TY  - JOUR
A1  - Glombitza, Clemens
A1  - Stockhecke, Mona
A1  - Schubert, Carsten J.
A1  - Vetter, Alexandra
A1  - Kallmeyer, Jens
T1  - Sulfate reduction controlled by organic matter availability in deep sediment cores from the saline, alkaline Lake Van (Eastern Anatolia,Turkey)
JF  - Frontiers in microbiology
N2  - As part of the International Continental Drilling Program deep lake drilling project Paleo Van, we investigated sulfate reduction (SR) in deep sediment cores of the saline, alkaline (salinity 21.4%0, alkalinity 155 m mEq-1, pH 9.81) Lake Van, Turkey. The cores were retrieved in the Northern Basin (NB) and at Ahlat Ridge (AR) and reached a maximum depth of 220 m. Additionally, 65-75 cm long gravity cores were taken at both sites. SR rates (SRR) were low (<22 nmol cm-3 day-1) compared to lakes with higher salinity and alkalinity, indicating that salinity and alkalinity are not limiting SR in Lake Van. Both sites differ significantly in rates and depth distribution of SR. In NB, SRR are up to 10 times higher than at AR. SR could be detected down to 19 mblf (meters below lake floor) at NB and down to 13 mblf at AR. Although SRR were lower at AR than at NB, organic matter (OM) concentrations were higher. In contrast, dissolved OM in the pore water at AR contained more macromolecular OM and less low molecular weight OM.VVe thus suggest, that OM content alone cannot be used to infer microbial activity at Lake Van but that quality of OM has an important impact as well. These differences suggest that biogeochemical processes in lacustrine sediments are reacting very sensitively to small variations in geological, physical, or chemical parameters over relatively short distances.
KW  - saline lake
KW  - alkaline lake
KW  - sulfate reduction
KW  - deep biosphere
KW  - organic matter
Y1  - 2013
U6  - https://doi.org/10.3389/fmicb.2013.00209
SN  - 1664-302X
VL  - 4
IS  - 28
PB  - Frontiers Research Foundation
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Zhang Chengjun, 
A1  - Fan Rong, 
A1  - Li Jun, 
A1  - Mischke, Steffen
A1  - Dembele, Blaise
A1  - Hu Xiaolan, 
T1  - Carbon and oxygen isotopic compositions - how lacustrine environmental factors respond in northwestern and northeastern China
JF  - Acta geologica Sinica : english edition
N2  - Surface lake sediments, 28 from Hoh Xil, 24 from northeastern China, 99 from Lake Bosten, 31 from Ulungur and 26 from Heihai were collected to determine C-13 and O-18 values. Considering the impact factors, conductivity, alkalinity, pH, TOC, C/N and carbonate-content in the sediments, Cl, P, S, and metal element ratios of Mg/Ca, Sr/Ca, Fe/Mn of bulk sediments as environmental variables enable evaluation of their influences on C-13 and O-18 using principal component analysis (PCA) method. The closure and residence time of lakes can influence the correlation between C-13 and O-18. Lake water will change from fresh to brackish with increasing reduction and eutrophication effects. Mg/Ca in the bulk sediment indicates the characteristic of residence time, Sr/Ca and Fe/Mn infer the salinity of lakes. Carbonate formation processes and types can influence the C-13-O-18 correlation. O-18 will be heavier from Mg-calcite and aragonite formed in a high-salinity water body than calcite formed in freshwater conditions. When carbonate content is less than 30%, there is no relationship with either C-13 or O-18, and also none between C-13 and O-18. More than 30%, carbonate content, however, co-varies highly to C-13 and O-18, and there is also a high correlation between C-13 and O-18. Vegetation conditions and primary productivity of lakes can influence the characteristics of C-13 and O-18, and their co-variance. Total organic matter content (TOC) in the sediments is higher with more terrestrial and submerged plants infilling. In northeastern and northwestern China, when organic matter in the lake sediments comes from endogenous floating organisms and algae, the C-13 value is high. C-13 is in the range of -4%o to 0 parts per thousand when organic matter comes mainly from floating organisms (C/N<6); in the range of -4 parts per thousand to 8 parts per thousand when organic matter comes from diatoms (C/N=6 to 8); and -8 parts per thousand to -4 parts per thousand when organic matter comes from aquatic and terrestrial plants (C/N>8).
KW  - Limnology
KW  - isotopic analysis
KW  - carbonates
KW  - organic matter
KW  - PCA
KW  - Tibet
KW  - Xinjiang
KW  - Northeastern China
Y1  - 2013
U6  - https://doi.org/10.1111/1755-6724.12133
SN  - 1000-9515
SN  - 1755-6724
VL  - 87
IS  - 5
SP  - 1344
EP  - 1354
PB  - Wiley-Blackwell
CY  - Hoboken
ER  -