Publication Details

Category Text Publication
Reference Category Journals
DOI 10.1021/acs.est.7b03087
Title (Primary) High resolution monitoring above and below the groundwater table uncovers small-scale hydrochemical gradients
Author Gassen, N.; Griebler, C.; Werban, U. ORCID logo ; Trauth, N.; Stumpp, C.
Source Titel Environmental Science & Technology
Year 2017
Department HDG; MET
Volume 51
Issue 23
Page From 13806
Page To 13815
Language englisch
UFZ wide themes TERENO; MOSAIC; RU5;
Abstract Hydrochemical solute concentrations in the shallow subsurface can be spatially highly variable within small scales, particularly at interfaces. However, most monitoring systems fail to capture these small scale variations. Within this study, we developed a high resolution multilevel well (HR-MLW) with which we monitored water across the interface of the unsaturated and saturated zone with a vertical resolution of 0.05–0.5 m. We installed three of these 4 m deep HR-MLWs in the riparian zone of a third-order river and analyzed for hydrochemical parameters and stable water isotopes. The results showed three distinct vertical zones (unsaturated zone, upper saturated zone, lower saturated zone) within the alluvial aquifer. A 2 m thick layer influenced by river water (upper saturated zone) was not captured by existing monitoring wells with higher screen length. Hydrochemical data (isotopes, total ions) were consistent in all HR-MLWs and showed similar variation over time emphasizing the reliability of the installed monitoring system. Further, the depths zones were also reflected in the NO3–N concentrations; with high spatial variabilities between the three wells. The zonation was constant over time, with seasonal variability in the upper saturated zone due to the influence of river water. This study highlights the use of high resolution monitoring for identifying the spatial and temporal variability of hydrochemical parameters present in many aquifer systems. Possible applications range from riparian zones, agricultural field sites to contaminated site studies, wherever an improved understanding of biogeochemical turnover processes is necessary. Keywords: Multilevel well, capillary fringe, groundwater, riparian zone, nitrogen, heterogeneity
Persistent UFZ Identifier
Gassen, N., Griebler, C., Werban, U., Trauth, N., Stumpp, C. (2017):
High resolution monitoring above and below the groundwater table uncovers small-scale hydrochemical gradients
Environ. Sci. Technol. 51 (23), 13806 - 13815 10.1021/acs.est.7b03087