Table of Contents

• Dataset Description
  • Methods & Sampling
• Data Files
• Parameters
• Deployments
• Project Information
• Program Information

Porosity and pore water nutrient chemistries, sediment cores

   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.
 
 

The U.S. EqPac process study consisted of repeat meridional sections (12°N -12°S) across the equator in the central and eastern equatorial Pacific from 95°W to 170°W during 1992. The major scientific program was focused at 140° W consisting of two meridional surveys, two equatorial surveys, and a benthic survey aboard the R/V Thomas Thompson. Long-term deployments of current meter and sediment trap arrays augmented the survey cruises. NOAA conducted boreal spring and fall sections east and west of 140°W from the R/V Baldridge and R/V Discoverer. Meteorological and sea surface observations were obtained from NOAA's in place TOGA-TAO buoy network.

The scientific objectives of this study were to determine the fluxes of carbon and related elements, and the processes controlling these fluxes between the Equatorial Pacific euphotic zone and the atmosphere and deep ocean. A broad overview of the program at the 140°W site is given by Murray et al. (Oceanography, 5: 134-142, 1992). A full description of the Equatorial Pacific Process Study, including the international context and the scientific results, appears in a series of Deep-Sea Research Part II special volumes:

Topical Studies in Oceanography, A U.S. JGOFS Process Study in the Equatorial Pacific (1995), Deep-Sea Research Part II, Volume 42, No. 2/3.

Topical Studies in Oceanography, A U.S. JGOFS Process Study in the Equatorial Pacific. Part 2 (1996), Deep-Sea Research Part II, Volume 43, No. 4/6.

Topical Studies in Oceanography, A U.S. JGOFS Process Study in the Equatorial Pacific (1997), Deep-Sea Research Part II, Volume 44, No. 9/10.

Topical Studies in Oceanography, The Equatorial Pacific JGOFS Synthesis (2002), Deep-Sea Research Part II, Volume 49, Nos. 13/14.

The United States Joint Global Ocean Flux Study was a national component of international JGOFS and an integral part of global climate change research.

The U.S. launched the Joint Global Ocean Flux Study (JGOFS) in the late 1980s to study the ocean carbon cycle. An ambitious goal was set to understand the controls on the concentrations and fluxes of carbon and associated nutrients in the ocean. A new field of ocean biogeochemistry emerged with an emphasis on quality measurements of carbon system parameters and interdisciplinary field studies of the biological, chemical and physical process which control the ocean carbon cycle. As we studied ocean biogeochemistry, we learned that our simple views of carbon uptake and transport were severely limited, and a new "wave" of ocean science was born. U.S. JGOFS has been supported primarily by the U.S. National Science Foundation in collaboration with the National Oceanic and Atmospheric Administration, the National Aeronautics and Space Administration, the Department of Energy and the Office of Naval Research. U.S. JGOFS, ended in 2005 with the conclusion of the Synthesis and Modeling Project (SMP).