CHARACTERIZATION OF MACROMOLECULAR ORGANIC-MATTER IN SEDIMENT TRAPS FROM THE NORTHWESTERN MEDITERRANEAN-SEA

Curie point-pyrolysis-gas chromatography (CuPy-GC) and Curie point-pyr olysis-gas chromatography-mass spectrometry (CuPy-GC/MS) were applied to chemically characterize the macromolecular content of large particl es collected from sediment traps in the northwestern Mediterranean Sea at 100, 200, 1000, and 2000 m depth. The samples were also examined b y scanning electronic microscopy (SEM). A field sample rich in the dia tom Biddulphia sinensis was used as a reference for contribution of ph otosynthetic organisms and compared to the four sediment trap samples. Several n-alkanes and n-alk-1-enes as well as aliphatic alkyl nitrile s could be assigned to aliphatic resistant biopolymers. Bound fatty ac ids were present in the upper traps (100 and 200 m) and absent in the lower ones ( 1000 and 2000 m), indicating the absence of esterified ac id moieties in the latter. These observations indicated that in the se diment trap material, ester hydrolysis has been completed probably via hydrolytic enzymes, and that in the lower trap samples, the alk-1-ene s and alkanes may be derived exclusively from aliphatic resistant macr omolecules, whereas in the upper samples, they represent aliphatic res istant macromolecules and esterified moieties in macromolecules. Fragm ents such as phytadienes and pristenes likely derive from photosynthet ic organisms, whereas their natural product precursors are different. In the upper samples, a suite of dipeptide-type pyrolysis products, as sumed to be ''true protein indicators,'' were detected. The same suite of compounds was present in the pyrolysates of the field B. sinensis- rich sample. In all pyrolysates, pyrroles, indoles and aromatic nitril es were also found. The important contributions of these N-containing compounds at greater depth, i.e., 1000 and 2000 m, is noteworthy. Exce pt for the pyrroles, their contribution to the pyrolysate of the B. si nensis-rich sample was also significant. Their abundances did not matc h those of the ''true protein indicators.'' This led to the conclusion that they were produced upon pyrolysis of a highly resistant precurso r, probably from algae, which is not proteinaceous in nature. In all s amples, some relatively stable polysaccharide-containing constituents could be observed. Aromatic hydrocarbons such as alkyl benzenes, napht halenes, indanes, and indenes present in all pyrolysates may partly be derived from proteins, especially in the upper samples, and from unkn own resistant precursors. A phenolic series detected encompassed pheno l, 1-, 2-, and 3-methylphenols and dimethylphenols. They were importan t contributors to all the pyrolysates and were also present in the pyr olysate of the field B. sinensis-rich sample. They are possibly produc ed from autochthonous resistant macromolecules occurring in algae. Ove rall, we concluded that the preservation of known and some presently u nknown biomacromolecules biosynthesized by algae, either by selective preservation or by rapid sinking, could be a major process determining the quality and quantity of sinking and depositing organic matter in the ocean.