Relationship between electrical conductivity, 18O of water and NO3 content in different streamflow stages

CALVI, CAROLINA; DAPEÑA, CRISTINA; MARTINEZ, DANIEL E.; QUIROZ LONDOÑO, ORLANDO M.

Environmental Earth Sciences

Springer

Año: 2018 vol. 77

1866-6280

The Ballenera creek is a small catchment in the Pampa plain in Argentina . This area has been deeply modified by human action through agricultural activities. From 2013 to 2017, Electrical Conductivity, 18O of water and nitrate concentration monitoring program was conducted. The sampling included weekly and bi-monthly samples in two sites along the stream, several groundwater wells and monthly precipitation. Chemical and isotopic tracers are used to discriminate the streamflow components and to evaluate their incidence in the nitrate concentration. The easiest conceptual model for gaining streams contemplates two main elements: direct runoff and groundwater (baseflow and pre-event water). The direct runoff has the lowest EC and 18Ow variable content. The baseflow component is characterized by the highest EC and isotope composition quite constant. Finally, pre-event water has an intermediate EC and isotopic content close to the rainfall weighted average composition. The nitrate concentration obtained was in general related to the different stream stages and was a useful indicator to evaluate the fertilization in agricultural zones.