Adebanjo Jacob Anifowose

Bio: Adebanjo Jacob Anifowose is an academic researcher from Osun State University. The author has contributed to research in topics: Environmental chemistry & Chemistry. The author has an hindex of 4, co-authored 10 publications receiving 48 citations. Previous affiliations of Adebanjo Jacob Anifowose include Hiroshima University.

Novel Fluorometric Method for the Determination of Production Rate and Steady-State Concentration of Photochemically Generated Superoxide Radical in Seawater Using 3',6'-(Diphenylphosphinyl)fluorescein.

Abstract: Superoxide radical (O2(•-)) is an important reactive oxygen species in seawater. Measurements of its production rates and steady-state concentrations generated by photochemical processes have been a Herculean task over the years. In this study, a probe - 3'6'-(diphenylphosphinyl)fluorescein (PF-1) - was used to trap photochemically generated O2(•-) in seawater, thereby yielding fluorescein. The fluorescein produced was measured by an isocratic fluorescence HPLC at excitation/emission wavelengths of 490/513 nm, respectively. The reaction rate constant of PF-1 with O2(•-) (kPF-1) was pH-dependent: (3.2-23.5) × 10(7) M(-1) s(-1) at pHTOT 7.65-8.50. By applying appropriate equations, both the production rate and the steady-state concentration of O2(•-) generated by photochemical reactions in the seawater were quantified. Under the optimized experimental conditions, fluorescein standards (3-50 nM) exhibited linearity in the seawater by HPLC. The photoformation of fluorescein, due to the reaction of PF-1 with the O2(•-) photochemically produced in the seawater, was linear within the 20 min irradiation. The detection limit of the fluorescein photoformation rate was 0.03 pM s(-1), defined as 3σ of the lowest standard fluorescein concentration per 20 min irradiation. Using this value, the yield of fluorescein, and the fraction of O2(•-) that reacted with PF-1 in the seawater, the detection limit of the O2(•-) photoformation rate was 1.78 pM s(-1). Superoxide measurements using the proposed method were relatively unaffected by the potential interfering species in seawater. Application of the proposed method to ten (10) seawater samples from the Seto Inland Sea, Japan, resulted in measured O2(•-) photoformation rates of 3.1-8.5 nM s(-1), with steady-state concentrations ranging (0.06-0.3) × 10(-10) M. The method is simple, requires no technical sample preparation, and can be used to analyze a large number of samples.

Heavy metals in water, sediment, fish and associated risks from an endorheic lake located in Southern Africa

Abstract: The study assessed heavy metals (Cd, Cu, Fe, Mn, Pb and Zn) and physico-chemical parameters in water, sediments and fish from an endorheic lake (Lake Chilwa) in Malawi. It was observed that pH (max. 9.7), EC (max. 2936 μS/cm), TDS (max. 2119 mg/L), NO3− (max. 6.6 mg/L) and PO43− (max. 1.3 mg/L) were higher in the dry season than in the rainy season. Pb was not detected in all samples. However, the rest of heavy metals were detected with significant values of Mn and Cu in fish (Mn: 0.015–1.18 mg/kg dry weight, dw; Cu: 0.41–0.92 mg/kg dw) and sediment (Mn: 2.25–10.66 mg/kg dw; Cu: n.d–1.63 mg/kg dw). The concentrations of heavy metals in fish samples were below the maximum limits for edible fish recommended by Food and Agriculture Organization/World Health Organization: Cd (0.1 mg/kg), Cu (3 mg/kg), Fe (43 mg/kg), Pb (0.2 mg/kg), Mn (2–9 mg/kg) and Zn (60 mg/kg). The calculated target hazard quotients (ranged from 0.001 to 1.07) indicated no human risks from fish consumption. Furthermore, dry season values for Mn, Cu and Zn in sediments were significantly higher (p < 0.05) than those of the rainy season. Conversely, Fe in sediments was significantly higher (p < 0.05) in the rainy season than in the dry season. The use of fertilizer and indiscriminate disposal of metal products contributes to the observed levels. This calls for reinforcement of suitable agricultural and waste management practices in the study area.

Evaluation and risks assessment of potentially toxic elements in water and sediment of the Dor River and its tributaries, Northern Pakistan

Abstract: The present study investigated the concentrations of potentially toxic elements in water and sediments of the Dor River and its tributaries. The physicochemical parameters of water and sediment samples were investigated, including potentially toxic elements (PTEs), such as Fe, Ni, Co, Zn, Cd, Pb, Mn, and Cr. Among the PTEs tested, the highest concentration in water was observed for Fe 787 μ g/L upstream and the lowest was observed for Cd 1.98 μ g/L downstream. The human risk posed by the PTE concentrations in water was evaluated. The maximum CDI value was observed for Fe 48.3 μ g/kg-day and the maximum HQ value was observed for Co 2.73 for children downstream owing to their water consumption. The PTE concentrations in sediments were evaluated for the quantification of pollution and the ecological risk index (ERI). The Dor River and its tributaries were classified according to the contamination factor (CF): Cr, Co, and Zn had low CF, Pb indicated a moderate CF and Cd had a considerable CF. The pollution level index values attributed to sediment concentrations were slightly higher than 1, suggesting pollution in the river. The highest and lowest ERI values in sediments were calculated for Cd of 168 and Zn 0.45, respectively. The downstream sediment of the study area posed a moderate ecological risk level to aquatic systems due to Cd.

Quantification of Plasma-Produced Hydroxyl Radicals in Solution and their Dependence on the pH.

Abstract: HO radicals are the most important reactive species generated during water treatment by non-thermal plasma devices. In this letter, we report the first quantification of the steady-state concentration and lifetime of plasma-produced hydroxyl radicals in water solutions at pH 3 and 7, and we discuss the differences based on their reactivity with other plasma-generated species. Finally, we show to what extent the use of chemical probes to quantify short-lived reactive species has an influence on the results and that it should be taken into account.

Hydroxyl radical generation with a high power ultraviolet light emitting diode (UV-LED) and application for determination of hydroxyl radical reaction rate constants

Abstract: We propose a simple, efficient and selective hydroxyl radical generation system based on the photolysis of submicromolar concentrations of nitrite using a high-power ultraviolet light emitting diode (UV-LED). Hydroxyl radical formation by the 6.75-W UV-LED was at least 10 times greater than that by a 300-W Xe lamp. In the UV-LED system, the hydroxyl radical formation rate from nitrite was about four orders of magnitude larger than that from nitrate and two orders of magnitude larger than that from hydrogen peroxide. Such efficient and selective hydroxyl radical formation can be attributed to the overlap of the emission spectrum of the UV-LED and absorption of nitrite. The system was used to determine the reaction rate constants between hydroxyl radicals and chemicals based on the competition method with terephthalate as the hydroxyl radical probe. The reaction rate constants between hydroxyl radicals and some low-molecular-weight organic compounds and inorganic halide salts with various reaction rate constants were determined. The values obtained ranged from 105 to 1010 M−1 s−1, and agreed well with previously reported values. The potential of the developed method to determine the reaction rate constants of hydroxyl radicals is discussed.

Bioremediation effect of pomegranate peel on subchronic mercury immunotoxicity on African catfish ( Clarias gariepinus )

Abstract: The primary aim of the present study is to evaluate the highest concentrations of heavy metals (HMs) in Nile catfish (Clarias gariepinus, C. gariepinus) and water samples, as well as to investigate the efficiency of pomegranate peels (PPs) (supplemented either through water or diet) in enhancing fish immunity and counteracting the toxicity of high concentrations of HMs. Water and C. gariepinus samples were collected from two private fish farms in Al Sharkia Governorate. Mercury (Hg) showed the highest concentration (0.13 ppm). The adsorption capacity of PP was evaluated by testing different concentrations, 0.3, 0.6, 0.9, 1.2, and 1.5 g L–1, wherein 1.5 g L–1 revealed the highest Hg adsorption efficiency. The results indicated that Hg concentration was decreased with increased PP concentration until 72 h. In a trial that lasted for 60 days, 240 C. gariepinus (75.12 ± 3.12 g) were randomly divided into eight equal groups with three replicates per group. The first group (CT) served as the negative control (fish fed on a basal diet). The second group (PPW) was fed on a basal diet and supplemented with 0.3 g L−1 of PP via water. The third (PPD1) and fourth (PPD2) groups received basal diets enriched with 1 and 2 g PP powder/kg diet. respectively. The fifth group (Hg) served as the positive control that was fed on a basal diet and exposed to 0.13 ppm of Hg. The sixth (Hg + PPW), seventh (Hg + PPD1), and eighth (Hg + PPD2) groups were exposed to 0.13 ppm of Hg and received the same type of treatment as in second, third, and fourth groups. Hg exposure significantly elevated aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea, and creatinine levels, as well as oxidative stress biomarkers, including reduced glutathione (GSH) and malondialdehyde (MDA). Pomegranate supplementation through diet elevated the levels of red blood cells (RBCs), hemoglobin (Hb), packed cell volume (PCV), lysozyme, and anti-protease activity. Moreover, PP supplementation through water revealed minimum urea and creatinine levels, and the highest nitric oxide level. Moreover, Hg residue level in fish muscles noticeably decreased in the PP-treated groups. These results demonstrated the efficiency of PP supplementation (either through water or diet) in enhancing fish immunity and counteracting subchronic Hg toxicity.