Seawater was transferred to 20 L carboys that were rinsed three times with water from the sampling depth. Experiments on (operationally defined) particles were carried out by gravity-filtering water through 3 um pore size filters.\u00a0Fractions of the filters (1/8 of each filter) was incubated in autoclaved seawater from the same depth/station; bacterial protein production was calculated to account for the volume of seawater that had passed through the filter.
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Bacterial protein production was measured from 3H-leucine incorporation by heterotrophic bacteria using the cold trichloroacetic acid (TCA) and microcentrifuge extraction method [as in Kirchman, 2001]. All work was performed aboard ship. In brief, triplicate live samples of 1.5 mL seawater as well as one 100% (w/v) TCA-killed control were incubated with 23 uL of L-[3,4,5-3H(N)]-Leucine (PerkinElmer, NET460250UC) for between 4 and 24 hours in the dark at as close to in situ temperature as possible. Live samples were then killed with 89 uL of 100% (w/v) TCA and centrifuged (10,000 rpm at 4\u00b0C for 10 min) to pelletize cell material.\u00a0 The supernatant liquid was removed and 1 mL of 5% (w/v) TCA solution was added, followed by vortex mixing and centrifugation. Supernatant removal, mixing, and centrifugation were repeated using 1 mL of 80% ethanol solution.\u00a0 Finally, the supernatant liquid was removed and each sample was dried overnight.\u00a0 After drying, 1 mL of scintillation cocktail (ScintiSafe 30% Cocktail, Fisher SX23-5) was added and incorporated radioactivity was measured using an LSA scintillation counter (PerkinElmer Tri-Carb 2910TR). Leucine incorporation rate was calculated from the incorporated radioactivity, compared to 1 mL of scintillation cocktail spiked with 23 uL of L-[3,4,5-3H(N)]-Leucine radioactivity, divided by incubation time.
Experiments on (operationally defined) particles were carried out by gravity-filtering water through 3 um pore size filters. Bacterial protein production was measured from 3H-leucine incorporation by heterotrophic bacteria.
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See Niskin Bottle and Cast List EN556 to link specific casts and bottles to each experiment: https://www.bco-dmo.org/dataset/717427.
BCO-DMO Processing Notes:
\n- added conventional header with dataset name, PI name, version date
\n- modified parameter names to conform with BCO-DMO naming conventions
\n- converted lat and lon to decimal degrees
\n- added cruise_id column
\n- replaced 'NA' and blank cells with 'nd' (no data)
\n-\u00a0removed from display the following columns with no data: NO2_NO3_uM, NH4_uM, PO4_uM, DOC_uM, cells_per_mL