Environmental Engineering Reference
In-Depth Information
Effects-based SQGs represent tools that can be
used to help establish sediment quality targets that
correspond to the specifi c management goals that
have been established for the site under considera-
tion. A variety of numerical SQGs have been devel-
oped to support sediment quality assessments in
North America. The approaches selected by indi-
vidual jurisdictions depend on the receptors that are
to be considered (for example, sediment-dwelling
organisms, wildlife, or humans), the degree of pro-
tection that is to be afforded, the geographic area to
which the values are intended to apply (for example,
site-specifi c, regional, or national), and their intended
uses (for example, screening tools, remediation
objectives, identifying toxic and non-toxic samples,
bioaccumulation assessment). Although such SQGs
can be used in many applications, the USEPA gener-
ally advocates their use primarily in screening-level
assessments of sediment quality conditions.
Guidelines for assessing sediment quality relative
to the potential for adverse effects on sediment-
dwelling organisms in freshwater systems have been
derived using a combination of theoretical and
empirical approaches, primarily including the equi-
librium partitioning approach ((EqPA) which is used
to develop equilibrium partitioning-derived sediment
benchmarks (ESBs)) (Di Toro
et al.
1991; USEPA
1997, 2003, 2005; NYSDEC 1999), screening-level
concentration approach (SLCA) (Persaud
et al.
1993), effects range approach (ERA) (Long
et al
.
1995; USEPA 1996), effects level approach (ELA)
(Smith
et al.
1996; USEPA 1996), the apparent
effects threshold approach (AETA) (Cubbage
et al.
1997), the consensus-based approach (Swartz 1999;
MacDonald
et al.
2000a,b, 2002a,b; USEPA 2000b;
Ingersoll
et al.
2001, 2002), and the logistic regres-
sion modeling approach (LRM) (Field
et al.
1999,
2002). Application of these methods has resulted in
the derivation of numerical SQGs for many COPCs
in freshwater, estuarine, and marine sediments.
Table 7.3 provides a summary of SQGs that can be
applied in screening-level assessments of sediment
quality conditions. Information on uses of such
SQGs is available in Engler
et al.
(2005), Ingersoll
et al.
(2005), and Word
et al.
(2005).
In addition to causing direct effects on aquatic
biota, sediment-associated COPCs can accumulate in
the tissues of sediment-dwelling organisms. Because
many benthic and epibenthic species represent
important components of the food web, such con-
taminants can be transferred to higher trophic levels
in the food web. In this way, contaminated sediments
represent a potential hazard to the wildlife species
that consume aquatic organisms. As such, sediment
chemistry represents an important indicator for the
potential for effects on aquatic-dependent wildlife
species. Information on the applications of bioaccu-
mulation-based SQGs is provided in Moore
et al.
(2005).
Residue-based SQGs provide practical tools for
establishing targets for sediment chemistry relative to
the potential for bioaccumulation (Cook
et al.
1992).
Residue-based SQGs defi ne the maximum concentra-
tions of individual chemicals or classes of chemicals
in sediments that are predicted to result in tolerable
levels of those substances in the tissues of aquatic
organisms (i.e., below the levels associated with
adverse effects in piscivorous wildlife). The fi rst step
in the development of residue-based SQGs involves
the derivation or selection of an appropriate tissue
residue guideline (TRG) for the substance or sub-
stances under consideration (e.g., the New York
State Department of Environmental Conservation
fi sh fl esh criteria for piscivorous wildlife) (Newell
et al.
1987). Subsequently, relations between concen-
trations of COPCs in sediments and COPC residues
in aquatic biota need to be established. In general,
the necessary biota-sediment accumulation factors
(BSAFs) are determined from fi eld studies, based on
the results of bioaccumulation tests, and/or estimated
using various modeling approaches. The SQGs are
then derived by dividing the TRG by the BSAF (Cook
et al.
1992; NYSDEC 1999). Because it is diffi cult to
predict accurately relations between sediment chem-
istry and the concentrations of COPCs in the tissues
of aquatic organisms, potential risks to piscivorous
wildlife identifi ed using the SQGs should be con-
fi rmed using site-specifi c tissue residue data and
appropriate TRGs.
Contaminated sediment represents a signifi cant
environmental concern for the protection of human
health. Humans can be directly exposed to contami-
nated sediments through primary contact recreation,
including swimming and wading in affected water-
bodies. In addition, indirect exposure to sediment-
associated contaminants can occur when humans
consume fi sh, shellfi sh, or wildlife tissues that have
become contaminated owing to bioaccumulation in
