Nutrients and trace elements

Nutrients and minor elements

Non-conservative elements

concentration change due to addition or removal processes

Abundance and residence times

removal reflected in low concentrations and short residence times - as they are corrlated

minor elements - intermediate levels, high variability

trace elements - trace levels, shortest RTs

Removal processes

- adsorption

-biological up take

remove dissolved substances and add this material to the particulate phase. subsequent settling leads to removal from water column via sedimentation dependent on partlcle size - larger = faster

Adsorption

most important for traced metals

positive ions are attracted to the surface of partical and binds to it, then it is removed via sinking and more are added as it sinks = decreasing ions with depth

scavenger- type depth profiles

highest levels near surface amd dcreasing levels with increasing depth

Biological uptakes

Determins depth profile of nuitrients

they are taken up in euphotic zone into the algal biomass. detritus sinks from the zone into the deep - no nutrient uptake below euphotic zone. however bacterial breakdown realses nutirents at depth and recycles them

the two layered ocean

there is a vertical segregration of processes

- thermocline- prevents diff temperature water mixing

nutrient cycling

- uptake in mixed surface layer

-transder of deriral biomass from top to bottom

- gradual microbial degradation of biomass

- release nutrients at depth

also recycling via up welling

Nutrient type depth profiles

controlled by uptake and regeneration

Nutrient-type elements

classification by biological requirements

-macronutrients - these are required in large amounts and are structural components of phytoplankton so can all limit growth

-micronutrients - these are required in small amounts and used in enzymes or photosynthetic apparatus

they are also called

- recycled elements

- biolimiting elements

Bio-limiting trace metal profiles

Zn

-near zero levels nar surface but highest in deep water

depth duration similiar to that of nitrate

zinc is used for enzyme carbonic anhydrase - uptake of carbon dioxide

Fe

essential for phtosynthetic apparatus, nitrate uptake and nitrogen fixing

it is supplied by aeolian transport - limitation may limit phytoplankton growth in remote open ocean areas with little duct deposition

conservative type depth profiles

concentration only varies with salinity - ratio of element over salinty constant depth

Depth profiles