MOLECULAR CHARACTERIZATION OF SUSPENDED AND SEDIMENTARY ORGANIC-MATTER IN AN ARCTIC DELTA

Curie-point pyrolysis-gas chromatography (CuPy-GC) and Curie-point pyr olysis-gas chromatography-mass spectrometry (CuPy-GC-MS) were used to characterize the macromolecular organic content of suspended particles in surface waters, at intermediate water depths, and in the surface s ediments of the Lena delta and the adjacent Laptev Sea, eastern Siberi a. The chromatograms of the pyrolysates of the Lena River particles re vealed several compound classes of biogenic significance: polysacchari des, phenolic substances, and lipid constituents of higher plants. The pyrolysates of the surface-suspended particles of the Laptev Sea sugg ested mixed inputs. Some fatty acids, phytadienes, and n-alkylnitriles were assigned to planktonic organisms. Pyrolysis products from terrig enous material encountered in the river were also present. At intermed iate water depths, major differences with respect to the surface parti cles were evident. In all cases we observed a substantial decrease of the precursors of phytadienes and the fatty acids that undergo biotran sformation processes. A peculiar pattern of three series of C-14, C-16 , and C-18 alkanes and alkenes [normal alkane, the alk-1-ene, the (E)- alk-2-ene, and the (Z)-alk-2-ene] was the prominent feature of these p yrolysates. Further investigations of the particle solvent extract and the corresponding residue suggested that these alkenes, as well as th e fatty acids, derived from wax esters. The composition of the sedimen tary material in the Laptev Sea indicated preservation of the refracto ry terrigenous constituents. However, the presence of some algal const ituents suggested that a fraction of marine-derived macromolecules is resistant to degradation.