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Effective solid waste management is a critical environmental challenge, particularly in rapidly growing Global South countries like Nigeria. This issue is exacerbated by burgeoning populations, lax waste regulations, and the widespread practice of open dumping. The deterioration of soil quality and alteration of water quality are major consequences of open waste dumping, posing significant environmental and public health risks. This study aims to assess the environmental risk and pollution status of soil and water resources near major dumpsites in Lagos. It aims to offer insights that can inform targeted interventions and policy measures not only in Lagos but also in comparable urban settings worldwide. Results indicated that important soil parameters, including TN (11.89-13.83 mg/kg), pH (6.45-7.35), sulfate (36.71-39.49 mg/kg), phosphate (9.31-14.39 mg/kg), and electrical conductivity (342-566 µS/cm), were significantly affected by the dumpsites. Additionally, concentrations of heavy metals varied, with some exceeding permissible limits set by international standards, highlighting the environmental challenges posed by improper waste disposal in urban settings like Lagos. The analyzed parameters for water were mostly within acceptable limits, indicating a lesser impact of the waste dump on water resources. Water samples from boreholes and hand-dug wells near three dumpsites showed that pH, TDS, and heavy metal concentrations were mostly within WHO limits, with borehole water deemed safe for drinking and hand-dug wells suitable for cleaning. To alleviate the environmental impacts of open dumpsites, it is recommended to implement effective waste segregation, recycling programs, controlled landfilling, and investment in waste treatment technologies, along with regular water quality monitoring to prevent further pollution and protect public health. While these measures offer opportunities, they also face significant challenges due to financial and land constraints. Therefore, strong public awareness, infrastructure investment, and government commitment are essential, along with coordinated efforts among the government, private sector, and communities., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

This comprehensive research investigates heavy metal contamination in the rapidly developing town of Jebba in north-central Nigeria, which is essential to the nation's economy due to its agro-allied and non-agro-allied businesses. The research focuses on soil samples, collecting and analyzing 137 surface soil samples to assess the presence of 25 distinct metals. After statistical analysis and simple mathematical models are applied to the data, the amounts of harmful metals and their probable causes are revealed. The study identifies geogenic and anthropogenic origins of toxic metals, with some elements exceeding average crustal concentrations. Non-homogeneous metal dispersion is shown in the region by spatial distribution maps. The geo-accumulation index reflects various amounts of contamination, with particular metals posing significant threats to the ecosystem. Additionally, the study compares results with worldwide studies, revealing distinct pollution patterns in Jebba. The research delves into weathering processes, employing chemical indices to quantify the level of soil weathering and uncovering a prominent role of geogenic activities in metal release. Bivariate correlation and principal component analysis indicate links and possibly common sources among heavy metals, emphasizing anthropogenic contributions. In addition, assessments of ecological and medical risks are conducted, indicating possible threats to human wellness and the ecosystem. Children, in particular, are regarded as especially vulnerable to non-carcinogenic health concerns, with various heavy metals posing potential threats through diverse exposure routes. The study emphasizes the need to implement remediation procedures to address the risks to public health and the environment related to metal pollution., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest regarding the publication of this article., (Copyright © 2024 Elsevier B.V. All rights reserved.)

An animal charcoal contaminated cottage industry soil in Lagos, Nigeria (ACGT) was compared in an ex post facto study with a nearby unimpacted soil (ACGC). Hydrocarbon content was higher than regulatory limits in ACGT (180.2 mg/kg) but lower in ACGC (19.28 mg/kg). Heavy metals like nickel, cadmium, chromium and lead were below detection limit in ACGC. However, all these metals, except cadmium, were detected in ACGT, but at concentrations below regulatory limits. Furthermore, copper (253.205 mg/kg) and zinc (422.630 mg/kg) were above regulatory limits in ACGT. Next generation sequencing revealed that the procaryotic community was dominated by bacteria in ACGC (62%) while in ACGT archaea dominated (76%). Dominant phyla in ACGC were Euryarchaeota (37%), Pseudomonadota (16%) and Actinomycetota (12%). In ACGT it was Euryarchaeota (76%), Bacillota (9%), Pseudomonadota (7%) and Candidatus Nanohaloarchaeota (5%). Dominant Halobacteria genera in ACGT were Halobacterium (16%), Halorientalis (16%), unranked halophilic archaeon (13%) Salarchaeum (6%) and Candidatus Nanohalobium (5%), whereas ACGC showed greater diversity dominated by bacterial genera Salimicrobium (7%) and Halomonas (3%). Heavy metals homeostasis genes, especially for copper, were fairly represented in both soils but with bacterial taxonomic affiliations. Sites like ACGT, hitherto poorly studied and understood, could be sources of novel bioresources., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Electronic waste (e-waste) dismantling and dumpsite processes are major sources of organophosphate flame retardant and plasticiser emissions and may pose potentially adverse effects on environment and human health. In 20 outdoor dust and 49 soil samples collected from four e-waste dismantling and three e-waste dumpsites in two States of Nigeria (Lagos and Ogun), we identified 13 alternative plasticisers (APs), 7 legacy phthalate plasticisers (LPs), and 17 organophosphorus flame retardants (OPFRs) for the first time in African e-waste streams. In the samples from dismantling sites, the range (median) concentrations of ∑ 13 APs, ∑ 7 LPs, and ∑ 17 OPFRs were 11-2747 μg/g (144 μg/g), 11-396 μg/g (125 μg/g), and 0.2-68 μg/g (5.5 μg), in dust respectively and 1.8-297 μg/g (55 μg/g), 1.3-274 μg/g (48.5 μg/g), and 1.6-62 μg/g (1.6 μg/g), in soil respectively. Results for soil samples from e-waste dumpsites were (6.6-195 μg/g (23.7 μg/g), 6.0-295 μg/g (54.8), and 0.4-42.3 μg/g (9.0 μg/g) for ∑ 13 APs, ∑ 7 LPs, and ∑ 17 OPFRs respectively. Overall, concentrations of APs were significantly higher at the dismantling sites (p = 0.005) compared to dumpsites, levels of LPs were higher at dismantling sites but not significant, while OPFR concentrations were significantly higher in dumpsite samples (p = 0.005). Plasticisers were found to be major contributors to pollution at e-waste dismantling sites, while OPFRs were associated with both automobile dismantling and e-waste dumpsite processes. Following particle size fractionation of selected soil samples, higher concentrations of targeted compounds were observed in the smaller mesh (180 μm) soil sieve fraction. For dust, the total median estimated daily intake via ingestion and dermal adsorption (EDI ing and EDI derm ) ranged from 43 to 74 ng/kg bw/day and 0.4-0.7 ng/kg bw/day, respectively. Correspondingly, 4.6-45 ng/kg bw/day and 0.015-0.57 ng/kg bw/day were the values found for soil, respectively. According to these results, the targeted chemicals do not appear to pose a non-carcinogenic risk to e-waste workers through ingestion or dermal contact of bio-accessible fractions of the chemicals. Human biomonitoring campaigns are recommended in the Nigerian e-waste environment considering the elevated concentration levels found for the majority of targeted compounds and that risk parameters required for exposure assessment were only available for a limited number of compounds., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The concentrations, sources, and risk of twenty organochlorine pesticides (OCPs) in soils and dusts from a typical urban setting in the Niger Delta of Nigeria were examined. The Σ20 OCP concentrations (ng g -1 ) varied from 4.49 to 150 with an average value of 32.6 for soil, 4.67 to 21.5 with an average of 11.7 for indoor dust, and 1.6 to 96.7 with an average value of 23.5 for outdoor dust. The Σ20 OCP concentrations in these media were in the order: soil > outdoor dust > indoor dust, which was in contrast with the order of the detection frequency, i.e., indoor dust (95 to 100 %) > soil (60 to 90 %) > outdoor dust (30 to 80 %). The concentrations of the different OCP classes in these media followed the order: aldrin + dieldrin + endrin and its isomers (Drins) > chlordanes > dichlorodiphenyltrichloroethane (DDTs) > hexachlorocyclohexane (HCHs) > endosulfans for outdoor dust and soil, while that of the indoor dust followed the order: Drins > chlordanes > endosulfans > DDTs > HCHs. The cancer risk values for human exposure to OCPs in these sites exceeded 10 -6 which indicates possible carcinogenic risks. The sources of OCPs in these media reflected both past use and recent inputs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

This research examined soil contamination and the uptake of potentially toxic elements (PTEs) by maize plants in mining communities. We collected 192 soil samples and 40 maize plant samples from two mining areas and a pristine site. We analyzed the physical properties and element content of the soil, including phosphorus, nitrogen, potassium, Fe, Zn, Co, Pb, Cd, Cr, and Ni. We also measured the elemental concentrations in the maize plants. The study found higher levels of Zn, Cu, and Pb at the mining sites compared to the control areas. The pollution factor (CF) indicated pollution with Cu > Pb > and > Zn at both mine sites. The pollution index (PLI) showed no pollution in the Nkalagu mine and control sites, but heavy and moderate pollution at the Ameka mine and control sites, respectively. The Ameka mine site was enriched with Zn. The bioaccumulation coefficient (BAC) was < 1 except for Zn at the Nkalagu mine and control site. The transfer factor for Fe and Zn from root to shoot was > 1. Pb was > 1 in all study areas except the Ameka mining areas. The results suggest remediation is needed for the two mine sites, especially at Ameka., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

The objective of the research was to examine microbial characteristics, metabolites produced, and the potential radiological risks present in mining soils located in Keana, North Central Nigeria. Soil samples were collected from various locations within Keana, Nasarawa State. Bacterial isolation was carried out, and molecular techniques were employed to characterize the bacteria found in the collected soil samples. Additionally, the susceptibility of these isolates to antibiotics was determined, and the bacteria screened for their ability to produce metabolites. The isolated bacteria were classified into three groups: Actinobacteria, Firmicutes, and Proteobacteria. The analysis of the spectra revealed that 1595 compounds were produced, including carboxylic acids, nitro compounds, aldehydes, anhydrides, esters, ketones, amides, phenols, alcohols, alkanes, alkenes, alkynes, and arenes. Some of the metabolites produced were oleic acid, 1,3-dioxolane, linoelaidic acid and oleic acid, 1-nonadecene, butylated hydroxytoluene, diisooctyl phthalate, bis(2-ethylhexyl) phthalate among others, and 1,2-benzenedicarboxylic acid (85.32%) as the most produced metabolite. Among the antibiotics tested, levofloxacin and ciprofloxacin exhibited the strongest antibacterial properties against the isolates. Airborne gamma-ray spectrometry analysis identified elevated levels of potassium, thorium, and uranium in the soils, indicating potential environmental hazards. However, no significant correlation was found between the presence of bacteria and radioactive elements. These findings emphasize the importance of comprehensive environmental monitoring in Keana to address potential health risks associated with microbial contamination and radioactive materials. Additionally, the study highlighted the role of microbial diversity in Keana soils in promoting the production of secondary metabolites with potential applications in pharmaceutical and industrial sectors.., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Heavy metal contamination in the soil and phytoremediation potential of the plants cultivated around the Gosa dumpsite were evaluated using pollution indices. The concentrations of heavy metals in the soil and plant samples were determined using an atomic absorption spectrophotometer (Agilent 280FS AA). The mean heavy metal contents in the upper and lower soil layers ranged from 0.37 to 1662.61 mg/kg and 0.32 to 1608.61 mg/kg, respectively, in ascending order of Cd < Cr < Cu < Ni < Pb < Co < Zn < Fe. The results revealed a steady depthwise decrease in heavy metal contents from the upper to lower soil layers. Co, Pb, Zn and Fe were introduced through geogenic and anthropogenic pathways, while Cr, Ni, Cu and Cd were derived mainly from anthropogenic sources. The mean soil enrichment in the heavy metals ranged from 0.96 to 237.04 in the ascending order of Fe > Co > Pb > Zn > Cu > Cd > Cr > Ni. The soil was moderately polluted with Co, Cu, Pb, Zn, Fe and Cd but heavily polluted with Cr and Ni. The results revealed that 37.5% of the sites studied had pollution load indices greater than 1.0, indicating gradual deterioration in overall soil quality. The concentrations of Pb, Cd and Fe exceeded the recommended limits for the five plant species assessed. The transfer factor (TF) values of okra plant 1 (0.7536), water hyacinth (1.3768), and Amaranthus hybridus (0.9783) indicated excellent Cd phytoremediation potential. Okra Plant, water hyacinth and Amaranthus hybridus had excellent potential for phytoremediation of Cu, Fe and Pb, respectively. The study area was strongly enriched in Fe, Cd, Cr, and Ni, suggesting some degree of soil pollution, while the plants demonstrated an excellent capacity to accumulate Cd, Cu, Fe and Pb. This dumpsite should be adequately monitored while proper remediation measures are adopted by government authorities., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Soil contamination due to industrial activity in ceramics production is of concern because of the risk of heavy metal pollution. Successive extraction was used to measure and identify the concentrations of Cd, Mn, Ni, and Pb in farming soils near a ceramics company in Nigeria. Furthermore, soil pH and particle size analyses were determined. The concentration of Pb was the highest, followed by that of Ni, Mn, and Cd (lowest), and the mean level of Cd exceeded the regulatory allowed limit of 1.4 mg kg -1 . The order of the metals' mobility factors was as follows: Cd > Mn > Ni, Pb. While the Fe-Mn oxide phase had 37% (Mn) and 20 to 83% (Ni), the residual fraction had approximately 30% (Cd) and 19 to 50% (Pb). Soil pollution evaluation was performed using enrichment factor (EF), contamination factor (CF), pollution load index (PLI), and geoaccumulation index (I geo ). Values of EF indicated significant enrichment for all metals, as the EF mean values for Cd, Ni, and Pb in soil were > 1.5. Total EF is of the order Cd > Pb > Ni > Mn. CF results revealed moderate to very high contamination (CF < 1: 3 ≤ CF ≥ 6). Similarly, the PLI indicated moderately to severely polluted soil. The order is 100 m > 200 m > 300 m > 400 m. The I geo ranged from 1.46 to 2.76 (Cd), 0.07 to 1.62 (Ni), and 0.05 to 2.81 (Pb). The PCA, CA, and EF analyses suggest that the metals are a consequence of anthropogenic activities., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Petroleum contamination constitutes a frequent incidence in various petroleum depots in Nigeria. In this study, the polycyclic aromatic hydrocarbons (PAHs) present in soil and water in communities around Petroleum Products Marketing Company (PPMC) Suleja, Nigeria, were evaluated and degraded using indigenous microorganisms. The samples sites were divided into 7 plots from where samples of water and soil were obtained: one within the PPMC depot, five from communities surrounding the depot, and the control 93,000 km from the depot. The microbial counts were determined using spread plate inoculation technique on minimal salt media. The microbial isolates were characterized and identified based on their cultural, biochemical, and molecular characteristics. The potential of the microbial isolates to utilize 0.05 mL of diesel, kerosene, engine oil, and crude oil was determined in a Bushnell Haas Broth, and the biodegradation was determined by total viable cell counts and spectrophotometry. The ability of the isolates to mineralize PAHs was also evaluated in a minimum salt media. The bacterial isolates were species of Streptococcus, Pseudomonas, Staphylococcus, Proteus, Escherichia, and Bacillus, while species of Penicillium, Aspergillus, Mucor, and Rhizopus were isolated among the fungi. Aspergillus niger strain ATCC 1015 and Bacillus thuringiensis strain M43 showed high capacity to utilize the 16 priority PAHs. The pahE1 gene was used by Bacillus thuringiensis, Pseudomonas aeruginosa and A. niger, while Penicillium notatum used pahE2 gene for the degradation of the PAH. The current study identified microbial isolates that can utilize priority PAHs, making them beneficial for oil spill bioremediation in tropical environments., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

This study investigates the concentrations, sources, and ecological and human health risks resulting from exposure to polycyclic aromatic hydrocarbons (PAHs) in soils of rural communities around gas flaring points in Delta State, Nigeria. PAHs were extracted from these soil samples with hexane/dichloromethane by ultra-sonication and the extracts were cleaned on a silica gel/alumina-packed column. The PAH concentrations in the extracts were quantified by gas chromatography-mass spectrometry (GC-MS). The Σ16 PAH concentrations in soils from these communities varied from 2370-134 000, 461-389 000, and 2130-34 900 μg kg -1 for Emu-Ebendo (EME), Otu-Jeremi (OTJ) and Ebedei (EBD), respectively. The estimated lifetime carcinogenic risk values recorded in this study were above the acceptable limit of 10 -6 , indicating a high potential carcinogenic risk resulting from human exposure to PAHs in these soils. The isomeric ratio and principal component analysis results suggest that emissions from high-temperature combustion, potentially gas flaring, vehicular emissions, burning of wood/biomass, and fossil fuel combustion are responsible for the high concentrations of PAHs in soils of these rural communities. This study recommends implementing remediation and source control measures to minimise the impact of PAHs in the affected soils on humans and the environment.

This study assessed the physicochemical properties of soils and their levels of heavy metal contents in soils along the Enyigba mining site in Ikwo, Ebonyi State, Nigeria. A total of 96 samples of soil were taken at depths of 0 to 20 cm using a soil auger and core sampler at a horizontal spacing of 100 m between each location and examined using standard laboratory techniques. The control soil samples were taken from the Alex Ekwueme Federal University Experimental and Research Farm in Ebonyi State, at a distance of 50 m from each spot at a depth of 0 to 20 cm. The results obtained from this study showed significant variations in the physicochemical properties and heavy metal levels of the soil from the Enyigba mining site, indicating that the mining activities have contaminated the soil. The result also indicated that mining operations may be responsible for the increase in sand and the decrease in silt and clay particles. The mining site's pH was typically low, indicating that the soil is naturally acidic. The contamination indices showed that lead recorded very high contamination factor of 27.068, while iron, nickel and zinc were low. The observed high concentration factor of lead had an impact on the soil's bulk density, saturated hydraulic conductivity, total porosity, calcium, potassium ion, magnesium ion, total nitrogen, organic carbon, cation exchange capacity, phosphorus and base saturation contents. It is recommended that the government's Ministry of Environment, at all levels, take a proactive stance in managing the excessive and subpar mining operations in the study area., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Lateritic soils are prevalent in the tropical regions, and they are used for various construction purposes including landfill liner applications. However, their contaminant attenuation potentials through sorption and the influence of parent rocks on this property are poorly understood. This study investigates lateritic soils from southwestern Nigeria as barrier to leachate migration in engineered landfills and related waste containment facilities. The lateritic soils were investigated through X-ray diffraction (XRD), geochemical analysis and batch equilibrium sorption test to evaluate the competitive sorption of Mn, Cd, Pb, Cu and Cr which are common in landfill leachates. The XRD analysis shows that the kaolinite and dickite are the dominant clay minerals present in the lateritic soils, implying low desiccation cracking and low shrink-swell behaviour. The geochemical analysis indicate that the lateritic soils are silico-alumino-feruginuous with average major oxide composition of SiO 2, Al 2 O 3 and Fe 2 O 3 of 50.86 wt%, 29.83 wt% and 14.29 wt%), respectively. Additional oxides with lower abundance include TiO 2 (1.55 wt%), Na 2 O (0.01 wt%), MgO (0.36 wt%), CaO (0.15 wt%) and K 2 O (1.52 wt%). The lateritic soils contain trace amount of heavy metals with average concentrations of Cd (0.039 ppm), Pb (0.548 ppm), Cr (0.189 ppm), Cu (0.964 ppm), Mn (0.145 ppm). Furthermore, the low abundance of sodium oxide in the lateritic soils indicates that the soil particles are not susceptible to dispersion while the presence of considerable amount of iron and manganese oxides signify its good heavy metal retention. The batch equilibrium sorption analysis shows that the lateritic soils derived from granite-gneiss and charnockite exhibit better sorption potential than those derived from schist and quartzite. This high sorption capacity is intricately related to the presence of goethite in the soils. The sorption of these trace metals onto the lateritic soils follows Langmuir type isotherm and these isotherms deviate from the corresponding desorption isotherms to different degrees indicating various extents of hysteresis. The sorption hysteresis indices for these trace metals range from 0.63 to 0.99 and imply that the trace metals may re-leached to the surrounding soils and groundwater. Thus, it is recommended that landfill liners utilizing these lateritic soils are design as a composite containment facility by integrating compacted soil liners, leachate collection systems and monitoring networks to ensure effective environmental protection., Competing Interests: Declaration of competing interest There is not conflict of interest among the authors. FUNDING: This research was funded by the Tertiary Education Trustfund (TETFund) (Grant number [TETF/DASDT/UNIV/ONDO/ASTD/2017VOL1]). Author S.O. Daramola. has received research support from TETFund., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Polycyclic aromatic hydrocarbons (PAHs) are known to be representative carcinogenic environmental pollutants with high toxicity. However, information on the potential ecological and environmental risks of PAH contamination in soil remains scarce. Thus, this study was evaluated the potential ecological risks of PAHs in soils of five Korean areas (Gunsan (GS), Gwangju, Yeongnam, Busan, and Gangwon) using organic carbon (OC)-normalized analysis, mean effect range-median quotient (M-ERM-Q), toxic equivalent quantity (TEQ) analysis, and risk quotient (RQ) derived by the species sensitivity distribution model. In this study, atmospheric particulate matter has a significant effect on soil pollution in GS through the presence of hopanes and the similar pattern of PAHs in soil and atmospheric PAHs. From analysis of source identification, combustion sources in soils of GS were important PAH sources. For PAHs in soils of GS, the OC-normalized analysis, M-ERM-Q, and TEQ analysis have 26.78 × 10 5 ng/g-OC, 0.218, and 49.72, respectively. Therefore, the potential ecological risk assessment results showed that GS had moderate-high ecological risk and moderate-high carcinogenic risk, whereas the other regions had low ecological risk and low-moderate carcinogenic risk. The risk level (M-ERM-Q) of PAH contamination in GS was similar to that in Changchun and Xiangxi Bay in China. The Port Harcourt City in Nigeria for PAH has the highest risk (M-ERM-Q = 4.02 and TEQ = 7923). Especially, compared to China (RQ Phe =0.025 and 0.05), and Nigeria (0.059), phenanthrene showed the highest ecological risk in Korea (0.001-0.18). Korea should focus on controlling the release of PAHs originating from the PM in GS., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: This study determined the levels of polycyclic aromatic hydrocarbons (PAHs) in the soil around typical automobile repair workshops in Nigeria. Risk assessment associated with human contact with the soil was carried out using hazard quotient (HQ) and incremental life cancer risk (ILCR) from human unconscious ingestion and dermal contact with the soil., Methods: Soil samples were obtained at different automobile workshops in Ado-Ekiti, Western Nigeria. The PAHS in the samples were extracted using dichloromethane and extracts were cleaned up using silica-alumina gel open column chromatography. Analysis of PAHs in the soil was done using a gas chromatograph coupled to a mass selective detector operated on electron ionization mode., Results: The results showed the mean PAHs concentration at the sampling locations ranged from 5.58 - 6.4 μg/g and the mean ∑ carcinogenic PAHs was 58.4 μg/g , equivalent to 59.39 % of total PAHs observed. The mean Toxicity equivalence (TEQs) ranged from 0.02 - 6.680 μg/g. Benzo (a) pyrene and dibenzo(a,h)anthracene have the highest toxicity equivalent. The total ILCRs from accidental ingestion and dermal contact in adults were 1 ×10^(-3) and 9.8 ×10^(-5) , for adults and children respectively; both are higher than the permissible limit stipulated by the World Health Organization.The HQs obtained are several folds higher than 1. This implies high carcinogenic and non-carcinogenic risks for children and adults., Conclusions: The study revealed the levels of PAHs and also revealed the risks associated with human contact with the soil around automobile repair workshops., Competing Interests: No competing interests were disclosed., (Copyright: © 2024 Adesina OA et al.)

Soil fertility, soil health and environmental management through the estimation of background concentration of potentially toxic elements is required for environmental safety. This study aims at investigating the concentration, fertility and potential health risks of some d-block metals (Ti, V, Fe, Mn, and Mo) in some agricultural soils, and establishes the relationship between the metals and some soil properties. Eight elevation ranges resulted from the digital elevation models of the study area; two in Ishibori (NG1, NG2), three each in Agoi-Ibami (CG1, CG2, CG3) and Mfamosing (SG1, SG2 and SG3). One soil profile pit was sunk along each of the elevations. Thirty-five composite soil samples were collected at 0-30, 30-60, 60-90, 90-120, 120-150, 150-180 and 180-200 cm depending on soil depth. Only the profile means of Mn (660.82 ± 612.89 mg/kg) and Mo (2.61 ± 0.73 mg/kg) exceeded permissible concentrations and would pose threats to the environment. Also, the concentrations of the d-block metals exceeded permissible values in Ishibori making them prone to toxicity. The metals were irregularly distributed with depth; however, Mn and Fe were concentrated in the subsurface soils. Clay and sand contents correlated positively and negatively, respectively with all the d-block metals at p < 0.05. The linear model was more efficient in estimating V and Mo via soil properties with adjusted R 2 of 33 - 67% for the metals. In conclusion, agricultural activities and geology may influence the accumulation of d-block metals, hence the call for environmental monitoring to curtail metals' assimilation by crops. HIGHLIGHTS: • Mn and Mo threaten the environment the most. • Soils in the Southern Guinea Savannah are most prone to d-block metals contamination. • BD, pH, Mg, and CEC are the best predictors of d-block metals in the soils. • The linear model was best performing in the estimation of V and Mo, respectively., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

This study investigates hydrocarbon pollution in the Ahoada community of the Niger Delta region of Nigeria. The study uses a geographic information system (GIS) for mapping oil spill hotspots in the region. The resistivity method was used to delineate the extent of hydrocarbon pollution to a depth of 19.7 m in the Ahoada area of the region. Three categories of soil samples, impacted soil (IMS), remediated soil (RS), and control soil (CS), were collected and analyzed for the presence of BTEX, PAH, TPH, TOC, and TOG. The concentrations of the samples from the IMS and RS were compared to that of the CS to determine the extent of pollution. The GIS mapping shows that the most polluted areas in the Niger Delta Region are Rivers, Bayelsa, and Delta states. Results of the geophysical images revealed contaminants' presence to depths beyond 20 m at some locations in the study area. The highest depth of contaminant travel was at Ukperede. Soil samples' analysis showed that the range of concentrations of TPH in IMS at Oshie was 17.27-58.36 mg/kg; RS was 11.73-50.78 mg/kg which were higher than the concentrations of 0.68 mg/kg in the CS. PAHs are more prevalent in Ukperede, ranging from 54.56 to 77.54 mg/kg. BTEX concentrations ranged from 0.02 to 0.38 mg/kg for IMP and 0.01-2.7 mg/kg for RS against a CS value of 0.01 mg/kg. The study revealed that there are characteristically high resistivity values in the samples which were corroborated by the findings from the resistivity survey. TOC was found to be higher in the IMS and RS than in the CS, demonstrating that a significant quantity of the hydrocarbon has undergone appreciable decomposition., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Crude oil exploitation in the Niger Delta, particularly in Ogoniland, brought environmental devastation occasioned by petroleum pollution, as farmlands and water sources were destroyed. This study was designed to remediate crude oil contaminated water obtained from water sources in Ogoniland using two green algal species. Thirty water samples were collected from eight different water sources. The samples were analysed for total petroleum hydrocarbon (TPH) using gas chromatography/flame ionization detector (GC/FID). Algal samples were collected from Ogba River and at wetland in Military Hospital Benin, Edo State, Nigeria. The algal samples were identified, screened, optimized and grown in Bold basal medium. Results obtained from the determination of TPH showed that the infiltrated pond (Exc) sample site had the highest concentration among all the sites sampled with 198.8329 μg/L, R 2 with 134.1296 μg/L, R 1 with 108.9394 μg/L, R 3 with 105.8011 μg/L, R 4 with 98.442 8 μg/L, the hand-dug wells (Wll) had 9.6586 μg/L while the borehole (Bhl) had the lowest with 1.8310 μg/L. It was deduced that pollution of water sources was principally because of pollutants washed from the soil environment into the open surface water sources via run-off rather than through the seepage from the underground aquifers, incriminating illegal oil mining and artisanal refining. Results obtained from the analysis of algal growth medium indicated that the two algal species were able to absorb the hydrocarbon contaminants, albeit at different rates, corresponding with the algal growth rate. Analysis of algal biomass after 4 weeks of remediation showed that from the initial 10.27 μg/20 mL added to the growth medium, the highest TPH mean value of 0.490 μg/20 mL was extracted from Ulothrix zonata (F.Weber & Mohr) Kützing biomass grown in Exc compared to 0.344 μg/20 mL of TPH extracted from Chlorella sorokiniana Shihira & R.W.Krauss grown in the same sample site. Also, Ulothrix zonata had higher TPH yield 0.023 μg/20 mL in Bhl compared to Chlorella sorokiniana 0.021 μg/20 mL of TPH from the same water source. This result indicated Ulothrix zonata had superior TPH phycoremediation ability to Chlorella sorokiniana. While the present study calls for deployment of the algal species for field trial, it is strongly recommended that crude oil pollution should be discouraged., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Potentially toxic elements (PTEs) occur naturally in most geologic materials. However, recent anthropogenic disturbances such as ore mining have contributed significantly to their enrichment in soils. Their occurrence in soil may portend a myriad of related risks to the environment and biota. Most traditional soil quality evaluation methods involve comparing the background values of the elements to the established guideline values, which is often time-consuming and fraught with computational errors. As a result, to conduct a comprehensive and unbiased evaluation of soil quality and its effects on the ecosystem and human health, this research combined geochemical, numerical, and GIS data for a composite health risk zonation of the entire study area. Furthermore, the multilayer perceptron artificial neural network (MLP-NN) was used to forecast the most important toxic components influencing soil quality. Geochemical, statistical, and quantitative soil pollution evaluation (pollution index and ecological risk index) showed that apart from mining, the spread and association of trace elements and oxides occur as a consequence of surface environmental conditions (e.g., leaching, weathering, and organo-metallic complexation). The hazard quotients (HQs) and hazard index (HI) of all PTEs were greater than one. This indicates that residents (particularly children) are more susceptible to risks from toxic element ingestion than dermal exposure and inhalation. Ingestion of As and Cr resulted in higher cancer risks and lifetime cancer risk levels (> 1.0E 04), with risk levels increasing toward the northeastern, western, and southeastern directions of the study area. The low modeling errors observed from the sum of square errors, relative errors, and coefficient of determination confirmed the efficiency of the MLP-NN in pollution load prediction. Based on the sensitivity analysis, Hg, Sr, Zn, Ba, As, and Zr showed the greatest influence on soil quality. Focus on remediation should therefore be placed on the removal of these elements from the soil., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

In Nigeria, artisanal mining has become a serious issue. In the Nigerian mining region of Arufu Pb-Zn-F, this study assessed the level of pollution, ecological hazards, and health risks related to the presence of metals in the water. In the dry and rainy seasons, 36 water samples (20 from the ground, 10 from the surface, and six from the mine) were gathered. Samples were examined for the presence of heavy metals such as Cr, Co, Ni, Cu, Zn, As, Cd, and Pb. Other than Cu, Zn, As, Cd, Sb, and Cd (surface water, dry season), which were below the acceptable norm, all water samples had metals over the suggested limits. Heavy metals from nearby mining activities polluted the water, according to contamination evaluations utilizing the contamination factor (CF). Metals in the water may pose very significant ecological dangers, according to ecological risk assessments. The evaluation of human health risks revealed that both adults and children in the region are susceptible to carcinogenic and non-carcinogenic health hazards since the hazard index (HI) values for both indices were above 1 × 10 -5 and above 1, respectively. This report emphasizes the need for monitoring mining operations in the nation to safeguard public health.

This report presents the findings of the concentrations, distributions and health risks assessment of heavy metals (HMs) and volatile organic compounds (VOCs) in topsoils of two typical automobile mechanic villages (MVs) situated within Ogun State, Nigeria. One of the MVs is located in basement complex terrain (Abeokuta), while the second is in the sedimentary formation (Sagamu). Ten composite samples were collected at depth of 0-30 cm with the aid of soil auger from spent oil-contaminated spots within the two MVs. The chemical parameters of interest were Pb, Cd, benzene, ethylbenzene, toluene, total petroleum hydrocarbon (TPH) as well as oil and grease (O&G). In addition, soil pH, cation exchange capacity (CEC), electrical conductivity (EC) and particle size distribution were also evaluated in order to find out their impacts on assessed soil pollutants. Results revealed that the soils in both MVs are of sandy loam texture, slight acidic to neutral pH, mean CEC < 15 cmol/kg and mean EC > 100 μS/cm. The mean concentration of each of analyzed HMs and VOCs in soils from the two MVs was < 5 mg/kg, while the mean values of TPH and O&G content were > 50 mg/kg. The mean Cd values in soils of both MVs were higher than the national soil screening level of 0.8 mg/kg, but lower than the Canadian and Italian guidelines. There is no significant correlation between each of HMs/VOCs and any of assessed soil physicochemical variables. The non-cancer risk expressed in terms of hazard index (HI) was > 1 via oral ingestion route for adults and children at the two MVs, indicating adverse non-carcinogenic health risk. The HI > 1 value was obtained for adults only through the dermal absorption pathway in Abeokuta MV. However, HI values for the two age groups at the two MVs via inhalation route were < 1, indicating no likelihood of any non-carcinogenic effects via the breathing exposure. The potential of non-cancer risk via oral ingestion route in both MVs was derived from the contributive ratios of HMs and VOCs in the order: Cd > benzene > Pb > toluene. The carcinogenic risk (CR) values due to ingested Cd, benzene and Pb for both age groups at the two MVs exceed the safe limit range of 10 -6 to 10 -4 . Cadmium, benzene and lead made considerable contributions to the estimation of CR through dermal exposure for adults only in Abeokuta MV. The CR values via inhalation pathway for adults and children in both MVs were within the threshold range. Artisans and children should circumvent accidental ingestion of contaminated soils in addition to wearing of protective clothes during routine vehicle maintenance activities., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

This study was designed to determine the level of potentially toxic elements (PTEs) contamination in soil and selected fruits and assesses the health risk of inhabitants in the abandoned tin mining community in Kuba, Bokkos LGA. Samples of the abandoned mine soil and selected fruits mango (Magnifera indica), guava (Psidium guajava), avocado pear (Persea americana), and banana (Musa spp)) from the vicinity of the abandoned mine were analyzed for the presence of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) using inductively coupled plasma mass spectrometry (ICP-MS). The results showed that the levels of all the PTEs analysed in the abandoned mine soil samples were significantly (p < 0.05) higher than their corresponding values in the control soil from the non-mining area. Except for Cd, the mean concentrations of As, Cr, Cu, Mn, Ni, and Pb were significantly higher than the FAO/WHO maximum permissible limit. Except for Zn in guava fruits and Cd in avocado fruits, the mean concentration of PTEs in fruits from abandoned mines was significantly (p < 0.05) higher than their corresponding control values. In contrast, the mean levels of As, Cr, Cu, Mn, Ni, and Pb in the investigated fruits were significantly (p < 0.05) higher than FAO/WHO maximum permissible limits established for fruits. The studied fruits remarkably took up and bioaccumulated PTEs from the abandoned mine soil. Mango fruit significantly bioaccumulated As (5.40), Cd (3.40), and Zn (2.81). Guava fruit bioaccumulated As (1.50) and Cd (4.60), while avocado bioaccumulated As (3.53), Cd (3.80), and Zn (6.48). Banana bioaccumulated As (0.96), Cd (0.80), and Zn (6.78). The hazard quotient values for PTEs investigated in fruits for adults, and children were several folds greater than 1. The hazard index (HI) for the PTEs through consuming fruits for children and adults was greater than 1, indicating that possible health risks exist for both local children and adults. However, the HI values for the children were higher than those for adults, implying that children were exposed to more potential noncarcinogenic health risks from PTEs than adults. The total cancer risk (TCR) values for Cr and Ni for all the fruits studied were within 10 -3 -10 -1 , which is several-fold higher than the permissible limits (10 -6  and < 10 -4 ), indicating high carcinogenic risk. TCR values for Cd and Pb in all the fruits, except for Cd in guava and avocado fruits for children, were within the range of 10 -5 -10 -4 , indicating that they are associated with moderate risk. The CR values for all the PTEs in all the fruits for adults and children except for mango fruit adults were within 10 -2 -10 -1 , indicating high carcinogenic risk. In conclusion, the results and risk assessment provided by this study indicate that human exposure to fruits from abandoned mines suggests a high vulnerability of the local community to PTE toxicity. Long-term preventive measures to safeguard the health of the residents need to be put in place., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

The concentrations of potentially toxic elements (PTEs) and their contamination indices were determined in urban soil from five different land-use zones, namely municipal solid waste landfill (MWL), industrial area (INA), heavy traffic area (TRA), residential area with commercial activities (RCA), and farmland (FAL) in Osogbo Metropolis. Ecological and human health risk assessments were also evaluated. Based on the average concentrations, the highest values of As, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn were found at INA, while the maximum concentrations of Ba, Cd, and Co were observed at MWL. The average enrichment factor (EF) values of Cd, Cu, Pb, and Zn showed very high to extremely high enrichment in the soils of INA, MWL, TRA, and RCA, while the EF values of Ba, Co, Cr, Fe, Ni, and V were significantly to moderately enriched in the aforementioned land-use zones. This trend was consistent with the average contamination factor (Cf) values of Cd, Cu, Pb, and Zn, which indicated considerable to very high contamination at INA, MWL, TRA, and RCA. However, Cf values of Ba, Co, Cr, Fe, Ni, and V had moderate contamination variously at the different land-use zones. Furthermore, the potential ecological risk factor (Er i ) values for all the PTEs were < 40, which indicated low Er i , except for Cd and to some extent Pb. The Er i value of Cd was high to very high at MWL, INA, TRA, and RCA, and low at FAL, while Er i of Pb was only moderate at INA. Assessment of health quotient (HQ) of non-carcinogenic health risks was within acceptable limit (< 1) for most of the PTEs in the different zones for adults and children, except the maximum HQ value of Pb at INA (HQ = 1.0), which was beyond the acceptable limit for children. The carcinogenic risk was within the acceptable limit (1.0 × 10 -6 ) in all the zones, except INA. This may pose health challenges to children in the vicinity of the pollution sources. Continuous monitoring of PTEs to reduce exposure to PTE should be considered., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

An assessment of the heavy metal levels associated with municipal waste in the vicinity of the Pele dumpsite, Ondo State, Nigeria, has been undertaken with the view of evaluating the environmental hazards associated with the dumpsite. A total of 23 composite soil samples were collected, measured, and analyzed for six toxic metals, and three dipole-dipole profiles were occupied within the study area. Six different pollution indices were used to evaluate the soil pollution level and ecological risk associated with the dumpsite. The 2D electrical resistivity method was used to delineate the extent of the pollution plume. The mean concentration (in µg/g) of the metals followed a descending order as Zn (75.78) > Cu (37.09) > Pb (25.96) > Cr (6.77) > Ni (5.43) > Cd (0.38). The geoaccumulation indexes revealed Cu (0.56-2.88), Pb (0.49-2.52), and Zn (0.58-2.37) as low to moderate pollutants, while Cd (1.70-6.80) was classified as a moderate-to-considerable high-level pollutant. The ecological assessment indicated moderate risk at most of the sampling points. The 2D resistivity model revealed the weathered layer, which makes up the primary aquifer units, had relatively low resistivity zones, indicating the influence of leachates from the dumpsite, and the vertical expanse of leachate movement was evaluated to be > 25 m. The existence of this pollution plume poses threat to the ecosystem and the health of the surrounding population. Proper management is recommended to resolve this probable ecosystem and health issue., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

In this study an attempt was made to determine the source(s) and nature of Pb in environmental media of Ibadan, one of the largest cities in west Nigeria. Seventy-three samples comprising forty stream sediments, twenty-five soils and eight rocks samples were used for the study. Mineralogical compositions of the samples were determined by X-ray diffraction. The elemental constituents were determined using ICP-MS; while the Pb isotopes were determined using Sector-field ICP-MS. Sequential analysis of selected samples was carried out using a modified Tessier's five-step method. The dominant minerals identified were quartz, kaolinite, k-feldspar, and plagioclase. The concentrations (mg/kg) of Pb in soils, sediments, and rocks ranged from 13.00-470.00; 89.00-3288.00 and 2.90-20.30, respectively. The 204 Pb, 206 Pb, 207 Pb, 208 Pb ranged from 1.72-47.41; 30.69-779.68; 27.00-664.46 and 65.67-1642.27 in the soils and sediments, respectively, while they ranged from 0.02-0.07; 0.56-2.33; 0.38-1.56 and 1.19-4.13 in the rocks. Further evaluation of Pb concentration in the soils and sediments revealed high to extreme Pb pollution status, while the calculated Pb isotopic ratios (IRs) in the soil and sediments varied from that of the underlying bedrocks. The IRS in soils and sediments were characterized by low (1.161-1.172 and 1.127-1.200, and 2.281-2.444 and 2.276-2.474) 206/207 Pb and 208/207 Pb, while those of the rocks were high (1.456-1.753 and 2.647-3.149), indicating additional anthropogenic sourcing of Pb in the soils and sediments. The analyzed Pb revealed fractions more partitioned in the reactive geochemical phases with the Pb partitioned in the exchangeable (0.11-0.23%), carbonate (9.00-43.58%), reducible (8.32-13.53%) and organic/sulfides (42.78-82.45%) phases. This implies that there may be enhanced mobility of Pb in the environmental samples and ultimately bio-adsorption into living tissues in the environment., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

Remediation of polluted environmental media is critical to realization of the goals of the United Nations Decade on Ecosystem Restoration (UNDER) project. Many natural-resource dependent economies in Africa are characterized by numerous contaminated sites resulting from conventional and artisanal natural-resource mining. Alongside these extractive activities, there are refining, processing, and power plant operations, agriculture, urban, and infrastructure developments that contribute to increased discharges of toxins into the environment, particularly polycyclic aromatic hydrocarbons (PAHs), which are carcinogenic in nature. As a result, human and environmental receptors (i.e., air, water, soil, and biota) face increasing risk of exposure to higher concentrations of PAH. Evidence exists of widespread PAH contamination and in some instances where corrective action has been taken, residual contaminant levels exceeding regulatory thresholds remain in the environment due to the use of inappropriate and unsustainable remedial methods. Considering the long-term harmful effects of PAH on human and ecosystem health, land use, and the complexity of Africa's environmental deterioration, it is essential to explore remediation strategies that benefit both the environment and the economy. This review examined the status, opportunities, and challenges related to the application of emerging green technologies to remediate PAH-contaminated sites in five African countries (South Africa, Nigeria, Angola, Egypt, and Kenya). This paper concludes that bioremediation presents a sustainable option, considering its low net emissions and environmental footprints, and its low economic cost to Africa's poor communities and overburdened economy. However, an integration of biological and physico-chemical approaches could address various compounds and concentrations of PAH contamination., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This study assessed the human health hazards and ecological risks of heavy metals from waste sites in residential vicinity. The heavy metals analyzed were Cr, Pb, Cd, Ni, Cu, and Zn. A total of 40 soil samples were collected from waste sites in two residential estates located in the urban and suburb areas of Umuahia, Abia state. Results revealed a trend in concentrations of the heavy metals for both sites in the following order: Cu > Ni > Zn > Cr > Cd > Pb. The concentrations of heavy metals were higher in rural soils than in urban soil. The contamination factor (CF) indices for Pb, Cr, Cu, Ni, and Zn were less than 1 for both sites, signifying a low contamination scenario. The contamination factor for Cd (6 > CF) for both sites indicated a very high contamination status. The estimated degree of contamination (Cdeg) was less than the lower threshold of 8.0, denoting a low degree of contamination. Cd was the highest contributor to ecological risk with Er index value of 184.2 among measured heavy metals. The overall potential ecological risk index for urban and rural sites are 187.1 and 196.1 respectively, classifying the sites as moderate risk. The overall non-carcinogenic hazard index values (HI) for adults and children in urban and rural soils are 0.00248, 0.0198 and 0.0028, 0.0223 respectively, which are below the acceptable limit (HI < 1), indicating that the exposed residents are unlikely to experience any apparent adverse health hazards. However, children are more susceptible to non-carcinogenic hazards than adults in the study areas., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Polycyclic aromatic hydrocarbons (PAHs) are a group of semi-volatile and persistent organic compounds considered priority pollutants because of their pervasive nature and high toxicity to the ecosystem and humans. Therefore, this study aimed to evaluate the PAH concentrations in dust and soils around informal trade sites (ITS) in Nigeria to determine the level of risk, sources, and significance of these activities to the PAH load of the environment. The 16 US EPA PAHs in dust and soils from ITS were determined by gas chromatography-mass spectrometry (GC-MS). The PAH concentrations in dust from these informal trade sites varied from 120 to 8790, 56 to 4780, and 102-1090 μg kg -1 for automobile mechanic workshops (AMW), car dismantling (CDS), and material recovery sites (MRS), respectively, whereas those of soils ranged from 3000 to 95,500, 554 to 14,700, and 966-25,200 μg kg -1 for AMW, CDS, and MRS respectively. The PAH profiles indicated that 3- to 5-ring PAHs were prominent in dust and soils around the ITS. The concentrations of the US EPA 16 PAHs in dust and soils from these ITS showed no correlation with organic matter, while the concentrations of PAH homologues in soils of these ITS showed no correlation with those of dust. Incremental lifetime cancer risk (ILCR) values in the magnitude of 10 -4 to 10 1 were obtained for adult and childhood exposure to PAHs in dust and soils from these ITS. Exposure to PAHs in dust from these ITS gives rise to less risk than for soils. The results indicated that automobile mechanic workshops contribute more PAHs to the environment than car dismantling and material recovery activities. The source analysis showed that the PAH contamination of these sites arises from burning of biomass, plastic materials, and oils, and emissions from vehicles., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Use of medicinal herbs is now gaining popularity especially among the low-income people because it is cheap, readily available and its "seeming" lack of side effects. However, environmental pollution is a potential threat to its continued use. This study examines the effect of air pollution on the soil and consequently on the medicinal herbs grown on such soils. Soil and four medicinal herbs, Chromolaena odorata, Vernonia amygdalina, Carica papaya and Ocimum gratissimum, commonly used in the south western part of Nigeria either as purely medicinal herbs, soup vegetables or both were carefully harvested from Fasina, a polluted area, and Moro, a relatively unpolluted area, all in Ile-Ife, Nigeria. Samples were prepared following standard practice and analysed for nickel, chromium, cadmium and lead using atomic absorption spectroscopy (AAS). The results showed that elemental concentrations at the two locations were within the permissible limit for both soil and herbs, the statistical test also established no significant difference between the two locations. However, toxic metals concentrations (chromium, cadmium and lead) were found higher at the polluted site while that of the essential metal, nickel, was higher at the unpolluted site. Of the four metals, cadmium has the highest transfer ratio (0.39 and 0.34) while lead has the least (0.21 and 0.25) for Moro and Fasina sites respectively. Similarly, Chromolaena odorata has the highest transfer ratio (0.34) while Carica papaya has the least (0.28). In conclusion, gradual build-up of the toxic metals at the polluted site is evident and may eventually contaminate the herbs., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Bioaccumulation of potentially toxic elements in soil threatens public health and the ecosystem. This study aims to assess the concentration of potentially toxic elements (chromium (Cr), lead (Pb), iron (Fe), arsenic (As), and cadmium (Cd)) in selected automobile workshop premises in Omu-Aran, Nigeria. Forty-eight samples were collected at a depth (15 cm) in six locations, including a control point. Acid digestion was carried out to prepare the soil samples before assessing their concentration via an atomic absorption spectrophotometer. Geo-accumulation index (Igeo) was used to classify the level of contamination. Statistical analysis, which includes principal component analysis (PCA) and Pearson's correlation, was also determined. The difference in concentration was determined using ANOVA. In the study area, the lowest observed concentration values for Cr, Pb, Fe, As, and Cd, which are 0.246 ± 0.002 mg/kg, 0.178 ± 0.001 mg/kg, 90.715 ± 0.038 mg/kg, 0.012 ± 0.004 mg/kg, and 0.078 ± 0.004 mg/kg, respectively, are relatively higher than observed for the control. The observed potentially toxic elements fall within three Igeo based on Muller's interpretation; heavily to extremely contaminated (Cd), moderately to heavily contaminated (Pb, Cr, and As), and uncontaminated to moderately contaminated (Fe). PCA shows that two principal components (PC) account for up to 91.052% of the original mean dataset variability. PC1 explains 67.723% of the total variance associated with Cd, Cr, Fe, Pb, and As, indicating anthropogenic is the primary source of these potentially toxic elements. The PC2 accounted for 23.329%, with Pb and As significant contributors. Cadmium contamination of soil was the most influential, with an Igeo value ranging from 4 to 5. Residents in the polluted region face considerable health risks from potentially toxic elements., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

In this study, the effect of galena mining with respect to heavy metal pollution of groundwater, surface water, soil and sediments in Enyimagalagu and Mkpuma-Akpatakpa Communities in Ebonyi State, Nigeria, was investigated to estimate the health and economic burden. The heavy metals were measured using atomic absorption spectrometry (AAS). The water quality of the groundwater and surface water was determined using the water quality index (WQI). The potential health burden was estimated by determining carcinogenic and non-carcinogenic health risks via risk index (RI) and hazard index (HI), respectively. The potential economic burden was estimated using the value of statistical life (VSL) and cost of illness (COI). Obtained results revealed that the WQI of the groundwater and surface water ranged from 197 to 327 indicating very poor to unsuitable water for drinking. No non-carcinogenic risks were associated with exposure to the soil and sediment components of the environment. However, there were non-carcinogenic risks associated with the surface and groundwater, with the HIs ranging from 1.8 to 5.4. Based on the carcinogenic risk threshold of 10 -6 , there were carcinogenic risks across all the environmental media ranging from 8.4*10 -5 - 2.1*10 -3 . The economic cost of heavy metal pollution ranged from 20.7 million USD (10.35 billion) to 543.3 million USD (271.6 billion) for the VSL, whereas it ranged from 0.141 million USD (70.8 million) to 3.72 million USD (1.86 billion) for the COI. These costs are quite huge and can be avoided via pollution abatement measures., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

In Zamfara state, Nigeria, rice is cultivated in fields contaminated with Pb (lead) from artisanal and illicit mining activities. Rice grown in such contaminated agricultural areas risks not only Pb contamination but also contamination from other toxic elements, like arsenic (As); co-contamination of Pb and As in rice cultivated in mining impacted areas has been previously reported and rice is a hyperaccumulator of As. A field study was conducted with ten different commonly-cultivated Nigerian rice varieties in the mining-impacted farmlands of Dareta village, Zamfara State. The aim was to determine the optimal rice variety for cultivation on these contaminated farmlands; an optimal variety would have the lowest contaminant concentrations and highest essential elements concentrations in the rice grains. A total of 300 paired soil and rice plants were collected. The mean As and Pb concentrations in paddy soils were 0.91 ± 0.82 mg kg -1 and 288.5 ± 464.2 mg kg -1 , respectively. Mean As (30.4 ± 15.1 μg kg -1 ) content in rice grains was an order of magnitude lower than the Codex recommendation of 200 μg kg -1 (for milled rice) while the Pb content in all the rice varieties (overall mean of 743 ± 327 μg kg -1 ) was approximately four times higher than the Codex recommendation of 200 μg kg -1 . Contrary to previous studies, a negative correlation was observed between As and Pb in rice grains across all the varieties. Rice variety Bisalayi was the variety with the lowest Pb transfer factor (TF = 0.08), but the average Pb concentration in rice grain was still above the Codex recommendation. Bisalayi also had the highest TF for iron. Variety ART&#95;15, which had the lowest As uptake (TF = 0.10), had the highest TF for essential elements (magnesium, potassium, manganese, zinc, and copper). In areas of Pb contamination, Bisalayi rice may therefore be a suitable variety to choose for cultivation., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Nigeria is experiencing continuous economic and industrial transformations, typical of many developing nations. In addition to its well-established oil industry, which is infamous for exuding various kinds of pollutants, there are increased mining operations, indiscriminate disposal and burning of wastes, illegal oil refinery and terroristic insurgency, all poised to increase the levels of heavy metal contaminants in the Nigerian environment. A recent revelation indicates that about 2 million people in South-western Nigeria alone could potentially be poisoned by lead (Pb) and mercury (Hg), emanating from illegal mining operations. This further underscores the importance of investigations of toxic trace metal levels in the country. The current review of 148 research articles was conducted to provide an understanding of the scope of heavy metals research in Nigeria and to prioritize needed research. The review recognized that the scope of heavy metals studies has been wide, covering matrices such as cosmetics, human blood, hair, medicines, foods, beverages, water, air, soil and crude oil. However, important toxic metals, especially mercury (Hg), arsenic (As) and antimony (Sb), are largely under-investigated. Also, there is a need for more studies to be conducted in the northern part of the country. Furthermore, studies need to focus on marine environments rather than the freshwater ecosystems alone. Techniques such as the inductively coupled plasma-optical emission spectrometry (ICP-OES) and particle-induced X-ray emission (PIXE) analyses are herein recommended to bridge the data gap and to overcome limitations in trace metals analyses in the Nigerian total environment., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Human exposure to heavy metal toxicity has been linked to the consumption of vegetables grown on polluted soils. The goal of this study was to see how much heavy metals accumulated in the soil, irrigation water, and vegetative sections of lettuce and cabbage planted in Wawan Rafi, Jigawa State, Nigeria. The concentrations of potentially harmful metals in soil, water, and crops are in the order Mn > Pb > Zn > Ni > Cd > Cu, except for lettuce, where Pb was found to be greater than Mn. Furthermore, the majority of the hazardous elements analyzed were below the allowed limit. Nevertheless, the presence of high levels of metals revealed evidence of contamination, which was attributed to human activities. The potential ecological risk index values for lettuce and cabbage are 86.488 and 225.463, respectively, and both are considered safe because the RI values for both lettuce and cabbage are below or within the range of 200 ≤ RI ˂ 400. This implies consumption of these vegetables may not pose a high health risk to the local public when individual heavy metal is considered, but the risk could multiply when all of the heavy metals are considered together., (© 2022. The Author(s).)

The past mining activities in Bokkos Local Government Area (LGA) were performed in an uncontrolled way and gave rise to many abandoned ponds now serving as domestic and irrigation water sources. Past research focused mainly on the environmental impact, and we show for the first time what the human health risk through consumption of contaminated food crops is in these communities. This study was designed to determine the level of Potentially Toxic Elements (PTEs) contamination in pond water, soil, and food crops and assess the health risk of inhabitants in the abandoned tin mining community in Bokkos LGA. Samples of the mining pond water, soil, and selected food crops from farms irrigated with the pond water: bitter leaf (Vernonia amygdalina), pepper (Piper nigrum), okra (Albelmoschus esculentus), maize (Zea mays), sweet potato (Ipomoea batatas), and Irish potato (Solanum tuberosum) were analyzed for each of the eight PTEs (viz. Cu, Cr, Fe, Mn, Ni, Zn, Cd, and Pb) using inductively coupled plasma optical emission spectrometry (ICP-OES). The results obtained showed that the levels of all the PTEs analyzed in the soil, pond water, and selected food crops except for Fe and Mn in soil and Cd in sweet potato were greater than their corresponding background area values (p < 0.05). Also, the mean concentrations of all the PTEs except for Cu in pond water were significantly (p < 0.05) higher than the WHO maximum permissible limit. With the exception of Fe, Ni, and Zn for pepper and okra, Cu and Fe for maize grains as well as Cu, Ni, and Zn for sweet and Irish potatoes and Fe and Cd for sweet potato, the mean concentrations of PTEs in the food crops were significantly higher than WHO maximum permissible limit. The EF values of Cd (0.39); Cu (3.59) and Ni (2.81); Cr (9.38) and Pb (17.84); and Mn (178.13) and Zn (83.22) classified the soil as minimally, moderately, significantly, and extremely highly enriched, respectively. The PI values of all the PTEs in the soil studied were all greater than 5, indicating that the soils were severely contaminated. There was evidence that food crops significantly bioaccumulated PTEs either as a result of contaminated soil and/or irrigation water. The bioaccumulation was not uniform and was dominated by transfer from the polluted irrigation water. The bitter leaf, okra, and to some extent maize had the highest transfer of PTEs, and Mn, Cu, and Zn had the highest bioaccumulation in the food crops investigated. The hazardous index (HI) for the eight PTEs through the consumption of food crops was 107 for children and 33 for adults which greatly exceeded the recommended limit of 1, thus indicating that possible health risks exist for both local children and adults. For every PTE, the values of HI for children are many-fold higher than those for adults, which is of particular concern due to the high HI values for Pb found for maize consumption, a typical staple food. The cancer risk values for Cr and Ni for all the food crops were within 10 -3 -10 -1 which is several fold higher than the permissible limits (10 -6  and < 10 -4 ) indicating the high carcinogenic risk. It can be concluded based on the results and risk assessment provided by this study that human exposure to mining pond water and soil in farms around the mining pond through the food chain suggests the high vulnerability of the local community to PTE toxicity. Long-term preventive measures to safeguard the health of the residents need to be put in place., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Snails are an important link in the transfer of contaminants, especially metals in the food chain. Yet, few studies have examined the toxicity and accumulation of metals in snails in the tropics. This study assessed the toxicity and accumulation of two non-essential metals (cadmium and lead) to the tropical snail Archachatina papyracea. Specimens of the snail A. papyracea were exposed in a loamy soil collected from Ile-Ife, Nigeria and spiked with varying concentrations of Cd and Pb over 28 days. Survival and weight change of snails were monitored weekly, while tissue accumulation was assessed at the end of the 28-day period. Survival was a more sensitive endpoint than the weight change of snails. The Cd median lethal concentration (LC50) value was 93 ± 4.4 mg/kg, while the median effect concentration (EC50) for snail weight change was 131 ± 41 mg/kg. For Pb, LC50 value was 1121 ± 457 mg/kg, while the EC50 value for weight change was higher at 4541 ± 1180 mg/kg. Therefore, Cd was a factor of about 10 to 30 × more toxic than Pb, consistent with findings on the relative toxicity of Cd and Pb to other soil organisms, including earthworms, springtails, and mites. Although not included initially as an endpoint, egg production in the snails decreased with increasing Cd and Pb concentrations in the substrate. Metal analysis of the foot and visceral mass of surviving snails showed progressive accumulation of Cd and Pb as concentration increased, showing the tendency to use body residue of A. papyracea as an indicator of metal pollution. It further suggests the role of this snail species in above-ground metal transfer in the food chain and highlights the potential danger for human consumption., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The occurrence of mercury (Hg) in the environment globally has been linked largely to its use for gold processing. In this research, ore samples, agricultural soil and mine wastes were taken within the vicinity of an artisanal gold mine and processing sites in Niger state, a north-central part of Nigeria to determine Hg contamination in the environment and estimate the potential hazard to health. The values of Hg measured in ore, agricultural soil and mine wastes ranged between 0.03 and 5.9, 0.002 and 5.57 and 0.19 and 20.99 mg/kg, respectively, with the majority of samples observed above the crustal average values of 0.003 mg/kg. All of the samples were 100 times greater than the USEPA residential soil screening level of 0.0023 mg/kg, but were lower than comparable mine sites within the same region. Contamination indices were used to demonstrate the potential exposure to Hg contamination in the study area which ranged from a medium to high level of contamination. Average daily dose and hazard quotient (HQ) were calculated for adults and children in the study area and decreased in the following order: ADDvapour > ADDingestion > ADDdermal > ADDinhalation. The non-carcinogenic health risk index (HI) of Hg calculated for children and adults in the study area was children: 7.42, 2.19, 1.49 and adults: 4.45, 1.26, 1.19, for mine wastes, agricultural soil and ore, respectively. All of these values were higher than a considered safe level (= 1) and therefore showed that Hg posed a serious non-carcinogenic HI for both adults and children exposed to the soil in the study area. The bioaccessible fraction as a measure of ingestion for Hg was generally < 13% across all sample matrices, suggesting a low bioaccessibility. An HQ incorporating bioaccessible data (BHQ) ranged between 0.000005 and 4.06 with a mean value of 0.62. Values for the BHQ were still > 1, threshold limit in some samples and showed that Hg could present a risk to health via ingestion, although further research is required to assess dermal and inhalation bioaccessibility to assess fully the risk to residents. However, the values were lower than the non-carcinogenic health risk index, which is assumed to be overestimated., (© 2021. The Author(s), under exclusive licence to Springer Nature B.V.)

Monitoring and assessment of soil quality are important in mining areas. In this study, indexical, spatiotemporal, and chemometric models were developed to monitor and assess the pollution level and health risk of potentially toxic elements (PTEs) within the Iyamitet-Okurumutet mine province, SE Nigeria. Surface soils were sampled within the mine area and analyzed for pH, cation exchange capacity, organic matter, and PTEs (Pb, Zn, Cd, Mn, Fe, Ba) following standard techniques. It was revealed that the soils are slightly acidic and the enrichment of PTEs except for Cd (4.08 mg/kg -1 ) was within recommended standards. Contamination factor, enrichment factor, and pollution index suggest that the soils are moderately polluted. Geospatial maps and ecological risk indices revealed that higher ecological risk imprints seem to increase towards the south-eastern parts of the area. Chemometric analysis revealed that PTE enrichment in the soil is majorly influenced by anthropogenic activities. Further, bioavailability/bioaccessibility risk assessment index (BRAI) and health risk assessment models were developed to quantify the bioavailable/human bioaccessible portion of elements in soils and the associated health risks. The BRAI ranged from high (3 ≥ 5) to very high (> 5) risk of human bioaccessibility; hence, greater amount of PTEs will be bioaccessible for absorption into the human gastrointestinal system than they would for plants uptake. The hazard index and lifetime cancer risk (LCR) revealed that most of the samples present high chronic cancer risks from dermal contact and ingestion for children and adults. The LCR values ranged between 1.0E-6 and 1.0E - 04, with the children population showing greater vulnerability to cancer risks., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

The environmental quality and toxicity of soil from some selected informal e-waste sites in West Africa was assessed on PLHC-1 liver cells. In addition, toxicity mechanisms such as apoptosis, necrosis and necroptosis were analysed in order to determine the effect of the actual chemical mixture present in the e-waste soil matrix. The investigation revealed that although e-waste soil extracts (polar and non-polar) and elutriates were significantly cytotoxic at the tested concentration (16 mg soil EQ/ml), PLHC-1 cell viability was not reduced below 50%. The non-polar extracts were more toxic compared to polar extracts and elutriates. The cytotoxic potency of soil from the informal e-waste-recycling sites ranged in this order: Alaba > Godome-Kouhounou > Agbogblosie. The study revealed that all e-waste soil extracts and elutriates induced significant (P < 0.01) PLHC-1 cell death by apoptosis and necrosis; however, cell death by apoptosis was higher compared to that by necrosis. The results indicated that except for non-polar extracts (N4, B4 and G4) from open burning areas that induced significant (P < 0.01) PLHC-1 cell death by necroptosis, other extracts and elutriates could not cause cell death by necroptosis. The study has demonstrated that soils from the Alaba e-waste site in Lagos could be more toxic than soils from Godome-Kouhounou (Cotonou) and Agbogblosie (Accra) e-waste sites and further highlighted open burning as an informal e-waste-handling method with greater negative impact on soil quality in the e-waste sites. The study emphasizes the urgent need for regulatory agencies to introduce regular residue-monitoring programmes in order to forestall the adverse effects of soil pollution episodes in the e-waste sites., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Municipal landfill leachates are a source of toxic heavy metals that have been shown to have a detrimental effect on human health and the environment. This study aimed to assess heavy metal contamination in leachates, surface water, and sediments from non-sanitary landfills in Uyo, Nigeria, and to identify potential health and environmental effects of leachate contamination. Over the wet and dry seasons, surface water and sediment samples were collected from an impacted freshwater ecosystem, and leachates samples from six monitoring wells. Elemental analyses of samples were conducted following standard analytical procedures and methods. The results indicated that leachate, surface water, and sediment samples all had elevated levels of heavy metals, implying a significant impact from landfills. Pollution indices such as the potential ecological risk index (PERI), pollution load index (PLI), degree of contamination (Cd), modified degree of contamination (mCd), enrichment factor (EF), geoaccumulation index (Igeo), and Nemerov pollution index (NPI) were used to assess the ecological impacts of landfill leachates. The following values were derived: PERI (29.09), PLI (1.96E-07), Cd (0.13), mCd (0.16), EF (0.97-1.79E-03), Igeo (0), and NPI (0.74). Pollution indicators suggested that the sediment samples were low to moderately polluted by chemical contaminants from the non-sanitary landfills, and may pose negative risks due to bioaccumulation. Human health risks were also assessed using standard risk models. For adults, children, and kids, the incremental lifetime cancer rate (ILCR) values were within the acceptable range of 1.00E-06-1.00E-04. The lifetime carcinogenicity risks associated with oral ingestion exposure to heavy metals were 9.09E-05, 1.21E-05, and 3.60 E-05 for kids, adults, and children, respectively. The mean cumulative risk values for dermal exposures were 3.24E-07, 1.89E-06, and 1.17E-05 for adults, children, and kids, respectively. These findings emphasized the risks of human and biota exposure to contaminants from landfills., Competing Interests: The authors have declared that no competing interests exist.

The presence of heavy metals and naturally occurring radioactive materials (NORMs) in high concentrations in soils can be hazardous to exposed humans. This study is aimed at measuring the concentrations of heavy metals (Cu, Pb, Ni, Zn, Cd, Co, and Cr) and activity concentration of 232 Th, 238 U, and 40 K in soils affected by and around a solid waste dumpsite in Osogbo metropolis, Nigeria. Atomic absorption spectrometry and gamma-ray spectrometric techniques were used to determine the concentrations of metals and NORMs, respectively. Possible environmental impact of the heavy metal content and the probable radiological hazard by the NORMs to the general public were assessed. The calculated pollution indices reported in this work for Co, Cr, Pb, and Ni show low pollution status. Geoaccumulation indices for Cu, Zn, and Cd indicated that the area under study is strongly contaminated by these metals. Evaluated ecological risk index narrowed down Cd as the poisonous metal with high concentration. The measured radionuclides' mean activity concentrations and the evaluated mean of radium equivalent and absorbed dose rate values are higher than the recommended safe limit, an indication of possible radiological hazard. The principal factor analysis results explained 76% of the collection of data and described chips of galvanized/chrome metals, scrap metals, waste from electronics, Cr, and Cd-containing waste as sources of the heavy metals. The practice of land cultivation around the dumpsite should be deterred to prevent the transportation of these vicious heavy metals into the food chain., (© 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Potential toxic metals from natural and anthropogenic sources accumulate in soil and plants, and represent important environmental contamination challenges. The ecological and human health risks of the potential toxic metals in rice grain, paddy soil, and rice plants of Omor rice field were assessed. The total metal concentration from the four sampling sections (mg/kg) were soil-Zn (29.51 ± 2.23), Mn (55.27 ± 8.10), Cd (5.49 ± 2.24), Cu (2.94 ± 1.47), Pb (14.35 ± 6.54), and Cr (27.06 ± 8.31); rice grain-Zn (21.70 ± 5.44), Mn (3.30 ± 0.21), Cd (00.14 ± 0.11), Cu (2.80 ± 0.34), Pb (11.98 ± 0.58), and Cr (15.86 ± 2.79); and for rice plant-Zn (5.24 ± 1.93), Mn (4.68 ± 1.91), Cd (0.21 ± 0.11), Cu (4.88 ± 0.61), Pb (15.24 ± 6.16), and Cr (46.5 ± 6.05). The estimated daily intakes for adult showed that Cd and Pb exceeded the safe limit by 1% and 93%, respectively. The metal hazard quotients (Zn-0.0007, Mn-0.00019, Cd-0.16, Cu-0.19, and Cr-0.0000077) were less than 1 indicating no probable health risk originating from their exposure. The total hazard index (0.35) also suggests no probable health risk connected with the rice consumption. The metals' ecological risk indices of the soil showed low-risk (< 40), except Cd in some sections of the rice field which indicated moderate potential ecological risk (40-80)., (© 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

E-waste is a global environmental problem that must not be underestimated. To ascertain the environmental pollution status of electronic waste dumpsites, an assessment of seasonal variation in concentrations of heavy metals in the soils and plants in electronic waste dumpsites in Lagos metropolis was undertaken during the two major seasons (wet and dry seasons) in Nigeria. The soils and plants samples collected in August during the rainy season and December during the dry season were digested using aqua regia, a wet digestion method. The heavy metal concentrations were quantified with flame atomic absorption spectrophotometer (FAAS) fitted with a hollow cathode lamp (Perkin-Elmer AA Analyst 200) using an air-acetylene flame. The soil samples and the plants analyzed were found to have high concentrations of heavy metals. All the plants analyzed were identified and classified as excluders and accumulators of heavy metals based on their shoot/root quotients. The results obtained experimentally were analyzed using statistical and multivariate techniques. The soil quality of the study area was evaluated using correlation factor, pollution load index, and geoaccumulation index. The heavy metal assessment in comparison with the EU and Canadian standards for both agricultural and residential soils showed that the e-waste dumping sites are highly polluted. The results obtained for both the soil and plants analyzed confirmed the great impact of the hazardous components of e-waste on the ecosystem., (© 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

The concentrations of 28 polychlorinated biphenyls (PCBs) were determined in soils collected at three depths from thirteen different sites along the floodplain of the lower reaches of the River Niger (LRRN) in Nigeria. The aim of the study was to provide data on the levels of contamination, sources of the contaminants, and risks to the ecosystem and humans. Soil samples were Soxhlet extracted with a solvent mixture of dichloromethane (DCM)/n-hexane and cleaned up on a column packed with Florisil and silica gel. The PCBs in the samples were quantified by gas chromatography-mass spectrometry. The Ʃ28 PCB concentrations in the floodplain soils varied between not detected (nd) and 11,151 ng g -1 for different sampling sites and depths. The PCB concentrations and homologue distribution patterns in soil profiles of the floodplain of the LRRN showed remarkable differences with respect to sites and depths. The results obtained were used to evaluate the ecological and human health risks, which indicated that there is a potential risk to organisms and humans from exposure to PCBs in these soil profiles. The source evaluation as determined by principal component analysis suggested that PCBs in these soil profiles came from burnt circuit boards, cable wires, use of paints, discharges from transformers, long-range migration, and deposition., (© 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Abstract: In most developing countries, mining is one of the major sources of toxic heavy metals, some of which are a major health concern to the surrounding populace through soil pollution and food contamination. We investigated the levels of Ti, Mn, Ni, Cu, Zn, Pb, Rb, Sr, Se, Nb, and V in 64 soil samples, 320 samples of regularly consumed staple food crops and vegetables (Manihot esculenta [cassava] tubers, Dioscorea rotundata [white yam], Arachi hypogea [groundnut] seed, Telfariria occidentalis [fluted pumpkin leaf]), and leaves of the medical plant Zanthoxulum zanthoxyloides on farmlands near Enyigba mining sites in Ebonyi state, Nigeria. We also examined the possible health risks due to consumption of these staple foods. Energy dispersive X-ray fluorescence was used to determine the metals present in the samples. The mean levels of metals, except for Mn, Pb, and Zn, were below the threshold limits recommended by various institutions for agricultural soils. Our data also showed that food crops cultivated near these sites bioaccumulated toxic levels of these metals above the proposed values set by the World Health Organization, National Agency for Food and Drug Administration and Control, and Codex Alimentarius Commission, especially for Pb, Zn, Cu, Ni, Se, and Rb. These findings may have potential health implications for the local dwellers. The estimated daily intakes of the toxic metals through the consumption of the crop samples were below the maximum tolerable daily intakes, except for Pb and Ni, by eating groundnut, cassava, and white yam. Furthermore, the target hazard quotient, computed based on the estimated daily intake of the heavy metals, was above unity for the metals for cassava, white yam, and groundnut consumption, suggesting significant health risk. Elevated amounts of heavy metals in cassava and groundnut samples, as revealed by their metal extraction coefficient computed in this study, hint that they may be used as bioindicators of ecological and health hazards and phytoremediators of Mn, Zn, Cu, and Pb., (Copyright ©, International Association for Food Protection.)

Coal mining activities have been ongoing in Okaba for years without adequate attention paid to pollution and reclamation. Soil and plants were sampled from Okaba coal mine to determine the metal content in the soil and to identify the plants that have potential for phytoremediation. The samples were prepared, separated into various tissues, and labeled and taken to the laboratory. Digestion was carried out using acid mixture of nitric acid (HNO 3) : perchloric acid (HCLO 4) for the plants, while the mixture of nitric acid (HNO 3): hydrochloric acid (HCl): perchloric acid (HCLO 4) was used for the soil. The concentrations of metals from the samples were determined using EDX3600B X-ray fluorescence spectrometer (Sky ray Instruments Inc., USA), a World Bank Assisted Project, Nigeria. Bioconcentration factor (BCF), translocation factor (TF), and bioaccumulation coefficient (BAC) or extraction coefficient (EC) were determined to identify the plants that have potential for hyperaccumulation, phytoextraction, and phytostabilization and ability to store up these metals for harvesting. Hierarchical cluster analysis was performed to highlight the relationship between the variables. This study has revealed that Ageratum conyzoides Linn (ACL), Desmodium velutinum (DV), Triumfetta rhiomdoidea Jacq. (TRJ), Gleichenia linearis (Burns) (GL), Selaginella myosurus (SM), and Sida linifolia juss.excav. (SL) had potential as hyperaccumulators of nickel. Eleven (11) plants have potential for phytoextraction of manganese (Mn), and six (6) plants have stabilization potential for the same metal. Eight (8) phytoextractors and seven (7) stabilizers plants were recorded for Ni. Eclipta alba (L) Hassk (EAH) (location 4) and TRJ were phytostabilizers plants for Pb. Six (6) other plants have potential as phytoextractors of Pb. Eight (8) of the studied plants were suitable for phytoextraction of Ni, and five (5) plants were suitable as phytostabilizers. Most of the plants were found to be useful for phytoremediation of the soil., (© 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

This study evaluated the level of heavy metal pollution in soils within the vicinity of hot mix asphalt (HMA) plants and the health risk consequences of human exposure to the heavy metals. Soil samples collected from two asphalt plants during dry and rainy seasons were analyzed for Cr, Co, Cu, Ni, Mn, Cd, Pb, and Zn with atomic absorption spectrophotometer (AAS). Health risk indices were assessed as chronic daily intake (CDI), hazard quotient (HQ), hazard index (HI), and carcinogenic risk (CR) while the degree of pollution was assessed with geo-accumulation index (Igeo) and contamination factor (CF). The pollution assessment revealed that the soil samples were moderately to highly polluted with Cd. In both seasons, Zn and Mn, respectively, had the highest CDI values for ingestion, inhalation, and dermal route for both asphalt plants while Cd has the least CDI values for all the routes in both plants. The HQ and HI values for all the metals were less than 1.00E + 00 indicating no non-carcinogenic risk from exposure to any of the metals. Furthermore, the dermal route was found to be the least likely model for health risks associated with human exposure to soil heavy metals within the vicinity of the plants. The CR values for the metals were also within threshold value indicating non-significant cancer risk from exposure to the metals. Though no significant health risks were observed in the study, clean and efficient production of hot mix asphalt should be encouraged to minimize health risks and environmental pollution during production and usage.

This study was aimed at determining mainly the concentrations of As and other metals (Cd, Cu, Hg, Pb, V and Zn) in samples of feed, soil, plants and foods (fish, chicken, goat and cow meat) grown and consumed in six areas of Niger Delta, Nigeria (Choba, Khana, Trans Amadi, Eleme, Uyo and Yenagoa). Principal Component Analysis (PCA) models were used for identifying groups of variables (i.e., elements) based on the loadings and groups of samples (i.e., plants, soil, fish, meet, feed) according to the scores that contributed most to the environmental pollution in each Nigerian area. In Choba and Khana sites, the results showed a cluster of elements like As, Pb, V and Zn, mostly associated with samples of goat and cow meat, as well as soils, and separated from another cluster of metals composed by Cu and Hg with different origin. In Trans Amadi area, a clustering of As, Cd and V was found associated to different types of meat (chicken, goat, and cow) located in the opposite side of Cu and Hg, which correlated to plants and soil. In Eleme, the strongest loadings were obtained for V and Zn associated with soil and meat (goat and cow) samples and separated from As and Cd. Finally, in Uyo and Yenagoa, dominant elements were As, Cu, Pb and Zn, with proximity to cow and goat liver samples, while Cd and V corresponded to a different pollution pattern. Lead intake trough meat and fish consumption for adults and children were much higher than the tolerable limits set by international organizations. The results of this study should allow a better understanding of the complex phenomenon of metal pollution in the feed-to-food chain and human health in Nigeria, which should help to manage a pollution reduction strategy and give priorities of research and monitoring., (Copyright © 2021 Elsevier Inc. All rights reserved.)

This study evaluates health risks associated with Arsenic due to mining activities in parts of North-central Nigeria. 306 samples of soil, water and guinea corn were collected for analysis using Atomic Absorption Spectrometry. The analysis reveals varying concentration of Arsenic that is in most cases, above the acceptable limits of consumption, signifying evidence of pollution. The estimated pollution evaluation indices indicates evidence of pollution due to the mining activities. The estimated values of the bioaccumulation factors are very low. The Average Daily Intake reveals that ingestion pathway is the dominant pathway of exposure. While most of the Hazard Index (HI) estimated for the soil and grain samples are « 1, the HI estimated for the water is ≈1. This therefore, means that the probable non-cancerous effect of Arsenic in the drinking water is high. Based on the Delphii method of classification, the Incremental Lifetime Cancer Risk ranges between level II and level III for the soil and grain samples and between level VI and level VII for the water samples within the study sites. This high cancer risks was confirmed by the mean, 5th and 95th percentiles of the cumulative probabilities using the Monte Carlo simulation., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The need to generate internal revenue by most individuals and government in Nigeria has led to the establishment of quarries in different parts of Ebonyi state of Nigeria. This study was aimed at determining the risk associated with the heavy metal burden in the state. Soil samples from the quarrying environments designated as MS1, MS2, and MS3 were analyzed for the metal profile using inductively coupled plasma optical emission spectrometry (ICP-OES). The result showed that the mean concentration of metals which is a representation of the whole sites showed a higher concentration of Ca (40.065 ± 1.011 ppm), Mg (12.450 ± 8.815 ppm), K (16.631 ± 14.670 ppm), and Mn (19.539 ± 3.225 ppm) while Na (1.326 ± 0.117 ppm) was low. The heavy metal profile showed Pb (0.120 ± 0.027 ppm), Fe (27.718 ± 1.523 ppm), Zn (2.227 ± 0.570 ppm), Cu (6.267 ± 1.402 ppm), Ni (1.856 ± 0.472 ppm), Mo (1.758 ± 0.258 ppm), Cd (0.023 ± 0.006 ppm), Cr (0.037 ± 0.011 ppm), etc. Hg was found to be below detectable limit while the Cs was not radioactive. The mean values were found to be lower than the permissible limit of each metal. The pollution index (PI) was calculated for the different sites, and the result reveals that MS3 (0.0426) had a higher PI when compared to MS1 (0.0341) and MS2 (0.0317). Therefore, the PI of the sites showed MS3 > MS1 > MS2. These results showed that the environment is still as safe as PI < 1. The geoaccumulation index also showed a safe environment since its values were less than 0 which means that the environment is practically uncontaminated. Other risk determining parameters showed that the three locations were still within a safe level. Although the results of the study have shown a safe environment, it is still necessary to keep close monitoring of the heavy metal profile of the environment, since these metals can bioaccumulate in living tissues with time.