Particulate organic carbon and nitrogen measurements from Go-Flo bottles sampling the water column from a zodiac during Palmer LTER station seasons at Palmer Station Antarctica, 1991 - 2012.

All organisms are composed of organic matter. Organic matter is synthesized from dissolved inorganic carbon (dissolved CO2) and inorganic nutrients by phytoplankton photosynthesis, and consumed (oxidized) by respiration by heterotrophs (zooplankton and bacteria). The organic matter in seawater is a variable mixture of dissolved and particulate organic matter (DOM and POM). Typically DOM predominates over POM by an order of magnitude, but the relative amount of POM can be highly enhanced during large phytoplankton blooms. The principal elemental components of POM include organic carbon (POC), organic nitrogen (PN), there is no particulate inorganic N) and phosphorus (POP). These elements exist in a relatively stable, characteristic ratio of 106:6:1 (C:N:P) in seawater, known as the Redfield Ratio. Marine particulate matter is a complex mixture of live and dead plankton and detritus, and of carbohydrates, proteins, lipids and nucleic acids. POC and PN are enhanced in the euphoric zone, reflecting their origin by photosynthesis. The particulate pool is also a complex assemblage of particles of different sizes, shapes and densities. A simplified scheme divides the particles into large, rapidly sinking particles (10s - 100s of meters per day) and smaller, suspended particles. The transition between small particles and dissolved organic matter is typically specified by filtration through GF/F filters. POC and PN are analyzed for all samples in the upper 50 meters at Palmer Station B (75 m depth) and the upper 65 m at Station E (200 m depth). There is a gradient of POM from higher values inshore to much lower values in deep ocean water beyond the continental shelf break (sampled on the annual cruise).