Heavy Metal Composition Research Articles

Fly ash from municipal solid waste incineration: types, composition, and leaching of heavy metals

The problems of heavy metals (HM) leaching from fly ash (FA) produced by municipal solid waste incineration during its burial or use are considered. The composition, chemical properties and mineralogy of FA are described, experiments on leaching from FA in waste incinerators and in buried FA are considered, the risk from HM release is assessed, and the results of calculation and modeling of HM leaching coefficients are presented.

Mineral and heavy metal variations and contaminations in raw honey of stingless bees, Heterotrigona itama, from selected geographical areas of origin in Malaysia

Introduction: Honey contains a complex matrix of different substances consisting of essential minerals, non-nutritive substances, and toxins, often due to environmental sources. The objectives of this study were i) to investigate the variation of mineral and heavy metal content in honey samples of Heterotrigona itama from different geographical origins, and ii) to evaluate the nutritional quality and safety of honey from different floral sources for human consumption. Methods: A total of 75 samples of raw H. itama honey were collected from 11 sites in Sabah, two sites in Sarawak, and two sites in Peninsular Malaysia. The mineral and heavy metal contents of honey were determined in triplicate using inductively coupled plasma mass spectrometry (ICP-MS). Results: There were significant differences in the composition of essential minerals and heavy metals in the honey samples according to geographical origins (p<0.001). All honey samples tested were below the permitted maximum proportion (ML) for cadmium (Cd) and lead (Pb) specified in the Malaysian Food Act 1983 for honey. However, all honey samples exceeded the ML for Pb set by Codex, with samples from bamboo sites having the highest levels for Pb. Conclusion: The composition of minerals and heavy metals in stingless bee honey was influenced by geographical origin. All measured Pb concentrations were above the ML value set by Codex, which raises concerns about possible toxicological risks to human health. Given the toxic nature of Pb in the environment, the measured concentrations emphasise the importance of monitoring Pb in honey from stingless bees.

Nutrient and heavy metals composition of dried fish varieties from Bangladesh

Nutrient and heavy metals composition of dried fish varieties from Bangladesh

Black Sands of Iwo Jima: How the Past Can Improve the Future of Warfare

Heavy metal soil contamination persists on Iwo Jima’s Invasion Beach, a site of historical significance from WWII, renowned for its critical role in the Pacific theater and its distinctive black volcanic sand. Despite the sand being collected as war memorabilia, limited research has specifically addressed the heavy metal composition of this sand and the associated contamination risks. This study aims to quantify heavy metal concentrations in soil samples from Invasion Beach, compare them with those from non-affected areas, identify sources of contamination, and assess the environmental and health impacts of these metals. Using X-ray fluorescence (XRF), soil samples were analyzed from various locations on Invasion Beach and compared to non-affected control sites. Statistical analyses, including t-tests, one-way ANOVA, Mann-Whitney U tests, and Multivariate Analysis of Variance (MANOVA), to compare the heavy metal concentrations between Iwo Jima and background samples. The t-tests and ANOVA revealed significant differences in the concentrations of metals such as chromium (Cr) and mercury (Hg), with p-values indicating strong statistical significance (p < 0.05). Mann-Whitney U tests further confirmed significant distributional differences for Cr, Hg, and Zn, while the MANOVA results highlighted a significant overall difference in metal profiles when considering all metals collectively (Wilks’ Lambda = 0.020, p = 0.049). These elevated levels are directly attributed to the intensive military activities and munitions used during the war, as evidenced by the specific metal signatures consistent with military debris. This underscores the potential environmental and public health risks, including disruptions to nutrient cycles, reduced soil fertility, impaired plant growth, and contamination of groundwater and surface water. This research emphasizes the urgent need for adopting environmentally friendly military technologies to minimize the ecological impact of warfare. It also highlights the importance of further studies, the development of sustainable alternatives, increased public awareness, and the implementation of environmental regulations, alongside long-term health monitoring of populations living near contaminated sites. There is limited literature on general soil contamination and the environmental effects of military operations, with no specific studies on Iwo Jima’s Invasion Beach. This study aims to fill this gap by providing empirical data on heavy metal concentrations and analyzing their sources.

CHARACTERIZATION OF BIOCHAR OBTAINED FROM MANURE AND ENVIRONMENTAL RISK ASSESSMENT

Animal manure has been used to manage soil fertility since the dawn of agriculture. Applying of this residual organic matter on agricultural soils can cause heavy metals accumulation, migration of pathogens to water sources, and food and generation of greenhouse gases. Biochar obtained through thermochemical conversion shows potential in agronomic uses. This study investigated the chemical composition and environmental risk of heavy metals in cattle manure and their biochar developed in the thermal range 700°C-850°C.

Microbial and Heavy Metal Evaluation of Sachet Drinking Water in the Hohoe Municipality, Ghana

Aim: To study microbial and heavy metal composition in sachet drinking water in the Hohoe municipality in the Volta Region of Ghana. Place and Duration of Study: The study was conducted in the Hohoe Municipality in the Volta region of Ghana and laboratory analyses were carried out at the Microbiology laboratory of the Department of Biochemistry and Biotechnology, Kwame Nkrumah University of Science and Technology between June 2018 and May 2019. Study Design: Cross-sectional study. Methodology: The study was conducted on three samples each of eight different brands of sachet water randomly selected across various towns from street vendors in the Hohoe Municipality for microbial and chemical analyses. 10ml of each sample was aliquoted under sterile conditions and cultured overnight in nutrient media. Enumeration and qualitative analyses of bacteria were performed using the pour plate method. For heavy metal analysis, 5 ml of concentrated HNO3 was added to 40 ml of each sample and heated at 100 °C for 20–30 minutes to reduce the volume to 20 ml. 30ml of distilled water was subsequently added and the mixture was analyzed using flame atomic absorption Spectroscopy. Results: Out of total twenty-four samples analyzed, 50% of the sachet water was contaminated with total and fecal coliforms with the highest average coliform forming unit (cfu/ml) being 16.2 x 105 cfu/ml and the least 0.01 x 105 cfu/ml. There were Klebsiella spp, and Pseudomonas aeruginosa contamination in 50% of the sachet drinking water but Salmonella spp and E. coli were absent in all brands. Chromium was detected to be within the range of 0.40mg/L - 0.56mg/L in the sachet water while zinc was in the range of 0.03mg/L– 0.94mg/L. Chromium concentration in all sachet brands were above the WHO standard while zinc was within the acceptable range. Cadmium and lead were below detectable limits (BDL). Conclusion: This study indicated that some of the sachet drinking water sold in the Hohoe Municipality is impure for human consumption. Inappropriate water purification procedures and improper handling of sachet water play a significant role in determining the overall quality of sachet drinking water.

Aflatoxin content and heavy metals composition of powdered pepper from selected markets in Kwara state, Nigeria

Aflatoxin and heavy metal concentrations may pose health risks to pepper consumers. No research has been published concerning aflatoxin and heavy metal contamination of powdered pepper in Kwara state, Nigeria, hence the need for this study. Powdered pepper samples from various Kwara state markets (Offa, Oja-Oba, Ganmo, Shao, Elemere, and Malete), were analyzed using standard methods for aflatoxins B1 (AFB1), B2 (AFB2), G1 (AFG1), and G2 (AFG2), and lead, cadmium, copper, and arsenic. A laboratory-prepared sample was used as the control. The samples’ mean AFB1 was 2.86 μg/kg, AFG1 4.34 μg/kg, AFB2 2.03 μg/kg, and AFG2 1.88 μg/kg. In general, the levels of aflatoxin in the powdered pepper samples were found in the order of AFG1 &gt; AFB1 &gt; AFB2 &gt; AFG2. The samples’ aflatoxin concentration is less than the US Food and Drug Administration’s (20 μg/kg) contamination threshold. The FDA’s guideline for lead level in food, which is 0.1 mg/kg, was surpassed by the lead concentration, which varied from 1.84 to 3.45 mg/kg. The range of arsenic concentration was 10.18-22.68 mg/kg, which is higher than the World Health Organization’s recommended limit of 0.0003 mg/kg. The copper concentration met the FDA’s 10-mg/kg threshold, which ranged from 2.66 to 4.42 mg/kg. The study’s findings demonstrate the need for a monitoring and education programme in Kwara state to ensure the public’s safety while consuming powdered pepper.

Prevalence of antibiotic resistance genes, heavy metal, and bacterial community composition in sea sediments influenced by Eriocheir sinensis breeding aquaculture.

Eriocheir sinensis is the main aquaculture species in China. With the continuous expansion of the aquaculture scale, the demand for E. sinensis seedlings was also increased. The water used in breeding has well-nourished and its discharge into the sea posed significant risks. This study sampled the wastewater discharge points of the E. sinensis seedlings in Sheyang County, Jiangsu Province, and the areas far from the discharge points that were not affected in March and May 2023, respectively. A large number of antibiotic resistance genes (ARGs) were found in the sediment of the wastewater discharge area, and the highest ARG was sulfonamide ARG-sul1 using qPCR analysis, while ARGs were almost undetectable in the areas not affected by wastewater discharge. The 16S rRNA sequence analysis results showed that the main bacterial phyla at the wastewater discharge point were Bacteroidetes, Proteobacteria, and Thermodesulfobacteria. In the control point, the main bacterial phyla were Proteobacteria, Chlorobacterium, and Thermodesulfobacteria. There were significant differences in the composition of microbial communities between the two points, and the samples at the wastewater discharge point were more clustered and had higher similarity. The correlation network and redundancy analysis indicated that the phyla Bacteroidetes, Firmicutes, and Proteobacteria at the wastewater discharge points were positively correlated with most ARGs. The wastewater discharge had no effect on heavy metals from the two points. This study sets a foundation for future research by identifying key microbial taxa as potential ARG carriers and examining the interactions between microbial communities, ARGs, and heavy metals.

Optimizing feedstock organic composition to regulate humification and heavy metal passivation during solid-state anaerobic digestion

This study uncovered the impacts of feedstock organic composition, comprising proteins, lignocellulose, and lipids, on humification and passivation of heavy metals (HMs) in solid-state anaerobic digestion (SSAD). Mantel tests and partial least squares structural equation modeling (PLS-SEM) results revealed that copper (Cu) and zinc (Zn) passivation predominantly occurred through complexation with humic acid (HA). In contrast, lead (Pb) and chromium (Cr) passivation were pH-dependent as influenced by substrate conditions in SSAD. Increasing protein content in the feedstock facilitated lignocellulose biodegradation to enhance HA formation, and thus augmenting Cu and Zn passivation. Furthermore, the improved biodegradation of organic components elevated the substrate pH, further enhancing Pb and Cr passivation. Such improvement was notable when the protein: lignocellulose: lipid ratio of feedstock was regulated to 4.1:3.7:2.2, which increased HA contents to 35.25% and pH to 9 to enhance the passivation of Cu, Pb, and Cr by 0.48%, 52.0%, and 17.9%, respectively.

Assessment of the Impact of Heavy Metals on Clarias gariepinus Burchell and Heterobranchus longifilis Fish Species of Omambala River Basin of Anambra State Nigeria

Heavy metals are natural occurring minerals that are found in nature, as deposits in pure and mostly ore form. They are referred to as transition metals due their variable oxidation state, which as a result have made them to develop special properties among other elements in the periodic table. This study aimed to assess the levels of heavy metals (Lead, Chromium, Mercury, Cadmium, Iron, Zinc, Copper and Magnesium) in Clarias gariepinus and Hetrobrancus longifilis collected from the Omambala River. The fish samples were collected by fishermen at the fish landing site. The heavy metal analysis in the two fish species was studied using Atomic Absorbtion Spectrophotometer (AAS) and the instrument was calibrated with standard solutions. The result of this work showed that the highest compositions of heavy metals were: lead (Pb) content in C. gariepinus was 2.69±1.417 mg/l while in H. longifilis was 3.14±1.395 mg/l. However, Chromium content in C. gariepinus was 3.11±0.826 mg/l and in H. longifilis was 4.04±1.073 mg/l. Mercury in C. gariepinus was 3.98±1.903 mg/l and H. longifilis was 4.77±2.283 mg/l. Cadmium in C. gariepinus was 4.90±2.100 mg/l while H. longifilis was 4.83±2.019 mg/l. Moreover, Iron in C. gariepinus was 3.94±1.414 mg/l and H. longifilis was 4.31±2.077 mg/l. Zinc in C. gariepinus was 4.02±1.917 mg/l and H. longifilis was 5.47±2.607 mg/l. Copper in C. gariepinus was 2.62±0.720 mg/l while in H. longifilis was 3.01±0.828 mg/l. Magnesium in C. gariepinus shows 4.66±2.774 mg/l and H.longifilis shows 3.72±1.466 mg/l. The most prevalent heavy metals from the study were Zn, Cd, Hg, Mg, Fe, Cr, Pb, and Cu. It is therefore recommended that further research be made, and awareness created on the high health risk associated with frequent ingestion of these harmful mineral elements found in trace deposits in the Omambala River by the appropriate authority to ascertain their concentrations.

Investigation of Heavy Metal Composition and Associated Health Risks from Selected Groundwater Wells in Temeke, Dar-es-Salaam

Water quality continues to be the challenge to residents in Dar es Salaam due to various anthropogenic activities in the city. This study was conducted to assess groundwater quality by determining concentrations of heavy metals. Both probability and Nonprobability sampling techniques were used to collect samples from 40 groundwater wells in 24 wards of Temeke municipal and analysed using Microwave Plasma Atomic Emission Spectrometer (Agilent 4210 MP-AES) at the Geochemistry Laboratory of the University of Dar es Salaam. Results indicated varying heavy metal concentrations ranging from 0.71 ± 0.08 to 6.64 ± 0.21 mg/l for As, 0.02 ± 0.01 to 0.07 ± 0.01 mg/l for Co and 0.16 ± 0.01 to 0.02 ± 0.01 mg/l for Pb. The As, Co and Pb concentrations exceeded (P &amp;lt; 0.05) the recommended TBS standards of 0.05 mg/l, 0.003 mg/l and 0.01 mg/l respectively. Other concentrations ranged from 0.01 ± 0.01 to 0.88 ± 0.01 mg/l for Cu, 0.02 ± 0.01 to 3.55 ± 0.02 mg/l for Fe, 0.00 ± 0.00 to 4.63 ± 0.03 mg/l for Mn and 0.01 ± 0.01 to 3.00 ± 0.01 mg/l for Zn. The Cu, Fe, Mn and Zn concentrations were below (P &amp;gt; 0.05) the allowable TBS limits of 0.05 mg/l, 0.3 mg/l, 0.1 mg/l and 3 mg/l respectively. Health risk analysis revealed potential adverse health effects from long term consumption of As, Mn and Pb with Hazard Quotient exceeding 1 (HQ &amp;gt; 1). The Hazard Index (HI) for all groundwater samples was also above 1 (HI &amp;gt; 1) indicating a higher likelihood of adverse health effects. The study concluded that groundwater wells in Temeke Municipal are affected through natural and anthropogenic activities leading to high levels of heavy metal concentrations. Also, this study provides valuable information on risk associated by continued usage of groundwater in Temeke region and hence informs respective stakeholders on groundwater quality and potential risks thereby emphasizing the need for remedial measures and stricter regulations to safeguard public health. The study recommends the need for regular groundwater quality and safety monitoring to assess the levels of heavy metals concentrations and implement sustainable groundwater management strategies to address the increasing water demand in Temeke municipal, Dar es Salaam.

Composition, distribution, and risk assessment of heavy metals in large-scale river water on the Tibetan Plateau

Heavy metals present in aquatic ecosystems constitute a significant threat to both the environment and human health. In this study, we analyzed various heavy metals (As, Cr, Co, Ni, Cu, Mo, Cd, Pb and Sb) using extensive surface water samples collected from the Tibetan Plateau in 2021 and 2023. Results showed that downstream water samples exhibited higher content (mean 12.6 μg/L) of heavy metals compared to those from the glacier basins. It is noteworthy that heavy metal content varied significantly both in the glacier basin and downstream (4.6–29.1 μg/L and 7.8–55.2 μg/L, respectively). However, elevated concentrations at certain sites (e.g., Saga County and Dangque Zangbu River) were primarily attributed to the disproportionate contribution of individual heavy metals, possibly stemming from specific human activities or natural conditions. In the glacier basin, only Cr exhibited a decreasing trend in enrich factors (EF) with increasing Sc concentration, whereas, in the downstream areas, most elements displayed a declining trend. Furthermore, apart from a few sampling sites, heavy metal concentrations in the glacier basin remained relatively balanced, suggesting that these metals predominantly originate from natural sources. The values of potential ecological risk for an individual element (Eri) and potential ecological risk index (PER) indicate that the ecological and human risks associated with almost heavy metals (except As) in the aquatic ecosystem are minimal. Environmental ImplicationHeavy metals in aquatic ecosystems pose a significant threat to ecological and human health. Due to delicate ecological balance of the Tibetan Plateau and its critical role as a water resource, we analyzed various heavy metals (As, Cr, Co, Ni, Cu, Mo, Cd, Pb and Sb) concentrations and EF in land surface river water, to find out the pollution levels and possible sources of heavy metals in the aquatic ecosystems. The results of risk assessment showed that the prevention and management of arsenic in Tibetan Plateau needs attention, but most heavy metals pose no threaten to ecological and human health.

PET microplastics influenced microbial community and heavy metal speciation in heavy-metal contaminated soils

Co-occurrence of microplastics and heavy metals is common in soils. The interactions between microplastics and heavy metals have received increasing attention in recent years, particularly for revealing the mechanisms underpinning their interactions. In the present study, Polyethylene Terephthalate (PET) microplastics are added in soil, which have led to variations in soil physicochemical properties, enzymatic activity, microbial community structure, and chemical speciation of chromium (Cr), cadmium (Cd), copper (Cu), and zinc (Zn) in heavy metal contaminated soils. Soil physicochemical properties (pH, SWC and SOC) and enzymatic activities (urease and dehydrogenase) alter as result of PET addition, which promoted the transformation of heavy metal chemical speciation from bioavailable fraction to oxidizable and residual fraction. The results suggested that PET microplastics in heavy metal contaminated soil may reduce the heavy metal bioavailability by altering the properties of the soil microenvironment. The significant variations in microbial community have been observed. The relative abundance of Gp6, Gaiella, Nocardia, Herbaspirllum and Gp16 changed dramatically throughout the incubation period, which were either heavy metal tolerant or played crucial roles in modifying the chemical composition of heavy metals. This work contributes to an in-depth understanding of the effects of microplastics on the biochemical transformation of heavy metal contaminated soils, which will be valuable to the development of clean up strategy for soils with co-contaminant of microplastics and heavy metals.

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.

Multivariate statistical analysis of bioavailability of heavy metals and mineral characterization in selected species of coastal flora

This study presents a thorough investigation into the concentration of heavy metals and mineral composition within four distinct coastal flora species: Cyperus conglomeratus, Halopyrum mucronatum, Sericostem pauciflorum, and Salvadora persica. Employing rigorous statistical methodologies such as Pearson coefficient correlation, principal component analysis (PCA), analysis of variance (ANOVA), and interclass correlation (ICC), we aimed to elucidate the bioavailability of heavy metals, minerals, and relevant physical characteristics. The analysis focused on essential elements including copper (Cu), iron (Fe), manganese (Mn), zinc (Zn), magnesium (Mg2+), calcium (Ca2+), sodium (Na+), potassium (K+), and chloride (Cl–), all of which are known to play pivotal roles in the ecological dynamics of coastal ecosystems. Through PCA, we discerned distinctive patterns within PC1 to PC4, collectively explaining an impressive 99.65% of the variance observed in heavy metal composition across the studied flora species. These results underscore the profound influence of environmental factors on the mineral composition of coastal flora, offering critical insights into the ecological processes shaping these vital ecosystems. Furthermore, significant correlations among mineral contents in H. mucronatum; K+ with content of Na+ (r = 0.989) and Mg2+ (r = 0.984); as revealed by ICC analyses, contributed to a nuanced understanding of variations in electrical conductivity (EC), pH levels, and ash content among the diverse coastal flora species. By shedding light on heavy metal and mineral dynamics in coastal flora, this study not only advances our scientific understanding but also provides a foundation for the development of targeted environmental monitoring and management strategies aimed at promoting the ecological sustainability and resilience of coastal ecosystems in the face of ongoing environmental challenges.

NUTRITIONAL AND HEAVY METAL COMPOSITION OF LOCAL AND FOREIGN RICE IN MAJOR MARKETS IN LAGOS STATE, NIGERIA

Rice is the second most important staple food in Nigeria, accounting for 10.5% of average calorie intake, necessitating the continuous availability of reliable information on its quality and safety to consumers. This study evaluated and compared nutritional and heavy metal (HM) composition in local rice (LR) and foreign rice (FR) sold in Lagos markets. Three each of LR (Umza, Ofada and Big Bull) and FR (Caprice, Simba and Mama gold) were randomly selected from three major rice markets in the study area. Samples were tested for crude protein, crude fat, carbohydrate, glucose, crude fibre, total ash, moisture, Na, Fe, Vitamins (C, B2, E and K), β- carotene, additives (Sodium benzoate, Saccharine) and HM (As, Cu, Cd, Pb and Hg) contents, using standard methods. Data were subjected to ANOVA using SPSS 25.0 software. The mean separation was by DMRT at p ≤ 0.05. The result showed that all the nutrients tested were present in all brands in varying amounts. Mean glucose (87.01±0.56%), As, Cd and Pb (0.31±0.02, 0.48±0.03 and 0.84±0.04 mg/kg respectively) in Ofada; crude protein (10.64±0.27%), β- carotene and vitamin C (10.11±0.43 and 88.07±2.67 mg/kg respectively) in Caprice, were significantly higher (p ≤ 0.05) than in other brands. All HM except Cu in Ofada; Cd and Pb in all other brands, exceeded FAO/WHO permissible levels. While, Caprice, and Ofada, respectively, showed better nutritive quality, mean values between other brands were not significantly different (p ≤ 0.05), suggesting comparable nutritive parameters in foreign and local rice. Since HM in food portends serious health risks, their presence above permissible levels in all brands, shows they are not suitable for consumption. However, washing grains several times in water and soaking them for two hours has been reported to effectively remove heavy metals from rice while cooking can reduce the bio accessibility of these elements. Further research is needed to establish the sources of heavy metal contamination of rice and possible ways of preventing future occurrences.

Risk of heavy metal(loid) compositions in fine particulate matter on acute cardiovascular mortality: a poisson analysis in Anyang, China.

Fine particulate matter (PM2.5) is a risk factor of cardiovascular disease. Associations between PM2.5 compositions and cardiovascular disease are a point of special interest but inconsistent. This study aimed to explore the cardiovascular effects of heavy metal(loid) compositions in PM2.5. Data for mortality, air pollutants and meteorological factors in Anyang, China from 2017 to 2021 were collected. Heavy metal(loid) in PM2.5 were monitored and examined monthly. A Case-crossover design was applied to the estimated data set. The interquartile range increase in cadmium (Cd), antimony (Sb) and arsenic (As) at lag 1 was associated with increment of 8.1% (95% CI: 3.3, 13.2), 4.8% (95% CI: 0.2, 9.5) and 3.5% (95% CI: 1.1, 6.0) cardiovascular mortality. Selenium in lag 2 was inversely associated with cerebrovascular mortality (RR = 0.920 95% CI: 0.862, 0.983). Current-day exposure of aluminum was positively associated with mortality from ischemic heart disease (RR = 1.083 95% CI: 1.001, 1.172). Stratified analysis indicated sex, age and season modified the cardiovascular effects of As (P < 0.05). Our study reveals that heavy metal(loid) play key roles in adverse effects of PM2.5. Cd, Sb and As were significant risk factors of cardiovascular mortality. These findings have potential implications for accurate air pollutants control and management to improve public health benefits.

Long-term and combined heavy-metal contamination forms a unique microbiome and resistome: A case study in a Yellow River tributary sediments

Microorganisms have developed mechanisms to adapt to environmental stress, but how microbial communities adapt to long-term and combined heavy-metal contamination under natural environmental conditions remains unclear. Specifically, this study analyzed the characteristics of heavy metal composition, microbial community, and heavy metal resistance genes (MRGs) in sediments along Mang River, a tributary of the Yellow River, which has been heavily polluted by industrial production for more than 40 years. The results showed that the concentrations of Cr, Zn, Pb, Cu and As in most sediments were higher than the ambient background values. Bringing the heavy metals speciation and concentration into the risk evaluation method, two-thirds of the sediment samples were at or above the moderate risk level, and the ecological risk of combined heavy metals in the sediments decreased along the river stream. The high ecological risk of heavy metals affected the microbial community structure, metabolic pathways and MRG distribution. The formation of a HM-resistant microbiome possibly occurred through the spread of insertion sequences (ISs) carrying multiple MRGs, the types of ISs carrying MRGs outnumber those of plasmids, and the quantity of MRGs on ISs is also higher than that on plasmids. These findings could improve our understanding of the adaptation mechanism of microbial communities to long-term combined heavy metal contamination.

A Comparison of Health Risks from PM2.5 and Heavy Metal Exposure in Industrial Complexes in Dangjin and Yeosu·Gwangyang.

Particulate matter (PM) can cause illness, including respiratory diseases, and PM2.5 compositions are likely to vary according to the emission profiles of industrial complexes. This study analyzed and compared the concentrations and distributions of PM2.5 and heavy metals in two regions of Republic of Korea: Yeosu·Gwangyang, which houses a massive national industrial complex, and Dangjin, which houses power plants. Further, we conducted a health risk assessment on the residents of the areas near these industrial complexes. Measurements were taken at five different points in each setting over a two-year period from August 2020 to August 2022. We found differences in PM2.5 concentrations and heavy metal composition ratios across the sites. Specifically, PM2.5 concentrations exceeded the standard of 1 at all measurement sites, while the specific heavy metals exceeding the standard varied across the sites. Ultimately, we observed regional differences in PM2.5 composition across measurement sites across and within the two regions and variations in health risks and according health effects due to the absence of PM2.5 toxicity values, and compared the health risks of two industrial complexes with different characteristics. These findings underscore the importance of considering not only PM2.5 but also its composition in exposure and health risk assessments.

Seasonal Variation of Indoor Dust Levels of Potential Toxic Heavy Metals in Early Childhood Education Classrooms

The study examines the seasonal variation in potentially toxic heavy metals found in indoor dust in early childhood classrooms, as heavy metal exposure becomes more common in Nigerian childcare settings. Six preschool dust samples from two Nigerian cities were collected during the dry and wet seasons, respectively. After being dried to a consistent weight, the dust samples were ground in a standard pulverizer. The Atomic Absorption Spectroscopy (AAS) method was used to conduct quantitative and qualitative analyses of the samples to determine the heavy metal and elemental composition of the dust in both locations. The dust samples contained seven heavy metals (As, Cd, Co, Cu, Mn, Pb, and Zn), with concentrations varying by season: Co 0.83 µgg-1 to Zn 38.43 µgg-1 during the rainy season, and 1.82 µgg-1 Cu to 80.00 µgg-1 Zn during the dry season. The study concluded that seven elements were present in the sample, and it is recommended that the government of the Federal Republic of Nigeria implement the necessary mechanisms to monitor the impact of dust on preschool children.