Chemical Characterization and Bioactivity of Polycyclic Aromatic Hydrocarbons from Non-Oxidative Thermal Treatment of Pyrene-Contaminated Soil at 250-1,000°C

In this paper we report yields, identities, and mutagenicities of products from heating a polycyclic aromatic hydrocarbon (PAH)-contaminated, Superfund-related synthetic soil matrix without exogenous oxygen. We heated batch samples of soil pretreated with 5.08 wt% (by weight) pyrene in a tubular fur...

Full description

Saved in:
Bibliographic Details
Published in:Environmental health perspectives 2000-08, Vol.108 (8), p.709-717
Main Authors: Richter, Henning, Risoul, Véronique, Lafleur, Arthur L., Plummer, Elaine F., Howard, Jack B., Peters, William A.
Format: Article
Language:English
Subjects:
Mutagenicity
Polycyclic aromatic hydrocarbons
Pyrolysis
Sand
Soil biochemistry
Soil composition
Soil heating
Soil pollution
Soil samples
Soil temperature regimes
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:In this paper we report yields, identities, and mutagenicities of products from heating a polycyclic aromatic hydrocarbon (PAH)-contaminated, Superfund-related synthetic soil matrix without exogenous oxygen. We heated batch samples of soil pretreated with 5.08 wt% (by weight) pyrene in a tubular furnace under a constant flow of helium gas at 250, 500, 750, and 1,000 ± 20°C. Dichloromethane (DCM) extracts of cooled residues of heated soil and of volatiles condensed on a cold finger after 1 sec residence time at furnace temperature were assayed gravimetrically and analyzed for PAH by HPLC, HPLC coupled to mass spectrometry, and gas chromatography coupled to mass spectrometry. All four temperatures volatilized pyrene and generated other PAHs, including alkylated pyrenes. We detected bioactive PAHs in the product volatiles: cyclopenta[cd]pyrene (CPP) at 750 and 1,000°C and benzo[a]pyrene (BaP) at 1,000°C. We found a clean soil residue, i.e., no pyrene or other DCM extracts, only at 750°C. Control experiments with uncontaminated soil, pyrene, and Ottawa sand plus 4.89 wt% pyrene revealed no CPP or BaP production from soil itself, but these experiments imply that pyrene interactions with soil, e.g., soil-bound silica, stimulate CPP and BaP production. We detected mutagenicity to human diploid lymphoblasts (in vitro) in volatiles from 1,000°C heating of soil plus pyrene and sand plus pyrene, and in the residue from 500°C heating of soil plus pyrene. Three plausible pathways for pyrene conversion to other PAHs are a) a reaction with light gas species, e.g., soil- or pyrene-derived acetylene; b) loss of C2-units followed by reaction with a PAH; and c) dimerization with further molecular weight growth via cyclodehydrogenation. This study shows that thermal treatment of PAH-polluted soil may generate toxic by-products that require further cleanup by oxidation or other measures.
ISSN:0091-6765
1552-9924
DOI:10.1289/ehp.00108709