Quiz 2

• Concentration of dissolved calcium is slightly lower in surface waters because phytoplankton (such as coccolithophores, foraminifera) require uptake of calcium for their shells. Since phytoplankton are photosynthetic organisms, they live near the surface so they can get the sunlight. This means the calcium from the surface is taken up by them. In the deeper ocean, there is dissolution of calcium when dead phytoplankton sink to the bottom.
• MORT - amount in oceans/flux into oceans
• If the flux into oceans is increased then the MORT will be lower because it will change the ratio
• If the residence time of an element is longer than the residence time of water, then the element will accumulate in the water
• micronutrients (such as iron and nitrates) have similar vertical profiles because they are both required by phytoplanktons which is a photosynthetic organism so it is found near the surface of the water, this means its concentrations will be lower near the surface. There will be higher concentrations in the deeper oceans through dissolution of phytoplankton once they die.
• There is lower concentrations if organic matter in deep water because recycling in the deep ocean takes longer, and in the surface water recycling is done via bacteria
• photosynthesis will fix carbon in the form of CO2 which will then convert to organic carbon. This removes CO2 from the atmosphere. When algal cells die, organic material is recycled back into CO2 and returned to the atmosphere, so the biological pump controls atmospheric CO2 levels.
• If the biological pump is strong enough then some organic material may not decay and will get buried in the ocean sediment -> if this happens then it is removed from the atmosphere