A molecular evaluation of contaminants and natural organic matter in bottom sediments from western Lake Ontario

Py-GC/MS analysis of bottom sediment from Lake Ontario was shown to be effe ctive in assessing organic contaminants, especially attractive as it is a r apid technique requiring little sample preparation. Pyrolyzates of samples richer in organic matter (OM) were relatively enriched in aliphatic hydroca rbons and pyrrolic nitrogen compounds, while leaner samples were more aroma tic and pyridinic. Alkylbenzene and alkylphenol distributions in the pyroly zates were most compatible with derivation from aquatic (algal, bacterial) OM. The organonitrogen compounds indicated the presence of degraded protein aceous material from aquatic sources and/or sewage. Normal and polycyclic a romatic hydrocarbon distributions indicate, at least in part, contributions of fossil fuels and combustion residues. These observations were confirmed by organic petrologic examination. The ubiquitous input of aquatic OM to t he sediments (enhanced by anthropogenic nutrient oversupply) was supplement ed by fossil fuel-derived contamination, in proportions varying with proxim ity to industrial sites and shipping lanes. (C) 1998 Elsevier Science Ltd. All rights reserved.