Schaper, J; Posselt, M; Bouchez, C; Jaeger, A; Nützmann, G; Putschew, A; Singer, G; Lewandowski, J: Fate of Trace Organic Compounds in the Hyporheic Zone: Influence of Retardation, the Benthic Biolayer, and Organic Carbon, Environmental Science & Technology, 53(8), 4224-4234 (2019), doi:10.1021/acs.est.8b06231 [Link]

The fate of 28 trace organic compounds(TrOCs) was investigated in the hyporheic zone (HZ) ofan urban lowland river in Berlin, Germany. Water sampleswere collected hourly over 17 h in the river and in threedepths in the HZ using minipoint samplers. The four relativelyvariable time series were subsequently used to calculatefirst-order removal rates and retardation coefficients via a one-dimensional reactive transport model. Reversible sorptionprocesses led to substantial retardation of many TrOCs alongthe investigated hyporheicflow path. Some TrOCs, such asdihydroxy-carbamazepine,O-desmethylvenlafaxine, and ven-lafaxine, were found to be stable in the HZ. Others werereadily removed with half-lives in thefirst 10 cm of the HZranging from 0.1±0.01 h for iopromide to 3.3±0.3 h fortramadol. Removal rate constants of the majority of reactive TrOCs were highest in thefirst 10 cm of the HZ, where removal ofbiodegradable dissolved organic matter was also the highest. Because conditions were oxic along the top 30 cm of theinvestigatedflow path, we attribute thisfinding to the high microbial activity typically associated with the shallow HZ. Frequentand short vertical hyporheic exchangeflows could therefore be more important for reach-scale TrOC removal than long, lateralhyporheicflow paths.

last modified 2019-10-28