Co2+ sorption capacity indicators of La Plata region's soils: insights and correlations with soil properties

Notwithstanding that the soil acts as a pollutant sink, its Co sorption capacity presents still controversial results. Here, Co2+sorption on soil samples from La Plata (Argentina) was analysed. Four sorption indicators were used: Kdis (estimated from the entire sorption isotherm), KF1 (estimated from the lineal part of the sorption isotherm), Kdx, (solid-solution distribution coefficient) and Kr, a dimensionless parameter recently developed. Pearson correlation coefficients between the parameters and soil properties were calculated. Significant and negative correlations with silt were obtained, whereas significant and positive correlations were established with clay and smectite content. Soil clay fractions were isolated and Co2+ sorption was evaluated, observing relatively high removal. The correlations with kaolinite, magnetite and Mn and Fe oxides showed debatable results: Kdis could be more sensitive than Kr to magnetite variations whereas Kr seems to be more sensitive to Mn changes. KF1 presented similar behaviour to Kr. The studied soils presented a high Co2+ sorption capacity, making them an effective barrier of this pollutant, avoiding its passage to groundwater and crops.