TY - JOUR

T1 - Transformation of organic micropollutants along hyporheic flow in bedforms of river-simulating flumes

AU - Jaeger, Anna

AU - Posselt, Malte

AU - Schaper, Jonas L.

AU - Betterle, Andrea

AU - Rutere, Cyrus

AU - Coll, Claudia

AU - Mechelke, Jonas

AU - Raza, Muhammad

AU - Meinikmann, Karin

AU - Portmann, Andrea

AU - Blaen, Phillip J.

AU - Horn, Marcus Andreas

AU - Krause, Stefan

AU - Lewandowski, Jörg

N1 - Funding Information: The work has received funding from the European Union’s Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant agreement No 641939 and additionally from the Research Training Group ‘Urban Water Interfaces (UWI)’ (GRK 2032/1) funded by the German Research Foundation (DFG). We thank the Birmingham University for providing the Environmental Change Outdoor Laboratory Facilities. We also thank all members of the HypoTrain project, especially Jonathan P. Benskin, Anna Sobek, Juliane Hollender, Anne Mehrtens and Tanu Singh, as well as Horst Jaeger for their help and contributions.

PY - 2021/6/22

Y1 - 2021/6/22

N2 - Urban streams receive increasing loads of organic micropollutants from treated wastewaters. A comprehensive understanding of the in-stream fate of micropollutants is thus of high interest for water quality management. Bedforms induce pumping effects considerably contributing to whole stream hyporheic exchange and are hotspots of biogeochemical turnover processes. However, little is known about the transformation of micropollutants in such structures. In the present study, we set up recirculating flumes to examine the transformation of a set of micropollutants along single flowpaths in two triangular bedforms. We sampled porewater from four locations in the bedforms over 78 days and analysed the resulting concentration curves using the results of a hydrodynamic model in combination with a reactive transport model accounting for advection, dispersion, first-order removal and retardation. The four porewater sampling locations were positioned on individual flowpaths with median solute travel times ranging from 11.5 to 43.3 h as shown in a hydrodynamic model previously. Highest stability was estimated for hydrochlorothiazide on all flowpaths. Lowest detectable half-lives were estimated for sotalol (0.7 h) and sitagliptin (0.2 h) along the shortest flowpath. Also, venlafaxine, acesulfame, bezafibrate, irbesartan, valsartan, ibuprofen and naproxen displayed lower half-lives at shorter flowpaths in the first bedform. However, the behavior of many compounds in the second bedform deviated from expectations, where particularly transformation products, e.g. valsartan acid, showed high concentrations. Flowpath-specific behavior as observed for metformin or flume-specific behavior as observed for metoprolol acid, for instance, was attributed to potential small-scale or flume-scale heterogeneity of microbial community compositions, respectively. The results of the study indicate that the shallow hyporheic flow field and the small-scale heterogeneity of the microbial community are major controlling factors for the transformation of relevant micropollutants in river sediments.

AB - Urban streams receive increasing loads of organic micropollutants from treated wastewaters. A comprehensive understanding of the in-stream fate of micropollutants is thus of high interest for water quality management. Bedforms induce pumping effects considerably contributing to whole stream hyporheic exchange and are hotspots of biogeochemical turnover processes. However, little is known about the transformation of micropollutants in such structures. In the present study, we set up recirculating flumes to examine the transformation of a set of micropollutants along single flowpaths in two triangular bedforms. We sampled porewater from four locations in the bedforms over 78 days and analysed the resulting concentration curves using the results of a hydrodynamic model in combination with a reactive transport model accounting for advection, dispersion, first-order removal and retardation. The four porewater sampling locations were positioned on individual flowpaths with median solute travel times ranging from 11.5 to 43.3 h as shown in a hydrodynamic model previously. Highest stability was estimated for hydrochlorothiazide on all flowpaths. Lowest detectable half-lives were estimated for sotalol (0.7 h) and sitagliptin (0.2 h) along the shortest flowpath. Also, venlafaxine, acesulfame, bezafibrate, irbesartan, valsartan, ibuprofen and naproxen displayed lower half-lives at shorter flowpaths in the first bedform. However, the behavior of many compounds in the second bedform deviated from expectations, where particularly transformation products, e.g. valsartan acid, showed high concentrations. Flowpath-specific behavior as observed for metformin or flume-specific behavior as observed for metoprolol acid, for instance, was attributed to potential small-scale or flume-scale heterogeneity of microbial community compositions, respectively. The results of the study indicate that the shallow hyporheic flow field and the small-scale heterogeneity of the microbial community are major controlling factors for the transformation of relevant micropollutants in river sediments.

UR - http://www.scopus.com/inward/record.url?scp=85108795206&partnerID=8YFLogxK

U2 - 10.1038/s41598-021-91519-2

DO - 10.1038/s41598-021-91519-2

M3 - Article

C2 - 34931003

VL - 11

JO - Scientific reports

JF - Scientific reports

SN - 2045-2322

IS - 1

M1 - 13034

ER -