I'r - Memorial University of Newfoundland

mo re pervasive background signature. Some compounds can also be generated internally,
with in the lake itself
5. 1.1 THECrrv ZONE
The City Zone (Cluster I) consists ofstations 971, 95 5, and BC The cluster is
genera lly characterized by the highest levels orPAH contamination (avg. TPAH=4997.1 7
nglg ; 0-=297 .69 nglg; Fig. 5.1.2a, 5.1.3) and the heaviest in the lake isotopic values (avg.
mean 5 lJC =.2 5.38%o; 0-=1 .13%0; Fig. 5.L2 b, 5.1.4). There are withic-cluster variations,
the most not iceab le ofwhich is the light isotopic values at station 97 1(Detroit) relative to
those at sites 955 (Cleveland) andespec ially Bf (Buffalo; Fig. 5.1.4; see also Fig. 4.1.5,
4 . [.8a and Section 4.1.1). The station at Detroit was included into this duster primarily
due to the very high level ofPAH contam ination. a major characteristic feature ofIbis
cluster (Fi g. 5. 1.3; see also Fig. 4 .1.1. 4.I.4a and Section 4 .1.1 ). Anothernoticeable
devi ation is the somewhat different mo lecular signature at Bffrom that at stations 971
and 955 as indicated by the concentration profiles and principal components analysis of
mo lecular composition (Fig. 4.1.1. 4. IAb. 5.1.3). Cluster t was probably formed by
sediments dire ctly deposited by the fluvi al outflow at the three major cities, Detroit,
Cleveland and Buffalo.
At station 971 the fluvial influence is suggested by the location ofthe sire. The
sample was collected approximately 10 kilometers south-east ofthe mouth ofthe Detroit
River. The majo r flow ofthe river discharging tremendous volume orwater (5,800 m 3 s· l)
15'