[Aztlan] A question on salt water and radio carbon dating

[Allan Shumaker]

Mike, 
Sorry for the delayed response but I was hoping some 'expert' would answer your question. Since that has not happened, I will give my amatuer opinion.

 I have heard through the grapevine that the dating was done at   
 Oxford and that only one of the samples gave that old date of   
 13,600 years which has gotten into print. Not even sure if that is   
 calendar years or rcybp. I do know that CSFA has requested a  
 sample  for dating "the proper way".

 In any case 14C is formed in the upper atmosphere by the action  
 of sunlight on nitrogen. The resulting 14C atom combines with oxygen to  
 form  CO2 which disperses through the atmosphere. Now sea water  
 does  absorb some CO2 but the concentration of 14C is less than  
 the  atmosphere and that concentration decreases with water depth.

Thus if the bones have absorbed sea water it seems to me that the  
 concentration of 14C would be reduced which would make the bones   
 appear older when the ratios 14C/12C are measured.

There is another effect that could alter the radio carbon dating, that is the leaching of carbon from the bones during submersion. However the leaching process does not seem to have any preference for the 12C, 13C or 14C isotopes so this is probably a minor problem in attempting to obtain an accurate date. 

The article mentioned that the 4th skeleton was to be recovered in September and those remains did include some teeth which could probably give a more accurate radio carbon date. I am sure we will be hearing more.

Allan Shumaker