@article{KallmeyerPockalnyAdhikarietal.2012,
  author    = {Kallmeyer, Jens and Pockalny, Robert and Adhikari, Rishi Ram and Smith, David C. and D'Hondt, Steven},
  title     = {Global distribution of microbial abundance and biomass in subseafloor sediment},
  series = {Proceedings of the National Academy of Sciences of the United States of America},
  volume    = {109},
  journal   = {Proceedings of the National Academy of Sciences of the United States of America},
  number    = {40},
  publisher = {National Acad. of Sciences},
  address   = {Washington},
  issn      = {0027-8424},
  doi       = {10.1073/pnas.1203849109},
  pages     = {16213 -- 16216},
  year      = {2012},
  abstract  = {The global geographic distribution of subseafloor sedimentary microbes and the cause(s) of that distribution are largely unexplored. Here, we show that total microbial cell abundance in subseafloor sediment varies between sites by ca. five orders of magnitude. This variation is strongly correlated with mean sedimentation rate and distance from land. Based on these correlations, we estimate global subseafloor sedimentary microbial abundance to be 2.9 center dot 10(29) cells [corresponding to 4.1 petagram (Pg) C and similar to 0.6\% of Earth's total living biomass]. This estimate of subseafloor sedimentary microbial abundance is roughly equal to previous estimates of total microbial abundance in seawater and total microbial abundance in soil. It is much lower than previous estimates of subseafloor sedimentary microbial abundance. In consequence, we estimate Earth's total number of microbes and total living biomass to be, respectively, 50-78\% and 10-45\% lower than previous estimates.},
  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}
}