Bioaccumulation and Oxidatives stress impact of toxic heavy metala and polycyclic aromatic hydrocarbons on selected mosses in Nigeria
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Date
2023
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Department of Botany, Faculty of Science, Obafemi Awolowo University.
Abstract
This study investigated the bioaccumulation of heavy metals and polycyclic aromatic hydrocarbons in Philonotis hastata (Duby) Wijk & Margad and Barbula lambarenensis P. de la Varde, and also determined the impact of oxidative stress on chlorophyll content and anatomical features of the mosses. These were with a view to providing detailed information on the bioaccumulation potential of the selected mosses as well as the antioxidant response of these mosses to oxidative stress.
The moss species were collected in industrial areas in Ile-Ife, Ibadan and Ikeja while the control samples were collected at Obafemi Awolowo University, Ile-Ife. The
concentrations of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in moss samples were determined using standard method. Estimation of chlorophyll content
(chlorophyll a, chlorophyll b and total chlorophyll) were determined using standard procedure. Stress biomarkers (hydrogen peroxide (H2O2) and proline contents), nonenzymatic antioxidant activity (ascorbate, total glutathione, lipid peroxidation and carotenoids) and enzymatic antioxidant activity (superoxide dismutase, catalase and
ascorbate peroxidase) were determined following standard procedures. General anatomical features of the stem and leaves of the mosses were studied and photomicrographs of the slides were taken. Data were analyzed using one-way Analysis of Variance (ANOVA) and
Duncan Multiple Range Test (DMRT) were used for separation of mean using SAS software, 2001.
The concentrations of heavy metals in moss samples in the study locations ranged from: Cu (1.200 – 2.330 μg/g), Zn (0.855 – 1.370 μg/g), Fe (0.525 – 1.050 μg/g), Mn
(0.027 – 0.052 μg/g), Cr (0.016 – 0.057 μg/g), Cd (0.018 – 0.045 μg/g), Pb (0.007 – 0.020μg/g), As (0.010 – 0.018 μg/g). The results revealed that the heavy metal concentrations in
the studied moss samples followed the trend: Cu>Zn>Fe>Mn>Cr>Cd>Pb>As. The study showed that copper, zinc and iron were the most accumulated heavy metals while lead and arsenic were the least accumulated heavy metals in all the sampling locations. Moss samples from control sites have the lowest concentration of metals in all the sampling locations. There is significant difference in the accumulation of heavy metals in the mosses with respect to the different locations in the study area. The concentrations of 19 PAHs varied from 0.02 to 3.81 mg/L in P. hastata and from 0.02 to 5.92 mg/L in B. lambarenensis in all the locations. The PAHs were not detected in the moss samples from control sites. Naphthalene and 3-methylcholanthrene were detected in all the study areas except for control sites. There was a significant decrease in chlorophyll a, chlorophyll b and total chlorophyll contents of the selected mosses when compared to chlorophyll contents of mosses from control sites. The selected mosses exhibited significant variations in the antioxidant response to oxidative stress in polluted sites and control sites. The anatomical studies of the stem and leaves of the selected mosses showed there is no feasible effect of pollutants bioaccumulation on micromorphological features of the moss species obtained from polluted sites when compared to moss species from the control sites.
The study concluded that accumulation of heavy metals and polycyclic aromatic hydrocarbons in the selected mosses from industrial areas induces oxidative stress and
causes reduction in their chlorophyll contents. The antioxidant response of these mosses indicated that the selected moss species were tolerant to oxidative stress.
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xv, 168p
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OLASOJI, K.O.(2023) Bioaccumulation and Oxidatives stress impact of toxic heavy metala and polycyclic aromatic hydrocarbons on selected mosses in Nigeria. Department of Botany, Faculty of Science, Obafemi Awolowo University