Methods on EN667:
One liter (L) samples were collected via CTD rosette for particulate lipid, carbohydrate, and organic carbon samples. Samples were filtered onto 47-millimeter (mm) 0.2-micrometer (um) Durapore filters (lipids, carbs; Millipore) and 25 mm 0.7 um GF/F filters (POC; Whatman), flash frozen in liquid nitrogen, and stored in LN2 headspace until extraction.

Particulate organic carbon (POC) samples were fumed for 24 hours with hydrochloric acid to remove inorganic carbon, and were then analyzed using an elemental analyzer coupled to an isotope-ratio mass spectrometer (EA-IRMS). POC samples were blank corrected using the average of three 1 liter filtered seawater blanks filtered through 0.7 um GF/F filters from the surface on EN667.

Methods on SR2310:
One liter samples were collected via CTD rosette for particulate lipid, carbohydrate, and organic carbon samples. Samples were filtered onto 47 mm 0.2 um Durapore filters (lipids, carbs; Millipore) and 25 mm 0.7 um GF/F filters (POC; Whatman), flash frozen in liquid nitrogen, and stored in LN2 headspace until extraction.

POC samples were fumed for 24 hours with hydrochloric acid to remove inorganic carbon, and were then analyzed using an elemental analyzer coupled to an isotope-ratio mass spectrometer (EA-IRMS). POC samples were blank corrected using the average of four 1 L filtered seawater blanks filtered through 0.7 um GF/F filters from the surface on SR2310.

Methods on AE2320:
Two liter samples were collected via CTD rosette for particulate lipid, carbohydrate, and organic carbon samples. Samples were filtered onto 47 mm 0.2 um Durapore filters (lipids, carbs; Millipore) and 25mm 0.7 um GF/F filters (POC; Whatman), flash frozen in liquid nitrogen, and stored in LN2 headspace until extraction.

POC samples were fumed for 24 hours with hydrochloric acid to remove inorganic carbon, and were then analyzed using an elemental analyzer coupled to an isotope-ratio mass spectrometer (EA-IRMS). POC samples were blank corrected using the average of three 2 L filtered seawater blanks filtered through 0.7 um GF/F filters from the surface on AE2320.