Publication Date:
2017-04-04
Description:
Among surface waters, lakes in volcanic areas display the greatest range in
pH values: from negative values up to about 12. The present chapter is a
short review of the main features of alkaline lakes, which belong to the
high-pH part of this range. They are characterised by saline or hypersaline
waters, pH values higher than 9 and high Na+, HCO3
− and CO3
2− and low
Ca2+ concentrations. Alkaline lakes are found in quiescent or recently
extinct volcanic areas where neither water vapour nor acidic magmatic
gases can reach surface waters. Their occurrence depends on peculiar
climatic and geological conditions that allow evaporative concentration of
the water (potentially evaporation much higher than water inputs and in
endorheic basins) and on geochemical factors that favour a chemical
evolution towards an alkaline environment (composition of the dilute
input waters characterised by a ratio between total dissolved inorganic
carbon and earth-alkaline elements much higher than 1). Such initial
composition, due to evaporative concentration, after the deposition of
earth-alkaline carbonate minerals, will lead to the above-mentioned typical
composition. Alkaline lakes also host microbial communities sometimes
characterised by extremely high productivity. These microbial communities
are scientifically remarkable because they comprise some interesting
extremophiles, which can grow not only at very high pH and salinity
conditions but also in the presence of elevated concentrations of toxic
elements (e.g. As, Se, Te).
Description:
Published
Description:
219-237
Description:
4V. Vulcani e ambiente
Description:
6A. Monitoraggio ambientale, sicurezza e territorio
Description:
open
Keywords:
Alkaline lake, Soda lake, Volcanic lake, Extremophile microbial community ,Saline and hypersaline water, Endorheic basin
;
03. Hydrosphere::03.04. Chemical and biological::03.04.99. General or miscellaneous
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
book chapter
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