Particulate matter in the oceans and trace elements Flashcards
Name two methods of measures ocean particulate matter
Light scattering (Nephelometry - to get a bulk picture (size and shape unknown). Sediment traps to produce an intergrated picture (different sampling times)
What are limitations of sediment trap data?
The hydrodynamics across top. Swimmers caught and poisoned. Problems worse in traps shallower than 1000m - more lateral currents and swimming organisms.
Name 4 sources of particles
Suspended matter from coastal erosion - Airborne dust - Cosmic dust - Biological particles from within system.
Name 6 forms of biological debris
Phytoplankton - Zooplankton - Faecal matter - Shell Debris - Fish and waste products - Marine snow
What does gross suspended matter distribution in the oceans depend upon?
On where you are in the oceans - short term seasonal changes - the effect of wind patterns/aridity on dust loading
In a particulate matter profile where is the maximun, and minimum?
Maximum at the surface from river and external input and productivity. Minimum in the middle of the water column
In a particle concentration map of the Atlantic why is there more suspended matter in the west than the east?
Western boundary currents - increases turbidity and potential to suspend and transport load
What is significant about bigger and denser particles?
They fall more quickly and therefore spend less time in mid water
What is significant about dust fallout into the oceans?
It acts as a mineral ‘ballast’ to create denser and larger particles and aid more rapid downward transport
WHat is POM?
Particulate organic matter
What is significant about settling POM?
Short bursts of rapid POM transport from productivity events control the composition of settling particles - chemical characteristics of the settling POM change significantly during transit through the water column,
What is important about re-suspension and lateral advection of particle matter?
Has an impact on the BBL (benthic boundary layer) (important in species reproductive strategies such as larvae dispersal - contains nutrients important to species)
What is the PAP (porcupine abyssal plain) in the North Eat Atlantic characterized by?
Strong seasonal fluxes of POM which are related to cycles of primary productivity in overly eutrophic surface waters
What is important to remember about trace element data in the oceans gathered before mid 1970’s
The data is probably wrong due to contamination and analytical problems
What controls trace element distribution?
Horizontal and vertical distribution is controlled by relative rates of supply and removal. Profiles are likely to be conservative in the oceans with a linear correlation to salinity