DEPARTMENT OF ENVIRONMENTAL MANAGEMENT AND TOXICOLOGY

This study assessed the levels of heavy metal contamination in artesian well water in Ikpoba Slope, Benin City, Nigeria. A community dependent on shallow artesian well water for essential domestic needs. Water samples from eight artesian wells (well sample 1–8) were analyzed for heavy metals using Atomic Absorption Spectroscopy (AAS). Lead concentrations ranged from 0.008 ± 0.0001mg/L in well 7 to 0.015 ± 0.002mg/L in well 8, with well 2 (0.013 ± 0.001 mg/L) , 5 (0.013 ± 0.0004 mg/L) , and 8 (0.015 ± 0.002 mg/L) exceeding WHO (2011) and NSDWQ (2007) recommended permissible limit of 0.01 mg/L. while chromium ranged from 0.017 ± 0.001 mg/L in well 8 to 0.037 ± 0.002 mg/L in well 4, iron from 0.017 ± 0.0003mg/L in well 1 to 0.264 ± 0.002 mg/L in well 3, copper from 0.019 ± 0.001 mg/L in well 3 to 0.038 ± 0.001mg/L in well 7 , and manganese from 0.012 ± 0.001mg/L in well 8 to 0.018 ± 0.001mg/L in well 7. They were all within WHO (2011) and NSDWQ (2007) recommended permissible limits. Cadmium was below the detection limit across all well samples. These findings offer critical data for public health interventions and sustainable water management in Ikpoba slope.

This study examines how the decline of vegetation has affected rainfall patterns in Abuja, Nigeria, between 2015 and 2024. Using Sentinel-2 satellite imagery and CHIRPS rainfall data, the research analyzed land use and rainfall changes over time through Google Earth Engine and ArcGIS. Findings revealed a major shift in Abuja’s landscape during the study period. Tree cover, which accounted for about 71.81% of the area in 2015, declined sharply to 23.71% by 2024, while built-up and farmland areas expanded significantly due to rapid urban growth. Rainfall trends also became more irregular, showing a noticeable decrease after 2018. Statistical analysis indicated a strong negative relationship (r = -0.76) between vegetation cover and rainfall, suggesting that as green spaces declined, rainfall reduced correspondingly. This loss of vegetation has weakened natural cooling and moisture recycling processes, contributing to hotter and drier conditions across the city. The findings show that the conversion of natural green areas into concrete surfaces has disrupted Abuja’s local hydrological balance and may be influencing recent changes in rainfall distribution. The study concludes that protecting and restoring green spaces is essential for improving rainfall stability and climate resilience. It recommends the implementation of sustainable urban planning strategies, reforestation initiatives, and stronger environmental policies to restore ecological balance and promote a healthier urban environment in Abuja.

This study was carried out to comparatively assess the effects of chromium (Cr) and lead (Pb), on the growth of two freshwater microalgae (Chlamydomonas reinhardtii and Scenedesmus cronies). The test algae were grown in seven concentrations (0, 1, 2, 4, 6, 8, and 10 mg/L) which were set up in triplicates. Growth response of the test microalgae was monitored at twoday intervals for 14 days using a visible spectrophotometer (Model No. HV-721. The growth rate, percentage inhibition, and analysis of variance (ANOVA) were computed using Microsoft Excel software. Physicochemical parameters such as hydrogen ion concentration (pH), electrical conductivity total dissolved solid (TDS) were also determined. The results revealed
that growth of both microalgae decreased progressively with increasing concentration with chromium exhibiting greater toxicity than lead. Growth rate analysis favoured Chlamydomonas reinhardtii in both heavy metal treatments. Statistical analysis using ANOVA showed that it was significant (p < 0.05) in growth response among the various concentrations for both species. Conversely, Lead showed negligible inhibitory effects, with final biomass statistically similar to the control across all concentrations. Results of the physico-chemical parameters showed a concentration dependent relationship. pH was noticed to increase in lead-treated cultures but remaining neutral in high-chromium cultures. Despite differential toxicity, both
species showed high biosorption capacity: C. reinhardtii was exceptionally efficient, removing nearly 100% of lead. Based on the findings of this study it can be concluded that Chromium is acutely toxic at the tested range, while Lead is comparatively benign, and that both microalgae, particularly C. reinhardtii for lead, is more suited for the bioremediation of wastewater polluted with lead.

The contamination of soils with heavy metals from anthropogenic activities like automobile repair poses a significant threat to ecosystem and human health. This study investigated the effectiveness of hydroxyapatite (HAp) and phosphate-solubilizing bacteria (PSB) for the remediation of heavy metals in a contaminated mechanic workshop soil in Ekosodin, Benin City, Nigeria. Soil samples were collected and subjected to four treatments: untreated soil (control), soil amended with PSB only, soil amended with HAp only, and a combined treatment of soil with both HAp and PSB. Hydroxyapatite was synthesized from cow bones via thermal calcination, and indigenous PSB were isolated from the contaminated soil. The concentrations of Chromium (Cr), Lead (Pb), and Nickel (Ni) were analyzed using Atomic Absorption Spectrophotometry, and microbial counts were monitored over the experimental period.The results demonstrated that the combined application of HAp and PSB was the most effective treatment, achieving the highest percentage removal efficiencies: 38.65% for Cr, 29.05% for Pb, and 33.12% for Ni. Individual applications of PSB or HAP showed significantly lower remediation effects. Furthermore, the combined treatment (Soil+PSB+HAp) supported a higher total heterotrophic bacterial count (2.75 ± 0.71 × 10⁶ CFU/g) compared to the PSB-only treatment (2.50 ± 0.00 × 10⁶ CFU/g), indicating improved soil microbial activity. The study concludes that the synergy between hydroxyapatite and phosphate-solubilizing bacteria enhances the immobilization of heavy metals and promotes a healthier soil microbiome, presenting a promising, eco-friendly strategy for remediating soils co-contaminated with heavy metals

Groundwater remains a vital source of potable water in Benin city, yet its quality is decreasing in most parts of Nigeria. This study assessed the effect of on-site sanitation facility proximity on the physiochemical, total and fecal coliform load of groundwater from selected boreholes in Ikpoba Hill and Sapele Road, Benin City. Water samples are collected from four boreholes located within varying distances (11.8m in Ikpoba Hill to 32m in Sapele Road) from onsite sanitation facilities. In-situ measurements of pH, Electrical conductivity (EC), and total dissolved solids (TDS) were performed using a multifunction water quality meter, while nitrate and ammonia-nitrogen concentrations were determined using spectrophotometric methods. The pH values ranged from 4.3±0.01 in Ikpoba Hill to 5.2±0.5 in Sapele Road, indicating slightly acidic water across all samples. EC and TDS values ranged from (19±0 in Ikpoba Hill - 133±0µS/cm in sapele road) and (9±0 in Ikpoba hill - 66±0 mg/L in Sapele Road), respectively, reflecting low mineralization. Nitrate (0.46±0.11 in Sapele Road – 0.713±0.04 mg/L in Ikpoba Hill) and ammonia-nitrogen (0.85±0.17 in Ikpoba Hill – 1.50±0.77mg/L in Sapele Road). Aside from ammonia-nitrogen, other parameters were below NESREA permissible limits and there were no total or fecal coliforms detected in the samples. The observed differences between the mean physiochemical values were not significant (p>0.05). Aside from borehole C and D, the other boreholes (A and B) were sited well above the minimum distance (15m) from the nearest sanitary facilities (septic tank). It is recommended that sensitization be conducted to enlighten intending property owners with respect to the health implications of improperly siting water sources from onsite sanitation facilities.

I wish to express my deepest gratitude to all who supported this journey. First and foremost, I thank God Almighty for the strength, wisdom, and opportunity to complete this work. My heartfelt appreciation goes to my rock, my mother, Mrs. Uzzi-Akode, for her unwavering love and support. Thank you also to my dear sister, Mrs. Esele Fatima, her husband Mr. Odino Esele, and their children, Ainose Esele and Omo jade Esele, for their constant encouragement. I am profoundly grateful to my project supervisor, Prof. Alex, for his invaluable guidance and dedicated mentorship. I also thank Dr. Charles, Dr. Nosa, Dr. Frank, and Dr. Jeff for their academic influence and support. A special thank you to my project partners for their collaboration, and to my friends, especially Patricia and Mark, for their motivation and unwavering belief in me. Finally, I acknowledge myself for the perseverance andhard work invested in bringing this project to a successful conclusion.

Garden egg (Solanum aethiopicum) is a staple vegetable in Nigeria, but concerns exist regarding potential heavy metal contamination and its impact on consumer health. This study investigated the presence of heavy metals (nickel, cadmium, and mercury) and oxidative stress markers (malondialdehyde, glutathione peroxidase, superoxide dismutase, and catalase) in garden egg samples collected from two markets (Uselu and Ikpoba Hill) in Benin City, Nigeria. A health risk assessment was conducted to estimate the potential health risks associated with nickel exposure. Garden egg samples (n=15) were purchased from each market. Samples were homogenized, and aliquots were used for eavy metal analysis via atomic absorption spectrometry, and oxidative stress marker assays (using standard protocols for MDA, GPx, SOD, and CAT activity measurement). The ean concentrations of Ni in Ikpoba Hill and Uselu Market were [0.032 ± 0.070] and [0.038 ± 0.068] respectively. The activities of SOD, CAT, GPx and MDA from Ikpoba Hill were 3.291 ± 0.792], [0.098 ± 0.058], [8.274 ± 2.043], and [0.728 ± 0.208] respectively, while for Uselu Market were [3.311 ± 0.938], [0.076 ± 0.020], [4.580 ± 1.287], and [0.668 ± 0.185] respectively. Relatively low levels of nickel were detected in both markets, while cadmium and mercury were undetectable. The Uselu market samples exhibited signifi antly higher levels of malondialdehyde, a marker of oxidative stress, and lower glutathione peroxidase activity, an antioxidant enzyme, compared to samples from Ikpoba Hill market. The reference dose (RfD) for nickel established by the US EPA and daily vegetable consumption recommendations from the WHO were used to estimate daily intake (EDI) and hazard quotient (HQ) for nickel exposure. The estimated daily intake and hazard quotient for nickel exposure from garden egg consumption were well below established safety thresholds, suggesting a low potential for non-carcinogenic health risks at the measured levels. These findings indicate minimal immediate health risks from heavy metal contamination in garden eggs sold at these markets. However, the observed variations in oxidative stress markers suggest potential differences in garden egg quality between the markets. Further research is needed to explore the factors influencing these variations, such as storage practices or agricultural techniques. Continued onitoring of heavy metal content in garden eggs is also recommended to ensure consumer safety.

This is carried out to assess the concentrations of Nitrogen dioxide (NO2) and Particulate matter (PM2.5), in Etsako East Local Government Area. Secondary data collection method was employed for the assessment. Levels of Nitrogen dioxide (NO2) and Particulate matter (PM2.5) were extracted biannually from Google Earth Engine using information from Sentinel-5-P satellite data (COPERNISCUS/5SP/NRT/L3_). A comparison of the levels of Nitrogen dioxide (NO2) and Particulate matter (PM2.5) was done iannually from the year 2019 to the year 2024 in Etsako East LGA. Results showed that the annual mean concentrations of itrogen dioxide (NO2) ranged from 0.000048mol/m2 to 0.000062mol/m2 , the highest and lowest concentrations were found in the first half of 2021, and the first half of 2022 respectively. Particulate matter (PM2.5) ranged from -0.2341 to 0.4357. The highest and lowest concentrations were found in the first half of 2021, and the second half of 2022 respectively. This condition as an implication of irritating airways and exacerbating respiratory conditions on the residents. Government should play their role in policy making so as to enforce a cleaner production process by the cement factory located there. GIS applications should also be employed and used to foster air quality and check for any deviations.

This study evaluated the operational and health risk factors associated with municipal solid waste scavenging in two privately-operated municipal Solid waste dumpsites in Benin City, Edo State. A well- structured questionnaire was administered to 100 randomly selected scavengers; the questionnaire covered demographics, personal details, and information on the types and frequencies of health hazards encountered by waste scavengers, providing insights into the challenges they face. The findings revealed significant health risks including injuries, respiratory problems, and gastrointestinal illnesses, highlighting the need for interventions to improve the safety and well-being of the scavenging operations. Furthermore, they also face several operational risks due largely to the lack of use of personal protection equipment, resulting in cuts, respiratory issues, and gastrointestinal illnesses, with a notable proportion experiencing frequent headaches and a high prevalence of malaria. We recommend that the operators of the dumpsites should be regulated by the Edo State Waste Management Board, with strict guidelines and punitive measures put in place for lack of compliance. On the part of the dumpsite operators, they should provide all necessary personal protection equipment and enforce their use as a standard operating procedure. Furthermore, first aid equipment for staff, drinking water and bathrooms with soap and water for their sanitation should be provided.

Access to safe drinking water is critical for achieving Sustainable Development Goal (SDG) 6, yet it remains a challenge in Nigeria, contributing to a high burden of waterborne diseases. This study aimed to evaluate the complex relationship between community perceptions of water quality and laboratory- confirmed health outcomes among residents in Ogbeson, a rural community in Edo State, Nigeria. The research employed a mixed-methods approach, combining socio-demographic and behavioral surveys with objective physicochemical and bacteriological analyses of drinking water samples. The population exhibited a relatively high educational level (49.5% with tertiary education) and moderate income. Water quality was assessed against World Health Organization (WHO) standards, and health status was determined through self-reported illness prevalence, particularly waterborne diseases.A major discrepancy was found between community confidence and actual water safety. A high proportion of respondents (78%) reported confidence in their main water source's reliability, often relying on sensory attributes (color, taste, odor) for quality assessment. This confidence directly contradicted laboratory findings of severe contamination, including pathogenic bacteria (E. coli, Klebsiella pneumoniae, Bacillus cereus, and Pseudomonas species) and chemical hazards like elevated nitrate (52.17 to 92.47 mg/L, exceeding the WHO limit of 50 mg/L) and acidic pH (4.43–6.37). The documented contamination correlated directly with a substantial acute disease burden: 42.7% of households reported water-related illnesses, with typhoid fever (55.7%) and diarrhea (42.3%) being the most prevalent. Despite high education and 74.1% of respondents treating water (predominantly by boiling), structural constraints undermined protective behaviors. Pervasive water supply intermittency (61.4% experiencing problems) and seasonal unreliability (94.2% during the dry season) necessitated unsafe water storage and increased recontamination risk. This was compounded by critical WASH infrastructure deficits, with 85.5% of the community lacking adequate facilities, particularly hand washing stations (87.1% lacking), alongside the near-total absence of community-based WASH programs (82.3% lacking). In conclusion, the Ogbeson community faces a public health emergency driven by the dangerous coexistence of high confidence in unsafe water sources, pervasive infrastructural failures, and an overwhelming burden of waterborne disease. Urgent, multisectoral interventions are required to resolve water supply intermittency, invest in foundational WASH infrastructure, and implement integrated community programs to align risk perception with objective reality, thereby achieving health equity and SDG 6 alignment