Interacciones de procesos fisicoquímicos y bioquímicos en lagunas sódico-alcalinas del Duero y salinas de la Mancha

Abstract

This work gives new insight into the physicochemical and biochemical interactions in six playa basins that host microbial mats. The study basins are distributed across two evaporitic endorheic drainage systems located in the Central part of Spain. One group, 150 km to the north of Madrid, consists of highly alkaline, brackish to saline lakes containing a high concentration of chloride with dominant carbonate over sulphates. A second group of lakes, 100 km to the south of Madrid, are mesosaline to hypersaline, with sulphate the dominant anion over chloride. Parameters such as pH, dissolved oxygen, redox potential and Ca2+ concentration are clearly affected by the microorganisms. The maximum values of dissolved oxygen and redox potential are related with photosynthetic organisms, while the sulphate-reduction organisms lead to the lowest redox potential values in highly concentrated waters. Geochemical changes induced in the environment by their metabolic activities modify the mineralogy that was expected to find according to previous studies that only considered physicochemical evolution of the brines in playa lakes.