EMRASS II Vienna jan 2011 Philippe GUETAT, Critical Parameters CEA - - PowerPoint PPT Presentation

Nara Tritium 2010 1

EMRASS II Vienna jan 2011

Philippe GUETAT, Critical Parameters

CEA France

October 2010

Calculation of soil water activity

• 700 L / year of rain

2

HTO soil (Bq/l) 2 69 231 132 HTO soil (Bq/l) 0.3 Avap +0.7 Arain 68 239 140

300 L.y-1 of dry vapor / 8 g.m -3 . => 1.2 10-3 m.s-1 Supposed to be between 10-3 and 10-2

Nara Tritium 2010

Free water activity assessment

October 2010 Tritium 2010 3

• C veg free w = Hr Cair m+ (1-Hr) Csoil IAEA tecdoc 1616
• this means that free water activity is practically equal to

air moisture activity

• In practice it is not true.

4

Free waters

(Boyer)

Nara Tritium 2010 October 2010

0,00 0,10 0,20 0,30 0,40 0,50 0,60 0,70 0,80 5 10 15 20 25 CHTO laitues (Bq L‐1) / CHTO air (Bq L‐1) Durée de l'exposition (h)

Measures in Free water of lettuce : light

5

43 , , h 5 , 1

2 / 1

   t 21 , , h 9 , 2

2 / 1

   t 42 , , h 4 , 22

2 / 1

   t

young matures

• ld

) 1 (

.t k HTO air HTO laitues

e C C



    

k t ) 2 ln(

2 / 1



Nara Tritium 2010

Exposure time ( hours)

October 2010

0,00 0,05 0,10 0,15 0,20 0,25 0,30 0,35 0,40 0,45 0,50 5 10 15 20 25 CHTO laitues (Bq L‐1) / CHTO air (Bq L‐1) Durée de l'exposition (h)

Measures in free water of lettuce : darkness

6

36 , , h 3 , 7

2 / 1

   t 07 , , h 9 , 6

2 / 1

   t 41 , , h 8 , 12

2 / 1

   t

) 1 (

.t k HTO air HTO laitues

e C C



    

k t ) 2 ln(

2 / 1



young matures

• ld

Nara Tritium 2010

Exposure time ( hours)

October 2010

IAEA tecdoc 1616 and Proposal

October 2010 7

Proposal for temperate climate – low rain intensity

Cfree w =[0.4 Cam +0.6.Csw]] and Csw = 0,3 Cam + 0,7 Crain Keep : Ccomb w = WEQp.Rp.[RH.Cam +(1-RH).Csw]] but RP to be reassessed Cvegetable = WCp. Cfree w + (1-WCp).Ccomb w

Nara Tritium 2010

Main parameters ?

jan 2011 IAEA vienna 2011 8

Chemical process = f(t°C) Incorporation rate in free water exchange velocity => Integ activity Bq.s/L Incorporation rate in organic matter s-1 Light when exists is not limiting Water : pressure structure temperature = keep cool mineral input transfer of photosynthesis products Soil humidity Stomata open or closed ? Light : osmotic pressure Absicic acid for water stress Air Relative humidity and soil Wilting point : 16 bars Field capacity: 0.2 bars depth 12 => 18 bars

To simplify

October 2010 Tritium 2010 9

The Machine income Given efficiency Fct(t°C) t0 tmax The transport from soil The door

Which approach ?

• Plenty parameters to know if the final yield

is 0.6 or 0.8 kg/m2. do we care ?

• Exchange velocity for free water :

Ve = LAI / r : m dAf/dt = Ve ( Cair-Csat Af)

Resistances should be more illustrated

• Incorporation rate in organic matter.

– When the plants feel well : Yield, day.°C, % of water in Org Matter. Incorporation rate of HTO in OM in easy conditions.

2011 Vienna 2011 10

Soil water contribution

October 2010 Tritium 2010 11

Rws= 1/(1-p) . (θ-θwp)/(θfc-θwp) ETP mm/day

What to know

• Potential Evapotranspiration
• State of soil water content humidity
• Real Evapotranspiration : give a correcting

factor, by a factor of max 5.

• To use directly for incorporation factor in
• rganic matter.

October 2010 Tritium 2010 12

Other points : soil

• Transfer from soil.
• Deposition on soil of the order of 10-3 to

10-2 m/s. about the same than in plants.

• Dilution in some 100 L/m2.
• But decrease much slower: ETR/Soil

content

• Can be considered as a “normal situation”

for the soil pathway.

October 2010 Tritium 2010 13

Other points : rain

• Concentration of rain about 3 to 5 times

lower than air moisture. (except at the foot

• f the stack)
• Dilution in the soil water about 100.
• Same approach as in previous slide.
• Question of the direct leaves transfer.

– Time of input = time of release + Time of evaporation.

October 2010 Tritium 2010 14

Day and night = not only light or not

15

Other points : night

• Say that the correction of temperature

could be OK. (Day °C)

• On metabolism of incorporation
• On possible input of water
• Should consider that decrease of activity
• ccurs in the next day.
• Do we need something for the stomata ?

October 2010 Tritium 2010 16

Field experiment in 2009 - Total OBT

October 2010 Tritium 2010 17

colza 85 wheat 55,9 potatoes 38,2 apple 70,1

Thank you for your attention

January 2011 Vienna 2011 18