The role of gravel-pit lakes in the removal of nitrate from phreatic aquifers of the Garonne valley. An attempt at an evaluation

Nitrate removal by several gravel-pit lakes was evaluated by constructing a budget of nitrate input and output and by direct measurement of denitrification at the sediment-water interface. There was no measurable denitrification activity in recently opened and working gravel pits. There was little a...

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Bibliographic Details
Published in:Annales de limnologie 1988-01, Vol.24 (1), p.31-38
Main Authors: Labroue, J, Tourenq, J N, Mieussens, C, Robert, J, Donville, B
Format: Article
Language:fre
Subjects:
Freshwater
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Summary:Nitrate removal by several gravel-pit lakes was evaluated by constructing a budget of nitrate input and output and by direct measurement of denitrification at the sediment-water interface. There was no measurable denitrification activity in recently opened and working gravel pits. There was little activity in the oldest pit which contained less than 1 ppm of nitrates. An enriched lake used for fishing and recreation showed high denitrification activity. There were seasonal differences. Temperature seemed most important in winter and spring. High measured activity in September and October was possibly due to organic matter enabling an algal bloom. Nitrate concentration was not a limiting factor in clogged gravel pits. To reduce nitrates sufficiently to produce potable water, a very large surface would be needed. It was calculated that for one of the gravel pits with a flow of 40 m3 per h, 7 ha would be needed to remove 10 ppm of the nitrates.
ISSN:0003-4088