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Sediment Quality Triad Index (Ongoing)
Both the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Environmental Protection Agency have used the Sediment Quality Triad (SQT) approach extensively for assessing environmental conditions in coastal bays and estuaries of the United States.
The approach, based on synoptic measures of contamination, toxicity, and faunal distribution offers weight of evidence to infer the state of pollution in a given area.
The resulting data are presented as listings, tabular matrices, pie diagrams, or as outcomes of multivariate statistical analyses.
Quite often, however, such presentations lack integration or need an expression that is readily interpretable by resource managers and the public.
In order to facilitate this process, the Chemical Impacts Team has developed an index based on the SQT approach. The index is calculated using observed or derived values for each component of the triad, presenting the results on a tri-axial plot, and estimating the area of the triangle to quantify the overall condition in the study area or in a sampling stratum.
The index can be used to compare environmental conditions in specified geographical areas and gauge information on the extent and severity of contamination over time.
It is relatively simple and transparent, for example, disaggregation of its components is possible for detailed examination (c.f., Factor Analysis).
It also avoids problems with spurious correlations, complex outcomes of multivariate analyses, and questionable sediment quality parameters and faunal indices.
To date, the index has been tested using SQT data from Galveston Bay, generated as part of the NS&T Program's Bioeffects Project.