ETM: The Estuarine Turbidity Maximum
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ETM: The Estuarine Turbidity Maximum PSO 2009
description
ETM: The Estuarine Turbidity Maximum. PSO 2009. St. Lawrence R. Elbe River. Hudson R. Chesapeake Bay. Gironde River. Columbia R. San Francisco Bay. Estuarine Turbidity Maximum (ETM). Depth. River. Ocean. 5. 10. May 2,1998. 15. 5. 10. May 17,1999. 15. 10. 20. 30. 40. 50. - PowerPoint PPT Presentation
Transcript of ETM: The Estuarine Turbidity Maximum
ETM: The Estuarine Turbidity Maximum
PSO 2009
Chesapeake Bay
Hudson R.
Elbe RiverSt. Lawrence R.
Gironde River
San Francisco BayColumbia R.
Dep
th
River Ocean
Estuarine Turbidity Maximum (ETM)
Dep
th (m
) 15
10
5
May 2,1998
0
200
Kilometers from River Mouth10 20 30 40 50 60 70
15
10
5
May 17,1999 0
50
May 1998 (above average freshwater flow)
Sanford et al. 2001, North and Houde 2001
May 1999 (below average freshwater flow)
Stratification, turbidity, salt front locationinfluenced by freshwater flow
NTU
Observations about particle trapping in ETMs
• Particle trapping in ETMs occurs by asymmetrical tidal transport of a pool of resuspendible particles with a limited range of settling velocities
• Fine sediments in estuarine environments almost always exist in aggregated (flocculated) form. Aggregation and disaggregation can be active processes, depending on concentration, stickiness, and small scale shear.
• Settling velocities of fine sediments trapped in ETMs are determined by the aggregate properties (size and specific density), not the individual particle properties
ETM particles are packed with organics> 63 um> 63 um 20 to 63 um20 to 63 um 10 to 20 um10 to 20 um
< 10 um< 10 um Close-upClose-up DAPI stainedDAPI stained
Columbia RiverCrump & Baross, 2000
