.

Microplastics with Heavy Metals Pollution in Water Supply of Litopenaeus Vannamei Aquaculture in Probolinggo, Indonesia

Microplastics with Heavy Metals Pollution in Water Supply of Litopenaeus Vannamei Aquaculture in Probolinggo, Indonesia

Accumulation of Copper (Cu) and Cadmium (Cd) Ions in Settling Basins to Assess the Effectiveness of the IPLT TPA Putri Cempo, Surakarta

Abstract Decreased water quality is caused by various human activities. One of the most dangerous types of water pollution is heavy metal pollution. Exposure to heavy metals can endanger human health even at low concentrations. One source of heavy metal pollution comes from domestic waste pollution from domestic activities, fecal waste. Fecal sludge contains solids dissolved in water, in the form of a mixture of organic materials and heavy metals, making it hazardous if not treated first before disposal. In this research, the author used water samples from the IPLT TPA Putri Cempo to determine the levels of Copper (Cu) and Cadmium (Cd) and the hazards posed by heavy metals, in order to assess the effectiveness of the Putri Cempo TPA IPLT system. The method used was wastewater sampling from the Putri Cempo landfill final sedimentation tank, sample preparation and analysis with atomic absorption spectrophotometer (AAS). The results of the investigation show that the final pool water at Putri Cempo landfill contains 0.0155 mg/L of copper and -0.0076 mg/L of cadmium, where these results are still below the threshold set by wastewater quality standards in Indonesia.

A Review on Bioremediation Using Nanobiotechnology and Microbial Heavy Metal Resistance Mechanisms

Abstract: Various human actions have raised the level of heavy metal (HM) pollution in the environment. From contaminated water and soil, the HMs infiltrate into the agricultural crops that are consumed by animals as well humans. Deposition of heavy metals leads to DNA damage and several digestive, reproductive, and respiratory system-related health problems. Various microorganisms have evolved mechanisms of HM resistance, tolerance, detoxification, and metabolization. Physicochemical methods of HM treatment are expensive and non-ecofriendly. Therefore, remediation of contaminated soil and water using microorganisms or bioremediation has become a topic of interest for scientists. Bioremediation is a cheaper, eco-friendly and more efficient method. The present review attempts to describe various mechanisms (biosorption, bioaccumulation, biotransformation and active export) by which microbes resist and remediate heavy metal pollution. In addition, the role of different types of consortia/co-culture in bioremediation has been discussed. Microbes, such as fungi, bacteria, and protozoa can remove metals both singly and in amalgamation. Furthermore, an advanced nanotechnology approach for metal ion treatment from wastewater has been briefly discussed. To fully utilize the microbial potential for heavy metal removal and create better strategies to alleviate environmental pollution, a deeper knowledge of the molecular, biochemical, and genetic mechanisms used by these species is required.

Review on the relationship between microplastics and heavy metals in freshwater near mining areas.

Microplastics (MPs), degraded from plastic wastes, have drawn significant attention worldwide due to its prevalence and rapid transition. Contamination of freshwater with MPs has become an emerging global issue. Heavy metals (HMs), a prominent global pollutant, also garnered much attention due to their potential interaction with MPs, presenting a multifaceted environmental threat. The primary source of HM contamination in freshwater has been identified as mining sites. Additionally, the increasing use of plastic materials within mining areas raises concerns about MP release into the surrounding freshwater environments. Recent studies only provide information on the contamination of HMs status with MPs. However, studies on the mechanism responsible for MPs contamination from both external and internal sources of freshwater MPs and HMs are limited. The knowledge gaps in the deposition and fate of MPs in various mining situations and the possibility of combined impacts of heavy metals and MPs in the ecosystem raise ecological concerns. Here, we review the origins of MPs and HM pollution within mining sites and explore the potential combined detrimental impacts on plants and animal life. We found out that polystyrene (PS) and polyethylene (PE) have higher adsorption affinity to heavy metals, and the mingle toxic consequence of the MPs and HM can depend on the MP surface properties, pH, and salinity of the neighboring water solution. The Langmuir and Freundlich isotherm models enable the efficient design of adsorption systems. The Langmuir model describes single-layer adsorption at homogeneous sites, while the Freundlich model addresses multilayer adsorption on heterogeneous surfaces. The crucial mechanism of adsorption and desorption that underlies the occurrence of both MPs and heavy metals is a decisive matter in this issue.

Enhanced simultaneous voltammetric detection of lead, copper, and mercury using a MIL-101(Cr)-(COOH)2@MWCNTs modified glassy carbon electrode.

Electrochemical methods, particularly those utilizing sensors, offer distinct advantages over classical analytical methods. They are cost-effective, compatible with mass fabrication, suitable for remote sensing, and can be designed as handheld analyzers. In this context, MIL-101(Cr)-(COOH)₂@MWCNTs was utilized for the first time as a modifier for GCE for the sensitive voltammetric detection of Pb(II), Cu(II), and Hg(II). The surface characteristics of the composite were examined using SEM, EDX, XRD, FTIR, and N₂ adsorption/desorption isotherms. The electrochemical behavior of the modified electrode was investigated using differential pulse anodic stripping voltammetry (DPASV). The DPAS voltammograms of the composite modified electrode are characterized by a remarkable increase in the oxidation peak currents for Pb, Cu, and Hg, indicating that MIL-101(Cr)-(COOH)₂@MWCNTs composite significantly enhances the electrocatalytic response towards the oxidation of the studied heavy metals. The impact of various parameters, such as accumulation potential, accumulation time, amount of MOF, composite thickness, and supporting electrolyte concentration on the developed sensor's response, were investigated. The analytical performances were also investigated using DPASV. The optimized MIL-101(Cr)-(COOH)₂@MWCNTs/GCE-based sensor exhibited a linear range of 0.11-15.4μM, 0.11-20.1μM, and 0.06-20.1μM, and lower limits of detection (LOD) of 0.08μM, 0.09μM, and 0.04μM for Pb(II), Cu(II), and Hg(II), respectively. This study introduces a novel MIL-101(Cr)-(COOH)₂@MWCNTs composite-modified GCE, offering exceptional sensitivity, selectivity, and repeatability for detecting Pb(II), Cu(II), and Hg(II). With broad analytical ranges, low detection limits, and successful application in real water samples, the work demonstrates significant potential for environmental heavy metal monitoring and pollution control.