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Measuring Dynamical Responses of Plants to Environment Change Using Short-lived Radioisotope

Measuring Dynamical Responses of Plants to Environment Change Using Short-lived Radioisotope. Calvin Howell Duke University Physics Triangle Universities Nuclear Laboratory. Measuring Dynamic Biological Responses in Plants using Radioisotopes. Collaboration. C.R. Howell (Physics)

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Measuring Dynamical Responses of Plants to Environment Change Using Short-lived Radioisotope

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  1. Measuring Dynamical Responses of Plants to Environment Change Using Short-lived Radioisotope Calvin Howell Duke University Physics Triangle Universities Nuclear Laboratory October 2008

  2. Measuring Dynamic BiologicalResponses in Plants using Radioisotopes Collaboration C.R. Howell (Physics) C. Reid (Biology) E. Bernhardt (Biology) A.S. Crowell (Physics Postdoc) M. Kiser (Physics graduate student) R. Phillips (Biology Postdoc) October 2008

  3. What is a Phytotron? • Controlled Environment Facility • Growth chambers can control many factors: • Soil type • Air Temperature • Light levels (total & UV) • Carbon dioxide concentration • Relative humidity • Nutrients • Air pollutants October 2008

  4. “Industrial Revolution” Evidence for Influence of Human Activities on Atmospheric CO2 Levels October 2008

  5. Long timeline Atmospheric CO2 Levels October 2008

  6. The Vostok Station in Antarctica Information:The coldest recorded temperature on Earth, -128.6°F (-89.2°C) was measured here on July 21, 1983. Latitude/Longitude: 78°27'51"S 106°51'57"EAltitude: 11484 ft3 (500 m) above sea levelAverage Annual Temperature: -67°F (-55°C) October 2008

  7. Ice Core Measurements at Vostok October 2008

  8. Atmospheric CO2 Concentration Measurements Since the 1950’s • Mauna Loa Observatory (MLO) is an atmospheric baseline station. Since the mid 1950's MLO has been continuously monitoring  and collecting data relating to atmospheric change . The observatory is under the Earth System Research Laboratory (ESRL) - Global Monitoring Division (GMD)   which is part of the National Oceanic and Atmospheric Administration (NOAA). October 2008

  9. Recent Atmospheric CO2 Concentration Data October 2008

  10. Sinks in units of billions of metric tons of carbon (GtC) Fluxes in units of billions of metric tons of carbon per year (GtC/year) Carbon Budget Intergovernmental Panel on Climate Change (IPCC): Climate Change 2001, “The Carbon Cycle and Atmospheric Carbon Dioxide” October 2008

  11. Sinks in units of billions of metric tons of carbon (GtC) Fluxes in units of billions of metric tons of carbon per year (GtC/year) Carbon Budget Intergovernmental Panel on Climate Change (IPCC): Climate Change 2001, “The Carbon Cycle and Atmospheric Carbon Dioxide” October 2008

  12. Interesting Aside Top 5 CO2 Emitters: 1. U.S. 2. China 3. Russia 4. Japan 5. U.S. autos • Total tonnage of CO2 produced by vehicles over 124,000 mile lifetime • Assuming ~10 year lifetime, vehicles emit more than their own weight in CO2 per year 13 mpg 18 mpg 22 mpg 36 mpg 65 mpg http://www.sierraclub.org/globalwarming/suvreport/pollution.asp October 2008

  13. Motivations Climate models predict atmospheric CO2 levels will double by the end of this century! How will plants respond? Intergovernmental Panel on Climate Change (IPCC): Climate Change 2001, “The Carbon Cycle and Atmospheric Carbon Dioxide” October 2008

  14. FACE Studies • Free Air CO2Enrichment (FACE) experiments • Large-scale research programs to study effects of increased CO2 levels • Many environmental variables • Difficult to correlate growth parameters with high precision • Findings from forest stands • Initially, trees grow faster in CO2 enhanced environment, but then grow a slower rate than trees grown in at ambient CO2 level Duke FACTS-I Aerial View October 2008

  15. FACE Sites October 2008

  16. Introduction to Plant Studies with Radioisotopes • 14C used in mid-1940’s • Long half-life (~5730 years) • Weak beta emitter • Tracer measured by destructive harvesting • Use of 11C for in vivo studies demonstrated in 1963 • 1973 – More and Troughton at the Department of Scientific and Industrial Research in New Zealand showed that useful amounts of 11C can be produced using small van de Graaf accelerators • Labs in USA, Canada, Scotland, New Zealand, and Germany start using 11C for mechanistic studies of photosynthate transport in the mid 1970’s • Present studies at: Julich, Germany; Univ. Tokyo; BNL; TUNL-Duke October 2008

  17. Planned Research at the TUNL-Phytotron Facility Studies of CO2 uptake and carbon translation under different environmental conditions Root exudate measurements Nutrient uptake and translocation under different environmental conditions October 2008

  18. Plant Physiology 101 • Sugars loaded into a sieve tube • Loading of the phloem sets up water potential gradient that facilitates movement of water into dense phloem sap from the neighboring xylem • As hydrostatic pressure in phloem sieve tube increases, pressure flow begins, and sap moves through the phloem • At the sink, incoming sugars actively transported out of phloem and removed as complex carbohydrates • Loss of solute produces high water potential in phloem, and water passes out, returning eventually to xylem http://home.earthlink.net/~dayvdanls/plant_transport.html October 2008

  19. p + 14N  11C + a 1 Produce H- ions in negative ion source Accelerate H- ions toward +5MV terminal Strip off electrons with carbon foil (H- p) Accelerate protons away from +5MV terminal Bend p in magnet and collide on 14N target 4 3 2 5 1 + 2 3 4 5 Carbon-11 Production October 2008

  20. Radioisotope Production October 2008

  21. Single Detector Measurements • Use detectors collimated for specific areas of plant to trace carbon allocation on a coarse (source/sink) scale • Develop quantitative flow models to describe dynamics October 2008

  22. Single Detector Measurements October 2008

  23. respiration respiration Leaf Source Shoot Sink A Total Sink respiration, exudation Root Sink B Discrete observation times: tk where k = 0, 1, 2, … Yk = counts in Sink B at time tk(output) Uk = counts in Total Sink at time tk (input) Yk=- a1 Yk-1 - a2 Yk-2 - … - an Yk-n+ b0 Uk + b1 Uk-1 + … + bm Uk-m Extract Physically Significant Quantities: • Gain – fraction of input that shows up at the output • Average transit time Statistical Model October 2008

  24. 2D Imaging October 2008

  25. For Example y (cm) x (cm) October 2008

  26. For Example y (cm) x (cm) October 2008

  27. Immediate Plans • Develop system for continuous loading measurements • Develop system for nutrient uptake studies • Continue root exudate experiments • Develop high-resolution 2D PET imager October 2008

  28. High resolution 2D imagers 5 cm x 5 cm x 1.5 cm 2mm x 2mm pixels (0.1 mm gap) 20 cm x 30 cm field of view October 2008

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