Details
| Original language | English |
|---|---|
| Pages (from-to) | 890-899 |
| Number of pages | 10 |
| Journal | Applied geochemistry |
| Volume | 24 |
| Issue number | 5 |
| Publication status | Published - May 2009 |
Abstract
The acidification of groundwater, due to acid rain, was investigated in a Quaternary sandy aquifer in the Fuhrberger Feld, near Hannover, Germany. The groundwater, recharged through an area covered by a coniferous forest, had a pH in the range 4-5 down to a depth of 5 m. The evolution in groundwater chemistry along the flow path was investigated in a transect of multisamplers. A 2D groundwater flow model was established delineating the groundwater flow field and a groundwater flow velocity of around 80 m/a along the flow path was derived. Speciation calculations showed the groundwater to be close to equilibrium with the mineral jurbanite (AlOHSO4) over the pH range 4.0-6.5. This suggests an accumulation of acid rain derived SO42 - in the aquifer sediment during the decades with high atmospheric S deposition. The groundwater has a pH of around 4.5 in the upstream part of the flow path increasing to near 6 further downstream. 1D reactive transport modelling, using PHREEQC, was used to analyze different combinations of buffering processes. The first model contains ion exchange in combination with jurbanite dissolution. At the ion exchange front Al3+ is adsorbed leading to the dissolution of jurbanite and an increase in pH. Comparison with field data showed that the simulated increases in pH and alkalinity are much lower than observed in the field. The second model includes organic matter degradation. In addition to ion exchange and jurbanite dissolution, the model included the reduction of SO42 - and Fe-oxides as well as the precipitation of Fe sulfide. This model matches the field data well and illustrates the importance of redox processes for pH buffering in the Fuhrberg aquifer. The current progress of the acidification front is about 4 m/a. This corresponds to an average value of 150 a of acid input, which covers large historical variations. Remediation is expected to take the same time span because it requires desorption and neutralization of adsorbed Al3+ from the aquifer sediment.
ASJC Scopus subject areas
- Environmental Science(all)
- Environmental Chemistry
- Environmental Science(all)
- Pollution
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
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In: Applied geochemistry, Vol. 24, No. 5, 05.2009, p. 890-899.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Acid groundwater in an anoxic aquifer
T2 - Reactive transport modelling of buffering processes
AU - Franken, Gudrun
AU - Postma, Dieke
AU - Duijnisveld, Wilhelmus H.M.
AU - Böttcher, Jürgen
AU - Molson, John
N1 - Copyright: Copyright 2009 Elsevier B.V., All rights reserved.
PY - 2009/5
Y1 - 2009/5
N2 - The acidification of groundwater, due to acid rain, was investigated in a Quaternary sandy aquifer in the Fuhrberger Feld, near Hannover, Germany. The groundwater, recharged through an area covered by a coniferous forest, had a pH in the range 4-5 down to a depth of 5 m. The evolution in groundwater chemistry along the flow path was investigated in a transect of multisamplers. A 2D groundwater flow model was established delineating the groundwater flow field and a groundwater flow velocity of around 80 m/a along the flow path was derived. Speciation calculations showed the groundwater to be close to equilibrium with the mineral jurbanite (AlOHSO4) over the pH range 4.0-6.5. This suggests an accumulation of acid rain derived SO42 - in the aquifer sediment during the decades with high atmospheric S deposition. The groundwater has a pH of around 4.5 in the upstream part of the flow path increasing to near 6 further downstream. 1D reactive transport modelling, using PHREEQC, was used to analyze different combinations of buffering processes. The first model contains ion exchange in combination with jurbanite dissolution. At the ion exchange front Al3+ is adsorbed leading to the dissolution of jurbanite and an increase in pH. Comparison with field data showed that the simulated increases in pH and alkalinity are much lower than observed in the field. The second model includes organic matter degradation. In addition to ion exchange and jurbanite dissolution, the model included the reduction of SO42 - and Fe-oxides as well as the precipitation of Fe sulfide. This model matches the field data well and illustrates the importance of redox processes for pH buffering in the Fuhrberg aquifer. The current progress of the acidification front is about 4 m/a. This corresponds to an average value of 150 a of acid input, which covers large historical variations. Remediation is expected to take the same time span because it requires desorption and neutralization of adsorbed Al3+ from the aquifer sediment.
AB - The acidification of groundwater, due to acid rain, was investigated in a Quaternary sandy aquifer in the Fuhrberger Feld, near Hannover, Germany. The groundwater, recharged through an area covered by a coniferous forest, had a pH in the range 4-5 down to a depth of 5 m. The evolution in groundwater chemistry along the flow path was investigated in a transect of multisamplers. A 2D groundwater flow model was established delineating the groundwater flow field and a groundwater flow velocity of around 80 m/a along the flow path was derived. Speciation calculations showed the groundwater to be close to equilibrium with the mineral jurbanite (AlOHSO4) over the pH range 4.0-6.5. This suggests an accumulation of acid rain derived SO42 - in the aquifer sediment during the decades with high atmospheric S deposition. The groundwater has a pH of around 4.5 in the upstream part of the flow path increasing to near 6 further downstream. 1D reactive transport modelling, using PHREEQC, was used to analyze different combinations of buffering processes. The first model contains ion exchange in combination with jurbanite dissolution. At the ion exchange front Al3+ is adsorbed leading to the dissolution of jurbanite and an increase in pH. Comparison with field data showed that the simulated increases in pH and alkalinity are much lower than observed in the field. The second model includes organic matter degradation. In addition to ion exchange and jurbanite dissolution, the model included the reduction of SO42 - and Fe-oxides as well as the precipitation of Fe sulfide. This model matches the field data well and illustrates the importance of redox processes for pH buffering in the Fuhrberg aquifer. The current progress of the acidification front is about 4 m/a. This corresponds to an average value of 150 a of acid input, which covers large historical variations. Remediation is expected to take the same time span because it requires desorption and neutralization of adsorbed Al3+ from the aquifer sediment.
UR - http://www.scopus.com/inward/record.url?scp=64749083617&partnerID=8YFLogxK
U2 - 10.1016/j.apgeochem.2009.02.001
DO - 10.1016/j.apgeochem.2009.02.001
M3 - Article
AN - SCOPUS:64749083617
VL - 24
SP - 890
EP - 899
JO - Applied geochemistry
JF - Applied geochemistry
SN - 0883-2927
IS - 5
ER -