Depth-related cycling of suspended nitrogen-containing lipids in the northeast Atlantic

We utilized high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to describe the depth-dependent distribution and molecular nature of nitrogen containing lipids (N-lipids) from suspended particles in an oceanic environment. Samples were collected at the Porcupine Abyssal Plain (PAP) sustained observatory in the northeast Atlantic (49.0°N, 16.5°W). Approximately 12.5% of FT-ICR MS observed lipids contain N. Only 19% of the lipids we recorded have elemental compositions that match those in the Nature Lipidomics Gateway database. Our results illustrate: (i) the proportional and selective accumulation of N-lipids with increased depth; (ii) that N-lipids which contain phosphorus are more stable than those without P; (iii) the majority of the deep Atlantic unsaturated N-lipids are highly unsaturated and (iv) there is depth-related increase in the saturated N-lipids which indicates that saturation is an important process for the export of lipid N and C to the deep ocean. These observations provide a description of N-lipid characteristics, transformation and preservation potential through the water column in the mesotrophic area of the North Atlantic Ocean.