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Ocean salinity and its affect on surface tension

  1. Sep 19, 2012 #1
    How would decreasing ocean salinity affect surface tension, and how would this reduced surface tension affect coastal zones?

    Seems to me that a decrease in salinity will decrease surface tension because density decreases with decreasing salinity. So I would think decrease in density would decrease surface tension. But I can't really find any solid evidence of this.

    Also, how would this decrease in ocean surface tension (if true) affect coastal zones? Would coastal acquifer-level rise, clay expansion, decrease tidal salt, and flora/faunal changes lead toward erosion or slumping of anykind? I don't think freshwater lakes have any anamolous type of erosion going on that saline lakes or the oceans do not.
  2. jcsd
  3. Sep 21, 2012 #2
    Google "surface tension of salt solutions"
  4. Sep 22, 2012 #3


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    You may want to consider what happens at river mouths, where salt and fresh water mix. Do you see anything unusual or different? I have never noticed any obvious effects on the surface of the water in these changing salinity regions.
  5. Sep 22, 2012 #4
    On the scale of ocean and river flows, surface tension has a negligible effect. It is not included in fluid mechanics models of the ocean or rivers. In practice, surface tension effects apply only on much smaller scales. The effect of salinity on density, on the other hand, can affect the hydrostatics and the dynamics, and is usually taken into account.

  6. Sep 24, 2012 #5
    Would you expect surface tension to impact evaporation rates? Intuitively it seems it should, but intuition is not science.
  7. Sep 24, 2012 #6
    Intuitively, I would think it's mainly an energy question imo, 2500 joule per gram, on which surface tension may not have much effect. But it's an excellent question to find out by experiment.
  8. Sep 24, 2012 #7
    No. Not on the scale of oceans or rivers. Only on the scale of very small droplets.
  9. Sep 30, 2012 #8
    it could affect the evaporization of droplets produced by breaking spray and thereby affect the generation of marin aerosols.
  10. Dec 30, 2012 #9
    I don't think surface tension has an important influence.

    Actually, surface tension is not even included in studies on the ocean skin layer dynamics. The only part where I'd see this in on bubble jets and spray production, but only to parameterize fluxes, mostly momentum and heat fluxes.

    Coastal aquifers (saline intrusion in them) would depend on regular aspects such as hydraulic conductivity, soil type and so on. Surface tension is a feature of the microscale, so I think it's negligible.
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