week 4

• the factors that determine the percentage of biogenic silica in sediments are rate of accumulation of other particle types, sedimentation rate of silica, burial rate of silica
• Carbon reservior sizes in order - sedimentary rocks, DIC in deep ocean, fossil fuels and shales, permafrost, surface ocean DIC, atmosphere, soils and ocean DOC, land biota, ocean biota
• the largest active reservoir of carbon is deep ocean dissolved DIC
• the total alkalinity of ocean is carbonate ion concentration plus bicarbonate ion concentration
• MORT assumptions

  Ocean is well mixed and mean cones are representative of the whole ocean

  riverine input is major input into the ocean and no other inputs are important

  oceans at steady state WRT the chemical
• water flux = volume/time
• chemical flux = water flux * conc in source water
• Nitrogen fixation provides significant inputs to ocean and denitrification and annamoxremove significant nitrogen from the ocean therefore residence time is overestimated• atmospheric nitrate deposition provides significant inputs to ocean therefore residenceoverestimated
• Other processes such as Fe limitation mean that significant nitrate uptake is not observed in the southern ocean
• Give two reasons why you might observe non-Redfield ratio nitrogen content in the upperwater column in the Atlantic and Pacific Ocean?Nitrogen fixation adds nitrogen (high N:P relative to Redfield Ratio), denitrification and annamoxremoves nitrogen (in areas of low oxygen: low N:P relative to Redfield Ratio).
• Total alkalinity (TA) is the excess of proton acceptors overproton donors with respect to a zero level of protons.
• Units: meq L-1 or meq kg-1 (an “equivalent” is a mole or charge) - units of alkalinity