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Sci Total Environ. 2014 Nov 1;497-498:594-606. doi: 10.1016/j.scitotenv.2014.07.129. Epub 2014 Aug 27.

Denitrification in a hypersaline lake-aquifer system (Pétrola Basin, Central Spain): the role of recent organic matter and Cretaceous organic rich sediments.

Author information

1
Hydrogeology Group, Institute for Regional Development (IDR), University of Castilla-La Mancha (UCLM), Campus Universitario s/n, 02071 Albacete, Spain. Electronic address: JuanJose.Gomez@uclm.es.
2
Grup d'Mineralogia Aplicada i Medi Ambient, Dep. Cristal·lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona, C/ Martí i Franquès s/n, 08028, Barcelona, Spain. Electronic address: raulcarrey@ub.edu.
3
Hydrogeology Group, Institute for Regional Development (IDR), University of Castilla-La Mancha (UCLM), Campus Universitario s/n, 02071 Albacete, Spain. Electronic address: Nicolas.Valiente@uclm.es.
4
Grup d'Mineralogia Aplicada i Medi Ambient, Dep. Cristal·lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona, C/ Martí i Franquès s/n, 08028, Barcelona, Spain. Electronic address: notero@ub.edu.
5
Grup d'Mineralogia Aplicada i Medi Ambient, Dep. Cristal·lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona, C/ Martí i Franquès s/n, 08028, Barcelona, Spain. Electronic address: albertsolergil@ub.edu.
6
Grup d'Hidrologia Subterrània (GHS), Institut de Diagnóstic Ambiental i Estudis de l'Aigua (IDAEA-CSIC), C/Jordi Girona 18, 08028 Barcelona, Spain. Electronic address: cayora1@gmail.com.
7
Hydrogeology Group, Institute for Regional Development (IDR), University of Castilla-La Mancha (UCLM), Campus Universitario s/n, 02071 Albacete, Spain.
8
Applied Tectonophysics Group, Departamento de Geodinámica, Universidad Complutense de Madrid, C/José Antonio Novais 2, 28040 Madrid, Spain. Electronic address: amunoz@geo.ucm.es.
9
Stable Isotope Laboratory, University of Salamanca, Plz. De los Caídos s/n, 37008 Salamanca, Spain. Electronic address: crecio@usal.es.
10
Stable Isotope Laboratory, University of Salamanca, Plz. De los Caídos s/n, 37008 Salamanca, Spain.

Abstract

Agricultural regions in semi-arid to arid climates with associated saline wetlands are one of the most vulnerable environments to nitrate pollution. The Pétrola Basin was declared vulnerable to NO3(-) pollution by the Regional Government in 1998, and the hypersaline lake was classified as a heavily modified body of water. The study assessed groundwater NO3(-) through the use of multi-isotopic tracers (δ(15)N, δ(34)S, δ(13)C, δ(18)O) coupled to hydrochemistry in the aquifer connected to the eutrophic lake. Hydrogeologically, the basin shows two main flow components: regional groundwater flow from recharge areas (Zone 1) to the lake (Zone 2), and a density-driven flow from surface water to the underlying aquifer (Zone 3). In Zones 1 and 2, δ(15)NNO3 and δ(18)ONO3 suggest that NO3(-) from slightly volatilized ammonium synthetic fertilizers is only partially denitrified. The natural attenuation of NO3(-) can occur by heterotrophic reactions. However, autotrophic reactions cannot be ruled out. In Zone 3, the freshwater-saltwater interface (down to 12-16 m below the ground surface) is a reactive zone for NO3(-) attenuation. Tritium data suggest that the absence of NO3(-) in the deepest zones of the aquifer under the lake can be attributed to a regional groundwater flow with long residence time. In hypersaline lakes the geometry of the density-driven flow can play an important role in the transport of chemical species that can be related to denitrification processes.

KEYWORDS:

Denitrification; Freshwater–saltwater interface; Hypersaline lake; Nitrification; Stable isotopes

PMID:
25169874
DOI:
10.1016/j.scitotenv.2014.07.129
[Indexed for MEDLINE]

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