Quantity Of Particulate Organic Matter Research Articles

Microscale characterization of algal and related particulate organic matter by direct temperature-resolved mass spectrometry

In this paper we report a preliminary investigation of laboratory algal cultures and natural populations of marine particles utilizing Direct (i.e. “in-source”) Temperature-resolved Mass spectrometry (DT-MS). With this technique the potential exists to characterize microgram quantities of particulate organic matter (POM) at the molecular level. Two particular aspects of the approach set DT-MS apart from previous pyrolysis (Py)-MS investigations. First, temperature resolution allows characterization of both desorption (biolipid) and pyrolysis (biopolymeric) products in a single measurement. Second, an improved sample inlet configuration enables compounds exhibiting a broad range of polarities and molecular weights to be transmitted to the analyzer. The above features, coupled with the rapid analysis time (typically 5 min/sample) and amenability to statistical data reduction procedures, renders DT-MS well suited for profiling or mapping molecular-level variations in POM composition at a spatial and temporal resolution hitherto impractical using conventional biochemical assays.

Experimental degradation of plant materials in Hudson river sediments

We examined photopigment degradation and transformation in sediment microcosms that received different detrital source materials (planktonic, littoral, terrestrial) in the presence or absence of amphidpods (Gammarus sp.). Additions of realistic quantities of particulate organic matter resulted in detectable changes in pigment concentration and composition despite insignificant changes in total organic matter. The transformation of chlorophyll a to total phaeophorbide was significantly higher in all high quality (high nitrogen) detritus treatments containing amphipods. The highest production of phaeophorbide was in the higher quality detritus (blue-green algae, Anabaena cylindrica, and macrophyte, Vallisneria americana) when compared to red maple (Acer rubrum). Phaeophytin formation was not related to amphipod grazing and thus may be determined more by microbial heterotrophic processes. The degradation product of the carotenoid lutein, lutein 5,6 expoxide, was formed in all treatments. Phaeopigment composition can be used to infer differences in heterotrophic activity and will help in the interpretation of photopigment distribution in field samples.