Anion Exchange Characteristics in a Loess Soil.

Loess soils of west Tennessee have been found to contain large amounts of subsoil Fe-oxides that retain and restrict the movement of conservative anions, such as nitrate and bromide. Concentrated levels of Fe-oxides, and accumulated anion concentrations, are located in the argillic horizons (30 to 46 cm depth) and in the underlying tertiary sands (220 cm depth). This study examined anion exchange characteristics of binary and ternary nitrate, sulfate, and chloride systems in the high Fe-oxide horizons of the loess soils. Exchange isotherms indicate that both chloride and nitrate are preferred by the soil anion exchange complex relative to sulfate, where preference is defined by a Vanselow selectivity coefficient that is greater than 1. The isotherms also show that the soil exchanger phase prefers chloride relative to nitrate. These findings enhance our understanding of how the addition of flue-gas desulfurization (FGD) gypsum will potentially affect anion dynamics in loess soils of west Tennessee.