Encl. (1) TO COMDTINST 16478.12
Appendix C:
Note:
Establishment of Effects Level Criteria
There are a variety of complexities in establishing a reliable relationship between the measured
level of a contaminant in sediment and a measureable biological effect due to that contaminant
effecting the surrounding aquatic environment. Uptake (and therefore, effects) of sediment-
associated contaminants is largely a function of bioavailability. Bioavailability is strongly
influenced by an array of physical, chemical, and biological factors in the sediments; that is,
the contaminant can be adsorbed at particulate surfaces, bound to organic matter, sulfide-bound,
matrix bound, or dissolved in the interstitial water. The relative bioavailability of trace
metals associated with these phases has the effect of hindering the prediction of effects, based
upon bulk sediment chemicals analyses. Ideally, sediment quality criteria guidelines should be
developed from detailed dose-response data which describe the acute and chronic toxicity of
individual contaminants to sensitive life stages of aquatic organisms. Unfortunately,
insufficient data are currently available to support the derivation of numerical sediment quality
guidelines using the ideal approach. Only a limited number of controlled laboratory studies
(i.e., spiked-sediment bioassays) have been conducted to assess the effects of sediment-
associated contaminants on estuarine and marine organisms. Many more studies are available that
match sediment chemistry to their corresponding biological effects data. This has led to other
methods of developing sediment quality criteria. National Status and Trends Program Approach
(NSTPA)
Overall Approach
With no nationally adopted, official effects-based standards available, NOAA developed a guidance
for interpreting sediment data. A three-step approach was followed to complete the evaluation:
(1)
Report Review
(2)
Determination of Contaminant Effects Ranges
Evaluation of the NS&T Program Sediment Data Relative to the Effects Ranges.
(3)
Report Review
The first step involved the compilation and review of available information in which estimates of
the sediment concentrations of chemicals associated with adverse biological effects were
determined or could be derived. Some reports included controlled laboratory studies of effects
of sediments spiked with individual chemicals. Others included field studies that matched
chemical and biological measurements. Calculations of unacceptable concentrations based upon
theoretical partitioning principles were considered (Long and Morgan, 1991.).
Determination of Contaminant Effects Ranges
The second step included screening the data by examining the degree of agreement between the
biological and chemical data, sorting the remaining data in ascending order, and determining
ranges associated with adverse effects. In order to develop a preponderance of evidence, data
compilation and analysis was as inclusive as possible and no weighing was given to data derived
from one approach or another. In addition, data derived in freshwater and saltwater were merged
and treated equally, despite the possibility that bioavailability may differ between the two
regimes and the concentration levels may affect the two different ecosystems differently (Long
and Morgan, 1991).
Approximately 150 reports were reviewed for possible use, and about half were incomplete for the
purposes of this analysis, and not used. An example of an incomplete data set is one that has no
biological data to accompany the sediment chemistry data for that report. The data from the
remaining 85 reports were assembled.
The report were then subject to a screening step, where no reports were considered where the
contaminant was not likely a contributor to the gradient in biological effects. These included
studies where the investigators observed high concentrations of other harmful compounds that
could have led to the observed biological effects. It is important to note that the screening
step was not performed to force consensus where none existed. It was performed before the data
were sorted, so that it was impossible to have a priori knowledge of the consensus range (Long
and Morgan, 1991).
The data that remained following this screening step were from studies in which effects were
either predicted or observed in association with increasing concentrations of the contaminant
levels measured in the sediment. Then they were sorted in ascending order of the contaminant
levels in the sediment. The sites which made up the list were located throughout the United
States in both saline and freshwater environments. The final sample size used for mercury and
lead were 32 and 49, respectively. Two values were determined from the remaining data for each
chemical: an ER-L and ER-M.
ER-L - Effects Range Low
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