Assessment of fluoride content in tropical surface soils used for crop cultivation

Abstract

Bongo district of the Upper East Region of Ghana relies on groundwater as the main source of potable water supply for domestic purposes. However, available literature indicated that groundwater in the area has elevated fluoride levels. Little work is done on fluoride contents in the soils of the area and its implication to plants and other living organisms. Hence the objectives of this study were to determine the level of fluoride (F) in cultivated soils and its implication to crops, since the soils form the essential medium for crops growth. Also to document fluoride concentrations in cropland soils in Ghana. Samples of selected cropland soils were collected at a depth ranged 1.0 cm to 30.0 cm and digested with aqua-regia, and analyzed for fluoride and calcium content using spectrophotometer DR/2000 and EDTA complexometric titration respectively. The mean pH of most of the soil samples ranged from 5.7 to 6.2, while the specific electrical conductivity ranged from 420.0 to 1735.0 μs/cm of soils used. The F content in the soils ranged from 219.26 to 1163.01 mgkg^-1 DW. The ions bioavailability is controlled by physical and chemical characteristics of the soils. Although, this was the first study of its kind in the district it depicted that excess fluoride in water reported in the area has a relationship with the trend reported in this paper.

Key words: Fluorine, laterite, Africa, fluorosis, toxicity, Bongo district, crops.