HOE_Legacy2A-KM1513-14C-NPP_2021-05-01_v1.0

This dataset comes from sampling performed during the Hawaii Ocean Experiment - Legacy 2A cruise aboard the R/V Kilo Moana (cruise KM1513) in the north Pacific subtropical gyre. Standard HOT protocols were used to measure in vitro primary productivity (PP) via the 14C radiotracer method [Karl et al., 1996]. Water samples were collected from 15m before dawn and incubated on deck in incubators screened to 30% of surface irradiance and plumbed with flow through surface seawater for temperature regulation. Duplicate 500-ml bottles were incubated in the incubator for ~12hr and 24hr, light bottles were paired with dark bottles. Following dawn to dusk or dawn to dawn incubations, each sample was filtered onto 25mm glass fiber filters. Filters were acidified with 1 ml of 2N hydrochloric acid in a fume hood for 12 hr to remove inorganic 14C after which 10 ml of Ultima Gold scintillation fluid was added each sample. Radioactivity was determined using a Perkins Elmer 2600 liquid scintillation counter; samples were recounted after 30 days.The rate of PP was calculated by multiplying the percent of carbon labeled by the total carbon available for photosynthesis (e.g. dissolved inorganic carbon, DIC, calculated from SST and salinity measured at each station as per Lee et al. [2006] and dividing by incubation time (t = 1 day) as follows. Rate measurements in light bottles were corrected to remove the rate measured in parallel dark bottles.

12L = 12hr on deck, light bottle
12D = 12hr on deck, dark bottle
12L-D = The difference between 12L and 12D
24L = 24hr on deck, light bottle
24L-D = The difference between 24L and 24D