hydrocarbons, we obtained sediment cores at several locations in coastal areas 
of the western North Atlantic (8). At Station P Pb-210, geochronology 
measurements were obtained (7). These measurements and the measurements 
of Pu-239/240 and Cs-137 at this same location by others (4) allowed us to 
estimate sedimentation rates. We then measured hydrocarbon concentrations in 
several core sections at Station P. We also applied quantitative GC-MF analyses 
to measure phenanthrene and Cj and C-> phenanthrenes. The results of these 
measurements, as reported in (8), are given in Table 6-3. It is clear that circa 
1900 concentrations of hydrocarbons constituting the unresolved complex 
mixture increased, as did the concentrations of phenanthrenes. The ratios of 
the C| and C 0 phenanthrenes are not those found in spilled oil. Instead, the 
ratios indicate that these aromatic hydrocarbons are from pyrolytic sources 
(13, 20). Our hypothesis is that these hydrocarbons are primarily from direct 
and remobilized urban air hydrocarbons (8). We have determined that there is a 
trend of decreasing concentrations of UCM hydrocarbons with increasing depth 
in a core at another station in Buzzards Bay (10), and a station in the Gulf of 
Maine (Figure 6-2). 
Furthermore, similar results have been reported for Lake Washington, 
Seattle, Washington sediments (16). A much more detailed analysis of the 
aromatic hydrocarbons in three sections of another core from Station P, 
Table 6-3. Hydrocarbons and Chlorinated Hydrocarbons 
in Station P Core Sections 
Section 
Average Time 
of Deposition 
UCM a 
(^g/g) 
Phenanthrenes 
(ng/g) 
C Q C-, 
c 2 
0-1 cm 
74 
NA b 
44 
38 
1-2 cm 
105 
34 
27 
28 
8-12 cm 
1940 
44 
NA 
31 
29 
20-24 cm 
1900 
12 
15 
11 
10 
54-58 cm 
1790 
5.2 
3.7 
2.9 
2.8 
58-62 cm 
1780 
6.2 
NA 
NA 
NA 
a Mixture of alkanes and cycloalkanes - indicates petroleum hydrocarbons. 
L 
°NA — not analyzed. 
73 
