Distribution of PCDDs and PCDFs in soils collected from the Denver Front Range--principal components analysis of diffuse dioxin sources

• Published in: Environmental science and pollution research international 2005-07, Vol.12 (4), p.189-198
• Main Authors: Jones, Paul D, Newsted, John L, Henningsen, Gerry, Slocomb, John, Giesy, John P
• Format: Article
• Language: English
• Subjects: Benzofurans - chemistry; Colorado; Congeners; Conservation of Natural Resources; Contaminants; Contamination; Dibenzofuran; Dibenzofurans, Polychlorinated; Dioxins; Dioxins - analysis; Environmental law; Environmental Monitoring - methods; Environmental protection; Humans; Industrial areas; Industrial Waste - analysis; Land use; Polychlorinated dibenzodioxins; Polychlorinated Dibenzodioxins - analogs & derivatives; Polychlorinated Dibenzodioxins - chemistry; Polychlorinated dibenzofurans; Principal Component Analysis; Principal components analysis; Remediation; Soil Pollutants - analysis; Soil pollution; Soil remediation; Soils; Studies; Superfund; Superfund Amendments & Reauthorization Act 1986-US
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1065/espr2005.06.271

The Rocky Mountain Arsenal (RMA) is a U.S. Army facility located northeast of Denver, Colorado that has been listed on the National Priorities List (NPL). It is currently being re-mediated under the authority of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) and the Superfund Amendments and Reauthorization Act of 1986 (SARA). As part of the remediation activities at RMA, indications were found that a source of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) had existed on the RMA. As a result, investigations were undertaken to assess the possible nature and extent of any potential sources of PCDDs and PCDFs on the RMA site. In addition, other studies were conducted that examined PCDD/PCDF contamination in the Denver area. The goal of these studies was to examine nature and extent of PCDD/PCDF contamination both on the RMA as well as in the surrounding Denver area. The intent of this study was to characterize sources of dioxins (PCDDs) and dibenzofurans (PCDFs) at low environmental concentrations which might have originated from diffuse sources in the Denver Colorado area and in particular, the Rocky Mountain Arsenal (RMA) using Principal Component Analysis (PCA). Over 200 soil samples were collected from the RMA and the Denver area. From the RMA, soil was collected as part of three studies that included a (1) random site-wide sampling of the RMA, (2) soils from the Western Tier Parcel (WTP), and (3) soils from Historic Use areas. Denver area soil samples were collected from five different land use categories: Residential, Agricultural, Open Space, Commercial, and Industrial. PCA was conducted on concentrations of 17 2,3,7,8-substituted PCDD and PCDF congeners in 220 soil samples collected from the RMA and the Denver Front Range region. PCA demonstrated the presence of possible minor sources of dioxins on the RMA. Current remediation efforts on RMA will result in the removal of these sources. Samples from the RMA were identified by the presence of a congener profile containing higher chlorinated PCDFs while the Denver Front Range areas were characterized by the presence of higher chlorinated PCDD congeners. The presence of a PCDF signature for the RMA samples does not necessarily indicate a major source of these contaminants on-site. Indeed, the relatively diffuse nature of the sample clusters would argue strongly against the presence of a single large source. Instead, the predo