Site-Specific Ecological Risk Assessment - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 705

of Ecosystem Integrity (Suter et al. 2000 ). However, assessment tools addressing
subcellular responses like biomarkers are rather sensitive and can be perfectly used
as early warning signals, but have a limited range on the effect scale, i.e. a rela-
tively low signal. On the contrary, field surveys at the population or community
level are less sensitive but generally 'closer' to the assessment endpoints, making
the response on the effect scale much stronger (closer to 1).
In cases with large and wide-spanning datasets, it might be feasible to apply
a suite of indices in order to take advantage of all data in the best suitable way
(Dagnino et al. 2008 ). Examples of such indices are:

•

Environmental Risk Index (ERI): Quantifying the level of biological damage at
the population level, comparable to the Triad with similar legs.

• Biological Vulnerability Index (BVI): Using e.g. biomarkers to assess the

potential ecosystem stress and threats to biological equilibria.

• Genotoxicity Index (GTI): Used to screen for genotoxicity effects.

Whereas the first index is assigned to the ecological leg of the Triad, the two
latter are assigned to the ecotoxicological leg.
These indexes were used on a site-specific case in north Italy by Dagnino et al.
( 2008 ). They showed that the Triad-based decision system (Environmental Risk
Index) as well as the biomarker-based index, identified the two contaminated indus-
trial areas as under risk. However, in contrast to the result from the Environmental
Risk Index, the results from the biomarker studies, i.e. the BVI, indicated that also
the chosen low-contamination site was under stress and that in some of the sampling
occasions, the GTI index at this site was comparable to the contaminated industrial
sites, indicating a general stress syndrome in soil organisms from that region.
These different indices allow for an elaboration on the plausible links between
causes and effects. Finally, when one answer is required to aid contaminated site
assessment and management decisions, these three indices should indicate adverse
ecological damage on the uniform effect scale (0-1 effect scale) too.
Projection of test results on the uniform effect scale requires a certain level of
experience. This expertise is fundamental to ERA, the importance of it can not
be overlooked. Without sufficient expertise one cannot expect a responsible under-
pinning of the decisions from the site-specific Risk Assessment. When the issue
of scaling is properly and responsibly solved, the information from separate tools
from individual disciplines can be effectively used together in ERA. Fortunately, the
WoE approach will help to address mismatches of specific scaling methods due to
wrong assumptions (Chapman et al. 2002 ). Together with ecotoxicological reason-
ing, this information can than be used to correct the scaling method of respective
tools. Accordingly, lower tiers in the Triad approach should contain tests which are,
to some extent, standardized, while at higher tiers the comparative less-standardized
tests should play a role in order to improve the level of site-specificity.
Once all results are quantified in the uniform effect scale, the overall response
of a set of (biological) methods can be calculated. To this purpose, a weighting
algorithm of different test results is required. This is described in Section 15.4.4 .