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

作者：Gomez Alday J J; Carrey R; Valiente N^*; Otero N; Soler A; Ayora C; Sanz D; Munoz Martin A; Castano S; Recio C; Carnicero A; Cortijo A

来源：Science of the Total Environment, 2014, 497: 594-606.

DOI：10.1016/j.scitotenv.2014.07.129

• Hypersaline lake
• Freshwater-saltwater interface
• Stable isotopes
• Nitrification
• Denitrification

Agricultural regions in semi-arid to arid climates with associated saline wetlands are one of the most vulnerable environments to nitrate pollution. The Petrola Basin was declared vulnerable to NW 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 (delta N-15, delta S-34, delta C-13, delta O-18) 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, delta N-15(NO3) and delta O-18(NO3) 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.

• 出版日期2014-11-1