Dataset: poros_nut_chem_pw

   PI:              Will Berelson and Doug Hammond
   of:              University of Southern California
   dataset:         Porosity and pore water nutrient chemistries, sediment cores
   dates:           November 03, 1992 to December 04, 1992
   location:        N: 8.925  S: -12.0032  W: -140.15  E: -134.9483
   project/cruise:  EqPac/Cruise TT013 - Benthic survey
   ship:            R/V Thomas Thompson
 
   Methodology:
 
   McManus, J.,  D.E. Hammond, W.M. Berelson, T.E. Kilgore.  D.J. DeMaster, O.
   G. Ragueneau, and R.W. Collier.  1995. Early diagenesis of biogenic opal:
   Dissolution rates, kinetics, and paleoceanographic implications.  Deep Sea
   Research. 42, 871-903.
 
   Hammond, D.E., J. McManus, W.M. Berelson, T.E. Kilgore, and R. Pope, 1996,
   Early diagenesis of organic material in Equatorial Pacific Sediments:
   Stoichiometry and Kinetics. Deep Sea Research II, 43, 1365-1412.
 
   PI Notes:
   1..Ammonia and Nitrate+Nitrite appear to be significantly influenced by artifacts
   related to core retrieval and centrifugation.
   2..Measured silicic acid has been temperature corrected for warming during
   centrifugation.
   3..Bottom water (BW) values are from (whole-core squeezing (WCS) cores, hydro data
   or landers).
   4..Porosity is defined as the fraction of sediment volume occupied by pore
   water, so it is dimensionless.  The prodecure used to measure it was to
   weigh sediment wet, dry the sediment at 60� C until it reached a constant
   weight, and re-weigh.  A density of solid phases D=2.6 g/cc, and a salinity
   S=35 psu were assumed.  The porosity was calculated from the expression
   below, where Ww is wet weight and Wd is dry weight (both corrected for the
   tare weight of the empty container):
 
   Porosity = Vpw/(Vpw+Vsed)
   where Vpw = Ww/(0.99)
   and Vsed = (Wd - (Ww-Wd)(S/990))/D
   The factor 0.99 is grams H2O per cc sea water, and the factor 990 is grams
   H2O per kg sea water.
 
   DMO Note:
   1..Additional porosity/pore water data for this area are available from PACFLUX II,
   a JGOFS pilot project.  See Berelson and Hammond's por_nut_chem_PF2 porosity and pore water
   nutrient chemistry data from the PACFLUX II cruise.