delta_13C

 PI:              Paul Quay
 of:              University of Washington
 dataset:         Total CO2 and delta 13C of seawater from CTD casts
 project/cruise:  AESOPS/NBP97-3 - Ross Sea Process 3 Cruise
 ship:            Nathaniel B. Palmer

 References:  1. Kroopnick, P.M. (1974), The dissolved O2-CO2-13C system in the 
                eastern equatorial Pacific.  Deep-Sea Research, 21, 211-227.

              2. Quay, P.D., B. Tilbrook and C.S. Wong (1992), Oceanic uptake of
                fossil fuel CO2: Carbon-13 evidence.  Science, 256, 74-79.

 Parameter   Description                               Units

 event       event number from event log
 sta         station number from event log
 cast        CTD cast number from event log
 bot         CTD bottle sequence number
 depth_n     nominal depth of sample                   meters
 TCO2_man    manometric total CO2 in seawater          micromoles C/kilogram
 delta13C    Carbon 13 to Carbon 12 ratio of TCO2      per mil
 nd          no/bad data