Peter Goedert Bot 437

The processes that influence the carbon cycle Photosynthesis: CO 2 is taken in and fixed during the calvin cycle energy (sunlight) + 6CO2 + H2O > C6H12O6 + 6O2 Respiration: CO 2 is released into the atmosphere as a bi- product C6H12O6 (organic matter) + 6O2 > 6CO2 + 6 H2O + energy

The Carbon Cycle and Biological Pump CO 2 fixed (Photosynthesis) products remain surface or sink out sequestration leads to more CO 2 pulled down into surface waters Biological Pump

Trends in the atmosphere The Earth’s atmosphere is composed of mostly Oxygen, Nitrogen, and Carbon Dioxide. Some rough estimates of the percentages that make up the atmosphere are as follows: 78% Nitrogen, 21% Oxygen, and.038% Carbon Dioxide. There are recent trends for increased CO 2 levels in the atmosphere with recent industry growth leading to increased emissions into the atmosphere.

Fluctuations in carbon dioxide throughout the year Northern Hemisphere summer time = decrease in CO 2 winter increase in CO 2 Southern Hemisphere shows opposite trends WHY??

Algae and decreasing CO 2 levels Two ways that algae have contributed to some declines in CO 2 despite the overall increasing trend. 1.) Algae produce organic compounds that cannot be oxidized by microbes to release CO 2. 2.) Algae generate large amounts of sediment material composed of carbonate minerals

Carbon Sequestration The burial of organic carbon and carbonates in the sediment which will remove carbon from the carbon cycle for long periods of time. organic carbon: degraded slower than it is produced leading to a loss of CO 2, partly because it sinks to the bottom with dead algae away from microbes that decompose it. ((remains in deep anoxic sediments away from the microbes) Examples: scytonemin (cyano, sheaths, UV protection) algaenans (green algae, tough cell wall, cross linked H- C) Cyst walls (dinoflagelates) Acylpolysaccharides (converted by aquatic bacteria, non- decomposable organic carbon originally from algae) * Marine snow: APS combined with other remains helps it sink out and reach sediment * Over time, converted to fossil fuels (temp and microbe conversions)

Carbon Sequestration Calcium Carbonate: many groups of algae use process of calcification -CO 2 or HCO 3 - incorporated into a hard exterior shell Ex: Cyanobacteria (stomatolites) Reds (rhodoliths) Haptophytes (coccoliths) HCO Ca 2+ > CaCO 3 + CO 2 + H 2 O CO 2 used in photosynthesis

The changing environment: Problems and Solutions Human activities increase CO 2 in atmosphere may lead to ocean acidification and dissolution of the calcium carbonate exoskeletons (coccoliths) this in turn will decrease the total amount of carbon sequestration (Godol et al. 2009) so much research is directed in this area. Experiments with iron fertilization in Fe limited areas have proved to increase blooms of algae, hopefully leading to more atmospheric carbon sequestration, but these were only short term experiments land may lead to possible extrapolation. However, to study performed by Blain et al. 2007, looked at natural fertilization In the Antarctic and were able to predict more about long term fertilization. They concluded that iron fertilization could be a key way in the future to lower the atmospheric CO 2.

Thank You References: Grahm, L., J. Grahm, and L. Wilcox Algae second edition. Pearson Education Inc. San Fransisco. Pg Godol, R., K. Aerts, J. Harlay, R. Kaegl, C. Ro, L. Cho and R. Van Grieken Organic surface coating on coccolithophores- Emiliania huxleyi: Its determination and implication in the marine carbon cycle. Microchemical Journal. 91: Stephane, B. et. al Effect of natural iron fertilization on carbon sequestration in southern ocean. Nature. 446: Figures taken from: vision learning website: