TY  - JOUR
A1  - Houben, Georg J.
A1  - Post, Vincent E. A.
A1  - Gröger‐Trampe, Jens
A1  - Pesci, María H.
A1  - Sültenfuß, Jürgen
T1  - On the Propagation of Reaction Fronts in a Sandy Aquifer Over 20+ Years: Lessons From a Test Site in Northwestern Germany
Y1  - 2021-08-09
VL  - 57
IS  - 8
JF  - Water Resources Research
DO  - 10.1029/2020WR028706
DO  - 10.23689/fidgeo-5238
N2  - Despite reduction measures, nitrate and aluminum concentrations remain high in aquifers in northwestern Europe. To evaluate the effectiveness of groundwater protection policies, the long‐term fate of these contaminants in groundwater needs to be understood. The groundwater catchment of the Haren water works, NW Germany, was characterized hydrogeochemically in the late 1990s, which provides an opportunity to study the solute fronts over a two‐decade period and conduct a post‐audit of the predicted front movement. Results indicate that, despite a significant reduction of the atmospheric acid loads, the acidification of soil and groundwater at the forest site persists. Removal of sorbed aluminum is required to induce a noticeable improvement, which will take at least several decades. The unexpected appearance of nitrate at the site, caused by a land use change in 1998, highlights the need for long‐term monitoring. Core data at the agricultural site show that the denitrification front has moved very little between 1998 and 2017, in accordance with previous forecasts. Denitrification by‐products, mainly sulfate and nitrogen, have migrated from the upper into the lower aquifer. A reactive transport model demonstrated how the link between the regional groundwater flow, pyrite oxidation, and the temporal variability of the nitrate concentration in recharge water, as reconstructed from age tracers, result in the observed vertical distribution of sulfate and nitrogen. This study demonstrates how long‐term monitoring, aided by model‐based data interpretation, can be used to successfully study and predict the fate of contaminants in groundwater.
N2  - Key Points: Position of reaction fronts for nitrate and acidification in aquifers checked after 20+ years. Acidification of soil and groundwater still strong, despite reductions of atmospheric input. Nitrate front has moved very slowly over last 20 years but denitrification products have migrated into lower aquifer.
UR  - http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/9584
ER  -