Monday, December 15, 2014

Chlorinated dibenzo-p-dioxin and dibenzofuran congener and homologue distributions in tree bark from Sauget, Illinois, USA.
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 to 92 years) were collected from residential and industrial areas near Sauget, IL USA to identify the trends of 2,3,7,8-Cl PCDD & PCDF congener distributions, toxic equivalents (TEQ), and PCDD & PCDF homolog 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 USA. Analysis of seven 2,3,7,8 Cl-substituted PCDD and 10 PCDF congeners showed ΣPCDD7 ranging from 2214 to 71821 pg g-1 lipid and ΣPCDF10 from 355 to 13707 pg g-1 lipid, the highest in trees < 20 years old in both cases. OctaCCD and octaCDF respectively dominated ΣPCDD7 (89% average) and ΣPCDF10 (57% average). The 2,3,7,8-Cl congener profiles were similar in all samples showing that all were affected by similar sources but at different magnitudes. ΣTEQ 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, while one sample showed effects of a local source.

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