Wednesday, November 11, 2009

Sun night science lecture

Biogeochemistry in Antarctic waters

talk by a scientist conducting DNA sequencing and protein analyses of local phytoplankton in order to study the effect of nutrients and micronutrients on their growth.

Interesting points:
- important elemental nutrients used by phytoplankton: N, Fe, K, Si, Zn, Co
- some nutrients only come from bacterial processes- B12 for example. Guiness beer is rich in B12 due to its special bacterial populations.
- about 30% of the world's ocean surfaces are Fe-deficient
- polar regions are more likely to be Fe-deficent because much iron comes from windblown dust. Dust is in shorter suppply in mostly snow-covered areas such as Antarctica.
- Some Antarctic plankton "hot-bunk" iron. They use iron to build photosynthesis-related proteins during the day, then tear these proteins apart each night so that the same iron is available for alternative purposes. This allows the plankton to produce more in iron-limited conditions, though at a high energy cost.
- The metal hulls of scientific ships can throw off study measurements by artificially enriching the immediate vicinity with Fe from underwater rust
- underwater volcanic vents release metals and other nutrients which are carried away by currents, forming a plume pattern
- scientists theorize that global warming is being caused in part by excess carbon released into the atmosphere by human activities such as burning fossil fuels. One of the geo-engineering solutions suggested is to fertilize the oceans with iron, thereby causing a plankton bloom which will form a massive sink for atmospheric carbon (and eventually carry this carbon back into the rock cycle). Experimental fertilization attempts thus far have caused blooms visible from space for a month or more.

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