Influence of soil texture and composition of the distribution of arsenic in soil and water

Abstract

Arsenic IS of significant environment concern In much of the world because of its concentration in underground water, which may be originated from the parent materials of soils, as soil is known as to act as a majOr sink of arsenic in its contaminated ground water belt. In the present study. some of the important cations (Iron, Manganese, Aluminum, Sodium and Magnesium), anions (Nitrate, Phosphate, Chloride and Carbonate), soil pH, Ehand soil texture from surface to 90ft depths of some selected spots were measured. Arsenic contents of water of 90ft depth of these spots were also measured. The main purpose of this study was to evaluate whether these properties and compositions of soil have any influence on the concentration of arsenic in underground water. It was found that the arsenic content of underground water has a good relation with the concentration of soil, Iron, Manganese, Aluminium, Magnesium, Phosphate and carbonates. Percentage of clay content was found as an important parameter for the adsorption of arsenic and the mentioned ions on soil, which have influences on the leaching of arsenic to the underground water. The first level of underground water of our study areas were found with in 80ft to 90ft depths. So soil compositions and texture of their near about levels may have important influence on the arsenic content of water, which accumulates through leaching from the soil materials. It was observed that underground water sample of Savar spot showed the lowest concentration of arsenic, 0.0104ppm and the water sample of Kholapara spot showed highest concentration of arsenic, O.0752ppm. Arsenic contents in underground water of Singair, Kiting Char and Vlail were found 0.0689ppm, O.035ppmand 0.0165 ppm respectively. It was observed that for the soil samples of Savar, Kiting Char and Vlail spots, near about the first level of underground water have higher percentages of clay contents. Iron, Manganese, Aluminium and Carbonate contents were also higher in these samples. Phosphate and •• Magnesium contents were found lower in these samples. Arsenic contents in water of thcse spots were found with in the safe level, below 0.05 ppm. Much higher contents of arsenic in underground water were found in Singair and Kholapara spots, where percentage of clay and concentration of soil Iron, Manganese, Aluminium and Carbonates were found lower near about the first levels of the underground water layer. But phosphate and magnesium contents were found higher in these samples. So it may be assumed that greater contents of Iron, Manganese, Aluminium, Carbonate and Clay in soil influence on the higher adsorption of arsenic in soil and lower leaching of arsenic to water. Where as greater contents of magnesium and phosphates in soil influence lower adsorption of arsenic in soil and higher leaching to underground water.