Rapid small-scale separation of saturate, aromatic and polar components in petroleum

Bastow, Trevor P.; Aarssen, B.G.K. van; Lang, Dale A.

doi:10.1016/j.orggeochem.2007.03.004

Cited by 152 publications

(74 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Earlier investigations (UBA, 2013) have noted a decline of viscosity and specific gravity along the direction of migration along the aquitard relief, with 40 mPa·s and a specific gravity of 1.1 in the center of the site, suggesting an impact of transport in the composition of migratory DNAPL. Subsurface chromatography effects have been observed for high molecular weight hydrocarbons in crude oil reservoirs (Bastow et al, 2007), and a similar depletion may have occurred during DNAPL migration presently. Other studies have found groundwater well DNAPL samples to be less weathered than those from the vadose zone, also with NAP remaining the dominant compound (Brown et al, 2006;Birak and Miller, 2009).…”

Section: Effect Of Migration On Physical Creosote Propertiessupporting

confidence: 56%

Composition and Dissolution of a Migratory, Weathered Coal Tar Creosote DNAPL

Scherr

Vasilieva

Lantschbauer

et al. 2016

Front. Environ. Sci.

View full text Add to dashboard Cite

Opaque, viscous tars derived from the carbonization of fossile carbon feedstocks, such coal tars and creosote, are long-term sources of groundwater contamination, predominantly with poly-and heterocyclic aromatic hydrocarbons (PAH). The dissolution, aging and migratory behavior of dense, non-aqueous phase liquid (DNAPL) coal tar blobs and pools forming at the aquitard is not sufficiently understood to estimate the risk and adequately design groundwater treatment measures at a contaminated site. In this study, we investigate the composition and dissolution of a migrated, aged creosote DNAPL, and corresponding experimental and groundwater profiles using comprehensive two-dimensional gas chromatography (GCxGC-MS). GC-FID unresolved compounds were attributed to methylated homocyclic species using GCxGC-MS in the Methylanthracene weight range. Equilibrium concentrations were estimated using Raoult's law, assuming non-ideal behavior. Low molecular weight compounds were found to be prevalent even after decades of weathering, with Naphthalene (8% by mass) representing the most abundant identified compound, contrary to the expected preferential depletion of hydrophilic compounds. Morevoer, dimethylnaphthalenes were relatively more abundant in the aqueous boundary layer than in the DNAPL. DNAPL migration over 400 m with the groundwater flow effected lower viscosity and specific gravity of the migrated phase body in a superposition of weathering, transport, and aquifer chromatography effects. Based on a decomposition of analyzed and estimated constituents using the group contribution approach, reference DNAPL values for activity coefficients γ i were used to model aqueous solubilities for selected compounds. Anthracene was close to its theoretical precipitation limit in the bulk DNAPL. While laboratory and modeled DNAPL dissolution behavior agree well, field data imply the presence of specific interfacial in situ processes significantly impacting dissolution processes. Based on aqueous GCxGC-MS profiles over the DNAPL, a hypothetical interfacial in situ film was calculated to be composed primarily of Phenanthrene, with minor contribution by Naphthalene, possibly forming a viscous barrier for the dissolution Scherr et al.Environmental Coal Tar DNAPL Weathering of lower molecular weight PAH. The main advances and gaps in electron donor DNAPL understanding are discussed regarding our conception of weathered, migrating hydrophobic DNAPL bodies in the aquifer of historic contaminated sites for the adequate treatment of contaminated water.

show abstract

Section: Effect Of Migration On Physical Creosote Propertiessupporting

confidence: 56%

Composition and Dissolution of a Migratory, Weathered Coal Tar Creosote DNAPL

Scherr

Vasilieva

Lantschbauer

et al. 2016

Front. Environ. Sci.

View full text Add to dashboard Cite

show abstract

“…Soil (5 g) was mixed with diatomaceous earth (1 : 1), packed into a 33 mL extraction cell and extracted with 50 % acetone and 50 % hexane at 200 • C and 1500 psi, with a static time of 5 min, a flush volume of 60 % and a purge time of 60 s. A soil sample freshly spiked with diesel fuel (10 000 mg kg −1 of diesel) was also extracted at this time. The saturated PHCs were then separated using small-column chromatography and eluted with n-pentane (Bastow et al, 2007). N-tetracosane was added as an internal standard.…”

Section: Saturated Petroleum Hydrocarbon Analysismentioning

confidence: 99%

Citrate and malonate increase microbial activity and alter microbial community composition in uncontaminated and diesel-contaminated soil microcosms

Martin

George

Price

et al. 2016

SOIL

View full text Add to dashboard Cite

Abstract. Petroleum hydrocarbons (PHCs) are among the most prevalent sources of environmental contamination. It has been hypothesized that plant root exudation of low molecular weight organic acid anions (carboxylates) may aid degradation of PHCs by stimulating heterotrophic microbial activity. To test their potential implication for bioremediation, we applied two commonly exuded carboxylates (citrate and malonate) to uncontaminated and diesel-contaminated microcosms (10 000 mg kg −1 ; aged 40 days) and determined their impact on the microbial community and PHC degradation. Every 48 h for 18 days, soil received 5 µmol g −1 of (i) citrate, (ii) malonate, (iii) citrate + malonate or (iv) water. Microbial activity was measured daily as the flux of CO 2 . After 18 days, changes in the microbial community were assessed by a community-level physiological profile (CLPP) and 16S rRNA bacterial community profiles determined by denaturing gradient gel electrophoresis (DGGE). Saturated PHCs remaining in the soil were assessed by gas chromatography-mass spectrometry (GC-MS). Cumulative soil respiration increased 4-to 6-fold with the addition of carboxylates, while diesel contamination resulted in a small, but similar, increase across all carboxylate treatments. The addition of carboxylates resulted in distinct changes to the microbial community in both contaminated and uncontaminated soils but only a small increase in the biodegradation of saturated PHCs as measured by the n-C17 : pristane biomarker. We conclude that while the addition of citrate and malonate had little direct effect on the biodegradation of saturated hydrocarbons present in diesel, their effect on the microbial community leads us to suggest further studies using a variety of soils and organic acids, and linked to in situ studies of plants, to investigate the role of carboxylates in microbial community dynamics.

show abstract

“…Biomarkers are commonly trace components in oils and bitumens and normally must be concentrated prior to analysis (Peters et al, 2005;Bastow et al, 2007). These types of separations are also useful when characterizing samples with large unresolved complex mixtures (UCMs) that are typical of biodegraded petroleum and can be difficult to characterize using a gas chromatograph-flame ionizing detector (GC-FID) or gas chromatograph-mass spectrometer (GC-MS) alone (Bastow et al, 2007).…”

Section: Liquid Chromatography (Lc)mentioning

confidence: 99%