Biokinetics of Tritium in Wheat Plants: Measurements and Model - - PowerPoint PPT Presentation

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Biokinetics of Tritium in Wheat Plants: Measurements and Model - - PowerPoint PPT Presentation

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Biokinetics of Tritium in Wheat Plants: Measurements and Model Calculations S. Strack, S. Diabat, W. Raskob, __________________________________________________________________ Objectives: Development of a process oriented model -

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Biokinetics of Tritium in Wheat Plants: Measurements and Model Calculations

  • S. Strack, S. Diabaté, W. Raskob,

__________________________________________________________________  Objectives: Development of a ‘process oriented’ model

  • general description of relevant mechanisms
  • risk assessments, based on predictions of expected concentrations in nutrients
  • Application in assessment codes like UFOTRI for decisions

 calculations by application only of general available parameters:

  • 1. air temperature
  • 2. relative humidity
  • 3. solar radiation
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Experiments:

  • 1993 and 1994 Laboratory chamber experiments with potted spring wheat
  • 1995 winter wheat in a small experimental field for short-term exposure

experiments during the grain-filling period.

  • transparent plexi-glass box (30 x 30 cm, 100 cm height)
  • tritiated water (HTO) evaporated by constantly heating
  • homogeneous tritiated air humidity in the box with a fan
  • concentration of HTO in the air humidity: detection by a calibrated bubbler

system (trapping in vials with a scintillation cocktail (for 5 minutes)

  • Further parameters:
  • Air temperature in °C
  • Relative air humidity in %
  • solar radiation inµE/m2s with a Quantum sensor (PPFD)
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0.0% 0.1% 0.2% 0.3% 0.4% 0.5% 0.6% 0.7% 0.8% 0.9% 1.0% 5 10 15 20 25 30 35

days after beginning of anthesis O B T in g ra in %

OBT concentrations in grains at the time of harvest, given as percentage of the TWT concentrations in leaves at the end of the exposure (2 h), chamber experiments 1993

MEANgrain filling period = 0.62 % night experiments

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Experiments:

  • 1993 and 1994 Laboratory chamber experiments with potted spring wheat
  • 1995 winter wheat in a small experimental field for short-term exposure

experiments during the grain-filling period.

  • transparent plexi-glass box (30 x 30 cm, 100 cm height)
  • tritiated water (HTO) evaporated by constantly heating
  • homogeneous tritiated air humidity in the box with a fan
  • concentration of HTO in the air humidity: detection by a calibrated bubbler

system (trapping in vials with a scintillation cocktail (for 5 minutes)

  • Further parameters:

Air temperature in °C Relative air humidity in % solar radiation in µE/m2s with a Quantum sensor (PPFD)

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Experiments:

  • 1993 and 1994 Laboratory chamber experiments with potted spring wheat
  • 1995 winter wheat in a small experimental field for short-term exposure

experiments during the grain-filling period.

  • transparent plexi-glass box (30 x 30 cm, 100 cm height)
  • tritiated water (HTO) evaporated by constantly heating
  • homogeneous tritiated air humidity in the box with a fan
  • concentration of HTO in the air humidity: detection by a calibrated bubbler

system (trapping in vials with a scintillation cocktail (for 5 minutes)

  • Further parameters:
  • Air temperature in °C
  • Relative air humidity in %
  • solar radiation in µE/m2s with a Quantum sensor (PPFD)
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Monitor Bubbler Cuvette of gas exchange system Temperatur, rel. humidity Inlet for air flushing Fan Heating unit Outlets for:

  • tritiated water (HTO) evaporated by constantly heating
  • homogeneous tritiated air humidity in the box with a fan
  • concentration of HTO in the air humidity: detection by a calibrated bubbler

system (trapping in vials with a scintillation cocktail (for 5 minutes)

  • and a Beckman Monitor
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Experiments:

  • 1993 and 1994 Laboratory chamber experiments with potted spring wheat
  • 1995 winter wheat in a small experimental field for short-term exposure

experiments during the grain-filling period.

  • transparent plexi-glass box (30 x 30 cm, 100 cm height)
  • tritiated water (HTO) evaporated by constantly heating
  • homogeneous tritiated air humidity in the box with a fan
  • concentration of HTO in the air humidity: detection by a calibrated bubbler

system (trapping in vials with a scintillation cocktail (for 5 minutes)

  • Further parameters:
  • Air temperature in °C
  • Relative air humidity in %
  • solar radiation in µE/m2s with a Quantum sensor (PPFD)
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  • TWT concentration after lyophilisation
  • removing all exchangeable Tritium in a tritium-free humid atmosphere
  • OBT concentration by combustion (Packard Oxidiser)
  • cultivation of residual wheat plants under normal field conditions until

harvest

  • in certain intervals: samples from leaves and ears
  • 7 exposures at different time of day and during the night in 1995

(improvement of existing model)

  • 1996: 7 experiments for validation the plant-OBT model.
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7 7 8 9 10 11 11 14 15 15 20 20 23 23 F3 F14 F 7 F 2 F 4 F 10 F 15 F 1 F9 F 13 F 5 F 11 F6 F 12 leaf OBTr meas-1h 0.84 0.50 0.56 1.39 0.87 0.60 1.56 1.45 1.49 1.42 0.50 0.42 0.44 0.33 leaf OBTr meas-2h 0.80 0.68 0.62 1.01 0.98 0.66 1.23 1.16 1.29 1.48 0.64 0.48 0.39 0.33 leaf OBTr meas-4h 0.62 0.53 0.85 0.69 0.73 0.71 1.39 0.85 1.27 0.46 0.39 0.33 leaf OBTr meas-1d 0.20 0.11 0.28 0.28 0.41 0.34 0.39 0.35 0.42 0.22 0.36 0.16 seed OBTr meas-harv 0.23 0.14 0.30 0.19 0.29 0.19 0.23 0.20 0.23 0.28 0.35 0.25 0.34 0.20 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

% Rel.OBT leaf 1,2,4h,1d,harv.

leaf OBTr meas-1h leaf OBTr meas-2h leaf OBTr meas-4h leaf OBTr meas-1d seed OBTr meas-harv

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Basic metabolism respiration gross- photosynth. photo- respiration

TWTgrain OBTgrain

TWTleaf

TRANS 1 rapid

OBTleaf

TRANS 2slow

ear 30%

atmos phere 1.part net-photosynthesis, basic metabolism and respiration

stem 10%

2.Teil Nettophotosynth. translokation

Plant-OBT Model leave 60%

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Relative OBT-concentrations in the grains at harvest

0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 6 8 10 12 14 16 18 20 22 24 time of the day (h) at the beginning of the exposure relative OBT concentrations, %

Korn OBTgemessen Korn OBT modelliert Polynom 2.Ordn. median 0,23 % ______________________________________________________________ Forschungszentrum Karlsruhe, Technik und Umwelt

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OBTgrain at harvest, related to time integrated TWTinteg. in leaves and ears 50 100 150 200 250 300 350 400 100 200 300 400 500 600 700 800

TWTinteg (kBq* h/ml)

OBT in grains at harvest, Bq/ml

  • TWTinteg. leaf + 0.5 (TWTinteg ear during day)
  • and during night (f=0.2)

F 15, July 3

Forschungszentrum Karlsruhe, Technik und Umwelt

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Thank you for your attention

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0,00 0,50 1,00 1,50 2,00 2,50 3,00 3,50 1 10 100 1000

F15

ear OBTmeas earOBTmod leaf OBTmeas leaf OBTmod

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0,00 0,10 0,20 0,30 0,40 0,50 0,60 0,70 0,80 1 10 100 1000

#F14

ear OBTmeas rel-meas earOBTmod rel-mod leaf OBTmeas rel-meas leaf OBTmod rel-mod

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Die wichtigsten Prozesse im Pflanzenmodell: „plant-OBT“ mit allgem.verfügb.meteorolog.Daten: Luft-Temperatur, rel.Feuchte, Licht

Wachstum Aufnahme in Blatt, Ähre, Stengel (TWT) Bildung von OBT: Photosynthese, Photorespiration Grundumsatz, Respiration Translokation und Speicherung

In 1995 and 1996 we switched to field experiments:

  • pportunity to use winter wheat

exposure more exactly for one hour (Plexiglas box) Uptake of HTO through Stomata: TWT

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Die wichtigsten Prozesse im Pflanzenmodell: „plant-OBT“ mit allgem.verfügb.meteorolog.Daten: Luft-Temperatur, rel.Feuchte, Licht

Wachstum Aufnahme in Blatt, Ähre, Stengel (TWT) Bildung von OBT: Photosynthese, Photorespiration Grundumsatz, Respiration Translokation und Speicherung

In 1995 and 1996 we switched to field experiments:

  • pportunity to use winter wheat

exposure more exactly for one hour (Plexiglas box) Uptake of HTO through Stomata: TWT