Ecological Risk Assessment of Diffuse and Local Soil Contamination Using Species Sensitivity Distributions - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 625

Chapter 14
Ecological Risk Assessment of Diffuse and Local
Soil Contamination Using Species Sensitivity
Distributions

Leo Posthuma and Glenn W. Suter

Abstract Ecological Risk Assessment related to soil contamination requires a con-
ceptual framework and practical tools to support Risk Management. The conceptual
framework is provided by the Risk Assessment paradigm, which means that risks are
assessed based on an Exposure Assessment and an Effect Assessment step. Current
practical tools to appraise soil quality by Ecological Risk Assessment are: (1) com-
parison of soil contaminant concentrations to ecological Soil Quality Standards;
(2) quantification of ecological risks by modeling; (3) quantification of impacts in
bioassays or in field monitoring; and (4) quantification of ecological risks by weight-
of-evidence approaches. The present chapter concerns the theory and practices of
Effect Assessment and risk modeling using Species Sensitivity Distributions (SSDs),
and similar Functional Sensitivity Distributions ( FSDs). SSD- and FSD-based Risk
Assessment outputs are used for the appraisal of soil quality, soil protection and
the management of (slightly and highly) contaminated sites, for both the upper soil
and the groundwater. For the appraisal of soil and soil protection, one can derive
Hazardous Concentrations (HCs) for individual contaminants, which are estimates
of the concentration of a chemical that would affect a defined fraction of species.
Likewise, one can derive Hazard Potentials (HPs) for contaminated soil samples,
which represent effects levels for a certain fraction of the tested soil species when
exposed in such a soil. This chapter introduces the theory of SSDs and illustrates
the types of practical applications of SSD-based effect and risk models in all four
of the aforementioned types of tools. Since Risk Assessment requires assessments
of exposure as well as effects, the chapter also discusses Exposure Assessments
for SSDs. Practical software models and database tools are described, to support
easy application of SSDs in practice. Through the examples, the reader is informed
on a multitude of useful options for SSD-based assessment. SSD-modeling is ver-
satile, and can be of use to a range of soil contamination problems, from diffuse
contamination in large areas to local contamination hot spots.