Hydrogeochemical characteristics of the Saliencia lakes (Somiedo Natural Park, NW Spain)trophic state and relationship with anthropogenic pressures

  1. Javier Sánchez-España
  2. Juana Vegas
  3. Mario Morellon
  4. M. Pilar Mata
  5. Juan A. Rodríguez García
Revue:
Boletín geológico y minero

ISSN: 0366-0176

Année de publication: 2019

Volumen: 130

Número: 2

Pages: 251-269

Type: Article

DOI: 10.21701/BOLGEOMIN.130.2.003 DIALNET GOOGLE SCHOLAR lock_openAccès ouvert editor

D'autres publications dans: Boletín geológico y minero

Résumé

The high-mountain lakes of Saliencia (El Valle, La Cueva, Calabazosa and Cerveriz), in the Somiedo Natural Park (Asturias, NW Spain), have been subject to different anthropogenic pressures, including metal mining, cattle grazing, damming activities and water channelling work for hydroelectric exploitation. This paper reports the results of a recent geochemical and limnological study conducted in these lakes, for which no previous study existed in the literature. Based on depth profiles of temperature, conductivity, pH and ORP, as well as dissolved oxygen, chlorophyll-a, organic carbon, nutrient and metal concentration, we discuss the impactof anthropogenic pressure on the lakes. In the sampling period (July to September, 2014-2016), most of the lakes showed a marked stratification with vertical gradients as a result of different physical and (bio)geochemical processes. All the lakes showed a good environmental state with no apparent metal pollution. However, this set of mountain lakes is not homogeneous with regard to nutrient availability, primary productivity, or hypolimnetic oxygen deficit and a range of trophic conditions exist from oligotrophic (El Valle) to eutrophic (Calabazosa). This trend shows a good correlation with total phosphorus concentration (e.g., 10 µg/L P in El Valle vs. 35 µg/L P in Calabazosa), though erosive processes in the catchment may also have contributed to increase the oxygen consumption rate through an import of allochthonous organic matter. Higher nitrate contents seem to characterize the areas with higher grazing pressure (e.g., El Valle), though the obtained data do not allow us to establish any evident relationship between cattle activity and eutrophication.

Information sur le financement

This work has been funded by the Instituto Geológico y Minero de España (IGME) through project SINGER (Ref. number 2459). The staff of the Somiedo Natural Park is acknowledged for permission given to conduct the field work. We thank Fernando Barreiro-Lostres and Maria Leunda for field-work assistance and bathymetric data for the La Cueva Lake.

Financeurs