BIOGEOCHEMICAL SPECIFICS OF SAPROPEL FORMATION IN CISBAIKALIAN UNDRAINED LAKES (by the example of Lake Ochki)
a:2:{s:4:"TEXT";s:191:"G.A. Leonova1, V.A. Bobrov1, S.K. Krivonogov1,2, A.A. Bogush1,3, V.A. Bychinskii4, A.E. Mal’tsev1, G.N. Anoshin1,2";s:4:"TYPE";s:4:"html";}
1V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
2Novosibirsk State University, ul. Pirogova 2, Novosibirsk 630090, Russia
3Moscow State University, Leninskie Gory 1, Moscow, 119991, Russia
4A.P. Vinogradov Institute of Geochemistry, ul. Favorskogo 1a, Irkutsk, 664033, Russia
Keywords: Live material (plankton), biophile elements, biosedimentation, organic sediments (sapropel), chemical species of elements
Abstract
The biogeochemistry of organic lacustrine sediments (sapropels) has been poorly studied in Siberia. In this paper we show the specifics of sapropel formation caused by low pH and mineralization of water by the example of Lake Ochki in Cisbaikalia. The main sources of organic matter are zoo– and phytoplankton, which concentrate mostly basic chemical elements and also some alkaline, alkali-earth, and chalcophile elements and more them to the sediment. The calculated enrichment factors (EF) have shown that the lake plankton is strongly enriched with phosphorus and chalcophile elements. The calculations have also revealed a great contribution of the plankton to the elemental composition of sapropel (Mebio, %): P (≈100), Cd (57), Hg (40), Se and Na (30), Zn (23), K (21), and Ca (15). Elements are rather uniformly distributed throughout the 3.2 m thick sapropel layer. Lithophile elements (Al, Sc, Ti, Y, Zr, Nb) and LREE are mostly from a terrigenous source. The high contents of mobile elements (Cd, Sb, Sn, Pb, Zn) in the upper part of sapropel are probably due to anthropogenic factors. The high Cu and Zn contents in some sapropel layers are probably related to the inflow of deep-level groundwaters, and the elevated contents of Hg, Cd, and Sb might have been caused by forest fires.
DOI: http://dx.doi.org/10.1016/j.rgg.2015.04.006
|
