algae: overview and importance for earth’s atmosphere
TRANSCRIPT
Earth’s Atmosphere: Not Much of It
Mass Atmosphere = 5.2 x 1018 kgMass Oceans = 1.4 x 1021 kgMass Earth = 6.0 x 1024 kgLive Biomass = 1 x 1015kgCarbon Dioxide = 3 x 1015 kgTrunover Time for carbon dioxide = 5 years in atmosphere, centuries in oceans
Carbon dioxide cycles between low values in summer andhigher values in winter in the Northern Hemisphere due toseasonal differences in photosynthesis.
Annual input from fossil fuels and deforestation: 3 x 1013 kg carbon dioxide. Half accumulates in the atmosphere, rest isabsorbed in oceans, leading to acidification.
Pre-industrial carbon dioxide level was 280 ppm, now 380 ppm.
Cyanobacteria and Oxygenic PhotosynthesisAbout 3 Billion Years Ago. Water is the electron donor. CO2 + H2O CH2O + O2
Oxygenic photosynthesis is complicated. It requires two photosystems and is thought to have arisen only once in the course of evolution.
Modern Stromatolites Fossil Stromatolite (2.5 Billion Years Old)
Banded Iron Formation
Oxygen Was A Poison to EarlyLife Forms on Earth. Took about 1 billion years before oceans and atmosphere were fully oxygenated
Oxygen in the air allowed the evolution of eucaryotes and aerobicrespiration, finally leading to the world’s life forms present today.
Ozone in the upper atmosphere (derived from O2) protects against the splitting H2O to H and OH, with H escaping to space.
Earth has lost about 25% of its water while water is nearly all gone on Venus andMars.
Oxygen also produced the ozone shield which protects water in the upperatmosphere from boiling away as hydrogen
GreenhouseGasses:
Water VaporCarbon Dioxide*Methane*Nitrous Oxide*
*Increasing Due To Human Activity
Evolution of the modern algae orders.
60 Ma
1500 Ma
In this course we emphasize the ecology and biology of the algae rather than the taxonomy. Main groups we will cover:
Cyanobacteria (blue-green algae)Green AlgaeRed AlgaeBrown algae – brown seaweeds, kelps, diatomsDinoflagellatesCoccolithophoresOthers