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Results | Food Web and its Function | Interesting Isotopic Studies

Fingernail Results

The wait is over

During the 2006 Open House June 3 and June 4, we analyzed fingernails of 501 visitors for carbon and nitrogen stable isotope ratios. This was even more than in 2003 (456 fingernails) and 3 times more visitors than at the 2000 Open House where we analyzed 150 fingernail samples. Hence, we have been much slower in getting the samples analyzed and posted on this web page than expected. Sorry about that! 

Below are several plots containing the new fingernail data, a table of values linked to visitor fingernail number, and some preliminary text material that provides a brief discussion of what the fingernail isotope values mean and how to locate the position of your sample on the plots. 


Data for visitors to the 2006 Open House:


Data for visitors to the 2003 Open House:

Note: The Carbon isotope ratio values (d13C) and the Nitrogen isotope ratio values (d15N) on the table and plots are slightly different than the preliminary values given to visitors lucky enough to have their fingernails analyzed while they waited. This is because the initial preliminary values had not been corrected for various mass spectrometer parameters that shifted during the day (and can only be corrected after the entire set of samples and standards are analyzed). 

Note: There were a few fingernail samples that were lost during preparation or analysis, and we did not have enough spare fingernail clippings to repeat the analyses. If there are no values for your sample number, and you would like to try again, send another (larger!) fingernail sample to the address below. If you provide an email address (or a mail address) we will send you the new data when available. 

Fingernail samples
c/o Steve Silva
USGS -- MS 434
345 Middlefield Road
Menlo Park CA 94025 


Fingernail results


Interpreting your data


Comparing 2006 with 2003


Where you fall on the food chain


Results | Food Web and its Function | Interesting Isotopic Studies

Please contact Carol Kendall ( for questions and comments regarding this page. 
This page was last changed in June 2006. 
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