Features of the Chemical Composition of Interstitial Water of the Holocene Section of Sapropel in Lake Dukhovoye (Southern Pribaikalia)
A. E. MALTSEV1, A. A. BOGUSH1,2 and G. A. LEONOVA1
1Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Pr. Akademika Koptyuga 3, Novosibirsk 630090 (Russia)
2Lomonosov Moscow State University, Leninskiye Gory 1, Moscow GSP-2, 119991 (Russia)
Keywords: interstitial water, sapropel, phytoplankton, element occurrence forms
Abstract
Comparative analysis of interstitial water in organic sapropel (0–167 cm) formed during middle Holocene for 5100 years, and the surface water of Lake Dukhovoye (Southern Pribaikalia) was carried out. Transformation of hydrocarbonate calcium–sodium–magnesium lake water into hydrocarbonate–sulphate interstitial water of sapropel is observed. It is established that mineralization of interstitial water increases with depth, that is, the transition from ultrafresh surface water to fresh interstitial water of organic sapropel occurs. Interstitial water is enriched with almost all the studied ions (Ca2+, Mg2+, Na+, K+, HCO3– and Cl–) and elements (Al, Fe, Mn, Pb, Cd, Zn, Cu, Ni and Co) in comparison with surface water. The series of element mobility show that the mobility of some elements changes substantially in the section of sapropel of Lake Dukhovoye. In surface water Na, K, Ca, Mg, Mn, Cd and Zn dominate in aqua ion forms, Al and Fe in hydroxide complexes, Pb and Ni in carbonate complexes, Cu in fulvate, hydroxide and carbonate complexes. The fraction of aqua ion forms of Na, K, Ca, Mg, Mn, Cd and Zn in interstitial water of sapropel decreases with depth, while the fraction of sulphate complexes increases. Redistribution of forms in comparison with surface water occurs.
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