Dataset: New Production - N15

See: SO-GasEx cruise report, Section 5.8.2 pgs 56-57

Operation description:
Discrete analysis of new production (NO3 uptake) on CTD casts (hydrography).

Sampling times and locations:
Sampled all evening CTD casts (20 total). See CTD cast logs and bottle
files for specific times, locations, and bottles for each cast. See event
log for times and locations when sampled underway seawater line.

Overall sampling strategy:
Collected one sample from each of six depths between SFC and 50m.
Full set of duplicates done on CTD25 and SFC only duplicates done on CTD46.
Nominal depths were 5m, 10m, 15m, 25m, 35m, 50m although this varied.
Nominal light levels as a % of SFC were 85%, 40%, 27%, 11%, 4% and 1%.

Analytical method:
Water samples were drawn into 1.17L polycarbonate bottles, no filling tube.
Sample bottles and caps were rinsed three times. Samples were usually
collected close to local midnight and kept in the dark and cool (outside
air temperatures) until ~4am local. Samples were spiked with 200uL of
~10mM K15NO3, roughly 1.6 to 2.0 uM NO3 per bottle or a ~10% enrichment
of NO3 over ambient. Samples were placed in the on deck incubator at local
dawn (~4:30am local) and incubated with surface running seawater (4-5degC)
for 24 hours. Samples were then filtered at <20kPa vacuum onto combusted
(450C for 12 hrs) Whatman GFFs. Filters were dried for 12-24 hrs at 23C,
<30% humidity, and stored, folded, in cryovials or aluminum foil (Fred Meyer)
envelopes. Samples were transported to OSU, then analyzed for 15N at the
UCSB Marine Science Institute Analytical Lab.

Instrument details:
Contact UCSB MSI Analytical Lab for details.