TY - JOUR

T1 - Diagenetic transformation of organic matter in sapropel sediments of small lakes (southern West Siberia and eastern Transbaikalia)

AU - Leonova, G. A.

AU - Maltsev, A. E.

AU - Melenevsky, V. N.

AU - Krivonogov, S. K.

AU - Kondratyeva, L. M.

AU - Bobrov, V. A.

AU - Suslova, M. Y.

N1 - Publisher Copyright: © 2019

PY - 2019/7/30

Y1 - 2019/7/30

N2 - Sapropels, biogenic lake sediments, are characterized by a reduction type of diagenesis, during which decomposition of organic compounds, modification of the pore water chemical composition and precipitation of authigenic minerals, mostly pyrite, occur. Pyrolysis data indicate that organic matter undergoes radical transformations already in the uppermost sapropel layers, and composition of the organic matter in the sediments is principally different from the composition of the organic matter of live organisms, which produce the sediments. The sapropels lose labile protein–carbohydrate compounds in the horizon of unconsolidated sediment (0–5 cm), and kerogen appears, whose macromolecular structures start to develop in the very early stages of diagenesis. Various physiological groups of microorganisms provide diagenetic transformations of the organic matter, where heterotrophic, ammonifying and sulfate-reducing bacteria play key role. Their effect is well-seen from the pore water transformation: a decrease in concentrations of SO 4 2− and consequent increase of reduced Fe and S as pyrite in the solid phase of the sediment. Comparative analysis shows that, unlike in lakes of the Baikal area, sapropels in southern West Siberia are affected by more active sulfate reduction, which can depend on both the composition of the organic matter and the SO 4 2− concentration in the pore waters.

AB - Sapropels, biogenic lake sediments, are characterized by a reduction type of diagenesis, during which decomposition of organic compounds, modification of the pore water chemical composition and precipitation of authigenic minerals, mostly pyrite, occur. Pyrolysis data indicate that organic matter undergoes radical transformations already in the uppermost sapropel layers, and composition of the organic matter in the sediments is principally different from the composition of the organic matter of live organisms, which produce the sediments. The sapropels lose labile protein–carbohydrate compounds in the horizon of unconsolidated sediment (0–5 cm), and kerogen appears, whose macromolecular structures start to develop in the very early stages of diagenesis. Various physiological groups of microorganisms provide diagenetic transformations of the organic matter, where heterotrophic, ammonifying and sulfate-reducing bacteria play key role. Their effect is well-seen from the pore water transformation: a decrease in concentrations of SO 4 2− and consequent increase of reduced Fe and S as pyrite in the solid phase of the sediment. Comparative analysis shows that, unlike in lakes of the Baikal area, sapropels in southern West Siberia are affected by more active sulfate reduction, which can depend on both the composition of the organic matter and the SO 4 2− concentration in the pore waters.

KW - Authigenic minerals

KW - Diagenesis

KW - Kerogen

KW - Organic matter

KW - Pore waters

KW - Sulfate reduction

UR - http://www.scopus.com/inward/record.url?scp=85063112046&partnerID=8YFLogxK

U2 - 10.1016/j.quaint.2019.03.011

DO - 10.1016/j.quaint.2019.03.011

M3 - Article

AN - SCOPUS:85063112046

VL - 524

SP - 40

EP - 47

JO - Quaternary International

JF - Quaternary International

SN - 1040-6182

ER -