HR: 0800h
AN: B41C-0216 [Abstracts]
TI: Preliminary Results of Bacteria Distribution in Chinese Loess and Their Control on the Calcite
Formation
AU: * Chen, Y
EM: chenyang@nju.edu.cn
AF: Institute of Surficial Geochemistry, Department of Earth Sciences, Nanjing University, 22 Hankou Road,
Nanjing, 210093
China
AU: Lian, B
EM: lianbin@njnu.edu.cn
AF: Department of Biology, Nanjing Normal University, 1 Ninghai Road, Nanjing, 210008
China
AU: Hu, Q
B41C-0216
AF: Institute of Surficial Geochemistry, Department of Earth Sciences, Nanjing University, 22 Hankou Road,
Nanjing, 210093
China
AU: Teng, H H
EM: hteng@gwu.edu
AF: Department of Chemistry, The George Washington University, 2029 G St. NW, Washington, DC 20006
United States
AU: Wu, T
B41C-0216
AF: Institute of Surficial Geochemistry, Department of Earth Sciences, Nanjing University, 22 Hankou Road,
Nanjing, 210093
China
AU: Ji, J
EM: jijunfeng@nju.edu.cn
AF: Institute of Surficial Geochemistry, Department of Earth Sciences, Nanjing University, 22 Hankou Road,
Nanjing, 210093
China
AU: Chen, J
EM: chenjun@nju.edu.cn
AF: Institute of Surficial Geochemistry, Department of Earth Sciences, Nanjing University, 22 Hankou Road,
Nanjing, 210093
China
AB:
Continuous loess-paleosol sequences on the Chinese Loess Plateau are viewed as one of best continental archives of
paleoclimatic and paleoenvironmental changes of the Late Cenozoic era. Carbonate, mainly calcite, commonly occurs throughout
the entire sequence; though some are detrital, most are in-situ pedogenic. TEM studies have shown various morphologies of
calcites in Chinese loess, especially nano-rod calcite widely occurring in loess and paleosols which are biogenic. In this
study, we collected fresh and undisturbed loess and paleosol samples and successfully separated dominant microbial
communities. These microbes are mainly bacteria, especially Bacillus anthracis, and a few fungi. The amount of bacteria
decreases sharply with the depth. Then we added the bacteria into the near saturated solution of CaCl2 and Na2CO3. It is
interesting that the original calcite crystals formed under abiotic conditions changed from quadrilateral face to pentagonal
or hexagonal and the crystal size enlarged almost twice. SEM and AFM observations display bacteria control on the growth of
calcite, which cause the lighter carbon isotopic ratios.
DE: 0419 Biomineralization
DE: 0448 Geomicrobiology
DE: 0463 Microbe/mineral interactions
DE: 0486 Soils/pedology (1865)
SC: Biogeosciences [B]
MN: Fall Meeting 2005