brandon j. okafor daniel o. breecker the university of texas at austin
DESCRIPTION
Investigating soil water movement and pedogenic carbonate formation by measuring the stable isotope composition of water in Vertisols. Brandon J. Okafor Daniel O. Breecker The University of Texas at Austin The Jackson School of Geosciences. Outline. Introduction Hypothesis Field Site - PowerPoint PPT PresentationTRANSCRIPT
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Brandon J. OkaforDaniel O. Breecker
The University of Texas at AustinThe Jackson School of Geosciences
Investigating soil water movement and pedogenic carbonate formation by
measuring the stable isotope composition of water in Vertisols
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Outline• Introduction • Hypothesis• Field Site• Methods• Meteoric Water Line• Results• Conclusion• Future sites and research
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Introduction Water Movement• Water limited ecosystems in Texas• Recharge to underground resources• Transport of dissolved species• Translocation of saltsPedogenic carbonate• Paleo-environmentVertisols• Used for many crops in Texas• Most abundant in rock record
2011 Drought in Texas
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Hypothesis
1. Evaporation occurs deeper in Vertisols than other soils
2. Pedogenic carbonate records oxygen isotope composition of mean annual precipitation.
Wilding and Tessier (1988)
L. Michel
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Field Site• Richland Creek Wildlife Management Area in
Fairfield, TX. (southeast of Dallas, TX)• Lies within the Trinity River flood plain• Average annual rain fall is 40 inches• Highly vegetated
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Methods
Samples in glass collection
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Meteoric Water Line
Evaporation Trend
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Results
:Wettest samples:Driest samples
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Conclusion1.Large rain events are the only source of
water that infiltrates past 1 meter in the soil, but more analysis will need to be done to prove this.
2.If true, pedogenic carbonates that are in equilibrium with this water will be biased towards large rain events.
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Future sites
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Future Research• Saturation state (with respect to
calcite) of soil water to better understand carbonate formation
• Calculated δ18O values (-9.0‰ vs. PDB) compare with measured δ18O values of pedogenic carbonate.
• Collect rain water samples • Calculate relative humidity within
cracks
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Thank you for your time
Any questions???