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

EMRASS II Vienna jan 2011 Philippe GUETAT, Critical Parameters CEA France October 2010 Nara Tritium 2010 1

Calculation of soil water activity • 700 L / year of rain HTO soil (Bq/l) 2 69 231 132 HTO soil (Bq/l) 68 239 140 0.3 A vap +0.7 A rain 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 2 Nara Tritium 2010

Free water activity assessment • C veg free w = H r C air m + (1-H r ) C soil IAEA tecdoc 1616 • this means that free water activity is practically equal to air moisture activity • In practice it is not true. October 2010 Tritium 2010 3

Free waters (Boyer) October 2010 4 Nara Tritium 2010

Measures in Free water of lettuce : light       HTO HTO k . t C C ( 1 e ) laitues air ln( 2 )  0,80 t    t 1 , 5 h , 0 , 43 1 / 2 k 1 / 2 0,70 C HTO laitues (Bq L ‐ 1 ) / C HTO air (Bq L ‐ 1 ) 0,60    t 2 , 9 h , 0 , 21 1 / 2 0,50 old 0,40 0,30 matures 0,20 0,10    young 22 , 4 h , 0 , 42 t 1 / 2 0,00 0 5 10 15 20 25 Exposure time ( hours) Durée de l'exposition (h) 5 October 2010 Nara Tritium 2010

Measures in free water of lettuce : darkness    t 12 , 8 h , 0 , 41 1 / 2       HTO HTO k . t ( 1 ) 0,50 C C e laitues air 0,45    t 7 , 3 h , 0 , 36 C HTO laitues (Bq L ‐ 1 ) / C HTO air (Bq L ‐ 1 ) 0,40 1 / 2 old 0,35 ln( 2 )  t 1 / 2 k 0,30 0,25 young 0,20 0,15    t 6 , 9 h , 0 , 07 0,10 1 / 2 0,05 matures 0,00 0 5 10 15 20 25 Exposure time ( hours) Durée de l'exposition (h) October 2010 Nara Tritium 2010 6

IAEA tecdoc 1616 and Proposal Proposal for temperate climate – low rain intensity C free w =[0.4 C am +0.6.C sw ]] and C sw = 0,3 C am + 0,7 C rain Keep : C comb w = WEQ p .R p .[RH.C am +(1-RH).C sw ]] but R P to be reassessed C vegetable = WC p . C free w + (1-WC p ).C comb w October 2010 7 Nara Tritium 2010

Main parameters ? Incorporation rate in free water exchange velocity => Integ activity Bq.s/L Incorporation rate in organic matter s -1 Chemical process = f(t°C) Stomata open or closed ? Light : osmotic pressure 12 => 18 bars Wilting point : Absicic acid for water stress 16 bars Air Relative humidity and soil Field capacity: Soil 0.2 bars Light when exists is not limiting humidity depth Water : pressure structure temperature = keep cool mineral input transfer of photosynthesis products jan 2011 IAEA vienna 2011 8

To simplify The transport from soil The Machine Given efficiency The door Fct(t°C) t 0 t max income October 2010 Tritium 2010 9

Which approach ? • Plenty parameters to know if the final yield is 0.6 or 0.8 kg/m 2 . do we care ? • Exchange velocity for free water : V e = LAI / r : m dA f /dt = V e ( C air -C sat A f ) 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 Rws= 1/(1-p) . ( θ - θ wp)/( θ fc- θ wp) ETP mm/day October 2010 Tritium 2010 11

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 organic 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/m 2 . • 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 of 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 occurs in the next day. • Do we need something for the stomata ? October 2010 Tritium 2010 16

Field experiment in 2009 - Total OBT colza 85 wheat 55,9 potatoes 38,2 apple 70,1 October 2010 Tritium 2010 17

Thank you for your attention January 2011 Vienna 2011 18