@article{MrlinaKaempfKroneretal.2009,
  author    = {Mrlina, Jan and K{\"a}mpf, Horst and Kroner, Corinna and Mingram, Jens and Stebich, Martina and Brauer, Achim and Geissler, Wolfram H. and Kallmeyer, Jens and Matthes, Heidrun and Seidl, Michal},
  title     = {Discovery of the first Quaternary maar in the Bohemian Massif, Central Europe, based on combined geophysical and geological surveys},
  issn      = {0377-0273},
  doi       = {10.1016/j.jvolgeores.2009.01.027},
  year      = {2009},
  abstract  = {Based on results of previous investigations of tephra-tuff volcaniclastic deposits and a geophysical survey in the surroundings of the Zelezna hurka Quaternary volcano, West Bohemia, we performed detailed geophysical Surveys using gravimetry, magnetometry and electrical conductivity techniques. Striking anomalies were revealed in a morphological depression near Mytina, West Bohemia, as a strong evidence of the assumed maar-diatreme structure. The sharp isometric gravity low of -2.30 mGal, as well as the corresponding positive magnetic anomaly of 200 nT with a negative rim on its northern side indicate a steeply clipping geological body of low density and containing magnetic rocks/minerals. Magnetic survey also showed pronounced local anomalies outside the depression that can reflect relicts of the tephra rim of the maar. This geophysical evidence was then proven by an exploratory drilling near the centre of the gravity anomaly. Macroscopic on-site evaluation of the core, and more detailed sedimentological, petrochemical, palynological and microbiological laboratory analyses further confirmed the existence of a maar structure filled by 84 m of lake sediments reflecting a Succession of several warm and cold climatic periods. Results Of palynological analyses confirm the presence of a continuous palaeoclimate archive, with at least three successive warmer periods of most probably interstadial character from the upper Quaternary Saalian complex. Therefore. the recovered sediment sequence holds strong potential for in-depth palaeoclimate reconstruction and deep biosphere studies. At the bottom of the Mytina-1 (MY- 1) borehole (84-85.5 M), Country rock debris Was found, containing also volcanic bombs and lapilli. The discovered volcanic Structure is considered to be the first known Quaternary maar-diatreme volcano on the territory of the Bohemian Massif. Because of hidden active magmatic processes in combination with earthquake swarm seismicity ca. 20-30 km north of the Mytina maar, reconstruction of the palaeovolcanological evolution is important for evaluation of hazard potential of the NE and E Part of the Cheb Basin.},
  language  = {en}
}
@article{IjiriInagakiKuboetal.2018,
  author    = {Ijiri, Akira and Inagaki, Fumio and Kubo, Yusuke and Adhikari, Rishi Ram and Hattori, Shohei and Hoshino, Tatsuhiko and Imachi, Hiroyuki and Kawagucci, Shinsuke and Morono, Yuki and Ohtomo, Yoko and Ono, Shuhei and Sakai, Sanae and Takai, Ken and Toki, Tomohiro and Wang, David T. and Yoshinaga, Marcos Y. and Arnold, Gail L. and Ashi, Juichiro and Case, David H. and Feseker, Tomas and Hinrichs, Kai-Uwe and Ikegawa, Yojiro and Ikehara, Minoru and Kallmeyer, Jens and Kumagai, Hidenori and Lever, Mark Alexander and Morita, Sumito and Nakamura, Ko-ichi and Nakamura, Yuki and Nishizawa, Manabu and Orphan, Victoria J. and Roy, Hans and Schmidt, Frauke and Tani, Atsushi and Tanikawa, Wataru and Terada, Takeshi and Tomaru, Hitoshi and Tsuji, Takeshi and Tsunogai, Urumu and Yamaguchi, Yasuhiko T. and Yoshida, Naohiro},
  title     = {Deep-biosphere methane production stimulated by geofluids in the Nankai accretionary complex},
  series = {Science Advances},
  volume    = {4},
  journal   = {Science Advances},
  number    = {6},
  publisher = {American Assoc. for the Advancement of Science},
  address   = {Washington},
  issn      = {2375-2548},
  doi       = {10.1126/sciadv.aao4631},
  pages     = {15},
  year      = {2018},
  language  = {en}
}
@article{D'HondtSpivackPockalnyetal.2009,
  author    = {D'Hondt, Steven and Spivack, Arthur J. and Pockalny, Robert and Ferdelman, Timothy G. and Fischer, Jan P. and Kallmeyer, Jens and Abrams, Lewis J. and Smith, David C. and Graham, Dennis and Hasiuk, Franciszek and Schrum, Heather and Stancin, Andrea M.},
  title     = {Subseafloor sedimentary life in the South Pacific Gyre},
  issn      = {0027-8424},
  doi       = {10.1073/pnas.0811793106},
  year      = {2009},
  abstract  = {The low-productivity South Pacific Gyre (SPG) is Earth's largest oceanic province. Its sediment accumulates extraordinarily slowly (0.1-1 m per million years). This sediment contains a living community that is characterized by very low biomass and very low metabolic activity. At every depth in cored SPG sediment, mean cell abundances are 3 to 4 orders of magnitude lower than at the same depths in all previously explored subseafloor communities. The net rate of respiration by the subseafloor sedimentary community at each SPG site is 1 to 3 orders of magnitude lower than the rates at previously explored sites. Because of the low respiration rates and the thinness of the sediment, interstitial waters are oxic throughout the sediment column in most of this region. Consequently, the sedimentary community of the SPG is predominantly aerobic, unlike previously explored subseafloor communities. Generation of H-2 by radiolysis of water is a significant electron-donor source for this community. The per-cell respiration rates of this community are about 2 orders of magnitude higher (in oxidation/reduction equivalents) than in previously explored anaerobic subseafloor communities. Respiration rates and cell concentrations in subseafloor sediment throughout almost half of the world ocean may approach those in SPG sediment.},
  language  = {en}
}
@article{KallmeyerPockalnyD'Hondt2009,
  author    = {Kallmeyer, Jens and Pockalny, Rob and D'Hondt, Steven},
  title     = {Quantifying global subseafloor microbial abundance : method and implications},
  issn      = {0016-7037},
  doi       = {10.1016/j.gca.2009.05.009},
  year      = {2009},
  language  = {en}
}
@article{KallmeyerSmith2009,
  author    = {Kallmeyer, Jens and Smith, David C.},
  title     = {An improved electroelution method for separation of DNA from humic substances in marine sediment DNA extracts},
  issn      = {0168-6496},
  doi       = {10.1111/j.1574-6941.2009.00684.x},
  year      = {2009},
  abstract  = {We present a method for the rapid and simple extraction of DNA from marine sediments using electroelution. It effectively separates DNA from compounds, including humic substances, that interfere with subsequent DNA quantification and amplification. After extraction of the DNA from the sediment into an aqueous solution, the crude sample is encased in 2\% agarose gel and exposed to an electrical current, which draws the DNA out of the gel into a centrifugal filter vial. After electroelution, the sample is centrifuged to remove contaminants <= 100 000 Da. Recovery of DNA using this method is quantitative and does not discriminate on the basis of size, as determined using DNA standards and DNA extracts from environmental samples. Amplification of DNA is considerably improved due to removal of PCR inhibitors. For Archaea, only these purified extracts yielded PCR products. This method allows for the use of relatively large volumes of sediment and is particularly useful for sediments containing low biomass such as deeply buried marine sediments. It works with both organic-rich and -poor sediment, as well as with sediment where calcium carbonate is abundant and sediment where it is limited; consequently, adjustment of protocols is unnecessary for samples with very different organic and mineral contents.},
  language  = {en}
}
@article{AdhikariKallmeyer2010,
  author    = {Adhikari, Rishi Ram and Kallmeyer, Jens},
  title     = {Detection and quantification of microbial activity in the subsurface},
  issn      = {0009-2819},
  doi       = {10.1016/j.chemer.2010.05.003},
  year      = {2010},
  abstract  = {The subsurface harbors a large fraction of Earth's living biomass, forming complex microbial ecosystems. Without a profound knowledge of the ongoing biologically mediated processes and their reaction to anthropogenic changes it is difficult to assess the long-term stability and feasibility of any type of geotechnical utilization, as these influence subsurface ecosystems. Despite recent advances in many areas of subsurface microbiology, the direct quantification of turnover processes is still in its infancy, mainly due to the extremely low cell abundances. We provide an overview of the currently available techniques for the quantification of microbial turnover processes and discuss their specific strengths and limitations. Most techniques employed so far have focused on specific processes, e.g. sulfate reduction or methanogenesis. Recent studies show that processes that were previously thought to exclude each other can occur simultaneously, albeit at very low rates. Without the identification of the respective processes it is impossible to quantify total microbial activity. Even in cases where all simultaneously occurring processes can be identified, the typically very low rates prevent quantification. In many cases a simple measure of total microbial activity would be a better and more robust measure than assays for several specific processes. Enzyme or molecular assays provide a more general approach as they target key metabolic compounds. Depending on the compound targeted a broader spectrum of microbial processes can be quantified. The two most promising compounds are ATP and hydrogenase, as both are ubiquitous in microbes. Technical constraints limit the applicability of currently available ATP-assays for subsurface samples. A recently developed hydrogenase radiotracer assay has the potential to become a key tool for the quantification of subsurface microbial activity.},
  language  = {en}
}
@article{GlombitzaStockheckeSchubertetal.2013,
  author    = {Glombitza, Clemens and Stockhecke, Mona and Schubert, Carsten J. and Vetter, Alexandra and Kallmeyer, Jens},
  title     = {Sulfate reduction controlled by organic matter availability in deep sediment cores from the saline, alkaline Lake Van (Eastern Anatolia,Turkey)},
  series = {Frontiers in microbiology},
  volume    = {4},
  journal   = {Frontiers in microbiology},
  number    = {28},
  publisher = {Frontiers Research Foundation},
  address   = {Lausanne},
  issn      = {1664-302X},
  doi       = {10.3389/fmicb.2013.00209},
  pages     = {12},
  year      = {2013},
  abstract  = {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.},
  language  = {en}
}
@article{CockellVoytekGronstaletal.2012,
  author    = {Cockell, Charles S. and Voytek, Mary A. and Gronstal, Aaron L. and Finster, Kai and Kirshtein, Julie D. and Howard, Kieren and Reitner, Joachim and Gohn, Gregory S. and Sanford, Ward E. and Horton, J. Wright and Kallmeyer, Jens and Kelly, Laura and Powars, David S.},
  title     = {Impact disruption and recovery of the deep subsurface biosphere},
  series = {Astrobiology},
  volume    = {12},
  journal   = {Astrobiology},
  number    = {3},
  publisher = {Liebert},
  address   = {New Rochelle},
  issn      = {1531-1074},
  doi       = {10.1089/ast.2011.0722},
  pages     = {231 -- 246},
  year      = {2012},
  abstract  = {Although a large fraction of the world's biomass resides in the subsurface, there has been no study of the effects of catastrophic disturbance on the deep biosphere and the rate of its subsequent recovery. We carried out an investigation of the microbiology of a 1.76 km drill core obtained from the similar to 35 million-year-old Chesapeake Bay impact structure, USA, with robust contamination control. Microbial enumerations displayed a logarithmic downward decline, but the different gradient, when compared to previously studied sites, and the scatter of the data are consistent with a rnicrobiota influenced by the geological disturbances caused by the impact. Microbial abundance is low in buried crater-fill, ocean-resurge, and avalanche deposits despite the presence of redox couples for growth. Coupled with the low hydraulic conductivity, the data suggest the microbial community has not yet recovered from the impact similar to 35 million years ago. Microbial enumerations, molecular analysis of microbial enrichment cultures, and geochemical analysis showed recolonization of a deep region of impact-fractured rock that was heated to above the upper temperature limit for life at the time of impact. These results show how, by fracturing subsurface rocks, impacts can extend the depth of the biosphere. This phenomenon would have provided deep refugia for life on the more heavily bombarded early Earth, and it shows that the deeply fractured regions of impact craters are promising targets to study the past and present habitability of Mars.},
  language  = {en}
}
@article{RoyKallmeyerAdhikarietal.2012,
  author    = {Roy, Hans and Kallmeyer, Jens and Adhikari, Rishi Ram and Pockalny, Robert and Jorgensen, Bo Barker and D'Hondt, Steven},
  title     = {Aerobic microbial respiration in 86-million-year-old deep-sea red clay},
  series = {Science},
  volume    = {336},
  journal   = {Science},
  number    = {6083},
  publisher = {American Assoc. for the Advancement of Science},
  address   = {Washington},
  issn      = {0036-8075},
  doi       = {10.1126/science.1219424},
  pages     = {922 -- 925},
  year      = {2012},
  abstract  = {Microbial communities can subsist at depth in marine sediments without fresh supply of organic matter for millions of years. At threshold sedimentation rates of 1 millimeter per 1000 years, the low rates of microbial community metabolism in the North Pacific Gyre allow sediments to remain oxygenated tens of meters below the sea floor. We found that the oxygen respiration rates dropped from 10 micromoles of O-2 liter(-1) year(-1) near the sediment-water interface to 0.001 micromoles of O-2 liter(-1) year(-1) at 30-meter depth within 86 million-year-old sediment. The cell-specific respiration rate decreased with depth but stabilized at around 10(-3) femtomoles of O-2 cell(-1) day(-1) 10 meters below the seafloor. This result indicated that the community size is controlled by the rate of carbon oxidation and thereby by the low available energy flux.},
  language  = {en}
}
@article{NoahLappeSchneideretal.2014,
  author    = {Noah, Mareike and Lappe, Michael and Schneider, Beate and Vieth-Hillebrand, Andrea and Wilkes, Heinz and Kallmeyer, Jens},
  title     = {Tracing biogeochemical and microbial variability over a complete oil sand mining and recultivation process},
  series = {The science of the total environment : an international journal for scientific research into the environment and its relationship with man},
  volume    = {499},
  journal   = {The science of the total environment : an international journal for scientific research into the environment and its relationship with man},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0048-9697},
  doi       = {10.1016/j.scitotenv.2014.08.020},
  pages     = {297 -- 310},
  year      = {2014},
  abstract  = {Recultivation of disturbed oil sand mining areas is an issue of increasing importance. Nevertheless only little is known about the fate of organic matter, cell abundances and microbial community structures during oil sand processing, tailings management and initial soil development on reclamation sites. Thus the focus of this work is on biogeochemical changes of mined oil sands through the entire process chain until its use as substratum for newly developing soils on reclamation sites. Therefore, oil sand, mature fine tailings (MFTs) from tailings ponds and drying cells and tailings sand covered with peat-mineral mix (PMM) as part of land reclamation were analyzed. The sample set was selected to address the question whether changes in the above-mentioned biogeochemical parameters can be related to oil sand processing or biological processes and how these changes influence microbial activities and soil development. GC-MS analyses of oil-derived biomarkers reveal that these compounds remain unaffected by oil sand processing and biological activity. In contrast, changes in polycyclic aromatic hydrocarbon (PAH) abundance and pattern can be observed along the process chain. Especially naphthalenes, phenanthrenes and chrysenes are altered or absent on reclamation sites, Furthermore, root-bearing horizons on reclamation sites exhibit cell abundances at least ten times higher (10(8) to 10(9) cells g(-1)) than in oil sand and MFF samples (10(7) cells g(-1)) and show a higher diversity in their microbial community structure. Nitrate in the pore water and roots derived from the PMM seem to be the most important stimulants for microbial growth. The combined data show that the observed compositional changes are mostly related to biological activity and the addition of exogenous organic components (PMM), whereas oil extraction, tailings dewatering and compaction do not have significant influences on the evaluated compounds. Microbial community composition remains relatively stable through the entire process chain. (C) 2014 Elsevier B.V. All rights reserved.},
  language  = {en}
}