Dear Isogeochemers,

 I tried to know CO2 absorption effects of roadside trees by
del-13C and del-18O of CO2.
  In my preliminary analysis, I found that del-18O of CO2 in urban air
 (near road) were 7 to 20 permil (PDB  base) in March in Japan.
But, I dont have any data set of del-18O of CO2 in air
Any information about del-18O of CO2would be greatly appreciated.  
Thanks, 

Dr. Kazushi TAKAHASHI
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