IMPACT ASSESSMENT OF CEMENT PRODUCTION ON VEGETATION AND SOIL OF OBAJANA COMMUNITY, KOGI STATE, NIGERIA
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Date
2021-05
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UNIVERSITY OF ILORIN
Abstract
The production activities of cement factories pollute the soil and vegetation in their environment with heavy metal-laden cement dust. Heavy Metals (HMs) are serious pollutants thus constituting threat to the biota. The study was designed to evaluate the impact of Obajana Cement Factory (OCF) on the environment. This study investigated the effects of cement dust on the vegetation and soil of Obajana community Kogi State, Nigeria. The objectives of the study were to: (i) evaluate the HMs contamination of soil around OCF; (ii) quantify the concentrations of HMs in Zea mays, Abelmoschus esculentus, Mangifera indica and Carica papaya growing around OCF; (iii) investigate the leaf epidermal responses of the studied plants to cement dust pollution; (iv) determine HMs mobility in the studied plants; and (v) assess the hazard quotient of HMs contamination of the studied plants.
Soil and plant samples were collected from the eastern, western and northern axes of OCF, at 1, 2 and 3 kilometres from the factory. Samples were digested using a mixture of concentrated HNO3 : HCl (1:3), while Zn, Pb, Cr, Cd and Cu concentrations were determined using Atomic Absorption Spectrophotometry. Epidermal responses of the studied plants to cement dust pollution were assessed using standard method. Transfer factor, bioaccumulation index, ecological risk and potential health risk were calculated using standard models. Data generated were subjected to Analysis of Variance, Carl Pearson Correlation Coefficient and t-test with significance level at p<0.05.
The findings of the study were that:
i. the soil samples contained Zn (8.70-196.00 mg/kg), Cr (3.95-115.87 mg/kg), Pb (4.18-29.65 mg/kg), Cd (0.00-6.75 mg/kg) and Cu (5.70-34.00 mg/kg). Chromium content of soil samples (62.65-111.87 mg/kg) was much higher than the CCME permissible limit of 64 mg/kg;
ii. the highest amounts of HMs (mg/kg) in the fruits of each of the studied plants were; Z. mays, Zn (67.01), Cr (5.97), Pb (3.02), Cd (1.00) and Cu (6.05); A. esculentus: Zn (90.54), Cr (2.43), Pb (2.84), Cd (0.50) and Cu (4.21); M. indica: Zn (60.31), Cr (2.65), Pb (1.83), Cd (0.05) and Cu (9.01); C. papaya: Zn (58.07), Cr (2.71), Pb (1.77), Cd (0.05) and Cu (10.03);
iii. stomatal sizes and densities of plants from the polluted sites were significantly (p<0.05) different from the control. Stomatal complex types remained unchanged;
iv. A. esculentus and M. indica accumulated Cu and Zn and excluded Cr, Cd and Pb; C. papaya accumulated Cu, Zn and Pb and excluded Cr and Cd while Z. mays accumulated Cr, Cu and Zn and excluded Pb and Cd; and
v. fruits of all the studied plants had Hazard Quotient values greater than 1 for Zn. Whereas, Z. mays fruit had Hazard Quotient values greater than 1 for Cr.
The study concluded that the soils of Obajana community had elevated levels of HMs, as evidenced by the accumulation of chromium in Z. mays grains. The study recommended remediation of soil around OCF to reduce its HMs load in order to avert health hazards that may result from consumption of crops grown around the location.
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Keywords
IMPACT ASSESSMENT, CEMENT PRODUCTION, VEGETATION, SOIL, OBAJANA COMMUNITY, KOGI STATE