Browsing by Author "Nkechinyere Veronica OTU-EKUMA"

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    Microplastic and Phthalate Esters Occurrences in Oreochromis niloticus and Clarias gariepinus Obtained from Lagos and Epe Lagoons
    (Lead City University, Ibadan, 2025-12) Nkechinyere Veronica OTU-EKUMA
    Microplastics are increasingly found in aquatic environments, yet data on their distribution and effects in Nigeria’s lagoons remain limited. This study assessed the occurrence of microplastics and phthalate esters in two commercially important fish species (Oreochromis niloticus and Clarias gariepinus) and heavy metals in surface and benthic waters from Makoko, Ikorodu, and Epe. Sampling occurred during four seasonal cycles (March, May, August, and November). Microplastics were isolated by density separation and identified via FTIR; phthalates were analyzed using GC-MS, and heavy metals analysed using standard method. The study recorded widespread contamination in all sample types and sites, with seasonal and spatial variations. Microplastic counts in Oreochromis niloticus ranged from 8.7±2.3 particles/fish (Epe, August) to 22.3±5.7 (Makoko, November), and in Clarias gariepinus from 7.6±1.9 (Epe, August) to 19.4±4.8 (Makoko, November). Fibers made up 58%, fragments 35%, films 5%, and pellets 2% of total particles. The most abundant polymers were PE (42%), PP (26%), PS (17%), and PET (15%), indicating mixed urban and household plastic sources. Phthalate esters occurred in all fish tissue samples, showing seasonal and spatial variation. The highest concentration (55.0 ± 5.4 mg/kg) was observed in C. gariepinus from Ikorodu in March, and the lowest (28.7 ± 3.2 mg/kg) in August, while Oreochromis niloticus from Makoko contained 49.3±4.1 mg/kg. Diethyl phthalate (DEP) and di(2-ethylhexyl) phthalate (DEHP) were the most abundant esters detected. Heavy metal concentrations exceeded WHO limits in all water samples. Notably, in November, Pb in Makoko benthic water reached 6.77mg/L, Ni 14.66 mg/L, Cd 2.84 mg/L, Cr 3.15 mg/L, and Cu 2.61 mg/L. Seasonal variations were evident across parameters: for instance, Pb in surface water at Ikorodu declined from 3.74 mg/L in May to 1.21 mg/L in August before rising again to 4.68mg/L in November. Similar seasonal trends were observed for Ni, Cd, Cr, and Cu, reflecting the influence of rainfall, mixing, and anthropogenic inputs. Morphometric analysis showed clear spatial and seasonal differences in Oreochromis niloticus and Clarias gariepinus. Epe consistently recorded the largest specimens, with O. niloticus reaching a mean standard length of 13.80 ± 1.56 cm and weight of 175.00 ± 31.31g in November, while Makoko recorded the smallest (13.00 ± 1.12 cm; 155.00 ± 33.54g). For C. gariepinus, Epe weights peaked at 390.00 ± 78.26 g, compared to 350.00 ± 67.08 g at Makoko. Physicochemical parameters varied seasonally; for example, dissolved oxygen was highest in August (6.24 mg/L surface water at Epe) during peak rainfall, while conductivity and TDS were elevated in March and November, with benthic conductivity reaching 329.50 µS/cm at Makoko. Turbidity also peaked in November, with surface water values up to 42.40 NTU at Ikorodu, reflecting increased runoff and anthropogenic input.These findings demonstrate that microplastics, phthalates, and heavy metals co-occur at ecologically concerning levels in Lagos and Epe lagoons, with site- and season-specific patterns. Targeted interventions—particularly improved waste management, focused monitoring in high risk areas such as Makoko, and seasonal pollution control—are essential to safeguard aquatic ecosystems and food security. Keywords: Microplastic, Phthalate, Heavy Metals, Pollution, Aquatic Ecosystems Word Count: 457