Chlorinated Dibenzo‑<i>p</i>‑Dioxin and Dibenzofuran Congener and Homologue Distributions in Tree Bark from Sauget, Illinois, U.S.

Polychlorinated dibenzo-<i>p</i>-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