Land use types and their influence on heavy metals concentration in soils of Yenagoa and Southern Ijaw local government area of Bayelsa State

Williams Perekekeme Agbai, Ufuoma Isaiah Efenudu

Abstract: The research aimed to determine the influence of different land use types on heavy metal concentrations in soils. The study was carried out in two local government areas in Bayelsa State namely: Southern Ijaw and Yenagoa; which embodies four land use types (oil palm plantation (OPT), plantain plantation (PPT), fallow land (FFL) and virgin land (VVL)). A total of twelve (12) composite and representative soil samples were taken with the aid of an auger at the respective land use type, and were subjected to some physical, chemical analysis. The samples were taken at three depths: 0-15, 15-30 and 30-45 cm. Heavy metals were determined using flame atomic adsorption spectrophotometry - GBC scientific equipment SENS AA. The VVL with higher hydraulic conductivity (13.6 cm/hr) adsorbed fewer heavy metals compared to the others (FFL – 13.2 cm/hr, OPT – 9.8 cm/hr, and PPT – 7.6 cm/hr). The soils of the plantain plantation, oil palm plantation, virgin land and fallow land recorded iron and cadmium toxicity as its Fe (25.09, 18.68, 13.18 and 18.67 mg/kg) and Cd concentration (1.31, 1.09, 0.83 and 1.13 mg/kg) were higher than the WHO/DPR permissible level of 0.8. Manganese, zinc, copper, chromium, lead, nickel and vanadium were non-hazardous in the different land use types as their concentrations were lower than the permissible levels. The contamination and pollution index showed that the Fe and Cd pollution was weakest in the virgin land, and higher in the other land use types (plantain plantation, oil palm plantation, fallow land) where human and agricultural activities had taken place. It is therefore advised that the activities of subsistent farmers in the area be checkmated because the residents of the area depend on the farms for survival.

Keywords: Bayelsa State; concentration; heavy metals; hydraulic conductivity; land use types

Date published: 2022-08-02