title: In-stream attenuation of neuro-active pharmaceuticals and their metabolites.
abstract: In-stream attenuation was determined for 14 neuro-active pharmaceuticals and associated metabolites. Lagrangian sampling, which follows a parcel of water as it moves downstream, was used to link hydrological and chemical transformation processes. Wastewater loading of neuro-active compounds varied considerably over a span of several hours, and thus a sampling regime was used to verify that the Lagrangian parcel was being sampled and a mechanism was developed to correct measured concentrations if it was not. In-stream attenuation over the 5.4-km evaluated reach could be modeled as pseudo-first-order decay for 11 of the 14 evaluated neuro-active pharmaceutical compounds, illustrating the capacity of streams to reduce conveyance of neuro-active compounds downstream. Fluoxetine and N-desmethyl citalopram were the most rapidly attenuated compounds (t1/2 = 3.6 ± 0.3 h, 4.0 ± 0.2 h, respectively). Lamotrigine, 10,11,-dihydro-10,11,-dihydroxy-carbamazepine, and carbamazepine were the most persistent (t1/2 = 12 ± 2.0 h, 12 ± 2.6 h, 21 ± 4.5 h, respectively). Parent compounds (e.g., buproprion, carbamazepine, lamotrigine) generally were more persistent relative to their metabolites. Several compounds (citalopram, venlafaxine, O-desmethyl-venlafaxine) were not attenuated. It was postulated that the primary mechanism of removal for these compounds was interaction with bed sediments and stream biofilms, based on measured concentrations in stream biofilms and a column experiment using stream sediments.
authors: Department of Civil, Environmental, and Architectural Engineering, University of Colorado , 428 UCB, Boulder, Colorado 80309-0428, United States. writer@colorado.edu
authors: Jeffrey H
authors: JH
authors: Writer
authors: Ronald C
authors: RC
authors: Antweiler
authors: Imma
authors: I
authors: Ferrer
authors: Joseph N
authors: JN
authors: Ryan
authors: E Michael
authors: EM
authors: Thurman
mesh_terms: D018407:Bacterial Physiological Phenomena; D018441:Biofilms; D002491:Central Nervous System Agents / Q000032:analysis / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003120:Colorado; D004784:Environmental Monitoring / Q000379:methods*; D019015:Geologic Sediments / Q000032:analysis; D018373:Peripheral Nervous System Agents / Q000032:analysis / Q000378:metabolism*; D045483:Rivers / Q000737:chemistry*; D012621:Seasons; D053719:Tandem Mass Spectrometry; D062065:Wastewater / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*
chemical_list: D002491:Central Nervous System Agents; D018373:Peripheral Nervous System Agents; D062065:Wastewater; D014874:Water Pollutants, Chemical