how the sea got its salt and nutrients in the ocean

what are four of the principle rock forming minerals that are abundant?

oxygen, silicon aluminum and iron

what are the least abundant elements in the earths crust?

gold, platinum and rhenium

what are the most abundant elements in seawater?

oxygen and hydrogen mostly in the form of water, sodium and chlorine

what are the most abundant elements in river water?

carbon in the form of bicarbonate, calcium and silicon

how is salinity of water nearly always calculated?

by using conductivity measurements

what is variation in salinity like in the top 100m of seawater?

very high variation

what is variation in seawater like in the bottom 1000m?

little varation

what is the redfield ratio a measure of?

the consistent atomic ratio of carbon, nitrogen, and phosphorus found in marine phytoplankton and throughout the deep oceans

what is the redfield ratio?

carbon: nitrogen: phospohorous

106:16:1

how do concentrations of major dissolved ions vary?

vary from place to place in the oceans but their relative proportions remain virtually constant

what is mass balance?

the idea that products must equal the reactant we started with

what is the principle source of elements in seawater?

rivers

what are other sources of elements into seawater?

volcanic gases, dust, hydrothermal vent fluid, sediment pore waters

what is the mean ocean residence time?

the time between the element entering the ocean and being removed from the ocean

what is used as a measure of geochemical activity?

removal constant

what elements are all organims made up of?

hydrogen, oxygen, carbon, nitrogen, and phosphorous

why are nutrients considered a limiting factor?

put a limit on how much primary production can take place

what are the uses of nitrogen in organisms?

amino acids, RNA and enzymes

what are the uses of phosphorous in organisms?

ATP, phospholipids, etc.

what are the uses of silicon in organisms?

diatoms and radiolaria

what are the uses of metal in organisms?

enzyme systems

what happens in the ocean when nutrients are limited?

phytoplankton may have limited growth, some other organisms may move into this ecological niche e.g. nitrogen fixers can carry on photosynthesising however this is more energy expensive

what are the main oceanic bio-limiting nutrients?

N, P, Si and Fe

why are phytoplankton key in the carbon cycle?

leads to the removal of atmospheric CO2 and transfer if carbon to deep water and sediments therefore has implications for climate change

where does photosynthesis take place in the ocean?

only the upper ocean where sunlight can penetrate

how is carbon transferred from the phytoplankton to the deep ocean?

some is consumed and excreted by zooplankton and die eventually leads them to sinking from the photic zone into the deep ocean

what are particles mainly made up of in the surface ocean?

soft tissue with a small proportion of skeletal material

what are organic particles mainly made up of in the deep ocean?

in the deeper layers a much greater proportion is made up of skeletal material rather than soft tissue

why does not all carbon reach the deep ocean?

many is recycled in the upper ocean with only some escaping to the deep ocean

what are the two main classes of falling particle?

feacal pellets and marine snow

what is snow fall?

snow particles are fragile aggregates of biogenic debris in the upper water column. this materal can build up to sizes at which readily leaves the surface and descends

why do carbon levels vary in the spring?

burst of organic material (phytoplankton) created

why is there a drop in carbon levels in the summer?

nutrients is used up