Preservation of Organic Matter in Marine Macroaggregates
Jadran Faganeli,a Oliver Bajt,a Boris Šket,b
Angela Šurca Vuk,c Boris Orelc and Patricija
Biological Station, National Institute of Biology, Fornače 41, SI-6330 Piran,
Chemistry and Chemical Technology, University of Ljubljana, Askerčeva 5, SI-1000
Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia
NMR and FTIR spectroscopy were applied to establish the chemical features of
bulk mucous macroaggregates of phytoplanktonic origin at two different depths,
surface and bottom, in the Gulf of Trieste (northern Adriatic Sea) in June 2000.
The bottom sample was poor in organic matter (5% Corg, 0.5% Ntot)
compared to the surface sample (17.2% Corg, 1.2% Ntot)
and contained mostly senescent and degraded cells. An increase in mineral
particles (quartz and calcite) was also evident. This was due to the degradation
of the organic fraction and the contribution of bottom sediment resuspension.
The 13C-NMR–based estimate showed the approximate composition of
sampled macroagregates: 26% aliphatic C, 14% O/N alkyl structures, 39%
carbohydrates, 15% aromatic and olefinic C and 6% ester and/or amide C. From the
solid-state 13C NMR spectrum of the sedimented macroaggregate
revealed the preservation of aliphatic (lipidic) material and a portion of the
labile nitrogen-containing compounds.
Key words: macroaggregates,
FTIR, solid-state 13C NMR, northern Adriatic