1 / 20

Composition of seawater Processes controlling seawater composition

This in an introduction to oceanography for 1st year students . In geochemistry, geology and misuse of the sea Resources are: Oceanography: An Illustrated Text C. P. Summerhayes, S. A. Thorpe John Wiley & Sons, May 1996 ISBN: 0470345373 or 0470235748 352 pages

studs
Télécharger la présentation

Composition of seawater Processes controlling seawater composition

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. This in an introduction to oceanography for 1st year students. In geochemistry, geology and misuse of the sea Resources are: Oceanography: An Illustrated Text C. P. Summerhayes, S. A. Thorpe John Wiley & Sons, May 1996 ISBN: 0470345373 or 0470235748 352 pages NASA visible Earth: http://visibleearth.nasa.gov/ Essentials of Oceanography (7th Edition) (Paperback)by Harold V. Thurman, Alan P. Trujillo A very good webpage can be found under: http://wps.prenhall.com/esm_thurman_essofocean_7/0,7261,382992-,00.html

  2. Composition of seawater Processes controlling seawater composition Major drainage systems of rivers Explain Rock weathering, vulcanic ashes, aerosols, hydrothermalism Formation of sedimentary rocks How does the salt get into the sea Dominant ocean sediment types and locations The biological pump (photosynthesis, settling etc) The physical/solubility pump Vertical profiles of chemical elements Atlantic versus Pacific comparison Explain the two box model Oxygen in surface waters The Marine Carbonate System CO2 determination from ancient atmospheres CO2 in surface waters current atmospheric CO2 concentration effect on global warming CO2 saturation in seawater (name the different ions) ∑CO2 concentrations in oceans Lysocline and Carbonate compensation depth Ocean CO2 disposal option Ocean resources EEZ overfishing/clima effects Oil/gas, Sand dredge, Manganese, Medicine, Biotechnology Sedimentology Landforms Beach characteristics Longshore current/drift Erosional coasts Depositional coasts Barrier islands Coastal protection What you should know for the Oceanography exam

  3. The Ocean: A Global Geochemical System Figure 1

  4. Deployment of a CTD cast. This instrument is routinely used during oceanographic expeditions for in situ measurements of water temperature and salinity. CTD casts can also collect water samples from different depths, stored in the dark grey cylinders visible on the photograph, which can then be used for further chemical analyses on board. Figure 2 : www.pcweb.liv.ac.uk/ocean/ oceanography/f1f7.htm

  5. Figure 3 Composition of seawater Seawater is a solution of salts of nearly constant composition, dissolved in variable amounts of water. There are >70 elements dissolved in seawater but only 6 make up >99% of all the dissolved salts; all occur as ions - electrically charged atoms or groups of atoms: their concentrations are mostly conservative and only affected by physical processes Oceanographers use salinity -- the amount (in grams) of total dissolved salts present in 1 kilogram of water -- to express the salt content of seawater. Normal seawater has a salinity of 35 grams/kilogram (or litre) of water -- also expressed as 35‰. Seawater from Wormly in southern England is used as the international standard for seawater composition. As well as major elements, there are many trace elements in seawater - e.g., manganese (Mn), lead (Pb), gold (Au), iron (Fe), iodine (I). Most occur in parts per million (ppm) or parts per billion (ppb) concentrations. These minor constituets are mostly non-conservative and actively participate in chemical and biological processes that change their concentrations They are important to some biochemical reactions - both from positive and negative (toxicity) viewpoints.

  6. River water Seawater Figure 18

  7. Figure 6

  8. precipitation Figure 7

  9. Figure 8 Processes controlling seawater composition Salts dissolved in seawater come from three main sources: • volcanic eruptions • chemical reactions between seawater and hot, newly formed volcanic rocks of spreading zones (mid-oceanic ridges) • chemical weathering of rocks on the continents

  10. FIGURE 4-3

  11. FIGURE 4-4

  12. Primary source for weathered material is crustal rock Limestone, sandstone and Shales are themselves sedimentary products Figure 2 Many salts in seawater originate from weathering of rocks on land. As rocks are weathered to form soils, they release soluble constituents like silica and elements like sodium, calcium, potassium and magnesium. River waters also carry bicarbonate (HCO3) - a by-product of weathering of silicate rocks or dissolution of limestone. Once they enter the oceans the dissolved salts remain, while the water continues to move through the hydrological cycle. Figure 10

  13. FIGURE 4-5

  14. FIGURE 4-7

  15. Vulcanic ashes Volatiles hydrochlord acid sulphur containimg gases carbon dioxide Figure 13 Volcanic eruptions produce large volumes of gases that eventually reach the oceans -- most important are sulphate and chloride. Submarine eruptions at spreading ridges inject gases directly into the oceans; gases from subaerial volcanoes are dissolved in rainfall.

  16. FIGURE 4-6

  17. Aerosols Aerosols are powders, or droplets, suspended in a gas, with a typical particle diameter of about one micrometer. they can act as a nucleus for the condensation of water to make a relatively large cloud droplet. Once formed, aerosol particles can collide and stick together, or they can grow by further condensation from the vapour phase. Aerosols Aerosols Figure 14 October 13, 2001

  18. Figure 9

  19. FIGURE 4-18

More Related