scholarly journals Methanogenic pathways,13C isotope fractionation, and archaeal community composition in lake sediments and wetland soils on the Tibetan Plateau

2013 ◽  
Vol 118 (2) ◽  
pp. 650-664 ◽  
Author(s):  
Yongqin Liu ◽  
Tandong Yao ◽  
Gerd Gleixner ◽  
Peter Claus ◽  
Ralf Conrad
Keyword(s):  
Tibetan Plateau ◽  
Lake Sediments ◽  
Community Composition ◽  
Isotope Fractionation ◽  
Archaeal Community ◽  
Wetland Soils ◽  
The Tibetan Plateau ◽  
13C Isotope

Metabarcoding of modern sedimentary DNA from the Tibetan Plateau and Siberia as a training dataset for vegetation reconstructions

2021 ◽  
Author(s):  
Weihan Jia ◽  
Kathleen Stoof-Leichsenring ◽  
Sisi Liu ◽  
Kai Li ◽  
Sichao Huang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Lake Sediments ◽  
Plant Diversity ◽  
Lake Water ◽  
Aquatic Plant ◽  
Freshwater Ecosystems ◽  
The Tibetan Plateau ◽  
Plant Dna ◽  
Continental Scale ◽  
Dna Metabarcoding

<p>Lake sedimentary DNA (<em>sed</em>DNA) is an established tool to trace past changes in vegetation composition and plant diversity. However, little is known about the relationships between sedimentary plant DNA and modern vegetational and environmental conditions. In this study, we investigate i) the relationships between the preservation of sedimentary plant DNA and environmental variables, ii) the modern analogue of ancient plant DNA assemblages archived in lake sediments, and iii) the usability of sedimentary plant DNA for characterization of terrestrial and aquatic plant composition and diversity based on a large dataset of PCR-amplified plant DNA data retrieved from 259 lake surface sediments from the Tibetan Plateau and Siberia. Our results indicate the following: i) Lake-water electrical conductivity and pH are the most important variables for the preservation of plant DNA in lake sediments. We expect the best preservation conditions for sedimentary plant DNA in small deep lakes characterized by high water conductivities (≥100 μS cm<sup>-1</sup>) and neutral to slightly alkaline pH conditions (7–9). ii) Plant DNA metabarcoding is promising for palaeovegetation reconstruction in high mountain regions, where shifts in vegetation are solely captured by the <em>sed</em>DNA-based analogue matching and fossil pollen generally has poor modern analogues. However, the biases in the representation of some taxa could lead to poor analogue conditions. iii) Plant DNA metabarcoding is a reliable proxy to reflect modern vegetation types and climate characteristics at a sub-continental scale. However, the resolution of the <em>trn</em>L P6 loop marker, the incompleteness of the reference library, and the extent of <em>sed</em>DNA preservation are still the main limitations of this method. iv) Plant DNA metabarcoding is a suitable proxy to recover modern aquatic plant diversity, which is mostly affected by July temperature and lake-water conductivity. Ongoing warming might decrease macrophyte richness in the Tibetan Plateau and Siberia, and ultimately threaten the health of these important freshwater ecosystems. To conclude, sedimentary plant DNA presents a high correlation with modern vegetation and may therefore be an important proxy for reconstruction of past vegetation.</p>

scholarly journals Stable carbon isotope discrimination and microbiology of methane formation in tropical anoxic lake sediments

2011 ◽  
Vol 8 (3) ◽  
pp. 795-814 ◽  
Author(s):  
R. Conrad ◽  
M. Noll ◽  
P. Claus ◽  
M. Klose ◽  
W. R. Bastos ◽  
...  
Keyword(s):  
Organic Matter ◽  
Lake Sediments ◽  
Carbon Isotope ◽  
Community Composition ◽  
Isotope Fractionation ◽  
Microbial Community Composition ◽  
Methanogenic Archaea ◽  
Methane Formation ◽  
Large Variability ◽  
Ch4 Production

Abstract. Methane is an important end product of degradation of organic matter in anoxic lake sediments. Methane is mainly produced by either reduction of CO2 or cleavage of acetate involving different methanogenic archaea. The contribution of the different methanogenic paths and of the diverse bacteria and archaea involved in CH4 production exhibits a large variability that is not well understood. Lakes in tropical areas, e.g. in Brazil, are wetlands with high potential impact on the global CH4 budget. However, they have hardly been studied with respect to methanogenesis. Therefore, we used samples from 16 different lake sediments in the Pantanal and Amazon region of Brazil to measure production of CH4, CO2, analyze the content of 13C in the products and in intermediately formed acetate, determine the abundance of bacterial and archaeal microorgansisms and their community composition and diversity by targeting the genes of bacterial and archaeal ribosomal RNA and of methyl coenzyme M reductase, the key enzyme of methanogenic archaea. These experiments were done in the presence and absence of methyl fluoride, an inhibitor of acetoclastic methanogenesis. While production rates of CH4 and CO2 were correlated to the content of organic matter and the abundance of archaea in the sediment, values of 13C in acetate, CO2, and CH4 were related to the 13C content of organic matter and to the path of CH4 production with its intrinsic carbon isotope fractionation. Isotope fractionation was small (average 10‰) for conversion of Corg to acetate-methyl, which was hardly further fractionated during CH4 production. However, fractionation was strong for CO2 conversion to CH4 (average 75‰), which generally accounted for >50% of total CH4 production. Canonical correspondence analysis did not reveal an effect of microbial community composition, despite the fact that it exhibited a pronounced variability among the different sediments.

scholarly journals Stable carbon isotope discrimination and microbiology of methane formation in tropical anoxic lake sediments

2010 ◽  
Vol 7 (6) ◽  
pp. 8619-8661 ◽  
Author(s):  
R. Conrad ◽  
M. Noll ◽  
P. Claus ◽  
M. Klose ◽  
W. R. Bastos ◽  
...  
Keyword(s):  
Organic Matter ◽  
Lake Sediments ◽  
Carbon Isotope ◽  
Community Composition ◽  
Isotope Fractionation ◽  
Microbial Community Composition ◽  
Methanogenic Archaea ◽  
Methane Formation ◽  
Large Variability ◽  
Ch4 Production

Abstract. Methane is an important end product of degradation of organic matter in anoxic lake sediments. Methane is mainly produced by either reduction of CO2 or cleavage of acetate involving different methanogenic archaea. The contribution of the different methanogenic paths and of the diverse bacteria and archaea involved in CH4 production exhibits a large variability that is not well understood. Lakes in tropical areas, e.g. in Brazil, are wetlands with high potential impact on the global CH4 budget. However, they have hardly been studied with respect to methanogenesis. Therefore, we used samples from 16 different lake sediments in the Pantanal and Amazon region of Brazil to measure production of CH4, CO2, analyze the content of 13C in the products and in intermediately formed acetate, determine the abundance of bacterial and archaeal microorgansisms and their community composition and diversity by targeting the genes of bacterial and archaeal ribosomal RNA and of methyl coenzyme M reductase, the key enzyme of methanogenic archaea. These experiments were done in the presence and absence of methyl fluoride, an inhibitor of acetoclastic methanogenesis. While production rates of CH4 and CO2 were correlated to the content of organic matter and the abundance of archaea in the sediment, values of 13C in acetate and CH4 were related to the 13C content of organic matter and to the path of CH4 production with its intrinsic carbon isotope fractionation. Isotope fractionation was small (average 10‰) for conversion of Corg to acetate-methyl, which was hardly further fractionated during CH4 production. However, fractionation was strong for CO2 conversion to CH4 (average 75‰), which generally accounted for >50% of total CH4 production. Canonical correspondence analysis did not reveal an effect of microbial community composition, despite the fact that it exhibited a pronounced variability among the different sediments.

Response of Archaeal Community Structure to Environmental Changes in Lakes on the Tibetan Plateau, Northwestern China

2009 ◽  
Vol 26 (4) ◽  
pp. 289-297 ◽  
Author(s):  
Hongchen Jiang ◽  
Hailiang Dong ◽  
Shicai Deng ◽  
Bingsong Yu ◽  
Qiuyuan Huang ◽  
...  
Keyword(s):  
Community Structure ◽  
Tibetan Plateau ◽  
Environmental Changes ◽  
Archaeal Community ◽  
Northwestern China ◽  
The Tibetan Plateau
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