Geochemical and petrographical characterization of natural and anthropogenic sedimentary organic matter in polluted sediments from the West Branch of the Grand Calumet River and Roxana Marsh, northwest Indiana and northeast Illinois

This research tested the hypothesis that certain sediment types preferentially concentrate contaminants. The primary goal was to provide a framework for conducting surveys of potentially contaminated sediments, by examining spatial distribution, composition and concentration of pollutants in organic matter (OM). OM in three sediment cores were collected from the West Branch of the Grand Calumet River and Roxana Marsh (NE Illinois and NW Indiana).; Petrographic analyses indicated the presence of eight types of sand- and silt-sized organic particles of which three were debris of natural vegetation. Other particles, including coal, metallurgical coke, petroleum coke, char, solid bitumen and fly ash are anthropogenic. They occur in the upper half of each of the three cores. These microscopic organic particles were derived from activities associated with the transformation of the Calumet Lacustrine Plain into a major industrial zone. Partially-degraded plant fragments and charcoal dominate the OM of the lower half of each core. These particles reflect the pristine environments of the plain prior to industrialization.; Analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) results indicated the presence of a wide range of chemical compounds. Pyrolyzates of the upper sediments of each core are determined by chemical compounds commonly present in sediments of industrialized, urbanized regions: polynuclear aromatic hydrocarbons, thioarenes, azaarenes and aliphatic hydrocarbons. Lower sediments, however, are dominated by lignin-derived compounds: phenols, methoxyphenols and dimethoxyphenols. The presence of lignin-derived compounds in pyrolyzates of the deeper sediments correlates with the abundant plant fragments.; Thermodesorption-gas chromatograph/mass spectroscopy (TD-GC/MS) was used to characterize low molecular weight compounds in sedimentary OM. The GC/MS of desorbed products were characterized by two features: resolved compounds and an unresolved complex mixture (UCM). The latter appear in the top 5 samples from the river bed core as a broad hump in the C{dollar}sb{lcub}12{rcub}{dollar}-C{dollar}sb{lcub}28{rcub}{dollar} range. For all samples, yields of GC-resolvable compounds were low, ranging between 5 and 15% of total extractable organic matter. Branched n-alkanes, polynuclear aromatic hydrocarbon and thioarenes dominate the resolved compounds in the top sediment samples, whereas low-temperature pyrolysis products of naturally-derived polysaccharides predominate in deeper sediments. Thermodesorption products from the younger sediments are interpreted to be industrial waste products. Detrital OM of natural origin carried by the river prior to industrialization are interpreted to be the precursors for the low-temperature pyrolysis products detected in the deeper sediments.; Principle component analysis (PCA) of Py-GC/MS data was performed for pre-industrial and industrial periods. Chemical compounds resulting from pyrolysis of dissimilar solid OM (e.g., partly combusted fuel, uncombusted fuel, and botanical) were easily discerned. PCA results were used to establish features that can serve as geometrical indicators to distinguish between natural and anthropogenic sedimentary OM.; The abundance of anthropogenic OM in pyrolyzates of sediments that correspond to the time of peak industrialization is over 10 times higher than the background levels detected in deeper sediments. Industrial activity has damaged the marshes and the wetlands of this area, with the result that plant life has never recovered. (Abstract shortened by UMI.)...