Abstract— Fluoride (F) is an essential element for life. At low concentrations, it is generally believed that fluoride deficiencies can arise, but at high fluoride concentrations other deleterious effects can certainly transpire. This study was conducted to evaluate F content and its spatial variability in Isfahan province. This area covers different land uses including agricultural, industrial, urban and uncultivated lands. Two hundred and fifty five topsoil samples (0- 20 cm) in a study area of 6800 km² were collected. Total fluoride and water soluble fluoride were measured. The results of this research showed that two forms of soil F were controlled by intrinsic factors such as parent material and extrinsic factors such as fertilization.
The total fluoride concentration in 96% of the data was less than the globule suggested average (200 mg kg‾¹) and water soluble fluoride concentration in 72 % of the samples exceeded the suggested averaged(0.5 mg kg‾¹).
Key words- water soluble fluoride; total fluoride; kriging; spatial distribution
Fluorine is one of the essential micronutrient for both human and animals. It is present in soils, rocks, water and the biological chains of animal and plant lives . The F concentrations vary in relation to many factors such as geogenic and anthropogenic processes. A large number of industries emit F in atmosphere, including brick and tile manufactures, steel and aluminum manufacture and the production of phosphoric acid, super phosphate fertilizer and elementary phosphorus . Application of phosphate fertilizers, sewage sludges and some pesticides also bring F to soil  but the majority of any added F becomes fixed by one or more of soil components  and F may nevertheless represent a risk for groundwater contamination, especially under strong acid or alkaline conditions .
Drinking water is often the main source of F intake by human, especially in the areas where F concentrations in groundwater /surface water is high [4,12]. It is estimated that more than 200 million people worldwide  rely on drinking water with F concentrations that exceed the present WHO guideline of 1.5 mg l‾¹.
High F- groundwater, causing fluorosis, is a considerable health problem in several regions of the world. Fluorosis is manifested mainly in three ways: fluorosis in soft tissues, such as muscles and ligaments , dental fluorosis and skeletal fluorosis.
Due to the threat to human health, many studies have been conducted on water fluoride but this is forgotten that F in water and food are coming from soil. Therefore, increasing attention should be paid to soil F quality. However, little attention has been paid on the spatial distribution of soil F concentration on the regional scale in world. In Iran, also, there is no information on spatial distribution of soil F. So, this study was conducted in central Iran (Isfahan province) to assess the water soluble fluoride and total fluoride...