Enclosure (1) TO COMDTINST 16478.12
migrates deeper into sediments. Mercury migration past the active benthic
layer into less biologically active zones reduces the overall exposure risk.
Samples were collected from these zones, using 30-cm-core tubes, to describe
this migratory path. An intact cross-section of the field sediments was
retrieved. The samples were separated into top (10 cm) and bottom (10 cm)
samples for independent laboratory analysis. Attached biota and species of
opportunity were also collected at AtoNs. These biota were analyzed for total
mercury content in tissue. Sediment samples were analyzed for total mercury,
lead, zonc, and total organic carbon. In addition, some sediment samples were
analyzed for methyl mercury.
Mercury concentrations and estimated risk to benthic invertebrates were
evaluated in local sediment and biological tissue samples. Sediments were
evaluated because elemental mercury concentrates in that medium due to low
solubility and affinity for particles. No water column samples were taken
because elemental mercury is insoluble and probably unmeasurable in the water
column, and any ionic mercury (potentially released when a primary battery was
first broken open) would have quickly dissipated after disposal. (Morel and
Mason 1993).
Environmental Transportation Consultants, (ETC), working under direction of
the Volpe Center, designed and implemented an investigation program to
evaluated the fate of mercury at battery disposal sites in a variety of
environments. The initial program design reflected recommendations from NOAA
(Hoff and Beckvar 1993) and later was modified to include a general conceptual
model of exposure also provided by NOAA (Matta, 1994). Scientists from the
Massachesetts Institute of Technology, and the U.S. Environmental Protection
Agency (EPA) provided comments on the initial program design. Throughout the
study presentations on the program design and results of the prototype
investigations were provided to scientists at NOAA. Their suggestions and
comments are reflected in the final study design.
Locations Studied
Due to the time constraints and cost considerations involved, only a few
locations could be characterized during the field studies. These locations
had to represent the range of possible environments, population/land use
zones, water types, and aid types operated by the Coast Guard. Given the
large number of lighted fixed aids, selection of the locations had to be based
both on the representation of the many test variables at each site and on the
likelihood that primary batteries would be found at the location. Some
locations are more environmentally sensitive than others or represent critical
variables (such as the presence of fresh water), and were thus included as
study sites. In addition, the likelihood of exposure through any of the
pathways (i.e., inhalation, skin, or ingestion) was included in the selection
criteria. Thus, terrestrial locations and
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