Abstract

Ammonium contamination is one of the most nocive forms of groundwater contamination caused due to the extensive use of nitrogen fertilizers. Contaminant transport is governed by the adsorption mechanism, which varies as the contaminant migrates through different types of soils. It is important to understand the adsorption mechanism of ammonium ions and the factors influencing them to predict and mitigate their contamination. This work attempts to thoroughly investigate the effects of clay content present in the soil on the adsorption and eventually on the retardation of ammonium ions movement in the porous media. Ammonium ions transport was examined for three soil types with different clay proportions, by column and batch experiments. The experimental results were verified by simulating ammonium ion migration by numerical modeling using HYDRUS 2D software. It was observed the ammonium ions adsorption increases with the increase in the clay content of the soil. Therefore, greater content of clay in the soil enhances the retardation of ammonium migration in the soil. Further, it can be construed that the soil clay fraction ensures a reduction in deeper penetration of ammonium ions as a contaminant into the subsurface.