Abstract:
Estradiol, estrone, and testosterone are pharmaceutical compounds that are commonly excreted and released into waterways where their fate is largely unknown. This study quantified the effect of these three hormone compounds on microbial activity in freshwater sediment. Sediment samples were collected from the White River in Muncie Indiana and exposed to varying concentrations of one of the three target hormones. Microbial activity was quantified as total respiration and nitrogen and phosphate uptake rates per unit dry mass. Increasing estrone concentration significantly decreased both respiration and nitrate uptake when compared to controls. Estradiol did not influence microbial respiration, but decreased nitrate uptake rates. Conversely, testosterone did not influence microbial respiration or nutrient uptake rates. Phosphate uptake was not significantly influenced by any experimental concentrations of the hormones tested. These results indicate that estrogenic compounds vary in their potential environmental effects. Further, hormones had pronounced effects on microbial activity even at trace concentrations currently measured in natural ecosystems. Thus, current estrogenic compound concentrations could be adversely affecting freshwater integrity.
