3Stockholm University (Stockholm University, SE-106 91 Stockholm, Sweden - Sweden)
4GR - Géosciences Rennes (Bâtiment 15 - Université de Rennes 1 - Campus de Beaulieu -263 Av du général Leclerc- CS 74205 - 35042 Rennes Cedex - France - France)
Abstract : The fate of 28 trace organic compounds (TrOCs) was investigated in the hyporheic zone (HZ) of an urban lowland river in Berlin, Germany. Water samples were collected hourly over 17 h in the river and in three depths in the HZ using minipoint samplers. The four relatively variable time series were subsequently used to calculate first-order removal rates and retardation coefficients via a one-dimensional reactive transport model. Reversible sorption processes led to substantial retardation of many TrOCs along the investigated hyporheic flow path. Some TrOCs such as dihydroxy-carbamazepine, O-desmethylvenlafaxine and venlafaxine were found to be stable in the HZ. Others were readily removed with half-lives in the first 10 cm of the HZ ranging from 0.1±0.01 h for iopromide to 3.3±0.3 h for tramadol. Removal rate constants of the majority of reactive TrOCs were highest in the first 10 cm of the HZ, where removal of biodegradable dissolved organic matter was also highest. Because conditions were oxic along the top 30 cm of the investigated flow path we attribute this finding to the high microbial activity typically associated with the shallow HZ. Frequent and short vertical hyporheic exchange flows could therefore be more important for reach-scale TrOC removal than long, lateral hyporheic flow paths
Jonas Schaper, Malte Posselt, Camille Bouchez, Anna Jaeger, Gunnar Nützmann, et al.. Fate of trace organic compounds in the hyporheic zone: influence of retardation, the benthic bio-layer and organic carbon. Environmental Science & Technology, American Chemical Society, In press, ⟨10.1021/acs.est.8b06231⟩. ⟨insu-02082924⟩
