ammonium_urea

 PI:              William Cochlan and Deborah Bronk
 of:              San Francisco State University (Cochlan),
                         University of Georgia (Bronk)
 dataset:         Ambient ammonium and urea concentrations
 project/cruise:  AESOPS/NBP-96-4A - Ross Sea Process 1 Cruise
 ship:            Nathaniel B. Palmer

 Methodology

 DMO Note on multiple-bottle events

 Parameter    Description                            Units

 event        event number from event log
 sta_name     unique station identifier
 sta          station number from event log
 cast         rosette cast number from event log
 cast_type    CTD = CTD rosette
               TM = Trace Metal rosette
 bot          rosette bottle number
 depth_n      nominal sample depth                   meters
 NH4          ammonium concentration                 micromoles N/liter
 Urea         urea concentration                     micromoles N/liter