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Mass Confusion About Air-Water Mass Transfer Damon Turney

Mass Confusion About Air-Water Mass Transfer Damon Turney Bren School of Environmental Science and Management Committee Members: Jeff Dozier, Sanjoy Banerjee, Sally MacIntyre, Jordan Clark. Fate and Transport - Carbon Toxins (DDT, Hg, Dieldrin, PCBs, many more)

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Mass Confusion About Air-Water Mass Transfer Damon Turney

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  1. Mass Confusion About Air-Water Mass Transfer Damon Turney Bren School of Environmental Science and Management Committee Members: Jeff Dozier, Sanjoy Banerjee, Sally MacIntyre, Jordan Clark

  2. Fate and Transport • - Carbon • Toxins (DDT, Hg, Dieldrin, PCBs, many more) • Aeration of Hypoxic Water • DeAeration of Water Below Dam Spillways • Industrial Cleaning of Water in Air Spargers • Bioreactors and Other Reactors in Industry • Steam Condensation in Power Plants

  3. from Kelly 1997 from Wanninkhof et al. 1992 from Rosso 2006

  4. Convection + Diffusion

  5. Convection + Diffusion = Confusion

  6. advection diffusion

  7. advection diffusion

  8. Advection into the water is not possible Air Water

  9. Advection into the water is not possible Air Diffusion Water

  10. Diffusion is ~10-5 m2/s Advection into the water is not possible Air Diffusion Water Diffusion is ~10-9 m2/s

  11. Air Water

  12. Surface Renewal Theory No unambiguous way of determining a value for average t

  13. Surface Divergence Theory

  14. Surface Divergence Theory 1 mm

  15. Surface Divergence Theory 100 μm

  16. Surface Divergence Theory 1 mm

  17. Surface Divergence Theory

  18. Surface Divergence Theory

  19. How do we visualize (or measure) the velocities in the top ~100 microns of the water column accurately?

  20. Surface Divergence Theory from Turney et al. 2005 from McKenna & McGillis 2004

  21. Surface Divergence Theory from Turney et al. 2005 from Xu et al. 2006

  22. Experimental Conditions No Wind, Channel Flow (Straight Channelized River) 4 water heights 3 water velocities Reynolds numbers ranging from 5000 to 30,000 Wind Waves, Microscale Wave Breaking 10 wind speeds fetch constant ~9 meters

  23. Measurements No Wind, Channel Flow - Mean Velocity, Depth, Temperature, - PIV Turbulence in Middle of Water Column - Friction of Water on Channel Bottom - PIV of Surface Divergence Motions - Oxygen Transfer Measurements Wind Waves - Mean Velocity, Depth, Temperature, - PIV Turbulence in Middle of Water Column - Friction of Water on Channel Bottom - Wind Speeds (~1mm apart) at Locations Above Interface - Friction of Wind on Air-Water Interface - Stereo PIV of Surface Divergence Motions - Oxygen Transfer Measurements - Standard Water Height Measurements and Shadowgraphs

  24. k 10-5 (cm/s) u* (cm/s)

  25. k=3.3 x 10-5 m/s F=3.3 x 10-5 ΔC

  26. Conclusions: • It’s possible that the Surface Divergence Models is too simple, i.e., it ignores organized flows such as waves. Perhaps it is time for a new theory. • Time-history effects are necessary for an adequate understanding of how the chemical is transported away from the interface. • Accurate knowledge of velocity near the interface is very valuable. These measurement techniques should be pushed forward.

  27. The Bigger Picture and Future Work

  28. from Sabine et al. 2004 Pg C: 3.2 (+/-0.2) = 6.3 (+/-0.4) + 2.2(+/-1.3) - 2.4(+/-1.2) – 2.9 atmosphere fossil fuel terrestrial oceanic error from Woods Hole Website

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