Enclosure (1) TO COMDTINST 16478.12
Chapter Four
Results and Conclusions
Sources of Potential Concern
The long-term potential for human health or environmental concern from AtoN
batteries is limited to the uncontrolled release of metals. Other contents of
the battery either pose no hazard, such as the plastic casing, or rapidly
dissipate and cause no long term threat, such as acid or caustic solutions.
Since the batteries of concern (primary batteries, which represent over 99
percent of the type found) have generally not been used since the mid 1980s,
only long-term effects are of concern. The metals present in batteries and
thus of potential concern are lead, zinc, and mercury. The demonstration and
prototype investigations revealed that virtually all the batteries found at
AtoN locations were primary batteries, which contain only zinc and mercury.
Prototype investigations in the Chesapeake Bay and in Tampa Bay analyzed the
sediments in the vicinity of batteries for lead and found no correlation of
lead concentrations with lighted AtoNs, proximity to batteries, condition of
batteries, or number of batteries. Consequently, it was concluded and fully
substantiated that lead, which is present in secondary but not primary
batteries, was not of concern and posed no hazard at U.S. Coast Guard AtoNs.
Elevated concentrations of both zinc and mercury were found associated with at
least some of the lighted AtoNs investigated during the prototype study.
Conseqently, these metals were determined to be the potential contaminants of
concern, and the presence of both metals were recorded at each prototype site.
(The site specific reports include the data for both metals.) Because of the
greater toxicity and bioaccumulation potential of mercury, however, the
following discussion focuses on mercury.
Mercury in AtoN batteries was originally present as an element amalgamate
coating the electrodes. As the batteries were used to light the AtoN,
laboratory investigations indicate that much of it vaporized to the
atmosphere. The remainder of the mercury either dissolved in the solution
within the battery, remained on the electrodes, or absorbed to the particles
associated with the discarded battery.
If mercury released from batteries is present in freshwater or marine systems,
it will be more concentrated in the sediments than in the water column. Most
of the mercury associated wioth batteries has low solubility (as determined by
the laboratory portion of this study), and thus is associated with particles.
In fact, studies have found that over 90 percent of mercury in lakes is
asociated with the sediments (Foust and Aly 1981). Similarly, at the one AtoN
where mercury was measured in the water (in the
4-1
Previous Page
