1 / 20

Introduction to the Marine Environment

Introduction to the Marine Environment. Ocean planet 72% of surface is water 70% seawater 2.0% fresh – 1.51% ice, 0.49% liquid, .00007 vapor Life present 10x longer than on land 3 D habitat 98% of biosphere. Origin of Water. 4.5 bya during planet formation

amal-hyde
Télécharger la présentation

Introduction to the Marine Environment

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Introduction to the Marine Environment Ocean planet 72% of surface is water 70% seawater 2.0% fresh – 1.51% ice, 0.49% liquid, .00007 vapor Life present 10x longer than on land 3 D habitat 98% of biosphere

  2. Origin of Water • 4.5 bya during planet formation • “dirty snowball” comets http://www.scienceclarified.com/scitech/images/lsca_0001_0001_0_img0017.jpg

  3. Hydrologic cycle • Vapor – short residence (~10 d), rapid travel (>100 km) • Molecule in cycle ~38,000 yrs

  4. Physical-Chemical Properties of Water • Polar molecule – binds with other charged ions • Hydrogen bonds – gives water cohesion, surface tension • Universal solvent - dissolves more substances than any other liquid (>65%)

  5. Hydrogen bondig produces • Surface tension • Makes water cohesive (tends to bond to itself) • Adhesive (bonds with other molecules)

  6. Heat and Water • High heat of vaporization • High boiling point • High latent heat of fusion • High specific heat (heat capacity) • High thermal conductivity • High freezing and melting points • Decreases density as it changes to solid

  7. An on-line Periodic Table is available by clicking here,

  8. Salinity – ppt or PSU • Amt of dissolved solid per unit water (gm/Kg) • Little variation in sfc waters worldwide • Sfc waters vary little in chemical composition • Constant for long geol periods - evaporites • Inorganic salts, organics, gases • Dissolved solids • Major (~99.28%) • Minor ions (~0.71%) • Nutrients and trace elements (<0.01%) - critical for marine life

  9. Dissolved solids 1000 g of seawater = 965 g water 35 g dissolved salts Avg. salinity = 35 ‰ (ppt) Cl most abundant, constant prop. Salinity = 1.80655 Cl Variations – add or remove water coastal zone, poles – Baltic Sea ~ 7 ppt – Red Sea > 40 ppt

  10. Nutrients and trace elements • Phosphate, nitrate for photosynthesis • ions not constant proportions: bio active, limiting • Si dioxide, Ca carbonate – shells • Fe, Mn, Co, Cu - bioactive • essential to marine life, may become limiting in sfc waters

  11. Density (g/cm3) • Affected by: • Temperature (colder = denser) • Salinity (saltier = denser) • Pressure (higher pressure = denser)

  12. Density –Add salts: • >24 ppt, density cont. to increase to freezing • At 35 ppt freezing point reduced to -1.9° C, even more dense • Salts excluded on freezing = so what happens??? • What happens to ice? • What happens to surrounding water?

  13. Salinity (cont.) • Dissolved gases – two metabolically important: oxygen, carbon dioxide; also nitrogen • Solubility – function of temp., pressure, salinity • Decrease temp., pressure, incr. solubility

  14. Oxygen and Depth • Not distributed evenly with depth • Oxygen Minimum Zone • Max @10-20m – atmosphere exchange, photosynthesis • Decline with depth: minimum @200-1000 m • Why? • No photosynth. • Decomposition • Deep water influx

  15. Carbon Dioxide and Solubility • Differs from oxygen; reacts with water • Abundant • Capacity to absorb

  16. Carbon Dioxide Chemically reactive in water – tends to equilibrium CO2(diss) + H2OH2CO3 H+ + HCO3- H+ + CO3-2 (carbonic acid) (bicarbonate) (carbonate) Provides buffering capacity for oceans -- keeps seawater at pH ~ 7.8 - 8.4

  17. pH of sea water • Produces H ions – extra H= acidic • Pure water – pH 7 (equal no. H and OH) • CO2, alkaline ions inc. pH to 7.5-8.4 • Does SW pH change??? CO2(diss) + H2O H2CO3 H+ + HCO3- H+ + CO3-2 (carbonic acid) (bicarbonate) (carbonate)

  18. Chemical cycles • Major cycles – carbon, phosphorous, nitrogen, sulpher (sulfate) • Sources and sinks - box model • Ocean well mixed, steady state (elements added and removed ~ equal rate) • Residence time – how long an element can be expected to stay in system • Reactivity

More Related