Enclosure (1) TO COMDTINST 16478.12
Potential for hazard from mercury in sediments was evaluated by comparing
measured concentrations at AtoNs to values reported in the literature to cause
adverse effects to benthic animals and sediment values in reference areas.
Possible hazards from mercury ingestion and bioaccumulation was evaluated in a
similar fashion by comparing mercury concentration in animals collected on or
near batteries to other values as was done for sediments.
In the Chesapeake Bay mercury concentrations in sediments were below even the
most protective benchmark concentration [National Oceanographic and
Atmospheric Administration Effects Range Low (ER-L), which represents the
lowest 10 percent of concentrations found to produce an effect in sediment
dwelling organisms]. All areas of all lighted AtoNs had values below the ER-L
(0.15 mg/kg) even though the values found at the unlighted AtoN and values
reported in the literature for the area were above 0.2 mg/kg. Consequently in
the Cheseapeake Bay, it is highly unlikely that mercury from AtoN batteries in
sediments is affecting sediment dwelling organisms, which represent the
segment of the marine community most likely to be adversely impacted.
The mercury concentrations found at AtoNs in the Tennessee River were slightly
higher than those found in the Chesapeake Bay (average values ranging from 0.1
to 0.4 mg/kg), but they were well below the Effects Range Medium (ER-M), i.e.,
the 50th percentile of reported values showing an effect, of 0.71 mg/kg.
AtoNs within the subwatershed where there were documented sources of mercury
were at the high end of the range but at other lighted AtoNs average values
were below the ER-L. Consequently it is unlikely that batteries are causing an
adverse effect to sediment dwelling and even where background concentrations
are elevated, adverse effects do not appear to be likely.
Sediment concentrations of mercury found in Puget Sound were slightly higher
than the ER-L, ranging from 0.1 mg/kg to 0.25 mg/kg. This was true for the
unlighted as well as the lighted AtoN investigated. The samples collected
adjacent to batteries were at the low end of the range and below the ER-L of
the 0.15 mg/kg. The state of Washington has also establish a sediment
standard of 0.41 mg/kg mercury for sediment quality that will result in no
adverse effects on biological resources and no significant health hazard to
humans. All of the areas associated with AtoNs in Puget sound were less than
half this value. Consequently no adverse effects are indicated.
The results from Tampa Bay differ somewhat from the findings from the other
prototype locations with regard to potential impacts to sediment dwellings
organisms. The results indicate that average concentrations 20 meters or more
from the lighted AtoNs are well
4-7
Previous Page
