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| Titel |
Predicting the denitrification capacity of sandy aquifers from shorter-term incubation experiments and sediment properties |
| VerfasserIn |
W. Eschenbach, R. Well |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 2 ; Nr. 10, no. 2 (2013-02-13), S.1013-1035 |
| Datensatznummer |
250017516
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| Publikation (Nr.) |
 copernicus.org/bg-10-1013-2013.pdf |
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| Zusammenfassung |
Knowledge about the spatial variability of denitrification rates and the
lifetime of denitrification in nitrate-contaminated aquifers is crucial to
predict the development of groundwater quality. Therefore, regression models
were derived to estimate the measured cumulative denitrification of aquifer
sediments after one year of incubation from initial denitrification rates
and several sediment parameters, namely total sulphur, total organic carbon,
extractable sulphate, extractable dissolved organic carbon, hot water
soluble organic carbon and potassium permanganate labile organic carbon.
For this purpose, we incubated aquifer material from two sandy Pleistocene
aquifers in Northern Germany under anaerobic conditions in the laboratory
using the 15N tracer technique. The measured amount of denitrification
ranged from 0.19 to 56.2 mg N kg−1 yr−1. The laboratory
incubations exhibited high differences between non-sulphidic and sulphidic
aquifer material in both aquifers with respect to all investigated sediment
parameters. Denitrification rates and the estimated lifetime of
denitrification were higher in the sulphidic samples. For these samples, the cumulative denitrification measured during one year of
incubation (Dcum(365)) exhibited distinct linear regressions with the stock of
reduced compounds in the investigated aquifer samples. Dcum(365)
was predictable from sediment variables within a range of uncertainty of 0.5
to 2 (calculated Dcum(365)/measured Dcum(365)) for
aquifer material with a
Dcum(365) > 20 mg N kg−1 yr−1. Predictions were
poor for samples with lower Dcum(365), such as samples from the
NO3− bearing groundwater zone, which includes the non-sulphidic
samples, from the upper part of both aquifers where denitrification is not
sufficient to protect groundwater from anthropogenic NO3− input.
Calculation of Dcum(365) from initial denitrification rates was
only successful for samples from the NO3−-bearing zone, whereas a
lag-phase of denitrification in samples from deeper zones of NO3−
free groundwater caused imprecise predictions.
In our study, Dcum(365) of two sandy Pleistocene aquifers was
predictable using a combination of short-term incubations and analysis of
sediment parameters. Moreover, the protective lifetime of denitrification
sufficient to remove NO3− from groundwater in the investigated
aquifers is limited, which demonstrates the need to minimise anthropogenic
NO3− input. |
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