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Nitrate Sorption in a Mexican Allophanic Andisol using Intact and Packed Columns

Prado, B., Duwig, C., Escudey, M., Esteves, M.
Communications in soil science and plant analysis 2006 v.37 no.15-20 pp. 2911-2925
allophanic soils, Andisols, sorption, nitrate nitrogen, groundwater, groundwater contamination, eutrophication, leaching, volcanic soils, aluminum oxide, iron oxides, ion transport, anions, mass flow, adsorption, soil chemistry, soil mineralogy, Mexico
Contamination of groundwater by nitrate is a worldwide environmental issue. A better knowledge of nitrate sorption characteristics by soils contributes to efficient fertilizer use and prevents aquifer contamination. In volcanic soils, nitrate sorption is induced by variable charges due to the presence of amorphous materials and aluminum (Al) and iron (Fe) oxides. Anion transport in packed and intact columns was investigated in a Mexican Allophanic Andisol, under different permanent flow regimes in unsaturated conditions and several NO3(-)-N and Br(-) input concentrations. In the packed columns, the NO3(-)-N adsorption in the soil was nonlinear. In the intact columns, the retardation coefficient variation was directly correlated to the increase of amorphous material with depth. The presence of preferential flow in the intact columns significantly increased the mobility and velocity of nitrate moving through the columns, whereas in the packed columns, NO3(-)-N fate was only affected by soil chemical composition and mineralogy.