title: Application of discriminant analysis with clustered data to determine anthropogenic metals contamination.
abstract: Environmental site assessments involve, among other things, characterization of the nature and extent of contamination. In general, environmental assessors are interested in empirical methodologies that can be applied to a broad range of environmental media (e.g., soils, sediments, etc.) and situations. To date, no unified guidance has been adopted, and site investigations usually involve a tiered process with multiple analyses. We propose a multivariate analysis methodology utilizing discriminant analysis with clustered chemical concentrations as a novel application to environmental site assessments that determine, in relative order of magnitude, contaminated chemicals. Finite mixture models are presented as a means to assess latent chemical clusters with some basis in statistical inference. The methodology is illustrated with a typical localized data set containing total metal and metalloid (i.e., chemical) concentrations, extracted from bulk soil collected from reference and site-related locations, obtained from a former military installation in the southeast United States. The illustration is particularly applicable because site-related soils inherently possessed higher background chemical levels than reference soils, which biased conventional analyses. However, contrasting chemical compositions were inferred within site-related samples illustrating the versatility of the proposed methodology. Using these results along with known information regarding the history of contamination at the site, a qualitative and quantitative assessment of contaminated chemicals was made. Results are intended for illustration purposes only and are discussed within the context of environmental site assessment.
authors.affiliation: National Center for Environmental Assessment, Office of Research and Development, United States Environmental Protection Agency, Cincinnati, OH 45268, United States. anderson.hunter@epa.gov
authors.forename: R H
authors.initials: RH
authors.lastname: Anderson
authors.forename: D B
authors.initials: DB
authors.lastname: Farrar
authors.forename: S R
authors.initials: SR
authors.lastname: Thoms
mesh_terms: D016000:Cluster Analysis; D016002:Discriminant Analysis; D004784:Environmental Monitoring / Q000379:methods / Q000706:statistics & numerical data; D005843:Geography; D019015:Geologic Sediments / Q000032:analysis* / Q000737:chemistry; D008670:Metals / Q000032:analysis*; D015999:Multivariate Analysis; D018570:Risk Assessment; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry; D015144:Southeastern United States
chemical_list: D008670:Metals; D012989:Soil Pollutants