Ecological Risk Assessment of Diffuse and Local Soil Contamination Using Species Sensitivity Distributions - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 685

contaminated sites using this approach, while the United States has about 1250
(seriously contaminated) Superfund sites.
The enormous difference between two jurisdictions originates from differ-
ent regulatory and historical contexts. While only a few tens of cases were
expected in the Netherlands in the 1980s (prior to the national inventory), the fac-
tual numbers of cases of serious contamination appeared enormous. The chosen
concentration- and volume criteria to define “a serious case of soil contami-
nation” resulted in large numbers of (small) sites, which subsequently required
ranking to determine (relative) urgency for remediation due to practical limita-
tions. The numbers of cases with serious soil contamination in the Netherlands
are similar to the numbers following from regulations for surface waters under
the U.S. Clean Water Act, which currently list more than forty thousand waters
as biologically or chemically impaired, based on chemical and biological sur-
veys ( http://iaspub.epa.gov/waters10/attains_nation_cy.control?p_report_type T ).

In contrast, the regulation of contaminated soils under Superfund is not based on
surveys of soil impairment. Rather, Superfund focuses on relatively large sites
with obvious contamination. In short: legal frameworks in which SSDs or other
Risk Assessment approaches are used determine the choice and implementation of
scientific methods, like SSD-methods.
SSD modeling is very versatile, and can be used in very different regulatory
and practical contexts. The examples given in this chapter provide an overview of
possible applications, including deriving soil quality standards (classical approach),
identifying the most influential contaminant in a local mixture, identifying the
likely most affected locations or taxa at a contaminated site, comparing effects
in Life Cycle Analysis (LCA) of industrial products and directing responses in
disaster assessments. Given the relative simplicity of the model, and its ease of use
given software and databases to support practical use (see below), it is left to the
readers to explore whether SSD-based modeling can help in resolving their soil
contamination problem.
We have presented evidence and examples for the following conclusions:

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• SSDs are statistics-based summary descriptions of species sensitivity data; they

are not meant to explain these differences, and they do not use ecological
information; nonetheless, the output of SSD-based assessments are useful for
Ecological Risk Assessment and Risk Management.

•

Various useful and easy-to-use software tools and databases are available,
including some on the web.

•

SSDs are practically relevant for Criterion Risk Assessments to derive soil qual-
ity standards (HCp) and for Conventional Risk-, Management-, and Outcome
Assessments of contaminated soils, even with mixtures of contaminants
(msPAF).

• The simplest and oldest use of SSDs is to derive quality standards for a contami-

nant, in soils or other media, which may then be used to calculate Hazard Indices
(that is, calculating the ratio of local exposure and the soil quality standard, so as
to indicate a potential impact and the need for a further assessment step or a Risk
Management action when the resulting index value is higher than 1).