Current Study 
The first collection was made from each station after an exposure period of 
three weeks. A second collection was made one week later. 
Analytical Methods 
The mussel tissue is analyzed for metal content by flame Atomic Absorption 
Spectrometry after wet digestion in concentrated nitric acid. Each sample is 
oven dried to constant weight, then digested in concentrated nitric acid in a 
simple reflux system. The digestate is filtered on transfer to 50 ml volumetric 
flasks, brought up to volume, and analyzed on a Perkin-Elmer Model 603 
Atomic Absorption Spectrophotometer using Deuterium arc background 
correction where necessary. The raw data are reduced to ug of metal/gram of 
tissue, on both a set and dry basis, by computer. 
RESULTS 
Results of analyses for Cd, Pb, Ni, Cu, chromium (Cr), V, and Zn on Mytilus 
from Stations 2 and 3, as well as from controls in the Wet Lab, are presented in 
Figures 3-4 and 3-5 and Table 3-1. 
Except in the case of Pb and V, where the numbers of samples having 
detectable limits were below the minimum number required for the statistic, 
the standard deviation is comparable between a sample of 41 or 10 (Table 3-1). 
This fact establishes that 10 Mytilus are a reasonable sample size with the 
noted exceptions of Pb and V. After four weeks, Cd levels in Mytilus from 
mid-Bay, Station 3, were slightly lower than either laboratory-held Mytilus or 
those collected from the polluted area at Station 2. However, the overlap in Cd 
values between the three sites renders differences insignificant (Figure 3-4). 
Lead, in those four animals from the polluted area (Station 2) having 
detectable levels, was higher than those levels detected in the laboratory-held 
animals, and the single animal having detectable levels from Station 3. 
However, due to the low number of sampling points, statistical significance 
cannot be established for these data (Figure 3-4). 
Nickel levels in Mytilus from Station 2 are significantly higher than those 
measured in laboratory-held animals. Mytilus from Station 3, while not being 
significantly different from Station 2, or laboratory-held animals, clearly fall in 
a range midway between those polluted and clean areas. A gradient of Ni, with 
highest levels in the polluted area of the Bay, diminishing in the mid-Bay, 
having lowest levels in the lower Bay, is demonstrated by these data. It is of 
interest to note that only 19 of the 41 laboratory-held animals had detectable 
levels of Ni. 
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