Seasonal variation, heavy metal pollution indices and health risk assessment in the Esa-Odo reservoir, Nigeria Oluwafisayo Azeez Ayodeji, Henry Adefisayo Adewole, Oluwadamilare Emmanuel Obayemi, Saanu Emmanuel Kosemani, Fatimah Adenike Ajadi, Adebukola Adenike Adedeji, Victor Folorunso Olaleye Scientific Reports, 2026 This study investigated the spatial and temporal variations in heavy metal concentrations in the water of the Esa-Odo Reservoir, located in Osun State, Nigeria. Surface water samples were collected from three designated stations using an improvised water sampler between March 2018 and December 2019, covering two distinct seasons. The Atomic Absorption Spectrophotometric (AAS) method was employed to analyse the acidified water samples (two millilitres of concentrated HNO3 per litre of water) for the selected heavy metals. Samples were collected bi-monthly, totaling thirty-six. The risk assessment utilized the hazard quotient and hazard index for non-carcinogenic risk, and the target cancer risk for carcinogenic risk. The findings indicated that zinc had the highest concentration, followed by iron and copper, with arsenic usually found in trace amounts. While spatial analysis showed no significant variation (p > 0.05) in heavy metal concentrations, seasonal variations were apparent, with notably higher concentrations during the wet season. Five of the analyzed heavy metals (Cr³⁺, Mn²⁺, Fe²⁺, Cu²⁺, and Zn²⁺) were within the NESREA and USEPA permissible limits. Cadmium and lead exceeded the recommended regulatory thresholds, indicating potential risks to human health and aquatic ecosystems. Although arsenic concentrations were below the WHO drinking water limit of 10 µg/L, they may still pose concern based on stricter NESREA/USEPA environmental quality criteria. Principal component analysis and cluster analysis identified correlations and grouping patterns among metals. The heavy metal pollution index (HMPI), calculated using a weighted index method, surpassed the critical threshold of 100 at all stations, with higher values recorded in the wet season (264.27) compared to the dry season (199.65). The hazard index (HI) values remained below the threshold of 1, suggesting a generally low health risk. Furthermore, the Esa-Odo Reservoir showed a low carcinogenic risk for both adults and children based on the target cancer risk (TCR) assessments for heavy metals from ingestion and dermal contact. The study linked increased heavy metal concentrations in the reservoir to agricultural runoff, artisanal mining, and other environmental disturbances surrounding the catchment area. The observed seasonal variations highlight the dynamics of pollution, emphasizing the need for ongoing monitoring and management strategies to mitigate pollution impacts and preserve water quality.
Application of water quality index (WQI) and multivariate analysis to assess the water quality of Emu stream for irrigation suitability N. Julius Ibrahim, Nathaniel Danazumi, Oluwadamilare Emmanuel Obayemi, Priscilla Ilesanmi, Taiwo Elizabeth Ogunsola, Ruth Oluwaseye Olodude, Mayowa Solomon Oladapo Discover Environment, 2026 Surface water is essential for multiple uses and its quality directly affects the derivable ecosystem services. Consequently, physicochemical parameters like pH, dissolved solids, hardness, and nutrient levels serve as vital indicators of whether water is suitable for irrigation. Emu Stream is an important local water source relied upon for irrigation and domestic uses, yet there is scarce information on its water quality and pollution status. This study evaluated the physicochemical characteristics and irrigation suitability of Emu Stream, an important freshwater resource in Bida, Nigeria. Twenty-four water samples were collected from four stations during the wet and dry seasons and analyzed using standard methods. The measured parameters ranged as follows: pH (4.20 ± 0.63–4.89 ± 0.70), Temperature (28.70 ± 1.23–30.00 ± 1.23 °C), Electrical conductivity (15.00 ± 5.02–30.00 ± 26.29 µS cm−1), Total dissolved solids (13.32 ± 3.34–19.97 ± 17.50 mg L−1), Total hardness (43.92 ± 21.27–49.20 ± 34.09 mg L−1 CaCO3), alkalinity (27.75 ± 34.10–162.6 ± 146.09 mg L−1 CaCO3), Dissolved oxygen (5.76 ± 3.93–10.16 ± 3.52 mg L−1), Biochemical oxygen demand (1.16 ± 0.41–2.01 ± 0.48 mg L−1), Chloride (24.76 ± 15.92–94.39 ± 78.62 mg L−1), Sulphate (0.39 ± 0.05–0.48 ± 0.10 mg L−1), Nitrate (2.92 ± 1.51–5.93 ± 3.94 mg L−1), and Phosphate (1.33 ± 0.21–2.41 ± 1.05 mg L−1). Significant seasonal variations (p < 0.05) were observed in pH, temperature, and sulphate. Strong correlations were recorded between pH and BOD (r = 0.981), electrical conductivity and nitrate (r = 0.957), and hardness and sulphate (r = 0.978). Multivariate analyses identified alkalinity as a major contributor to carbonate buffering. The Water Quality Index ranged from 39.16 to 52.01, indicating good water quality for irrigation. Also, the irrigation indices, such as SAR (0.07), Na% (1.88%), KI (0.02), and PS (1.66), indicated that the Emu stream has potential for irrigation use, except for PI (16.39%). In conclusion, this study suggested that Emu Stream water is of good quality for irrigational purposes, though regular monitoring is advisable to prevent potential pollution from human activities.
Assessment of physico-chemical parameters of sediment and arginase distribution in organs of Schilbe mystus and Parachanna obscura inhabiting an abandoned afrotropical gold mine reservoir, Igun, Southwestern Nigeria Sakirat Temitope Asafa, Oluwadamilare Emmanuel Obayemi, Olusola Olaniyi Komolafe, Rapheal Emuebie Okonji, Oluwakemi Victoria Okunola Discover Applied Sciences, 2026 Arginase is a hydrolytic enzyme that catalyzes the hydrolysis of L-arginine to produce L-ornithine and urea for excretion by fish in polluted habitats. To identify the coping mechanism of fish in an abandoned gold mine reservoir, this study assessed the variation in the distribution of arginase in the selected organs of fish in relation to the physicochemical properties of the sediment. Live fish and sediment samples were collected from Igun reservoir monthly between November 2016 and October 2017 at the reservoir landing site by resident fisherman in reservoir 6. Sediment samples were collected using a Van Veen grab and analyzed for their physicochemical parameters using various standard methods. Arginase activity in the organs (gills, fillet and liver) of fish samples (Schilbe mystus and Parachanna obscura) was determined using a spectrophotometer, and values were recorded accordingly. The collected data were analysed using appropriate statistical methods. Our findings showed that the sediment temperature (28.40 ± 0.55 ̊C) was significantly higher during the dry season (p = 0.015) than during the rainy season (26.83 ± 2.04 ̊C). Organic matter showed a strong positive correlation with arginase activity in the fillet of P. obscura (r = 0.872), while pH showed a strong positive correlation with arginase activity in the fillet of S. mystus (r = 0.500). Also, arginase distribution in the fillet (0.372 ± 0.017 µmol/ml/min) and liver (0.427 ± 0.010 µmol/ml/min) of P. obscura were significantly higher (p = 0.018; p = 0.001, respectively) during the dry season than in the fillet (0.325 ± 0.013 µmol/ml/min) and liver (0.350 ± 0.009 µmol/ml/min) in the rainy season. Our study showed that changes in the physico-chemical properties of sediment in the Igun reservoir enhanced arginase activity in the organs of the fish, enabling them to produce urea rather than ammonia at a higher rate during unfavourable conditions, thereby helping them survive in the polluted habitat.
Assessment of water quality index in an afrotropical stream impacted by palm oil mill effluents Fatimah Adenike Ajadi, Henry Adefisayo Adewole, Oluwadamilare Emmanuel Obayemi, Oluwaseun Oyebisi Odetola, Victor Folorunso Olaleye, Oluwafisayo Ayodeji Plos Water, 2025 This study evaluated the impact of palm oil mill effluents (POME) on the water quality of the Agbogbo stream by analysing physicochemical parameters and calculating the Water Quality Index (WQI) across five sampling stations (A–E), including upstream, discharge, and downstream points, over a twenty-month period. Parameters such as temperature, pH, turbidity, total dissolved solids (TDS), total suspended solids (TSS), nitrate, sulphate, and conductivity were measured using standard methods. Results showed that the WQI values ranged from 60.1 to 65.5, with the lowest observed at the effluent discharge point, and an overall average WQI of 64.04, indicating poor water quality unsuitable for potable use. The consistent degradation in water quality across all sites highlights the adverse impact of untreated POME on aquatic ecosystems and community health. Practical implications include the urgent need for effective wastewater treatment prior to discharge, stricter enforcement of environmental regulations for palm oil mills, and continuous water quality monitoring. Future efforts should involve treating of the palm oil mill effluents before discharging it into the nearby waterbody, stakeholder engagement and sustainable practices in palm oil processing to safeguard water resources.
Assessment of climatic and environmental parameters on fish abundance of an afro-tropical reservoir Oluwadamilare Emmanuel Obayemi, Olaniyi Olusola Komolafe, Oluwafisayo Azeez Ayodeji, Olayemi Ajayi, Patricia Oluwatobi Adewumi, Isaac Idowu Adeniran, Kehinde Omobolanle Olalekan, Titilayo Kirmadei Oladimeji Scientific Reports, 2024 This study assessed the impacts of climatic parameters (rainfall and temperature) and environmental variables (transparency, depth, chloride, TS, TSS, TOC) on the abundance of commercially important fish species in Esa-Odo. The research question was to find out if climatic and environmental factors influence the abundance of fish species in an afro-tropical reservoir. Fish species were collected on a monthly basis for two annual cycles covering both dry and rainy seasons. GIS-based climatic data was used to determine the relationship between climatic conditions and fish species abundance. Results showed that the highest abundance of fish was recorded during the rainy season, with Oreochromis niloticus being the most dominant species throughout the sampling period. Trend analysis revealed that variations in climate and environmental parameters influenced the abundance of different fish species in the reservoir. Mann-Kendal analysis indicated that an increase in rainfall led to an increase in reservoir depth, a decrease in transparency levels, and a reduction in temperature, with a Sen's slope value of -38. Additionally, CCA and correlation matrix results demonstrated that climate and environmental parameters significantly influenced fish species abundance. The study emphasized the importance of climatic and environmental factors in the abundance of fish species in the reservoir, providing valuable information for future research on fishery resources. Governments and stakeholders were urged to prioritize the conservation and management of the reservoir's fish population to prevent declines.
Shea Butter (Vitellaria paradoxa G.) Production in Nigeria: Constraints and Prospects a Multifaceted Industry in the 21st Century Adebayo Adedeji, Ibikunle Olalekan Ogundari, Adebukola Adenike Adedeji, Frank Abimbola Ogundolie, Babatunde Sunday Ogunsina, Obayemi Oluwadamilare Emmanuel International Conference on Science Engineering and Business for Driving Sustainable Development Goals Seb4sdg 2024, 2024 Shea butter (SBR) is a seed fat obtained from the Shea tree which is native to the savannah regions of Africa. Nigeria is one of the top producers of SBR. In Nigeria, the Shea tree grows in states such as Kwara, Oyo, Niger, Ogun, Kogi, and Benue states among others. The application of SBR ranges from cosmetics, medicine, and food among others. SBR has been reported to be rich in antioxidants and is used for skin treatment against skin diseases such as psoriasis, rash, eczema, acne, dandruff, and dry skin. It is also used traditionally for treating hay fever, jaundice, osteoarthritis and rhinosinusitis, wound healing, stomach aches, and muscle soreness. SBR serves as a seed fat for cooking and for various cosmetics products. In recent years, nutritional benefits and the application of SBR as an alternative source of energy have increased the global demand for SBR. While this natural product offers several societal, economic, and health advantages to the country and global markets as a whole, limited processing facilities, transportation, open market and inconsistency in its quality remain major challenges facing its production in Nigeria. This results in Nigeria’s current exports of over 350,000 MT out of a projected 1 million MT of SBR annually. In this systemic review, the challenges facing the production, preservation, transportation, and exportation of this with were discussed. This could be a profound solution as Nigeria targets increased production exportation and cements its global position as the world's leading player in this thriving industry.
Health risk assessment of heavy metals in Coptodon zillii and Parachanna obscura from a tropical reservoir Oluwadamilare Emmanuel Obayemi, Mary Adebola Ayoade, Olaniyi Olusola Komolafe Heliyon, 2023 In this study, the concentrations of trace metals were examined in commercially important fish, Coptodon zillii and Parachanna obscura from Osu reservoir. These were with a view to providing baseline information on the levels of heavy metals and its associated risks to human health through fish consumption. Fish samples were collected fortnightly for five months using fish traps and gill nets with the assistance of local fisherman. They were brought into the laboratory in an ice chest for identification. The fish samples were dissected and the gills, fillet and liver kept in freezer and later analyzed for heavy metals based on Atomic Absorption Spectrophotometric (AAS) method. The data collected were subjected to appropriate statistical software packages. The results revealed that the concentration of the heavy metals in P. obscura and C. zillii across the tissues were not significantly different (p > 0.05) from each other. Also, the mean concentration of heavy metals in the fish were below the recommended limits of FAO and WHO. The target hazard quotient (THQ) for each heavy metals were below one (1) while the estimated hazard index (HI) for C. zillii and P. obscura showed no threat to human health risk through the consumption of the fish species. However, continuous consumption of the fish could probably cause health risk to the consumers of the fish. According to the study's findings, human consumption of fish species with low concentration of heavy metals at the current accumulating level is safe.
Limnological variables as a determinant of fish parasites abundance in the Esa-Odo reservoir, Esa-Odo Southwestern Nigeria Oluwadamilare Emmanuel Obayemi, Olaniyi Olusola Komolafe, Edith Ediseimokumoh Onana Journal of Water and Health, 2023 This study investigated fish parasites in relation to limnological variables of the Esa-Odo reservoir since the quality of the aquatic environment might influence parasitic infestation in fish. The purpose of this study was to provide information on the parasite species of the reservoir due to their public health concern and their relationship with selected water quality parameters. The water quality and parasite examinations were analyzed based on standard protocols in the laboratory. The results showed that water quality parameters were not significantly different (p > 0.05) across the zones. Seasonally, mean water temperature, pH, TDS, DO, organic matter, COD and turbidity were significantly different (p < 0.05) across the different zones of the reservoir while electrical conductivity, alkalinity, NO3-, and PO43- were not significantly different (p > 0.05). Clinostomum tilapiae, Clinostomum sp., Euclinostomum heterostomum, Procamallanus laevionchus, and Lytocestus sp. were recovered in all the fish sampled. The overall prevalence of the fish parasites was 9.8% with an intensity of 2.13. The result indicated fish parasites had a strong positive correlation with certain water quality properties and parasite abundance which suggested that water quality could determine parasitic loads in fishes of the Esa-Odo reservoir.
