week 7

• More double-bonds are biosynthesised by coccolithophores at lowertemperatures to maintain membrane fluidity (in alkanones)
• alkanone is an aldehyde and and alkene
• Gibbs free energy equation is delta G = -RT ln K
• iron is the fourth most abundant element in the crust - 5%
• Rapid reactions thus occurred and resulted in highly reducingconditions in the paleo ocean
• Transport from continents occurred as they were formed andhydrological cycle initiated weathering
• Early life evolved in environment rich in dissolved Fe
• Fe levels and bioavailability are controlled by redox processes
• Dust deposition – the major source of Fe to surface ocean• Very low input into Pacific subtropical gyres and Southern OceanMain HNLC regions – Southern Ocean and Equatorial Pacific
• the diagenetic sequence is determined by the respective change in the electrode potential in reduction of these compounds - the energy yield is highest with o2 and then decreases downwards
• diagenetic sequence - O2, NO3-, Mn (IV), Fe(III), SO42-,CO2