Oceanic Particulate Inorganic Carbon as an Estimate of Calcification Measured during the JGOFS Equatorial Pacific Process Study (EQPAC)

The Equatorial Pacific Process Study (EQPAC) was conducted along 140 deg W longitude during 1992. Four cruises took place: February 3 - March 9, March 19 - April 15, August 5 - September 18, and September 24 - October 21. A fifth benthic cruise and sediment trap legs were added. During the first cruise (TT007), 15 stations were occupied along 140 deg W longitude from 12 deg N latitude to 12 deg S latitude. During the second cruise (TT008), data were collected at 8 stations along 140 deg W longitude from 9 deg S latitude to 9 deg N latitude. During the third cruise (TT011), data were collected at 15 stations along 140 deg W from 12 deg N latitude to 12 deg S latitude. During the fourth cruise (TT012), data were collected at 5 stations along 140 deg W longitude from 17 deg S latitude to the equator. During the third cruise (TT011), calcification (calcite production) was measured at each site using carbon-14 techniques. Particulate inorganic carbon (PIC) was used as an estimate of calcite. Water was collected using the trace metal (TM) clean rosette, inoculated with carbon-14 solution, incubated for 24 hours in situ, split into two aliquots, and filtered. The replicate filters were fumed in the presence of concentrated HCl to drive off activity due to calcite. Radioactivity on the filters was measured in a liquid scintillation counter. Calcification rates were calculated based on the difference between unfumed filter counts and fumed filter counts. In addition, primary production, chlorophyll, and phaeopigments were measured. The data is public domain and can be retrieved on-line at "http://usjgofs.whoi.edu/jg/dir/jgofs/" [The information in this summary was taken from the JGOFS World Wide Web pages.]