Enclosure (1) TO COMDTINST 16478.12
1.2 percent, and the vast majorities of samples were below 0.6 percent. These
values are at the extreme low end of the range reported in the literature for
unaffected sites. Thus bioavailability of mercury from batteries is low and
hazard to aquatic organisms is low.
Applicability of Results
In combination with the laboratory examinations, the four prototype
investigations (Chesapeake Bay, Tampa Bay, Tennessee River, and Puget Sound)
examined a wide range of AtoN types and environments. The conditions examined
represent most, but not all, of the situations where lighted U.S. Coast Guard
AtoNs exist. There were commonalties in results among the different
locations, permitting general conclusions. As discussed below, even though
some findings varied among prototype locations, the entire range of results
was well below levels known to produce hazard to humans or the environmental.
Therefore, the general conclusions regarding the absence of a hazard can be
drawn and apply to virtually all AtoNs.
The general conclusions may not apply to coral and endangered habitats, floc,
and areas where the total organic carbon is high and the sediment grain size
is small. These exceptions are due to (1) the absence of data for coral
environments (they were not sampled), (2) the elevated levels observed in
floc, and (3) the elevated levels observed in samples where the total organic
carbon was high and the small grain sizel.
Also, unusual conditions at some of the AtoNs examined indicate environmental
factors or AtoN conditions that may represent a higher-than-normal hazard
potential. Based on the findings of the prototype investigations, site
specific consideration of hazards should be considered at AtoNs with hard
substrate (i.e., other than silt, sand, or mud) where a large number of
primary batteries were used and discarded at the site. The presence of hard
substrate increases probability of broken batteries and accumulation of fine
particles and high biological activity.
Certain trends were consistently observed during the prototype and laboratory
investigations which substantiate general conclusions, however site specific
conditions which may cause variations from general conclusions were noted.
The potential hazard posed by AtoN Batteries is generally limited to mercury
and in aqueous environments. Sediments and aquatic biota are the only media
of concern.
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