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Title: Environmental stability of PAH source indices in pyrogenic tars

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants found in soil, sediments, and airborne particulates. The majority of PAHs found in modern soils and sediments arise from myriad anthropogenic petrogenic and pyrogenic sources. Tars and tar products such as creosote produced from the industrial pyrolysis of coal or oil at former manufactured gas plants (MGPs) or in coking retorts are viscous, oily substances that contain significant concentrations of PAH, usually in excess of 30% w/w. Pyrogenic tars and tar products have unique PAH patterns (source signatures) that are a function of their industrial production. Among pyrogenic materials, certain diagnostic ratios of environmentally recalcitrant 4-, 5- and 6-ring PAHs have been identified as useful environmental markers for tracking the signature of tars and petroleum in the environment. The use of selected PAH source ratios is based on the concept that PAHs with similar properties (i.e., molecular weight, partial pressure, solubility, partition coefficients, and biotic/abiotic degradation) will weather at similar rates in the environment thereby yielding stable ratios. The stability of more than 30 high molecular weight PAH ratios is evaluated during controlled studies of tar evaporation and aerobic biodegradation. The starting materials in these experiments consisted of relatively unweathered tars derivedmore » from coal and petroleum, respectively. The PAH ratios from these laboratory studies are compared to those measured in PAH residues found in tar-contaminated soils at a former MGP that operated with a carburetted water gas process.« less

Authors:
;  [1]
  1. New Fields Environmental Forensics Practice, Rockland, MA (United States)
Publication Date:
OSTI Identifier:
20813168
Resource Type:
Journal Article
Resource Relation:
Journal Name: Bulletin of Environmental Contamination and Toxicology; Journal Volume: 76; Journal Issue: 4; Other Information: auhler@newfields.com
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; 02 PETROLEUM; POLYCYCLIC AROMATIC HYDROCARBONS; COAL TAR; TAR; PETROLEUM PRODUCTS; POLLUTION SOURCES; STABILITY; BENCH-SCALE EXPERIMENTS; MOLECULAR STRUCTURE; SOILS; COAL GASIFICATION PLANTS; CONTAMINATION; TOWN GAS

Citation Formats

Uhler, A.D., and Emsbo-Mattingly, S.D. Environmental stability of PAH source indices in pyrogenic tars. United States: N. p., 2006. Web. doi:10.1007/s00128-006-0975-1.
Uhler, A.D., & Emsbo-Mattingly, S.D. Environmental stability of PAH source indices in pyrogenic tars. United States. doi:10.1007/s00128-006-0975-1.
Uhler, A.D., and Emsbo-Mattingly, S.D. Sat . "Environmental stability of PAH source indices in pyrogenic tars". United States. doi:10.1007/s00128-006-0975-1.
@article{osti_20813168,
title = {Environmental stability of PAH source indices in pyrogenic tars},
author = {Uhler, A.D. and Emsbo-Mattingly, S.D.},
abstractNote = {Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants found in soil, sediments, and airborne particulates. The majority of PAHs found in modern soils and sediments arise from myriad anthropogenic petrogenic and pyrogenic sources. Tars and tar products such as creosote produced from the industrial pyrolysis of coal or oil at former manufactured gas plants (MGPs) or in coking retorts are viscous, oily substances that contain significant concentrations of PAH, usually in excess of 30% w/w. Pyrogenic tars and tar products have unique PAH patterns (source signatures) that are a function of their industrial production. Among pyrogenic materials, certain diagnostic ratios of environmentally recalcitrant 4-, 5- and 6-ring PAHs have been identified as useful environmental markers for tracking the signature of tars and petroleum in the environment. The use of selected PAH source ratios is based on the concept that PAHs with similar properties (i.e., molecular weight, partial pressure, solubility, partition coefficients, and biotic/abiotic degradation) will weather at similar rates in the environment thereby yielding stable ratios. The stability of more than 30 high molecular weight PAH ratios is evaluated during controlled studies of tar evaporation and aerobic biodegradation. The starting materials in these experiments consisted of relatively unweathered tars derived from coal and petroleum, respectively. The PAH ratios from these laboratory studies are compared to those measured in PAH residues found in tar-contaminated soils at a former MGP that operated with a carburetted water gas process.},
doi = {10.1007/s00128-006-0975-1},
journal = {Bulletin of Environmental Contamination and Toxicology},
number = 4,
volume = 76,
place = {United States},
year = {Sat Apr 15 00:00:00 EDT 2006},
month = {Sat Apr 15 00:00:00 EDT 2006}
}
  • It has been recognized during recent years that polycyclic aromatic hydrocarbons (PAH) may form nonextractable residues in soil and that this process may be stimulated by microbial activities. To use that process intentionally for soil bioremediation, one must ensure that the formed nonextractable PAH residues will not be released from the soil on the long run. The long-term stability of four different nonextractable [{sup 14}C]PAH residues ([{sup 14}C]naphthalene, [{sup 14}C]anthracene, [{sup 14}C]pyrene, and [{sup 14}C]benzo[a]pyrene) was therefore monitored under different ecological stress conditions. It was found that a considerable fraction of the total [{sup 14}C]PAH residues could be released asmore » {sup 14}CO{sub 2} from the soil being partly due to a biogenic reduction of the nonextractable {sup 14}C residue fraction. The turnover of this fraction was comparable to the natural turnover rate for humic substances. Neither the addition of humus-degrading microorganisms nor a mechanical stress treatment of the soil structure by freezing and thawing led to a mobilization of the nonextractable [{sup 14}C]PAH residues. However, a significant mobilization of the nonextractable {sup 14}C activity occurred when EDTA was added to the soil. The metal-organic soil complexes were destabilized by this complexing agent and released {sup 14}C activity that was attached to colloidal or dissolved organic matter.« less
  • We show an analysis of the spectral and timing properties of X-ray radiation from Z-source GX 340+0 during its evolution when the electron temperature of the transition layer (TL) kT{sub e} monotonically decreases from 21 to 3 keV. We analyze episodes observed with BeppoSAX and RXTE. We reveal that the X-ray broadband energy spectra during all spectral states can be reproduced by a physical model composed of a soft Blackbody component and two Comptonized components (both due to the presence of the TL that upscatters both seed photons of T{sub s1} {approx}< 1 keV coming from the disk (first componentmore » Comptb1), and seed photons of temperature T{sub s2} {approx}< 1.5 keV coming from the neutron star (second component Comptb2) and the iron-line (Gaussian) component. Spectral analysis using this model indicates that the photon power-law indices {Gamma}{sub com1} and {Gamma}{sub com2} of the Comptonized components are almost constant, {Gamma}{sub com1} and {Gamma}{sub com2} {approx} 2 when kT{sub e} changes from 3 to 21 keV along the Z-track. We interpret the detected quasi-stability of the indices of Comptonized components to be near a value of 2. Furthermore, this index stability now found for the Comptonized spectral components of Z-source GX 340+0 is similar to that previously established in the atoll sources 4U 1728-34 and GX 3+1, and earlier proposed for a number of X-ray neutron stars (NSs). This behavior of NSs both for atoll and Z-sources is essentially different from that observed in black hole binaries where {Gamma}{sub com} increases during a spectral evolution from the low state to the high state and ultimately saturates at a high mass accretion rate.« less
  • In Quebec, Canada the production of primary aluminum using the Horizontal Stud Soderberg process is a significant source of atmospheric emissions. Since 1984, in the area surrounding a Soderberg plant at Jonquiere, Quebec, regular monitoring of the ambient air has made it possible to follow the evolution of PAH levels in urban areas. B[a]P is used as an indicator of total PAH. The ambient air is sampled twice a week using Hi-Vol samplers to collect particulate PAH on glass-fiber filters. From 1984 to 1990, there has been a 67 percent reduction in PAH emissions at the Jonquiere plant. The twomore » factors contributing to this situation are the shutdown of certain Soderberg production units and an ongoing program of reduction of PAH emissions into the atmosphere. Annual geometric mean ambient levels of 1 to 3 ng/m[sup 3] (B[a]P) for 1990 have been reported at sampling stations affected by prevailing winds within a 6 km radius of the emissions source. This paper shows the representativeness of the PAH sampling network in the area surrounding the industrial site. There is a general trend towards lower levels of B[a]P in air coincident with the emissions reduction program. A verification of the data shows that they are not normally distributed but are highly right-skewed and generally follow lognormal distributions. 9 refs., 5 figs., 5 tabs.« less
  • Geochemical analyses of beach-stranded tars from Seychelles can be correlated to comparable analyses of an oil sample from a well in the Seychelles offshore. The analyses also enable the precursor source rock to be characterized. Such a source rock was encountered in the three offshore wells and is extensively developed to the west and south of the granitic islands. The paper describes the first samples collected in 1978, recent correlation, a geochemical anomaly commonly occurring at the n-C30 peak, and prospectivity relevance.
  • Tarballs have been found stranded as traction deposits on a beach on northwest Mahe Island, Seychelles, with every ebbing tide. Weekly collections from mid-1993 to mid-1994 gathered nearly 4750 samples of two types of tar: a dominant black malleable tar and a less common brownish-black hard tar. Both tars represent moderately degraded extracts of crude oils seemingly derived from mature source rocks dominated by a combination of oil-prone phytoplanktonic and algal organic matter over gas-prone land-plant organic matter. Source rock deposition occurred principally in paralic to open-marine environments. The presence of minor oleanane and bicadinane, and a general preponderance ofmore » diasteranes and tricyclic terpanes in the hard tar suggest derivation from a Late Cretaceous clastic source rock with possible carbonate interbeds. By contrast, no samples of the malleable tar contain oleanane or bicadinane, but all contain significant norhopane and tetracyclic terpanes, which, along with significant sulfur and low diasterane contents, indicate derivation from a carbonate source rock of perhaps pre-Late Cretaceous age. Additionally, maturity and limited geochemical data from proven and potential source rocks present in the offshore wells enable the malleable and hard tars to be equated with specific units in the Seychelles stratigraphy; the malleable tar is seemingly derived from a Middle Jurassic carbonate of Tethyan affinity and the hard tar possibly originated from either Campanian or Maastrichtian-Paleocene shales. These tars are thus concluded to be natural seepage products derived from source rocks indigenous to Seychelles, and their persistent beach stranding significantly reduces the risk of hydrocarbon exploration in this frontier province.« less