Environ. Sci. Technol, 1992, 26, 2528-2534
Hydrocarbon Wastes at Petroleum- and Creosote-Contaminated Sites: Rapid Characterization of Component Classes by Thin-Layer Chromatography with Flame Ionization Detection Slmon J. Pollardt and Steve E. Hrudey“
Environmental Health Program, Faculty of Medicine, University of Alberta, Edmonton, Alberta, T6G 2G3,Canada Bryan J. Fuhr, Randy F. Alex, Larry R. Holloway, and Frank Tosto Oil Sands and Hydrocarbon Recovery Analytical Laboratory, Alberta Research Council, P.O. Box 8330,Station F, Edmonton, Alberta, T6H 5x2, Canada ~
Adaptation of thin-layer chromatography with flame ionization detection for the semiquantitative characterization of residual hydrocarbon contamination at petroleum and wood-preserving hazardous waste sites is described. Soils collected from an abandoned oilfield battery site and a former creosote wood treatment facility in Alberta were solvent extracted and the residues characterized using two mobile-phase systems, one capable of separating polar waste components and the other of separating constituent aromatics according to ring number. The method provides a rapid component class fingerprint of the saturate, aromatic, and polar components of heavy hydrocarbon wastes, is analogous to column chromatography, and is useful for estimating the extent of weathering experienced by aged hydrocarbon wastes in the soil environment. As such, it can be useful for preliminary screening of the potential biotreatability or inherent recalcitrance of hydrocarbon waste mixtures.
Introduction Site assessments at petroleum and wood-preserving hazardous waste sites invariably face the problems posed by a complex matrix of contaminants having a diverse range of environmental and toxicological properties (1-3). Elaborate analytical techniques such as conventional gas chromatography-mass spectrometry (GC-MS) are essential for indicator compound quantitation but are often unable to estimate the full extent of hydrocarbon contamination at these sites because quantitative recovery of nonvolatile components (isopropenoid alkanes, naphthenic acids, asphaltenes) from the column is rarely achieved. Furthermore, GC-MS usually requires extensive sample cleanup and analytical costs may be prohibitive for adequate site evaluation (4). As a result, many remedial investigations have relied on the ”oil and grease” content of contaminated soils for determining the presence and extent of hydrocarbon contamination (1,4, 5 ) and for the performance monitoring of contaminated soil treatment technologies, particularly enhanced land treatment (solid-phase bioremediation) (6-8). A measure of the free and residual oil phases at contaminated sites has merit because these phases represent the primary sink for hydrophobic organic contaminants. The oil and grease parameter, however, represents a simple gravimetric determination of “solvent-extractable organics”, irrespective of origin or character (1). This parameter provides no information on waste composition or on the distribution of problem contaminants such as the higher molecular weight polynuclear aromatic hydrocarbons (PAHs). +Currentaddress: Department of Chemistry, University of Edinburgh, King’s Buildings, West Mains Road, Edinburgh EH9 355, United Kingdom. 2528 Environ. Sci. Technoi., Vol. 26, No. 12, 1992
Informative and cost-effective techniques are required which can address the complexity of waste mixtures at contaminated sites, improve site evaluation efforts, and aid in the selection and assessment of remedial technologies ( 4 , 5 ) . Thin-layer chromatography with flame ionization detection (TLC-FID) offers some advantages for these purposes. TLC-FID involves separation of solvent-extractable organics on silica-coated quartz rods into saturate, aromatic, and polar chemical component classes combined with semiquantitative detection by automated FID (9). This procedure has been employed widely in the petroleum industry for the component class characterization of heavy oils, bitumens, and coal-tar liquids (9-15). Fuhr et al. (9, 12, 13) described application of the technique for the characterization of bitumens from oil sand deposits and for process monitoring during the upgrading of heavy oil residues. Poirier et al. (15) used TLC-FID for the class analysis of residues obtained from the coprocessing of bitumen and sub-bituminous coal in order to establish the degree of coal conversion in the liquefaction process. In this paper, we present an extension of the TLC-FID methodology for the rapid analysis of soil extracts obtained from contaminated petroleum and creosote wood-preserving sites and compare the separation achieved with that obtained by the more time-consuming preparative column fractionation technique.
Experimental Section Site Descriptions. Soils from two abandoned hydrocarbon-contaminated sites in Alberta were selected for the evaluation of the TLC-FID methodology (Tables I and 11). An abandoned oilfield battery site in east-central Alberta was selected as representative of similar plants operating in the 194oS-195Os. At these sites, crude oil was dewatered and desalted, the light fractions were removed for further processing off-site, and the residual heavy crude process wastes were disposed of on-site, typically in unlined pits. Wastes currently identified at this site include spilled crude, flowing heavy oil seepage, and consolidated asphaltic material. Creosote-contaminated soils were obtained from the process area of a former wood-treatment facility in central Alberta which, over a period of 60 years, used pentachlorophenol (PCP), coal-tar creosote, and chromated copper arsenate (CCA) treatment solutions for the preservation of railway ties, utility poles, and foundation piling. Surficial soils comprising the drip pad of the central process area were highly contaminated with wood treatment solutions, most visibly in front of the creosote pressure treatment retorts. Soil Sampling and Sample Preparation. Surficial (0-0.25-m depth), grab samples (3.0 kg) representing a range of visible hydrocarbon contamination were collected
0013-936X/92/0926-2528$03.00/0
0 1992 American Chemical Society
Table I. Sample Identification and Solvent-Extractable Organics
organics
% moisture (freeze-dried)
% soil solids
sampling location crude loadout area cultivated area former process area drainage channel residuum pit site boundary
Oilfield Battery Site 0.59 f 0.15 0.81 f 0.13 0.13 f 0.01 1.70 f 0.56 0.79 f 0.02 0.012 f 0.0001
24.8 17.6 19.2 31.2 19.1 6.8
74.7 h 0.3 81.1 f 0.2 80.7 f 0.0 67.1 f 1.7 79.7 f 0.1 93.3 f 0.1
central process area central process area central process area central process area central process area site boundary
Creosote Site 1.68 f 0.01 6.18 f 0.15 6.02 f 0.21 7.23 f 0.27 1.83 f 0.08 0.017 0.0001
7.2 10.3 8.2 7.0 9.6 17.1
90.8 f 0.1 83.5 f 0.2 85.6 f 0.1 86.1 0.2 88.4 0.1 85.0 f 0.1
% extractable
sample
A C E G
Y
bckgrd 1
4 9 10
13 bckgrd
*
Table 11. General Site Characteristics at Former Refinery and Wood-Preserving Facilities
oilfield battery site sand (% w/w) silt (% w/w) clay (% w/w) organic C (% w/w) PH elec conduc, dS/m
solvent-extractable organics (% w/w) elec conduc (dS/m)
Na adsorptn ratio
5.4 0.47
**
Sample Collection (3.0kg)
I
Homogenize, Sieve < 2.38 mrn
Background Soil Characteristics 61 14 33 45 7 41 2.30 1.04
site stratigraphy
PH
wood-preserving site
I
(wet basis)
6
7.7 0.97
Soxhlet Exuaction.DCM (3 h)
Site Conditions fine-grained brown clay, silt, and minor sands to 10 m; till sands to 1.2 m; to 25 m; sands fractured silty and gravel to 36 m clay till to 4.25 m; unfractured till to >10 m disposal pits, 0.07- product storage area 28.2; drainage 1-15.0; former process area, to 7.2; channel, 32.6south ditch to 44.0 71.2: north site. 2.3-i9.7 disposal pits; 14no site data available 67.7: drainage channel 60% of residual organics isolated from this soil sample are polar in nature. The heavier composition of this sample is believed to result from repeated tilling and crop growing in the cultivated area from which it originated. These factors may have enhanced biotransformation of the residual oil contamination. This hypothesis is supported by a significant reduction (-40% of the class) in the more degradable saturate and group 1aromatic (-60%) fractions combined with a proportional increase in combined polars (-70%) compared with the other samples from this site. While numerous reports continue to demonstrate the biotransformation of n-alkanes (22), aromatic hydrocarbons (23),and certain heterocyclic components (24) in petroleum, several authors have noted the refractory nature of the asphaltenes (25-27). Westlake et al. (26) observed changes in the chemical composition of four crude oils toward more recalcitrant class components following microbial utilization by a mixed culture over a 10-day period. Increases in the asphaltene content of weathered 2582
Envlron. Scl. Technol., Vol. 26, No. 12, 1992
oils suggest that, during biotransformation, other hydrocarbon fractions are transformed into polymeric asphaltenes. Such changes apparently occur via free-radical-initiated polymerizations to yield cross-linked, high molecular weight, refractory residues (27). Huddleston and Cresswell (28) noted for an oil initially containing 22% (w/w) paraffins, 28% (w/w) aromatics, and 50% (w/w) resin-asphaltenes that 82% (w/w) of the paraffin, 60% (w/w) of the aromatic, and only 1% (w/w) of the resinasphaltene fractions of petroleum refinery wastes were lost over a 22-month period during land treatment. Recent investigations (29, 30) into the persistence of heavy oil constituents in soil microcosms, including N-, S-, and methyl-substituted PAHs, have also indicated that certain heterocyclic components (acridine, carbazole, dibenzothiophene) are sufficiently recalcitrant to be proposed as residual indicators of soil contamination by heavy oil wastes. The enrichment of refractory petroleum residues other than asphaltenes such as the pentacyclic hopanes, the steranes and diasteranes, and the high molecular weight n-alkanes has also been reported (31,32). Elucidation of refractory compounds in contaminated soil extracts will require extended characterization and biotreatability studies of individual class components isolated by preparative column chromatography. One proposed application of the TLC-FID method, therefore, is the estimation of refractory components in weathered waste-soil matrices. Such information related to residual soil contamination would clearly be of use to remediation specialists prescreening hydrocarbon wastes for biotreatability but is not provided by oil and grease measurements. Aged wastes at the oilfield battery site exhibited a class composition heavily weighted toward the more refractory hydrocarbon components, suggesting limited potential biotreatability of in-situ residual contamination. Confirmation of component class biotransformation potential, however, will still require waste-specific treatability studies in soil microcosms. (ii) Creosote Waste Components. Soil extracts isolated from the wood-preserving site exhibit substantial deviations in class composition from the reference creosote treating solution (Figures 5 and 6). The most striking differences are in the proportion of saturates (-130% higher than reference), polars A (-120% higher), and group 1 (one and two ring, -85% lower) aromatics. The reduction in group 1aromatics for the weathered soil extracts is attributed to biotic (biotransformation) and abiotic (leaching, photolysis, volatilization) losses of benzene, toluene, ethylbenzene, and xylene (BTEX), naphthalene, and alkyl-substituted naphthalene constituents from surficial soil.
C
1
2 8
10
Y Sample Designation
10
SAPnPb Aromatics
C
B
Y Sample Designation
*O1
W
SAP&
Combined Polm
0 SAlAZA3PA4 Palm
0
SAPA Polars+Asph
40 20 0 C
Y Sample Designation
10
Flgure 7. Component class analysis of samples 10, Y, and C by SAP,Pb and SA,A,A3P+A, and SAPA column fractlonatlon.
The higher proportion of saturate and polar A classes in creosote site soils may be attributed to the documented use of No. 2 fuel oil and Bunker C as carrier oils for coal-tar creosote during wood treatment at this abandoned site. The residual contamination at this site differs from that at the oilfeld battery site most notably in the contribution from group 2 (three and four ring) aromatics (phenanthrene, fluoranthene, pyrene) which are often the most dominant PAHs in weathered/degraded creosote wastes (33,34). Comparisons with Column Fractionation. Approximate agreement between TLC-FID and the preparative column chromatography (Figure 7) is desirable for the preparation and characterization of useable amounts of representative class components for toxicity testing and fate and transport studies. The most notable discrepancy between the chromarod and column separations is a 3540% lower fraction of aromatics reported by the column method. GC-MS investigations c o n f i i e d this effect to be largely caused by the elution of high molecular weight PAHs in the polar cut during column separation (data not shown) as indicated by the higher proportion of “combined polars” for samples Y and 10 (Figure 7). A more detailed column chromatographic elution sequence will allow separate collection of the higher molecular weight PAH fraction and reduce discrepancies in observed class compositions between methods. Comparisons of the destructive TLC-FID method with preparative column chromatography have also been made by other workers (10,13). Selucky (10)characterized component classes of anthracene oil obtained by gravity column fractionation on activated fuller’s earth using TLC-FID analysis. Using 80:20 benzene-n-hexane solvent for development of the chromarods, resins supplied approximately 15% of the material to the hydrocarbon (saturates + aromatics) fraction collected by preparative
column chromatography. Fuhr et al. (13)have partially overcome discrepancies between the two techniques by using the medium-pressure column method (SAPA) reported in the present study. Limitations of the TLC-FID Method. The speed, convenience, and reliability of the TLC-FID technique are considerable advantages over the use of conventional gravity column separation for the class analysis of heavy hydrocarbon samples. However, the class compositions obtained must be regarded as semiquantitative because individual class components respond slightly differently in the FID. Calibration with bitumen fractions appears to be appropriate for heavy hydrocarbon extracts containing different distributions of components, although the method should not be used for hydrocarbon wastes with highly volatile hydrocarbons as their principal constituents because they may be lost from the chromarod before FID quantitation. The equating of polars A with resins and polars B with asphaltenes is recognized to be approximate and most applicable to refinery residues (9, 12). Furthermore, the sulfur heterocyclic components are not sufficiently polar to fall within the polar A class and commonly report with the aromatics as noted by Fuhr et al. for dibenzothiophene (12). Caution should be also exercised when separations achieved by the TLC-FID are compared with column methods because they employ different stationary and mobile p h e s . Furthermore, the conventional description of component classes in fossil fuel products is based on solubility alone without reference to the adsorption mechanisms which also contribute during chromatographic separation. Extension of the methodology to a wider range of soil textures and hydrocarbon waste type is currently underway in our laboratory, as is the identification of specific class components likely to present the greatest challenge to bioremediation strategies. This information will complete our initial evaluation of the methodology and place the TLC-FID technique within a tiered analytical protocol for the characterization of hydrocarbon wastes in the soil environment. Conclusions Thin-layer chromatography with flame ionization detection provides a rapid, semiquantitative characterization of heavy hydrocarbon residue extracts according to component type. Selection of the mobile-phase system allows separation of the polar or aromatic components, the latter providing a relative distribution of aromatic components according to ring size. The method is particularly useful for revealing the extent of weathering experienced by petroleum and creosote-derived wastes in soil. As such, the method offers potential for screening the biotreatability or inherent recalcitrance of hydrocarbon waste mixtures and for monitoring the progress of biotreatment technologies for petroleum- and creosote-contaminated soils. Acknowledgments The technical assistance of Sandra Kenefick (Environmental Health Program), Deb Henry, and Janet Hay (Alberta Research Council) is gratefully acknowledged. Literature Cited (1) Nyer, E. K.; Skladany, G. J. Groundwater Monit. Rev. 1989, 9,54-59. (2) Gilbert, C. E.; Calabrese, E. J. In Petroleum Contaminated Soils; Kostecki, P. T., Calabrese, E. J., EMS.; Lewk Chelsea, MI,1990; Vol. 3, Chapter 20. Envlron. Scl. Technol., Voi. 26, No. 12, 1992 2533
Environ. Sci. Techno/. 1992, 26, 2534-2536
(3) Mueller, J. G.; Chapman, P. J.; Pritchard, P. H. Environ. Sci. Technol. 1989,23, 1197-1201. (4) Martin, J. H., Jr.; Siebert, A. J.; Loehr, R. C. J. Environ. Eng. 1991,117,291-299. (5) Baugh, A. L.; Lovegreen, J. R. In Petroleum Contaminated Soils; Kostecki, P. T., Calabrese, E. J., Ede.; Lewis: Chelsea, MI, 1990; Vol. 3, Chapter 12. (6) Song,H.-G.; Wang, X.; Bartha, R. Appl. Environ. Microbiol. 1990,56,652-656. (7) Wang, X.; Bartha, R. Soil Biol. Biochem. 1990,22,501-505. ( 8 ) Mahaffey, W. R.; Compeau, G.; Nelson, M.; Kinsella, J. Water Sci. Technol. 1991,3, 83-88. (9) Fuhr, B. J.; Holloway, L. R.; Reichert, C. AOSTRA J. Res. 1986, I, 281-288. (10) Selucky, M. Anal. Chem. 1983,55, 141-143. (11) Behar, F.; Pelet, R. J. Anal. Appl. Phys. 1984, 7,121-135. (12) Fuhr, B. J.; Holloway, L. R.; Reichert, C. J. Can. Petrol. Technol. 1986,25 (51, 28-32. (13) Fuhr, B. J.; Holloway, L. R.; Reichert, C.; Barua, S. K. J. Chromatogr. Sci. 1988,26, 55-59. (14) Poirier, M.-A,; George, A. E. J . Chromatogr. Sci. 1983,21, 331-333. (15) Poirier, M.-A.; Rahimi, P.; Ahmed, S. M. J. Chromatogr. Sci. 1984, 22, 116-119. (16) Speight, J. Proceedings: International Symposium on
Characterization of Heavy Crude Oils-and Petroleum Residues; June 25-27,1984, Lyon, France, Editions Technip: Paris, France, 1984; pp 32-41. (17) Enminger, J. D.; Ahlert, R. C. Environ. Technol. Lett. 1987, 8, 269-278. (18) Clement International Corp. Toxicological Profile for Creosote. TP-90-09; Agency for Toxic Substance and Disease Registry, U.S.Public Health Service, 1990. (19) Konasewich, D. E.; Henning, F. A. Creosote Wood Pres-
ervation Facilities: Recommendations for Design and Operation; Environmental Protection Series EPS2/WP/l; Environment Canada: Ottawa, ON, Canada, 1988. (20) Kennedy, J. B.; Neville, A. M. Basic Statistical Methods for Engineers and Scientists, 2nd ed.;IEP: New York, 1976; pp 319-322. (21) American Society for Testing Materials Preparing Precision
Statements for Test Methods for Construction Materials C 670-81; ASTM Annual Book of Standards; American Society for Testing and Materials: Philadelphia, PA, 1984.
(22) Watkinson, R. J.; Morgan, P. Biodegradation 1990,1,79-82. (23) Arvin, E.; Jensen, B.; Godsy, E. M.; Grbic-Galic, D. Pro-
ceedings: International Conference on Physiochemical and Biological Detoxification of Hazardous Wastes;Technical (24) (25) (26) (27) (28)
University of Denmark, Lyngby, Technomic: Lancaster, PA, 1988; pp 828-847. Fedorak, P. M.; Grbic-Galic, D. Appl. Environ. Microbiol. 1991,57,932-940. Semple, K. M.; Cyr, N.; Fedorak, P. M.; Westlake, D. W. S. Can. J. Chem. 1990,68, 1092-1099. Westlake, D. W. S.; Jobson, A.; Phillippe, R.; Cook, F. D. Can. J . Microbiol. 1974, 20, 915-928. Bossert, I.; Bartha, R. In Petroleum Microbiology; Atlas, R. M., Ed.; Macmillan: New York, 1984; pp 435-473. Huddleston, R. L.; Cresswell, L. W. Proceedings: Man-
agement of Petroleum Refinery Wastewaters Forum; (29) (30)
(31) (32) (33) (34)
EPA/API, WPRA & UT, Tulsa, OK, 1976. Bulman, T. L.; Jank, B. E.; Scrooggins, R. P. In Petroleum Contaminated Soils; Kostecki, P. T.; Calabrese, E. J., Eds.; Lewis: Chelsea, MI, 1990; Vol. 3, Chapter 5. Hosler, K. R.; Bulman, T. L.; Booth, R. M. Presented at Sixth Annual Conference on Hydrocarbon Contaminated Soils: Analysis, Fate, Environmental & Public Health Effects, University of Massachusetts, Amherst, MA, Sept 23-26, 1991. Atlas, R. M. Microbiol. Rev. 1981, 45, 180-209. Volkman, J. K.; Holdsworth, D. G.; Neill, G. P.; Bavor, H. J., Jr. Sci. Total Environ. 1992, 112, 203-219. Mueller, J. G.; Lantz, S. E.; Blattmann, B. 0.;Chapman, P. J. Environ. Sci. Technol. 1991, 25, 1045-1055. Ellis, B.; Harold, P.; Kronberg, H. Environ; Technol. 1991, 12,447-459.
Received for review April 29,1992. Revised manuscript received August 17, 1992. Accepted August 28, 1992. This work was primarily funded by Alberta Environment, through the Alberta Help End Landfill Pollution Project, by an Imperial Oil Ltd. University Research Grant, by grant support from the Natural Sciences and Engineering Research Council, and infrastructure funding of the Environmental Health Program provided by CN Rail Ltd., Shell Canada Ltd., and Weldwood of Canada Ltd. The Alberta Research Council provided initial financial support for S.J.P.
COMMUNICATIONS Photocatalytic Wastewater Treatment Combined with Ozone Pretreatment Kellchl Tanaka," KelJIAbe, Chen Yln Sheng,?and Teruakl Hlsanaga
National Chemical Laboratory for Industry, Higashi 1-1, Tsukuba, Japan Introduction The photocatalytic process provides a new method for wastewater treatment (1). In this process, pollutants are degraded by strong oxidizing power generated on an illuminated surface of a catalyst. The advantage of this method is that many pollutants degrade fairly rapidly and only a small amount of intermediate products are formed (2, 3). However, some stable compounds, such as agricultural chemicals, take a long time to be completely +Permanentaddress: Chemical Engineering Design & Research Institute, Wulmiqi, Xinjiang, China. 2534
Environ. Sci. Technol., Voi. 26, No. 12, 1992
mineralized (4). This is one of the great obstacles to the practical application of this method. We found that pretreatment by ozonation prior to photocatalytic treatment facilitates the degradation of pollutants greatly. Experimental Section The TiOz used throughout the experiment was a Katayama product (rutile). Ita specific surface area is 2.7 m2/g. DEP (dimethyl 2,2,2-trichloro-l-hydroxyethylphosphonate) and asulam (sodium N-methoxycarbonylsulfanilamide) were reagent grade. Fenitrothion (0,O-dimethyl 0-4-nitro-m-tolyl phosphorothioate) in emulsified solution
0013-936X/92/0926-2534$03.00/0
0 1992 American Chemical Society
