High Concentrations Of Heavy Metals Research Articles

Typha domingensis (Pers.) Poir. ex Steud. Potential to Restore Contaminated Wetlands in Egypt

AbstractSeveral studies have reported Typha domingensis (Typhaceae) as a heavy metal (HM) hyperaccumulator. This study aims to assess the seasonal variations in the accumulation potential of T. domingensis (TD) for HM in polluted wetlands in Greater Cairo, Egypt. Sampling of fresh wild plants from the TD’s subterranean (Root and stem) and surface components were gathered from different polluted sites distributed in the canal of Ismailia and Nahia drain, as well as from the River Nile as an unpolluted site (control). The findings showed that pollution negatively affected the chemical characteristics of sediment and water. Except for the TD’s leaf area, there were significant seasonal variations in the growth characteristics (density, stem diameter, leaf length, and width, fresh and dry biomass). The subterranean parts stored higher amounts of HM than the aboveground shoots. Manganese (Mn) concentration (413.2 mg kg− 1) was greater in the roots of autumn plants, whereas their shoots recorded the highest Pb (225.8 mg kg− 1). Al, Cd, Cu, Fe, Ni, and Zn concentrations in summer plant roots (1499.9, 74.8,1356.1, 3948.8, 403.8, and 1294.2 mgkg− 1, respectively). The factor of metal bioaccumulation (BF) values, was high in TD plants growing in a polluted Ismailia canal, but translocation factor (TF) values for all measured elements were lower than one, except for Pb. Summer is the best season for TD growth to sequester high HM concentrations. The authors recommended that TD be employed to mitigate HM pollution in wetlands and restore them.

Spatiotemporal distributions, sources, and health risks of heavy metals in an acid mine drainage (AMD)-contaminated karst river in southwest China

Acid mine drainage (AMD), characterized by its acidity and high content of heavy metals, is a significant global environmental problem that harms human health through its impact on rivers. Therefore, this study aims to identify heavy metals in both surface and underground AMD-polluted karst rivers, focusing on the Zhijin River area which is severely affected by AMD, and assess their health risks to residents. Through the collection of 30 surface water samples and 16 groundwater samples from both wet and dry seasons, the study examines the concentration, sources of pollution, and health implications of six heavy metals (Fe, Mn, Cr, Cd, As, and Hg). The results showed that Fe and Mn levels in surface water were highly polluted during both seasons, especially during the wet season, with Fe levels reaching 20.0 mg/L and Mn levels reaching 1.9 mg/L. Further correlation and principal component analyses revealed that mining activities are the primary contributors to the contamination in this region. Health risk assessments and Monte Carlo simulation, including both deterministic and probabilistic, showed that the noncarcinogenic health risk indices for surface water and groundwater were within acceptable limits for both seasons. However, groundwater poses a higher carcinogenic risk to children, with As levels during the wet season and Cr levels during the dry season warranting close monitoring. Factors such as body weight and intake rate played a crucial role in health risk evaluations. This study underscores the need for further attention to groundwater risk, temporal heterogeneity in the Zhijin River.

Assessment of the Environmental Impact of Fly Ash on the Concentration of Heavy Metals around Cement Company of Northern Nigeria

This study assessed the impact of Coal Fly Ash on the concentration of Heavy metals in water, soil, and vegetables (moringa and spinach) in the environment of Cement Company of Northern Nigeria. The samples collected were digested, and analysed for heavy metals concentration using Atomic Absorption Spectroscopy. The concentrations of heavy metals obtained in water samples were higher than the WHO/SON permissible limit, except for Cu and Zn which are below the standard limits. The average concentration of Pb, Mn, Cd, and Ni in all plant samples was higher than the permissible limit, except Cd in spinach sample. The roots of the spinach accumulate higher concentrations of heavy metals than the leaves and stem, while leaves of moringa accumulate higher than the roots and stem. The concentration of heavy metals in soil sample was below the WHO limit. Comparatively the plants samples have the highest concentrations of heavy metals than the water and soil samples. The coal fly ash from the Cement Company must have contributed to the significant concentration of Heavy metals in the environment making the water and plants from the study area unfit for human and animal consumption.

Geoelectrical resistivity and geochemistry monitoring of landfill leachates due to the seasonal variations and the implications on groundwater systems and public health

Understanding the seasonal variations in the landfill leachate plumes (LLPs) properties and complex connections between concentrations of leachate variability, and its environment is essential for environmental and public health management. This study explores the combined electrical resistivity (ER) data and physiochemical water analysis (PWA) coupled with the excavations to monitor the landfill physiochemical properties (LPPs) due to seasonal variations and their implications on environmental vital organs and public health. The variations in ER and LLP distributions across the overburdened top layer due to seasonal changes were examined. The low ER contrasts were encountered within the ranges of 1.5 Ωm – 19.0 Ωm which was mapped as LLP accumulated zones within the landfill, while high ER values varied between 15 Ωm – 260 Ωm off-the landfill extending beyond 15 m. The results of the PWA indicate high concentrations of heavy metals (HMs) such as iron (Fe), lead (Pb), zinc (Zn), and cadmium (Cd) decreasing with wet seasons and increasing with dry seasons. The overall high concentration of HMs in the LLPs was indeed varied between 9.81 ± 2.15–19.07 ± 3.68, while the electrical conductivity (EC) significantly increased from 17.99 ± 1.92 mg/L to 24.87 ± 3.31 mg/L towards the wet season. The increment and decrement encountered in the LPPs are due to seasonal variation and dilution. The order of decrement in the HMs in the LLPs treads as follows EC > Fe > Zn > Pb > Cd in values, respectively. The near-surface EC aligned well with the ER results and boundaries of the waste disposal site, which was verified by the soil excavations. In addition, the ER method was extended beyond the landfill for adequate monitoring, identifying the subsurface layers, conductive shallow zones mapped as the zones of LLP accumulation, resistive deep and shallow zones mapped as the consolidated lateritic topsoil and crystalline basement rocks in some cases, and a dipping conductive lineament zones identified as fracture zones just before the crystalline basement. In conclusion, the ER technique reveals the vertical and horizontal extents of the LLP escapade, the PWA expressed the concentrations of HMs in the LLPs, heightening the implications on the environmental and human health. Finally, the combined techniques deployed for monitoring the physiochemical properties of LLPs due to seasonal variation and the impacts on the integrity of groundwater quality systems and public health inform sustainable waste management practices, which contributes significantly to the protection of groundwater resources and the development of effective strategies to safeguard groundwater systems and public health for present and future generations.

Gut heavy metal and antibiotic resistome of humans living in the high Arctic

Contaminants, such as heavy metals (HMs), accumulate in the Arctic environment and the food web. The diet of the Indigenous Peoples of North Greenland includes locally sourced foods that are central to their nutritional, cultural, and societal health but these foods also contain high concentrations of heavy metals. While bacteria play an essential role in the metabolism of xenobiotics, there are limited studies on the impact of heavy metals on the human gut microbiome, and it is so far unknown if and how Arctic environmental contaminants impact the gut microbes of humans living in and off the Arctic environment. Using a multiomics approach including amplicon, metagenome, and metatranscriptome sequencing, we identified and assembled a near-complete (NC) genome of a mercury-resistant bacterial strain from the human gut microbiome, which expressed genes known to reduce mercury toxicity. At the overall ecological level studied through α- and β-diversity, there was no significant effect of heavy metals on the gut microbiota. Through the assembly of a high number of NC metagenome-assembled genomes (MAGs) of human gut microbes, we observed an almost complete overlap between heavy metal-resistant strains and antibiotic-resistant strains in which resistance genes were all located on the same genetic elements.

Environmental Impact of Automobile Wastes on Surface Water Quality in Ebonyi State, Southeast Nigeria

ABSTRACTThe negative impact of operations in informal auto mechanic workshops is a major public health concern, and its effect on surface water pollution cannot be overlooked. This current work evaluates the environmental impact of automobile waste on surface water quality in Ebonyi State, Southeast Nigeria. A total of 108 surface water samples were taken in 2022 and 2023 from Abakaliki, Onueke, and Afikpo streams, and WHO as controls using standard analytical methods. Data sets were analyzed using Fisher's Significance Least Difference (F‐LSD) at the 0.05 probability level. The study showed that surface water appearance was slightly brown, and the observed upstream is acidic in nature, the midstream is alkaline, and the downstream is natural. Water samples from Abakaliki, Onueke, and Afikpo streams were observed to be hard since their concentration levels were above the WHO standard. Furthermore, the high concentrations of heavy metals (Pb and Mn) as well as the oil and grease content indicate that the surface water in the area of study is polluted and its overall quality is degraded. The study therefore concluded that automobile waste had a negative influence on the surface water quality in the study area. Based on these new findings, it is recommended that automobile waste be properly treated and disposed of to avoid their adverse effects on surface water quality. In addition, given the uncontrolled development of these informal auto workshops across the nation in recent years, there is a need for the execution of environmental standards connected to automobile service activities.

Study of Some Heavy Metals on Roasted Grains (Nuts) Present in Local Markets of AL-Diwaniyah City, Iraq

This study was conducted to examine some heavy elements in a number of imported and local roasted grains that are available and most consumed in local markets in AL-Diwaniyah Governorate. The heavy metals were (Pb, Mn, Fe, Zn and Cu). The results showed that the highest values were recorded for Fe, where 232 µg/g dry weight were recorded in sample No. 6., while Zn recorded 80 μg/g in sample No. 8. The concentration of Mn and Cu were 90 and 37.44 μg/g dry weight, respectively. The lowest value for Pb was 0.034 μg/g dry weight. From the current results, it is noted that the local, unpackaged samples recorded the highest concentration of heavy metals for all the samples studied.

The Use of Waste Materials Red Mud and Fly Ash as Road Embankment Fill

This study provides a comprehensive evaluation of red mud as a sustainable material for road base construction, particularly in combination with bottom ash. Red mud, a by-product of the Bayer process used in alumina extraction, is known for its high alkalinity and heavy metal content. For this reason, this waste material causes environmental challenges. Red mud sourced from the Eti Aluminum Factory in Seydişehir, Konya (Turkey), was stabilized with bottom ash. Then, these waste materials were tested through a number of experiments, such as in relation to their Atterberg limits, compaction characteristics, unconfined compressive strength (UCS), California bearing ratio (CBR), and microstructure through a scanning electron microscopy (SEM) analysis. The results highlight that the UCS of stabilized red mud samples significantly improved with the addition of bottom ash and longer curing periods. Specifically, the UCS values increased from 0.5 MPa to 2.5 MPa after 28 days of curing. Moreover, RM specimens stabilized with 25% bottom ash achieved a CBR value of 146.64% after 28 days, far exceeding Turkey’s road fill material requirement, which mandates a minimum unsoaked CBR value of 15%. These findings indicate that red mud stabilized with bottom ash not only meets but exceeds the structural requirements for road base materials. This approach provides a sustainable solution for the environmental management of red mud while contributing to infrastructure development. Through the recycling of these industrial by-products, this study presents a viable method to reduce waste and support economic and environmental sustainability in road construction projects.

Metal tolerance of Río Tinto fungi.

Southwest Spain's Río Tinto is a stressful acidic microbial habitat with a noticeably high concentration of toxic heavy metals. Nevertheless, it has an unexpected degree of eukaryotic diversity in its basin, with a high diversity of fungal saprotrophs. Although some studies on the eukaryotic diversity in Rio Tinto have been published, none of them used molecular methodologies to describe the fungal diversity and taxonomic affiliations that emerge along the river in different seasons. The aim of the present study was to isolate and describe the seasonal diversity of the fungal community in the Río Tinto basin and its correlation with the physicochemical parameters existing along the river's course. The taxonomic affiliation of 359 fungal isolates, based on the complete internal transcribed spacer DNA sequences, revealed a high degree of diversity, identifying species belonging primarily to the phylum Ascomycota, but representatives of the Basidiomycota and Mucoromycota phyla were also present. In total, 40 representative isolates along the river were evaluated for their tolerance to toxic heavy metals. Some of the isolates were able to grow in the presence of 1000 mM of Cu2+, 750 mM of As5+ and Cd2+, and 100 mM of Co2+, Ni2+, and Pb2+.

GENOMIC INSTABILITY IN ONION (ALLIUM CEPA L.) IRRIGATED WITH INDUSTRIAL WASTEWATER: A CYTOGENETIC STUDY

Wastewater negatively affects the production of plants. The impact can vary depending on the wastewater content and the sensitivity of the plant type. The purpose of the current study was to look at the hazardous effects of wastewater from the steel and rubber industries on onions (Allium cepa). Twenty-four pots were filled with soil. Three replicates are used in this study to investigate the impact on Allium cepa. To evaluate the level of toxicity of the rubber and steel industries' waste waters, three concentrations of each wastewater and a control were selected. The concentrations for rubber industry effluent were chosen: 80% (S1), 90% (S2), and 100% (S3) and for steel industry 80% (R1), 90% (R2), and 100% (R3). Wastewater treatment inhibited root development when compared to control. Genotoxic research at different intensities showed chromosomal abnormalities. As the concentrations increased, the mitotic index fell and chromosomal abnormalities grew. Chromosome bridges, nuclear budding, sticky and coagulated anaphase and metaphase, and other chromosome abnormalities were seen. Overall, it was shown that the application of wastewater from the steel sector and wastewater from the rubber business had a detrimental effect on plant growth. However, when compared to rubber industry wastewater, steel sector wastewater has a higher level of toxicity. Compared to rubber sector waste water, steel industry wastewater has a higher concentration of heavy metals.

Heavy Metals Distribution in Mangrove Leaves in Various Sudanese Coastal Zones at The Red Sea

<p style="text-align:justify;"><span style="font-family:"Times New Roman",serif;font-size:10.0pt;line-height:107%;">Mangrove ecosystem contamination, especially in the Red Sea region, has caused major concerns on a worldwide scale. The heavy metal accumulation typical of a mangrove species, </span><em><span style="font-family:"Times New Roman",serif;font-size:10.0pt;line-height:107%;">Avicenna marina </span></em><span style="font-family:"Times New Roman",serif;font-size:10.0pt;line-height:107%;">L. (</span><em><span style="font-family:"Times New Roman",serif;font-size:10.0pt;line-height:107%;">A. marina</span></em><span style="font-family:"Times New Roman",serif;font-size:10.0pt;line-height:107%;">) leaves and soluble salts in sediments have not been studied on the Red Sea coast of Sudan.  The present study investigates the two nutrients calcium (Ca) and iron (Fe) and heavy metals such as barium (Ba), titanium (Ti), and strontium (Sr) in the mangrove species </span><em><span style="font-family:"Times New Roman",serif;font-size:10.0pt;line-height:107%;">A. marina</span></em><span style="font-family:"Times New Roman",serif;font-size:10.0pt;line-height:107%;"> in the leaves of six different locations in the Red Sea coastal area, as follows: (Hamasyat (HM) Keligo (KG), and Enkfel (EK) of the Gulf of Dunnabeb, and three sites were selected in the south of the Sudanese coast as follows: (Amarat Island (AM), Ibn Abbas Island (BN), and Ras Kassar (RK). The results demonstrate that the maximum calcium (Ca) and iron (Fe) concentrations in mangrove leaves were 35.9 mg/kg and 4.10 mg/kg recorded at RK and AM, respectively, in the south region of the Red Sea. The heavy metal concentrations (mg/kg) vary between different locations. The higher concentration of heavy metals in mangrove leaves increased as Ba was 1.1 mg/kg in the EG north region. While Ti (0.5 mg/kg) and Sr (2.80 mg/kg) higher concentrations were recorded in AM and EK, respectively, in the south area than in the other experimental sites.   Heavy metals and soluble salts in sediments are continuously monitored in mangrove habitats to ensure they keep within allowed limits. These results could be useful as a database for prospective ecological research, preservation efforts, and long-term sustainable management of the Sudanese mangrove ecosystems throughout the Red Sea coastal.</span></p>

Ecological risk assessment of heavy metals contaminated mining sites of eastern india using soil and moss.

The blooming industrialization and urbanization is leading to increased mining operations. These intensified mining activities emit heavy metals into the environment, posing serious threats to ecosystems. Hence, this study focused on assessing heavy metal pollution in mining soil, utilizing mosses as bioindicators. The ecological risk, geo-accumulation factor, and contamination factor have been calculated to know the harmful effect of heavy metals on ecosystem. The study covered three distinct mining sites of eastern India within Odisha: Jajpur's Sukinda Valley (SP1, Cr), Keonjhar's Joda-Barbil (SP2, Fe and Mn), and Sundargarh's Koira-Joda (SP3, Fe). The collection of 48 soil samples through random sampling revealed significant variations in heavy metal concentrations. SP1 recorded Cr concentration of 6572 ± 445mg/kg and Ni of 8042.47 ± 501.38mg/kg, surpassing eco-toxicological levels. The storage site in SP2 exhibited the highest Fe concentration at 9872 ± 502mg/kg, and Mn levels in SP3 were at 7884 ± 432mg/kg. Storage areas in all three regions held the highest concentrations of heavy metals. Mosses in studied area demonstrated as potential bioindicators for monitoring heavy metal pollution. EF and Igeo assessments showed Cd, Pb, Hg, and other heavy metal contamination compared to earlier investigations. This study indicated higher ecological risks for Pb, As, Cu, Ni, and Zn. The Hyophila involuta accumulates Mn, Cr, Cd, Pb, Fe, and Hg, while Barbula arcuata accumulates Mn, As, and Cu in SP1. Hyophila involuta and Trematodon longicollis accumulate Mn, Cr, Cd, Pb, Fe, Hg, and Zn in SP2. Trematodon ambiguous accumulates Cd, Fe, and Ni, while Fissidens diversifolius accumulates Mn, Cr, Hg, As, Cu, and Zn in SP3. These findings emphasize the necessity of monitoring heavy metal pollution in contaminated zones using moss as a potential bioindicator.

Analysis of Fibropapillomatosis in Roe Deer (Capreolus capreolus) Confirms High Content of Heavy Metals.

In recent decades, there has been an increase in European wild ungulate populations, often associated with a decline in health and spread of disease. This is true for the roe deer (Capreolus capreolus), the most common European cervid, with populations apparently affected by fibropapillomatosis, an increasingly common cancer. To date, however, there has been little research into this disease, thus many interactions remain unclear and descriptions of tumour composition are poorly validated. The main aim of the present study was to evaluate the presence and concentration of toxic heavy metals in roe deer skin tumours. Our results confirmed the presence of virtually all the metals tested for, i.e., Pb, Hg, Cd, As, Cr, Mn, Al, Co, Cu, Ni, Se, Zn, and Fe, with the highest average concentrations found for Cr (0.99 mg/kg-1 ± 2.23 SD), Cd (0.03 mg/kg-1 ± 0.03 SD), and Hg (0.02 mg/kg-1 ± 0.02 SD), exceeding FAO limits for meat from slaughtered animals. We also observed a significant positive relationship between heavy metal concentration and age, especially for Pb, As, Hg, Mn, Se, Al, Zn, and Ni. Our findings provide a strong baseline for further research on the impact of fibropapillomatosis, not only on the welfare and health status of game but also on the final consumer of venison, which in many respects is regarded as a high-quality, ecological, and renewable wild resource. While deer with this disease are not considered qualitatively or medically defective, they could represent a potential reservoir of substances toxic to humans and could affect substance levels in adjacent tissues or the animal as a whole.

Health and Environmental Risk Assessment of Heavy Metals Contamination from Medical Wastes Ash of Baghdad Hospitals

Abstract One of the complex problems that many countries suffer from is how to deal with medical waste because of its harmful and devastating effects on humans and the environment. Hospitals around the world use and consume many different products. These products are composed of various materials, and many of them contain heavy metals in their production and manufacturing, which are ultimately emitted into the environment, posing a major danger and risk to human health. This work focused on assessing the contamination levels of medical waste ash after the incineration process. Ash samples were collected from major hospitals in the capital, Baghdad. The health risks resulting from heavy metal pollution were calculated. Medical waste ash was collected at different times from three major hospitals within the capital, Baghdad, and tested for contamination with heavy metals. To measure the bottom ash samples, X-ray spectroscopy (XRF) technology was used to determine heavy metal concentrations. The results showed the presence of more than twenty elements in the ash of medical waste, including the heavy metals found in Baghdad hospitals. Work was done on eight of these heavy metals due to their high concentrations. These selected elements are considered highly toxic and dangerous if exposed to them, including zinc (Zn), lead (Pb), arsenic (As), cobalt (Co), and copper. (Cu), nickel (Ni), chromium (Cr), and mercury (Hg). To evaluate the health risks of this pollution. All of these elements are a major problem if exposed to them. The amount of contamination was calculated using the contamination factor (CF). The results showed that the percentage of As, Cd, Hg, Zn, Pb, and Cu was very high. Meanwhile, the concentrations of Co and Ni were moderate values in medical waste ash. Adult health risks were calculated using the non-cancer health risk ratio (HL). The calculated values show values higher than the safe level in Imam Ali Central Hospital, indicating a potential high health risk. Meanwhile, other hospitals (Sheikh Zayed and Dhari Al Fayyad) recorded risk values below the safe level, indicating no health risks. The health risk assessment indicated that there are three main routes of human exposure: “ingestion, inhalation, and skin contact.” The cancer risk index (Risk) was also calculated. The values obtained were within the acceptable range. An analysis of the metal pollution index was also conducted, and it was found that heavy metals pose a non-cancerous risk. But the harmful effects of pollution from ash disposal have been particularly serious because they may contain high concentrations of heavy metals.

Chemical composition of sediment and macrozoobenthos of small urban lakes, the Republic of Karelia, Russia

Assessing the benthic communities in water bodies under increasing anthropogenic pressure seems to be an urgent task of scientific research aimed at short-term and long-term monitoring of water bodies. This study focuses on the chemical composition of modern sediment and the current state of macrozoobenthos of small lakes in the Republic of Karelia (Kitaiskoe and Plotichie) influenced by anthropogenic factors. It was discovered that the lakes of Medvezhyegorsk have a higher concentration of heavy metals (such as lead (Pb), cadmium (Cd), molybdenum (Mo), and antimony (Sb),) compared to the Earth’s crust and natural background levels. The current study established the significant impact of industry and transportation on the movement and build up of pollutants in these lakes. The qualitative and quantitative parameters analysed for the benthic communities in the littoral and profundal zones included the species diversity, the structure of dominant species, and their percentage in the samples. According to the level of macrozoobenthos development, both reservoirs (lakes) were classified as mesotrophic, and according to the values of the chironomid index “K” as moderately polluted. The Pantle–Buck method (saprobic index) showed that the lakes can be classified as polluted (water quality class 4). Macrozoobenthos groups most tolerant to environmental conditions, for example, Chironomidae larvae, prevailed in the studied urban lakes. The economic development of the lakes leads to ecosystem transformation and long-term eutrophication over time affecting the biotic indicators of surface water quality. The results obtained can serve as a basis for complex environmental monitoring of the urbanized territories in the taiga zone.

Impact of petroleum contamination on soil properties in Absheron Peninsula, Azerbaijan

This study aims to assess the extent of hydrocarbon and heavy metal contamination in soils from specific areas on Azerbaijan's Absheron Peninsula, including Absheron, Suraxanı, and Baku, and to evaluate the impact of this contamination on soil properties. Soil samples were analyzed for Total Petroleum Hydrocarbons (TPH) and heavy metals, including aluminum, arsenic, cadmium, lead, and iron, alongside assessments of soil physical, chemical and biological properties. The results revealed significant contamination across all studied areas, particularly in Suraxanı, where TPH levels reached 190 ± 20 mg/kg, exceeding the environmental standard of 100 mg/kg. Similarly, Suraxanı soils exhibited alarmingly high concentrations of heavy metals, with aluminum at 30,128 ± 1,500 mg/kg, arsenic at 50.94 ± 2.5 mg/kg, and cadmium at 0.153 ± 0.01 mg/kg, all surpassing acceptable limits. These contaminants severely degraded soil health, evidenced by increased bulk density (1.7 g/cm³ in Suraxanı) and reduced soil porosity. Microbial activity, a key indicator of soil fertility, was also markedly lower in contaminated regions, with the total bacterial count in Suraxanı being less than half that of the uncontaminated area. The findings underscore the urgent need for comprehensive soil management practices and stricter environmental regulations to mitigate contamination's adverse effects and protect both ecosystems and public health in Azerbaijan’s petroleum contaminated areas.

Heavy Metals in Tree Parts (Roots, Bark, Leaves) and Fruits Grown in Mechanic Workshops in Nigeria

The day-to-day activities carried out at the mechanic workshop like panel beating, welding, and automobile battery servicing may result in high amounts of heavy metals in the soil near mechanic workshops. Spent engine oils also emit a huge number of toxic metals, when disposed of on the floor at workshops, they settle on soil and are absorbed into nearby trees and plants. Therefore, making the tree parts and fruits at mechanic workshops prone to attack by heavy metals. This work is focused on testing if the presence of heavy metals would have adverse effects on the tree parts (roots, shoots, upper leaves, lower leaves) and fruits of mechanic workshops. A mechanic village in Abeokuta, Ogun State was chosen as the case study. The tree parts were oven-dried, ground, digested, and taken for analysis using AAS. Zinc (Zn), Lead (Pb), and Mercury (Hg) were found in higher amounts than the recommended allowable limits by WHO/FAO. Results show that the upper bark had the highest heavy metal concentration. In general, the tested heavy metals were recognized in the order: Zinc (Zn) > Lead (Pb) > Mercury (Hg) > Nickel (Ni) > Manganese (Mn) > Iron (Fe) > Copper (Cu). It is recommended that mechanic villages should be sited far from residential areas. Remediation of polluted soil should be encouraged. Phytoremediation was suggested to be the best method for reducing the concentration of heavy metal in the soils and tree parts at mechanic workshops. Continuous education and training should be provided for automobile repairers/ mechanics, emphasizing the environmental implications of their poor occupational waste management and the dangers of eating fruits and taking herbs from trees planted in workshops.

Spatial distribution, ecological and ecotoxicity evaluation of heavy metals in agricultural soils along Lala-Manjo Highway, Cameroon Volcanic Line

This study aims at assessing the spatial distribution, ecological and toxicity levels of heavy metals in agricultural soils of Lala-Manjo Highway in Cameroon. The soil samples were collected and analyzed by inductively coupled plasma-mass spectrometry. The result shows that Co, Cr, Cu, Hg, Mn, Ni, Sr, V and Zn concentrations are higher than those of the upper continental crust reference values except those of As, Cd and Pb. Correlation coefficient indicate similar input sources governed by same geochemical characteristics. Spatial distribution maps show high concentration of heavy metals in east, south and western part of the study area. Pollution indicators show that enrichment factor varied from moderate to high enrichment of heavy metals. The contamination degree (27.12–35.59), geo-accumulation index (0.01–4.94), and potential ecological risk index (RI = < 150) revealed a low to moderate levels of metallic pollution. The majority of stations have pollution load index and Nemerow integrated pollution index values greater than one, indicating serious pollution. Modified hazard quotient and toxic risk index suggest significant severity of pollution and low toxicity risk of heavy metals, pointing low toxicity effects of heavy metals to fauna and flora in the soil ecosystem. Considering the factors governing soils accumulation such as geology, climate and anthropogenic activities as well as the correlation with commonly used environmental background, it is proposed that the data from this study can be considered as a baseline of pollution to plan major agricultural developments in the area. The study underlines the importance of continuous monitoring and adaptive management for the preservation of soil ecosystem. The results may assist companies and local population in setting realistic targets for monitoring and remediation programs.

Comparative Analysis of Concentrations of Heavy Metals in Surface Water of Nafada, Ashaka and Almakashi Corridors of River Gongola, Nigeria

A study on comparative analysis of heavy metals concentrations in surface water was carried out in three selected stations: Nafada, Ashaka and Almakashi along the corridors of River Gongola in Gombe state for a period of eighteen months. The water samples were collected in triplicate from the sampling stations. Water samples were collected using sampling bottles of 250ml dipped below the water surface for water collection. Zinc, lead, copper, cadmium and manganese were determined using Atomic Absorption Spectrophotometer. The result elucidates that most of the heavy metals were found to be within the recommended ranges as compared to standard limits. The result of concentrations of heavy metals in the surface water elucidates that there was a significant difference (P&gt;0.05) among the months with respect to zinc and there was no significant difference in the concentration of lead (P&lt;0.05). The concentrations follow the order (Zn &gt;Cd&gt;Cu&gt;Mn&gt;Pb). The higher concentration of heavy metals was found in Ashaka corridors with Zinc concentration ranging between 0.99±0.01 and 0.33±0.01, Cadmium 0.88±0.02 and 0.03±0.00, Cupper 0.58±0.02 and 0.14±0.02, Manganese 0.87±0.56 and 0.17±0.01, Lead 0.28±0.36 and 0.01±0.01. The wastewater from the cement effluent factory in Ashaka might have impacted negatively on the water chemistry by elevating the levels of some heavy metals. Therefore, more intensive treatment of the factory effluents before discharging into the River Gongola is recommended.

Methane oxidation coupling with heavy metal and microplastic transformations for biochar-mediated landfill cover soil

The impact of co-occurring heavy metal (HM) and microplastic (MP) pollution on methane (CH4) oxidation by methanotrophs (MOB) in landfill cover soil (LCS) and the role of biochar in mediating these collaborative transformations remains unclear. This study conducted batch-scale experiments using LCS treated with individual or combined HMs and MPs, with or without biochar amendment. Differentiation in methanotrophic activities, HM transformations, MP aging, soil properties, microbial communities, and functional genes across the groups were analyzed. Biochar proved essential in sustaining efficient CH4 oxidation under HM and MP stress, mainly by diversifying MOB, and enhancing polysaccharide secretion to mitigate environmental stress. While low levels of HMs slightly inhibited CH4 oxidation, high HM concentration enhanced methanotrophic activities by promoting electron transfer process. MPs consistently stimulated CH4 oxidation, exerting a stronger influence than HMs. Notably, the simultaneous presence of low levels of HMs and MPs synergistically boosted CH4 oxidation, linked to distinct microbial evolution and adaptation. Methanotrophic activities were demonstrated to affect the fate of HMs and MPs. Complete passivation of Cu was readily achieved, whereas Zn stabilization was negatively influenced by biochar and MPs. The aging of MPs was also partially suppressed by biochar and HM adsorption.