4 items with the tag “carbon flux

  • Stoichiometry of Life, Task 4: Biogeochemical Impacts on Planetary Atmospheres
    NAI 2009 Arizona State University Annual Report

    The abundance of molecular oxygen in planetary atmospheres may be a useful way to look for evidence of life. The amount of photosynthetically produced oxygen that accumulates in an atmosphere depends in part on the export of photosynthetically produced organic carbon from the ocean surface to the seafloor, which in turn may depend on the availability of bioessential elements. We are using a computer model to determine how this carbon export processes might operate in an ocean dominated by prokaryotes rather than eukaryotes, as may have been common in Earth’s past and as an analog for hypothetical extrasolar planets.

    ROADMAP OBJECTIVES: 4.1 4.2 5.2 6.1 7.2
  • Stoichiometry of Life, Task 4: Biogeochemical Impacts on Planetary Atmospheres
    NAI 2010 Arizona State University Annual Report

    Oxygenation of Earth’s early atmosphere must have involved an efficient mode of carbon burial. In the modern ocean, carbon export of primary production is dominated by fecal pellets and aggregates produced by the animal grazer community. But during most of Earth history the oceans were dominated by unicellular, bacteria-like organisms (prokaryotes) causing a substantially altered biogeochemistry. The NASA Ocean Biogechemical Model (NOBM) is applied using cyanobacteria (blue-green algae) as the only photosynthetic group in the oceans. The analyses showed that the early Earth ocean had 19% less primary production and 35% more nitrate due to slower growth by the cyanobacteria, and reduced nutrient uptake efficiency relative to modern phytoplankton Additionally there was 8% more total carbon in the oceans as a result of higher atmospheric pCO2. We plan to optimize this early Proterozoic ocean model in combination with a 1 D model to account for changes in aggregate formation and sinking speed in response to varying nutrients.

    ROADMAP OBJECTIVES: 1.1 4.1 4.2 5.2 6.1 7.2
  • Stoichiometry of Life, Task 4: Biogeochemical Impacts on Planetary Atmospheres
    NAI 2011 Arizona State University Annual Report

    Oxygenation of Earth’s early atmosphere must have involved an efficient mode of carbon burial. In the modern ocean, carbon export of primary production is dominated by fecal pellets and aggregates produced by the animal grazer community. But during most of Earth history the oceans were dominated by unicellular, bacteria-like organisms (prokaryotes) causing a substantially altered biogeochemistry. In this task we experiment with the marine cyanobacterium Synechococcus sp. as a model organism and test its aggregation and sinking speed as a function of nutrient (nitrogen, phosphorus, iron) limitation. We have found so far that aggregation and sinking of these minute cyanobacteria is influenced by the concentration of nutrients in the growth medium.

    ROADMAP OBJECTIVES: 4.1 4.2 5.2 6.1 7.2
  • Stoichiometry of Life - Task 4 - Biogeochemical Impacts on Planetary Atmospheres
    NAI 2012 Arizona State University Annual Report

    Oxygenation of Earth’s early atmosphere must have involved an efficient mode of carbon burial. In the modern ocean, carbon export of primary production is dominated by fecal pellets and aggregates produced by the animal grazer community. But during most of Earth’s history the oceans were dominated by unicellular, bacteria-like organisms (prokaryotes) causing a substantially altered biogeochemistry. In this task we experiment with the marine cyanobacterium Synechococcus sp. as a model organism and test its aggregation and sinking speed as a function of nutrient (nitrogen, phosphorus, iron) limitation. We have found so far that these minute cyanobacteria form aggregates that can sink gravitationally in the water column, and we are currently experimenting with minerals that might have been present in the Proterozoic ocean to see if those can accelerate sinking.

    ROADMAP OBJECTIVES: None Selected