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Speciation and bioavailability studies of toxic metals in the alluvial soil of Onukun River floodplain in Okitipupa, Southwestern Nigeria
Author(s) -
Aiyesanmi Ademola Festus,
Oladele Mayowa Festus,
Adelodun Adedeji Adebukola,
Idowu Gideon Aina
Publication year - 2020
Publication title -
environmental quality management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.249
H-Index - 27
eISSN - 1520-6483
pISSN - 1088-1913
DOI - 10.1002/tqem.21720
Subject(s) - environmental chemistry , bioavailability , floodplain , genetic algorithm , soil water , chemistry , environmental remediation , organic matter , alluvium , pollution , carbonate , enrichment factor , heavy metals , environmental science , contamination , geology , soil science , ecology , biology , bioinformatics , organic chemistry , geomorphology
We report on the speciation study of five toxic metals in the floodplain alluvial soils of Onukun river of Okitipupa, Ondo State, Nigeria. The bulk metal concentrations in the soil samples were in the order: Fe > Cr > Zn > Cu > Pb > Cd. Speciation analysis via sequential extraction was used to fractionate the metals into five operationally defined pools: exchangeable, carbonate, easily reducible, organic, and residual fractions. Generally, the organic, residual, and reducible fractions were the most abundant pools for Cu, Cr and Fe, Pb and Zn, respectively, whereas Cd was undetected. The soils were loamy sand, with pH and organic matter content ranging from 4.71% to 7.00% and 1.92% to– 4.62%, respectively. Furthermore, three pollution indices viz. geoaccumulation index, enrichment factor, and mobility/bioavailability evinced the trends: Fe > Cr > Zn > Cu > Pb, Cr > Zn > Cu > Fe > Pb, and Zn > Pb > Cu > Fe > Cr, respectively, with the pollution load index highest of 0.39. Conclusively, the floodplains’ soils are considered contaminated with the target toxic metals, necessitating their periodic monitoring and remediation.