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Our understanding of the effects of pharmaceuticals on key biogeochemical processes and biofilm assemblage composition in surface waters is limited despite the prevalence of ng/L to µg/L concentrations of these compounds. We examined the effects of 3 commonly-prescribed pharmaceuticals: ciprofloxacin (140 ng/L), diphenhydramine (300 ng/L), and fluoxetine (20 ng/L); both individually and as a mixture, on key ecosystem processes at environmentally-realistic concentrations. We used mesocosms to expose naturally-occurring biofilm communities and artificial benthic substrates to these pharmaceuticals and measured the effects of exposure on biofilm, seston, and sediment communities. Established biofilm functions were unaffected by pharmaceutical treatments. However, successional biofilms experienced 42 to 81% reductions in primary production and 59 to 83% reductions in community respiration. Denitrification in sediment communities was reduced by 41 to 73% in shaded conditions, but was not affected when left in ambient light. Diatom assemblage structure was unaffected by pharmaceuticals in successional biofilms, whereas the composition of established biofilm assemblages changed with exposure to treatments that contained ciprofloxacin, diphenhydramine, and all 3 pharmaceuticals. Our study adds to a growing body of evidence indicating that chronic exposure to sub-lethal concentrations of pharmaceuticals may substantially alter key ecosystem processes and communities. [ABSTRACT FROM AUTHOR]

A simple sample preparation method based on a modified liquid‐phase extraction approach to extract selected pharmaceuticals and personal care products from freshwater organisms is described. Extracted samples were analysed using liquid chromatography with Q‐Exactive plus hybrid quadrupole Orbitrap mass spectrometry, using 2.6 μm C18 media. A 0.1% v/v acetic acid/acetonitrile mobile phase was applied over a 20 min gradient. Method detection limits in full scan mode were ca. 0.04–2.38 ng of analyte per g of sample. Linearity ranged from 0.9750 to 0.9996 over the calibration range of 0.01–100 μg/L; MS mass accuracy was <2 ppm for most analytes. This method was applied to quantify six pharmaceuticals and personal care products in seven invertebrate samples. For tandem mass spectrometry analysis, selection of precursor ions was performed for each pharmaceutical, with Mass Frontier software illustrating the fragmentation mechanism. Effects of collision energy on intensities of ions was further investigated. The tandem mass spectrometry condition resulting in the highest signal of respective selected product ion was selected to confirm each pharmaceutical, which was initially observed in the full scan mode. Results indicate that pharmaceuticals and personal care products found to be present in water‐ways, may be incorporated into organisms that live in the environment of affected water streams. [ABSTRACT FROM AUTHOR]