Amino acids isotopes: Particle 15NsrcAA values from Station Aloha.    
   Published as Table S2 in Gloeckler et al (2018) L&O, doi: 10.1002/lno.10762 
   PI: B. Popp (UH) 
   version: 2018-12-05 
     NOTE: Delta15N values are averages weighted by error for glycine, serine, lysine and phenyalanine