Adsorption/desorption and Transport of Sulfadiazine, Sulfachloropyridazine, and Sulfamethazine, in Acid Agricultural Soils

Batch-type experiments were used to study adsorption-desorption of three sulfonamides: sulfadiazine (SDZ) sulfachloropyridazine (SCP), and sulfamethazine (SMT), in five crop soils, whereas laboratory soil column experiments were employed to obtain data on transport processes. Adsorption results were satisfactorily adjusted to Linear and Feundlich equations, with R values above 0.95. Adsorption followed the sequence SDZ < SMT < SCP, showing higher values for soils with higher levels of organic carbon (OC) content. Conversely, desorption was higher in soils with less OC, and lower in soils with higher OC contents. The temporal moment analysis method gave values for the transport parameters τ and R which were significantly correlated with soil parameters related to organic matter, specifically OC and N concentrations. The higher retention of the three sulfonamides in soils with high organic matter content is a relevant fact, with value when programming management practices in agricultural soils, and specifically in relation to the spreading of animal manures, slurries, or waste containing these emerging pollutants.