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Posts Tagged ‘early Earth’

Lured by the promise of posters and breakfast, I wandered down to the Ice Rink area to check out the posters this morning, and I’m glad I did, because I got to meet Stuart Daines, a postdoctoral researcher in Tim Lenton’s Earth Systems Modelling Group (http://researchpages.net/ESMG/). They have developed a model of “oxygen oases” before the Great Oxidation Event 2300 million years ago. Oxygen oases are hypothesized regions of the ocean where, due to high primary production by oxygenic phytoplankton, the ocean could have had a much higher concentration of oxygen than the ocean did on average. These oxygen oases are important for understanding the evolution of life on Earth because they were regions in which the modern ocean carbon-oxygen system probably evolved. In their box model, organic carbon is converted to CO2 and methane during methanogensis; this is starkly contrasted with our groups model, where organic matter is used to feed sulfate and ferric iron reduction. Contrasting these two systems – their methane-oxygen coastal system with our global redoxcline ocean – gives us a broader picture of the biogeochemistry of the early Earth. However, like our model, it raises more questions than it answers. For example, what impact would the Paleoproterozoic global glaciations (~2400 million years ago – Kirschvink et al., 2000) have on primary production? What was the dominant limiting factor on primary production at this time? Could the ocean even support a redoxcline globally for such a long time period? These questions will hopefully be answered not only through future modelling endeavors, but also through direct analysis of the rock record. Hopefully, some of these answers will be discussed at later sessions, such as 07c: Records of Ocean Anoxia and their Impact on Life.

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Writing a conference blog hasn’t turned out to be as easy as I thought.  I don’t know about the other posters, but I’ve logged in six times, looked at the blog, said to myself, “What should I write?” and promptly logged out.

So I’ll start with where I’m passionate.  My field is mathematical biogeochemistry, which means I try, either statistically or theoretically, to describe how the biosphere and geosphere interact with each other.  It also means I get to work in a variety of fields – for example, biology, oceanography, paleontology, geochemistry, and physics.

When Rotten Eggs Ruled the World

Right now I’m focused on a model that combines the statistical with the theoretical – a multiscale model of life in the late Archean (Archean: 3800 to 2500 million years ago) and early Proterozoic (Proterozoic: 2500 to 542 million years ago).  Our group – Nordic Center for Earth Evolution (NordCEE) – has been trying to understand what the carbon, sulfur, iron, and oxygen cycle like in the earliest part of Earth’s history.  Now, with the model I’ve built working with Christian Bjerrum at the University of Copenhagen, we can actually quantify how much life there was in the ocean.  Better yet, we can describe what those living things were doing.  During the earliest phase of Earth’s history, when there was life but very little oxygen, we would expect the ocean to be ferruginous (iron-rich) and, later, sulfidic (rich in sulfide, the smell in rotten eggs).

What we found was rather interesting.  When the oceans were ferruginous, they could only support a tiny fraction of the amount of primary production that we observe in the modern ocean.  However, when we considered a sulfidic ocean, what we found was that the oceans were almost as productive as today (about 25% of modern primary production).  This is a great result, and we’ll be presenting it at the conference.

Life at the Extremes

One of the things that makes mathematical biogeochemistry both difficult and fascinating is that the “rules” of life are poorly understood.  What is the maximum temperature that life can exist?  What is the minimum?  How small can the smallest photosynthesizer be?  What can bacteria use as “food” in extreme environments?

There will be a lot of disussion at this year’s Goldschmidt on this issue.  For example, I’m really looking forward to Fernandez-Remolar et al.’s presentation on life in the Rio Tinto – a bright red, acidic river in southwestern Spain – and what those observations can tell us about the paleontology of Mars.

Only One Day Left!

There’s only one day left before we all meet up on Sunday.  It’s going to be a great conference!  I’m looking forward to meeting my fellow bloggers face-to-face.

See you all on Sunday!

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