Isomer-specific investigation of PCDD/F mobility and other fate processes in deep soil cores

Forensic Analysis of Polychlorinated Dibenzo-p-Dioxin and Furan Fingerprints to Elucidate Dechlorination Pathways

“…Barkovskii and Adriaens observed both HpCDD congeners as products of OCDD dechlorination after seven months in microcosms containing sediment from the Passaic River, which is within the CARP study area, with a 9/8 HpCDD ratio greater than 1, although this ratio was influenced by the fact that both HpCDD congeners were included in their spike mixture (their microcosms were spiked with a combination of OCDD, both HpCDD isomers, and some HxCDD isomers). Likewise, Grant et al and found that dechlorination of OCDD was a key process controlling the congener patterns observed in Australian deep soil cores. They found that congeners containing chlorines at the peri positions were relatively abundant.…”

“…Due to the difficulty in measuring environmental concentrations of PCDD/Fs, most studies examining their degradation have been conducted in laboratory microcosms using high concentrations of parent PCDD/F congeners. ,− Due to the toxicity of the 2,3,7,8-substituted PCDD/F congeners, laboratory studies sometimes employ surrogate compounds such as 1,2,3,4-tetrachlorodibenzo- p -dioxin (TeCDD) and 1,2,3,4-tetrachlorodibenzofuran (TeCDF). ,− Because it is difficult to replicate environmental conditions precisely, such laboratory studies can provide valuable information about the dechlorination pathways that can theoretically occur. However, information about the degradation of PCDD/Fs that actually transpires in environmental settings has been extremely limited. ,,,− , …”

“…The peri -lateral dechlorination products in this case were assumed to be 1,2,3,6,7,9-/1,2,3,6,8,9-hexachloro-dibenzo- p -dioxin (HxCDD). Building on this work, Grant et al investigated deep soil cores from Australia that were contaminated with octochlorodibenzo- p -dioxin (OCDD) and other PCDDs from pesticide residues. They concluded that dechlorination, particularly lateral dechlorination, was a key process that determines PCDD/F congener fingerprints in these cores.…”

“…However, information about the degradation of PCDD/Fs that actually transpires in environmental settings has been extremely limited. 12,13,16,[24][25][26][27]5 In one of the few environmental investigations of PCDD/F dechlorination, Gaus et al 24 examined dated estuarine sediment cores contaminated by PCDD/Fs from unknown sources in Queensland, Australia in which dechlorination was thought to have occurred based on the relatively high abundance of non-2,3,7,8-substituted congeners. The peri-lateral dechlorination products in this case were assumed to be 1,2,3,6,7,9-/ 1,2,3,6,8,9-hexachloro-dibenzo-p-dioxin (HxCDD).…”

New Polymer Passive Sampler for Sensitive Biomonitoring of Lipid-Rich Matrices

“…All extracts were concentrated to near dryness and reconstituted in an internal standard solution containing 300 pg μL –1 1,2,3,4,7,8,9-heptachlorodibenzofuran (HpCDF) in toluene. Analysis was performed on a Hewlett-Packard 5890 Series II gas chromatograph (30 m × 0.25 mm DB-5 fused silica capillary column) coupled to an electron capture detector (GC-ECD) and is described in more detail elsewhere . Quantification of dioxins and PCBs was conducted using their response relative to that of the internal HpCDF standard against a five-point calibration series containing all analytes and a constant concentration of HpCDF.…”