Microbial responses to selected pharmaceuticals in agricultural soils: Microcosm study on the roles of soil, treatment and time

Evaluating microbial responses to pharmaceuticals in agricultural soils is essential to improve our fundamental understanding of the fate of micropollutants and their potential implications for the environment and human health. In this study, we focused on the immediate (1 d), short- (13 d) and long-term effects (61 d) of pharmaceutical amendment on microbial communities in seven soils differing in physical chemical properties. Basal respiration was used to indicate microbial activity, while phospholipid fatty acids were used to determine microbial biomass and community structure. We identified four microbial responses to pharmaceutical amendment: stimulation, inhibition, stress and dormancy, which were highly significant in the short-term. The largest stimulatory effect accompanied by shifts in the microbial community structure towards fungi and G- bacteria was detected for sulfamethoxazole. The inhibitory effect was mainly observed for citalopram, irbesartan and pharmaceutical mixture in Cambisol Dystric with minor alterations in microbial community structure compare to a non-amended control. The stress effect was detected for all pharmaceuticals in Arenosol and Cambisol Haplic. While the dormancy effect was mainly observed in Chernozem Siltic for most of the pharmaceuticals. Microbial responses were highly dependent on the soil type, pharmaceutical compound and time, highlighting the importance to consider these parameters including a resilience of soil microbial communities to micropollutants within a long-term agricultural soil management.