Enclosure (1) TO COMDTINST 16478.12
silt and organic carbon content and elevated mercury levels from a variety of
sources (CNMS 1992). The AtoNs sampled at the mouth of the Alafia River
reflected this condition and at one AtoN (Alafia River Range Front Light) even
exceeded the Hillsborough Bay background levels.
At the terrestrial locations examined numerous batteries were located and the
soil under and adjacent batteries piles had elevated mercury levels. However,
the elevated levels were confined to a small area within a meter of the
batteries and surface water samples collected within a meter of a battery pile
had non detectable levels of mercury.
Even maximum soil mercury levels found were well below levels associated with
human health risk.
A wide variety of marine species were collected in Tampa Bay and mercury
concentrations in all samples where well below benchmark values (NOAA 1991)
(see Figure 3-4). The broad food web spectrum of animals collected, all with
low mercury concentrations, in combination with the low percentages of methyl
mercury measured provides strong evidence for a lack of human health or
environmental risk. However the broad range of animals collected, with little
overlap among AtoNs and conditions within AtoNs, makes it difficult to compare
samples and evaluate bioconcentration of mercury originating from batteries.
Even though all samples showed low levels there were some indications that the
animals attached to batteries had slightly higher levels than similar animals
attached to structures a few meters away. The animals on the AtoN structures
adjacent to piles of batteries generally showed mercury concentrations at or
below levels seen at reference stations with no batteries.
3-4
Previous Page
