Chlorinated Dibenzo-p-Dioxin and Dibenzofuran Congener and Homologue Distributions in Tree Bark from Sauget, Illinois, U.S.

Abstract

Polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) are ubiquitous urban/industrial contaminants found in tree bark, which acts as a long-term passive atmospheric sampler. Twenty seven bark samples (tree age 8–92 years) were collected from residential and industrial areas near Sauget, IL to identify the trends of 2,3,7,8-Cl PCDD & PCDF congener distributions, toxic equivalents (TEQ), and PCDD & PCDF homologue distributions. The Sauget area is heavily industrialized, with a long history of chlorine production, and is the largest single contributor to air pollution exposure risk in St. Louis. Analysis of seven 2,3,7,8 Cl-substituted PCDD and 10 PCDF congeners showed ∑PCDD7 ranging from 2214 to 71821 pg g(–1) lipid and ∑PCDF10 from 355 to 13707 pg g(–1) lipid, the highest in trees <20 years old in both cases. OctaCCD and octaCDF respectively dominated ∑PCDD7 (89% average) and ∑PCDF10 (57% average). The 2,3,7,8-Cl congener profiles showed slight differences among samples showing that all were affected by similar sources but at different magnitudes. ∑TEQ ranged from 35 to 624 pg g(–1) lipid, dominated by 1,2,3,7,8-PeCDD (average = 41.3% of total TEQ). Tetra-Cl through hepta-Cl homologues were dominated by non-2,3,7,8-Cl compounds for both CDD and CDF. Homologue profiles for 26 samples had a “sink” profile dominated by octaCDD, whereas one sample showed effects of a local source.

Polychlorinated Dibenzofurans and Dibenzo-p-Dioxin in Tree Bark from an Industrialized Area: What the 2,3,7,8-Cl Substituted Congeners Tell Us, and What Is Missing

“…Figure 1 shows the average profile of % of ten 2,3,7,8-Cl substituted PCDF congeners of ΣPCDF and % of seven PCDD congeners of ΣPCDD. In both cases, the octa congener dominates, suggesting that all 17 of these PCDF and PCDD congeners have been in the environment long enough that some decomposition of the lowerchlorinated congeners has occurred [1]. The only congeners making up >9% of the total (other than OCDF and OCDD) in either class are 1,2,3,4,6,7,8-HPCDF and 1,2,3,4,6,7,8-HPCDD.…”

“…ΣPCDD homologue (tetra-through octa-Cl) results range from 3302 pg•g −1 lipid to 88,603 pg•g −1 lipid. ΣPCDF 10 (Σ of ten 2,3,7,8-Cl congeners) range from 355 to 13707 pg•g −1 lipid, while ΣPCDD 7 (Σ of seven 2,3,7,8-Cl congeners) 2214 to 71821 pg•g −1 lipid [1]. Figure 1 shows the average profile of % of ten 2,3,7,8-Cl substituted PCDF congeners of ΣPCDF and % of seven PCDD congeners of ΣPCDD.…”

“…Here we investigate the 2,3,7,8-Cl PCDF and PCDD profiles in a forensic effort to identify a source of these contaminants in trees growing in a residential area adjacent to a highly industrialized area that is predominantly upwind. The analytical results have been reported [1]. In this paper, we expand on that work by reporting and discussing results of a chemometric anlaysis of these data.…”

“…Using this method, 193 specific congeners are not analyzed, including no report at all for mono-Cl, di-Cl and tri-Cl PCDF (48 congeners) and PCDD (26 congeners) [9]. The results, with QC methods and data, were reported earlier [1]. Among the results was calculation of percent of total PCDF or PCDD for each reported congener.…”

“…Tree bark has been used as a passive air sampler for a variety of organic contaminants, including PCDD/ PCDF, polychlorinated biphenyls (PCBs), brominated flame retardants (BFRs), and chlorinated pesticides [1]- [7]. We analyzed PCDF/PCDD in tree bark in this investigation in order to identify areas of high and low concentrations in an effort to elucidate sources.…”