Sorption behavior of sulfamethazine on unamended and manure-amended soils and short-term impact on soil microbial community

In this study we investigated the sorption of sulfamethazine (SMZ) in two soils with different physico-chemical properties and the sulfonamide short-term influence on the microbial community structure and function. The presence of manure increased the SMZ sorption, the uppermost level being measured on soil with the lower pH and the higher manure content allowed by the Italian regulation. The sulfonamide desorption was hysteretic on both soils. SMZ addition to soil at the concentration of 53.6 μg/g had a significant short-term negative impact on readily culturable bacteria, potential metabolic activity (Biolog CLPP) and soil enzyme activity. Moreover, a shift of the culturable microbial populations towards a lower bacteria/fungi ratio was observed after SMZ addition. Despite the observed SMZ effects disappeared almost completely after 7 day, structural changes of microbial communities were still present in SMZ-treated soils. The results presented are remarkable since previous studies addressing the SMZ impact on soil microbial parameters failed to highlight any significant effect of the sulfonamide on microbial abundance and diversity.

► We examine sulfamethazine (SMZ) sorption and its microbiological effects in two soils.
► Manure presence in soil increases SMZ sorption.
► SMZ desorption is hysteretic on both soils.
► SMZ (53.6 μg/g soil) has detrimental short-term effects on microorganisms.
► SMZ has detrimental short-term effects on soil functionality.