| Summary: | Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution March 1998 This thesis applied direct temperature-resolved mass spectrometry (DT-MS), flow cytometry, and multivariate statistics to the study of marine particulate organic matter (POM) collected from the North Atlantic. DT-MS is an important asset to marine organic geochemistry as a single two minute analysis (with 16 eV, EI+ ionization) provides information on polysaccharides, proteins, and lipids within concentrated and desalted samples. Although the molecularlevel information obtained with DT -MS is less detailed than traditional analyses of specific compound classes, DT-MS can act as a useful molecular-level screening technique (as illustrated in this thesis), indicating what samples and compound classes to investigate more thoroughly. In addition to its rapidity, DT-MS only reqires microgram quantities of sample. This sensitivity permits t.l-J.e coupling of DT -MS and preporative flow cytometry. In this thesis, preparative flow cytometry was used to isolate "phytoplankton" and "detritus" (i.e., non-phytoplankton particles) in 2~53 !liD POM. The molecular-level differences between and within small-particle POM (<53 !liD), large-particle POM (>53 !liD), "phytoplankton" and "detritus" were explored using DT -MS and discriminant analysis. For POM collected from the Mid-Atlantic Bight and from Great Harbor, Woods Hole, MA, small-particle POM contained more phytoplankton chemical characteristics than large-particle POM. In Great Harbor, the molecular-level characteristics of large-particle POM indicated a significant grazer biomass component. On the MAB (in March 1996), the large-particle POM appeared more phytodetrital. "Phytoplankton" was enriched in protein, chlorophyll and lipids as compared to "detritus," which was enriched in selected polysaccharides. As the polysaccharide composition of POM subclasses was a major ...
|
|---|