week 3

• thermohaline circulation - ocean circulation largely driven by temperature and salinity
• nutrient concentrations in seawater increases during remineralisation of organic matter as it is released from breakdown of organic matter upon respiration (which is remineralisation)
• nutrient concentrations also increase when a water parcel ages along the ocean conveyer belt in the deep ocean - as the water parcel leaves the surface ocean (age), it has longer to accumulate nutrients from remineralisation and since there's no photosynthesis there is no nutrient uptake
• nutrient concs dont always increase with depth due to events such as upwelling
• in a 1-d box model steady state means the total number of outputs balances the total number of inputs and there is no change in the size of the reservoir
• Redfield ratio is not the same with all organism, it varies
• at subtropical latitudes nitrate occurs at low concs near the surface due to the fact phytoplankton takes up nutrients near the surface ocean because this is where photosynthesis occurs
• in deep waters nutrient concs are usually higher due to remineralisation and decay of the phytoplankton which will release nutrients
• in subtropical regions there is heating of the surface water which strengthens the thermocline, this drives stratification of the ocean so there is less mixing. This means nutrient concentrations of surface waters only increase in areas of upwelling.
• nutrient concentrations are much higher in the North Pacific as opposed to the North Atlantic. this is because deep water formation begins in the North Atlantic which means cold water sinks from the surface to the deep ocean. it is then transported along the conveyer belt
• conveyer belt is NA - SO - IA - SP - NP
• since NP is last on the ocean conveyer, this means water has had time to accumulate nutrients and the water is older
• no ions get evaporated out of the ocean
• ppb is the same as 10^-6 g/kg
• ppm is the same as 1 mg/l
• to convert these to moles use equation moles is equal to mass over mr
• Low latitudes are a source for CO2• Higher latitudes are a sink