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Particulate Carbon, Nitrogen and Phosphorus

 Particle Filtration
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Analytical Method

Samples for elemental analysis of Particulate carbon (PC) and nitrogen (PN) were prefiltered through 202-µm Nitex mesh to remove large zooplankton and collected onto combusted 25 mm GF/F glass fiber filters. They were analyzed using a Carla Erba NC 2500 Elemental Analyzer with a Finnigan MAT ConFlo II coupler & Finnigan MAT Delta S mass spectrometer. The average precisions during 2006 determined from duplicate analysis are presented in the Table below.

Samples for elemental analysis of Particulate phosphorus (PP) were prefiltered through 202-µm Nitex mesh to remove large zooplankton and collected onto combusted, acid washed 25 mm GF/F glass fiber filters. Samples were analyzed using high temperature ashing followed by acid hydrolysis and subsequent determination of the liberated orthophosphate by colorimetry. These procedures are detailed in Karl et al. (1991). The average precisions during 2006 determined from duplicate analysis are presented in the Table below.


PC PN PP
Cruise mean CV
(%) 		mean SD
(µg/l) 		N mean CV
(%) 		mean SD
(µg/l) 		N mean CV
(%) 		mean SD
(µg/l) 		N
177 7.8 1.856 2 3.1 0.131 2 23.6 0.057 1
178 5.7 1.043 2 3.5 0.110 2 24.7 0.035 2
179 11.7 2.227 2 5.8 0.223 2 27.1 0.046 2
180 27.5 2.878 2 24.6 0.622 2 14.1 0.039 2
181 7.3 1.704 2 10.7 0.445 2 12.2 0.028 2
182 19.7 3.214 2 12.3 0.392 2 72.1 0.138 2
183 4.9 1.114 2 5.9 0.265 2 6.7 0.021 2
184 10.3 2.443 2 3.4 0.127 2 9.4 0.028 2
185 11.8 2.107 2 14.0 0.417 2 11.4 0.018 2
186 2.9 0.651 2 6.9 0.247 2 4.2 0.011 2
187 11.8 2.655 2 18.5 0.598 2 10.1 0.000 2
188 5.6 0.902 2 5.5 0.184 2 0.0 0.000 2
Mean 10.6 1.900 12 9.5 0.313 12 18.0 0.037 12


Results

Particulate carbon (PC), nitrogen (PN) and phosphorus (PP) concentrations in the surface ocean over the 18 years of the program are shown in Figure 39, Figure 41, and Figure 43 and contour plots are presented in Figure 40, Figure 42, and Figure 44. PC ranges from about 1-3 µmol/kg, PN from 0.1-0.6 µmol/kg and PP from 10-25 nmol/kg in the upper 100 meters of the water column. An annual cycle is suggested with the greatest particulate bioelement concentrations in summer/fall and lowest in winter. Substantial interannual variability is also noted, especially for PP.