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) - 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

from Wanninkhof et al from Rosso 2006 from Kelly 1997

Convection + Diffusion

Convection + Diffusion = Confusion

advectiondiffusion

advectiondiffusion

Air Water Advection into the water is not possible

Air Water Advection into the water is not possible Diffusion

Air Water Diffusion is ~10 -9 m 2 /s Diffusion is ~10 -5 m 2 /s Advection into the water is not possible Diffusion

Air Water

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

Surface Divergence Theory

1 mm

Surface Divergence Theory 100 μm

Surface Divergence Theory 1 mm

Surface Divergence Theory

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

Surface Divergence Theory from Turney et al from McKenna & McGillis 2004

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

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

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

u* (cm/s) k (cm/s)

k=3.3 x m/s F=3.3 x ΔC

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.

The Bigger Picture and Future Work

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 Sabine et al from Woods Hole Website

1 cm Air Water

from Herlina & Jirka 2004

Air Water 1 cm

from Tokoro et al 2007 from Belanger 1991

Surface Divergence Theory 1 mm

Surface Divergence Theory 1 mm

Surface Divergence Theory 1 mm

Surface Divergence Theory 1 mm

Surface Divergence Theory 1 mm

Surface Divergence Theory 1 mm

Surface Divergence Theory 1 mm

Surface Divergence Theory 1 mm

Depth (cm)Flow Speed (cm/s) Macro ReTurbulent Re No Wind

Depth (cm)Wind Speed (cm/s) Wave Height (cm) Windy

from Takahashi et al. 2008

from Richey et al. 2002

Chemical Budgets Change in Amount per Unit Time = Flux In - Flux Out

Surface Renewal Theory

Surface Divergence Theory 1 mm

Surface Divergence Theory 100 μm

Surface Divergence Theory 1 mm

Surface Divergence Theory 1 mm

Surface Divergence Theory

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 Chemical Budgets Change in Amount per Unit Time = Flux In - Flux Out

from Blais et al. 2001

from Schimpf et al. 2004

from Herlina & Jirka 2004

Surface Renewal Theory

“Renewed” Spot

Surface Renewal Theory “Renewed” Spot

Surface Renewal Theory