Assessment of Trace Metals Concentration in Tree Barks as Indicator of Atmospheric Pollution within Ibadan City, South-West, Nigeria.

Ikechukwu P Ejidike,Percy C Onianwa

doi:10.1155/2015/243601

Abstract

Tree bark species were randomly collected from 65 sites having different anthropogenic activities, such as industrial, high traffic commercial, residential high and residential low traffic volume areas of Ibadan City, Nigeria. Levels of Cd, Cu, Pb, Zn, Co, and Cr of the dry-ashed bark samples were determined by AAS. The mean metal concentrations (mg kg−1) in samples from industrial zone were found as Pb: 3.67 ± 1.97, Cd: 0.10 ± 0.07, Zn: 30.96 ± 32.05, Cu: 7.29 ± 5.17, Co: 0.91 ± 0.58, and Cr: 2.61 ± 1.84. The trend of mean trace metal concentrations at high traffic commercial zone follows the order: Zn > Pb > Cu > Cr > Co > Cd. Residential high traffic and low traffic zones revealed the same trend as Cd < Co < Cr < Pb < Cu < Zn. Relatively strong positive correlation between the heavy metals at ρ < 0.05, such as Zn versus Cu (r = 0.79) and Co versus Cu (r = 0.77), was observed. The results of the study suggest that tree bark samples could potentially serve as bioindicators for Cu, Pb, Zn, Cr, and possibly Co and Cd. Furthermore, interspecies variation of heavy metal concentrations in plants barks is recommended.

Highlights

Air pollution was not perceived as a major problem in most countries until late 1960s and early 1970s; it was the global cooling forecast that captured public imagination in urban and industrialized areas [1]
High values of Cu and Zn obtained indicate that emission and tyre wear from motor vehicle as a source of the environmental zinc contamination; high level of copper could come from the fabrication of brass alloy, brake linings, and electrical and mechanical working while lead could be the use of leaded gasoline in the Nigeria petrol. This is because lead additives in the form of tetraethyl lead (TEL[Pb(C2H5)4]) are added to gasoline as the cheapest means of boasting the octane number of Nigeria petrol and zinc in the form of organometallic compounds such as zinc dialkyl dithiophosphate (ZDDP), lubricating oils, and tyres [46, 52, 53]. The results of this survey demonstrate the suitability of Terminalia catappa, Azadirachta indica, Gmelina arborea, Mangifera indica, Prosopis juliflora, and Murraya species, and Gliricidia sepium bark species as potential bioindicators for Cu, Pb, Zn, Cr, and possibly Co and Cd as well as the pointers of some degree of temporal heavy metals contamination
The levels of the metals were higher in bark samples from highly trafficked commercial zone than in other zones

Summary

Introduction

Air pollution was not perceived as a major problem in most countries until late 1960s and early 1970s; it was the global cooling forecast that captured public imagination in urban and industrialized areas [1]. In 2014, WHO released a report on air pollution, as the instigator of about 7 million people’s death in 2012 These air contaminants are released into the ecosystem from immobile sources, such as power stations and other industries, and itinerant sources such as motorpowered vehicles, airplanes, and ships [2, 3]. The release of these gaseous volatile organic and inorganic pollutants in the form of particulate matters with sizes

Methods

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Discussion

Conclusion