Marine Chemistry and Biological Oceanography

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Marine Chemistry and Biological Oceanography

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Biology starts with chemistry

• Biological processes the levels of elements and
  compounds
• Abundance of biota and tropic relationship
  chemical parameters, salinity, dissolved oxygen
  and nutrient

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Global water cycle
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turnover time

• The ocean has a turnover time of about 37,000
  years with respect to river inflow. This is how
  long it would take to fill the ocean if it were
  totally dry.
• Turnover times are defined as the mass in the
  reservoir divided by the input or removal rate.
  By comparison the average residence time of water
  in the atmosphere with respect to evaporation
  from the oceans and continents is only about 10
  days.

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Scope of Chemical Oceanography Fundamental
Questions

• - What are the chemical controls on biological
  production and food web structure of the ocean?
  In some ocean areas iron limits phytoplankton
  growth.
• Martin (1991) conducted experiments where he
  added iron to samples and showed that adding iron
  stimulated growth rate and also stimulated diatom
  production.

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• Martin (1991) conducted experiments where he
  added iron to samples and showed that adding iron
  stimulated growth rate and also stimulated diatom
  production.

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- In what ways do biological processes control
the distributions of chemicals in the ocean?

• Photosynthesis and respiration control the
  distribution of many elements in seawater.

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Compositions of sea water

• 0.45 mm filter
• Passed
• Can not pass
• Humic acid, protein and amino acid,
  polysaccharide, pigments, inorganic colloids
  (iron hydroxide)

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salinity

• Total amount of salts in water

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Bioavailability

• Can be utilized by cells - membrane
• related to dissolved materials and particulate
  materials
• Most particulate materials can not be efficiently
  utilized by phytoplankton and algae
• ?? large size of particulate materials can not
  pass through cell membrane or via the channel

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Speciation and global hydrological cycle
7 days
3550 days
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Global hydrological cycle
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Time-dependent events
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Dissolved gases

• Oxygen dissolved oxygen (DO)
• Surface, temperature, biological utilization and
  emission
• 2.0-10 mg/L intertidal regions
• Vertical distribution 50 m no variation
• Photosynthesis (O2)
• Respiration (-O2)

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Primary productivity
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CO2 cycle

• CO2 (gas) ? CO2 (dissolved)
• H2O CO2 ? H2CO3
• H2CO3 ? H HCO3-
• HCO3- ? H CO32-
• Ca2 CO32- ? CaCO3 (solid)
• ??? alkalinity (A) the number of moles of
  hydrogen ion required to convert all anions of
  weak acids to their unionized form in 1 kg of
  water

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pH and CO2
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CO2 cycle
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C cycle
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Nutrient

• Phosphorus (P)
• Nitrogen (N)
• Co-variation of N and P
• Refield atomic ratio CNP106161 (1934, 1963)
• NP ratio gt 301 ? P limitation
• NP ratio lt 101 ? N limitation
• Silicon

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Spatial variations
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Temporal variations
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Organic carbon

• Dissolved organic carbon DOC
• Particular organic carbon POC
• POC in photic zone is recycled by micro-organisms.

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