Monday, October 25, 2010

Tropical rainforests on the deep sea floor?

Professor Kai Hinrichs is coming from Germany to talk to us about archaea (single celled, microrganisms with no cell nucleus or organelles) on the bottom of the ocean. He describes himself as

'a biogeochemist studying the interactions between microbial life and the carbon cycle on a range of spatial, temporal and molecular scales. I am interested in which and how microbes shape element cycles and what the related environmental consequences are. In order identify and ideally quantify microbial processes, my research group studies the information encoded in distributions and isotopic compositions of organic biomarker molecules in geological and environmental samples, ranging in size from 1 to ~100 C-atoms. My group consists of closely collaborating biologists, chemists, geochemists, and marine geoscientists. In our research projects, we combine analyses of environmental samples with experimental, laboratory-based approaches. Our current research foci encompass the deep subsurface biosphere, methane biogeochemistry, life in extreme environments, development and application of new geochemical-analytical techniques, prokaryotic membrane lipid taxonomy, and the study of paleoenvironments associated with major perturbations of the C-cycle.'

The reading this week is an early nature paper Hinrich wrote discussing the decomposition of a methane hydrate (ice forming in sediment that contains large amounts of methane ), where the methane is being consumed by archaea. As no organism can consume methane without oxygen being present, scientists think that the consumption of methane must be done with a consortium of bacteria with some being sulfate (SO4) reducing (providing the oxygen) and some being a reverse type of methanogen (consuming methane rather than producing it). Hinrichs shows using very negative carbon isotopes that his archaea are feeding on methane and he suggests methane consuming archaea have evolved alongside methane producing archaea. Their presence is important if you want to estimate future or past methane concentrations in the atmosphere (faint sun paradox or at Permian-Triassic Boundary)- because when balancing carbon reservoirs consumption is just as important as production.


  1. While the reading was extremely confusing and dense (honestly, I felt like I was looking up 2/5 words), this lecture looks interesting. Part of that is simply my interest in seeing a German professor give a lecture in English in the US. It would also be remarkable to see how this lecture related to several prior lectures, especially in terms of shifts in the early earth and methane traps. The risk of global warming causing these traps to release their stored greenhouse gasses and then increase warming further is a topic which needs to be discussed more.
    Finally, the picture of the burning methane ice (from one of the linked wikipedia pages) was really cool.

  2. I agree with a lot of what Nick said: that is a cool picture of burning methane, and that it will be interesting to compare what Hinrichs presents with the previous lectures about early Earth.

    I also think it is interesting to see where the various lecturers come from. Is it typical to have people from another country come and speak about their research? Is it only people with "big names" that are invited overseas? Are these two foreigners we're heard from a really big deal and that's why they came? What are the draws to speaking overseas; is it just getting your research out there and more recognized?

  3. The reading was a little..confusing. I could understand the general concept of traces of "rainforest" being left in now submerged areas but it took me a few reads to get through.

    I still don't completely understand the process behind water levels rising but the thought of methane invading solid ice was very intriguing.

  4. This lecture was very confusing for me but I got lost in the structures he was using for his research. It was too bad because I was really looking forward to his talk but I did not understand what was going on.