I'r - Memorial University of Newfoundland

The processes ofweathering do not seem to be important at this station. This is
indicated by the position ofsite in the right part ofthe generalized graph logether with a
group ofprimary and secondary sources (fig. 5.2.3). The latter is due to overall
predominance of4- over 5-ring compounds at this station as indicated by PC I for
molecular composition (Fig. 4.2.5a). Site Bfalso plots close to the end members and
their mixing arrays in graphs with mixing curves for molecular ratios (Fig. 4.2.2, 4.2.3).
The similarity of the PAH assemblage at this site 10the signatures ofprominent primary
and secondary sources can possibly beattributed to the proximity ofthis station to the
area of PAH production. This site is located close to a highly urbanized area (the City of
Buffalo), hence a constant supply oflow molecular weight compounds to the sediments
may be suggested.
To summarize, the assemblage of PAH at major cities is generally dominated by
combustion sources. The greatest contribution ofpetroleum-related sources is seen at
Detroit and the least at Buffalo. The increased role ofpetroleum at Detroit may possibly
be attributed to its spills and leaks from tankers and city barborsidc facilities, since
petroleum products are a major part ofthe city's waterborne commerce. Possible seepage
of oil originating from upstream reservoirs (e.g.• Meyers, 1984) may also have
contributed to the increased importance ofpetroleum in the formation ofthe PAH
assemblage close to the mouth ofthe Detroit River. Among combustion sources, car
soots seem to be more important at Detroit while fire soots appear to dominate at Buffalo.
Both sources have almost equally contributed to the PAR assemblage at Cleveland.
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