N15_uptake

  PI:              Raymond Sambrotto
  dataset:         N-15 uptake rates for nitrate, ammonium and urea; 
                          Concentration of ammonium, urea and particulate C & N
  project/cruise:  Arabian Sea/TTN-045 - Process Cruise 2
  ship:            Thomas Thompson
  
Note from R. Sambrotto:

   The data served as of August 12, 1997 have been modified in the 
   following ways from the data served prior to this date:
     1) More particulate nitrogen, particulate carbon and nanomolar 
        ammonium data have been added that were not included with the  
        initial data release.
     2) The uptake rates for nitrate, ammonium and urea needed to be
        recomputed using the correct 15N isotope addition concentrations.

Methodology.
 
 Parameter  Description                                Units

 event      event number from event log
 sta        station number from event log
 sta_std    Arabian Sea standard station identifier
 cast       cast number from cruise event log
 bot        rosette bottle number
 depth_n    nominal depth                              meters
 NH4_orig   ammonium, as originally sent by PI         nanomoles/liter
 NH4        ammonium, unit magnitude changed by        micromoles/liter
                 US JGOFS Data Management Office
 Urea       urea                                       micromoles N/liter
 TPC        total particulate carbon                   micromoles/liter
 PON        particulate organic nitrogen               micromoles/liter
 pNO3       nitrate uptake rate                        micromoles/liter/day
 pNH4       ammonium uptake rate                       micromoles/liter/day
 pUrea      urea uptake rate                           micromoles N/liter/day