Literature Cited (1) Applegate, V. C.; Howell, J. H.; Moffett, J. W. Johnson, B. G. H.;
Smith, M. Ann Arbor, MI, 1961, Great Lakes Fishery Commission Technical Report No. 1. (2) Meyer, F. P.; Schnick, R. A.; Cumming, K. B.; Berger, B. L. ‘‘Registration Status of Fisherv Chemicals.” Feb. 1976:, Prop. FisL-Cult. 1976, 38, 1. (3) Braem, R. A.. Bureau of SDorts, Fisheries and Wildlife. Marquette, MI, personal communication, 1973 and 1977. (4) Tibbles, J. J., Environment Canada, Saul Saint Marie, Ontario, Canada, personal communication, 1977. (5) Schnick, R. A. In “Investigations in Fish Control”; Bureau of Sports Fisheries and Wildlife: Washington, DC, 1972, Bulletin No. 44. (6) Kempe, L. L. Ann Arbor, MI, 1973. Great Lake Fishery Commission Technical Report No. 18. (7) Magadanz, H. E.; Kempe, L. L. “The Removal of 3-(Tri-fluoromethyl)-4-nitrophenol from Natural Waters by Bottom Sediments”; proceedings of the ACS Student Affiliate Regional Convention, Indianapolis, IN, April 1968. (8) Bothwell, M. L.; Beeton, A. M.; Lech, J. J. J. Fish. Res. Board Can. 1973,30,1841-6. (9) Olson, L. E.; Marking, L. L. J . Fish. Res. Board Can. 1973,30, 1047-52. (10) Swisher, R. D. J. Am. Oil Chem. SOC.1963,40,648-56. (11) Danials, S.; Kempe, L.; Billy, T.; Beeton, A. Ann Arbor, MI, 1965, Great Lakes Fishery Commission Technical Report No. 9. (12) Smith, M.; Applegate, V. C.; Johnson, G. H. Anal. Chem. 1960, 32,1670. (13) Allen, J. L.; Sills, J. B. J . Assoc. Off. Anal. Chem. 1974, 57, 387-8. (14) Lech, J. J. Toxicol. Appl. Pharmacol. 1971,20,216-26. (15) Warner, T. B.; Bressan, D. J. Anal. Chim. Acta 1973,63,16573. (16) Thingvold, D. A. Ph.D. Dissertation, University of Wisconsin, Madison, WI, 1975. (17) American Public Health Association, American Water Works Association, Water Pollution Control Federation. “Standard Methods of the Examination of Water and Wastewater”. 12th ed.: New York, 1965. (18) Pfeil, B. H.; Lee, G. F. Enuiron. Sci. Technol. 1968,2,543-6.
(19) Alexander, M. In “Principles and Applications in Aquatic Microbiology”; Heukelekian, H., Dondero, N. C., Eds.; Wiley: New York, 1964; pp 15-42. (20) Alexander, M. In “Agriculture and the Quality of our Environment”; Brady, N. C., Ed.; American Association for the Advancement of Science: Washington, DC, 1967. (21) Hayaisha, 0.;Nozaki, M. Science 1969,164,389-95. (22) Pfister, R. M. CRC Crit. Reu. Microbiol. 1972,2, 1-34. (23) Okey, R. W.; Bogan, R. H. “Synthetic Organic Pesticides: An Evaluation of their Persistence in Natural Waters”; Proceedings of the 11th Pacific Northwest Industrial Waste Conf. Eng. Expt. Sta., Oregon State University Corvallis, OR, 1963; Circular No. 29, pp 222-51. (24) Okay, R. W.; Bogan, R. H. J. Water Pollut. Control Fed. 1965, 37,692-712. (25) Graetz, D. A.; Chesters, G.; Daniel, T. D.; Newland, L. W.; Lee, G. B. J . Water Pollut. Control Fed. 1970,42, R76-R94. (26) Alexander, M.; Aleen, M. I. H. J. Agric. Food Chem. 1961,9, 44-7. (27) Focht, D. D.; Duxbury, J. M.; Alexander, M. “Degradation of DDT Metabolites and Analogs”; Amer. SOC.Microbiol. Bacteriological Proc. Abstract, 70th Annual Meeting, Boston, MA, 1970, p 8-9. (28) Chambers, C. W.; Kabler, P. W. Deu. Ind. Microbiol. 1964,5, 85-93. (29) Dagley, S.; Evans, W. C.; Ribbons, D. W. Nature (London)1960, 188,560-6. (30) Lee, G. F.; Jones, R. A. In “Biotransformation and Fate of Chemicals in the Aquatic Environment”; Maki, A., et al., Eds.; American Society for Microbiology: Washington, DC, 1980; pp 8-21. Received for review January 22,1979. Revised Manuscript Receiued April 14,1981. Accepted July 8,1981. This project was funded in part by the Office of Sea Grant, National Oceanic and Atmospheric Administration, U.S. Department of Commerce, and the National Science Foundation through institutional grants to the University of Wisconsin system. I n addition, support was given preparation of this paper by the Department of Civil Engineering, Colorado State University and EnuiroQual Consultants & Laboratories, Fort Collins, CO.
Composition of Leachate from Surface-Retorted and Unretorted Colorado Oil Shale Kenneth G. Stollenwerk*t and Donald D. Runnells Department of Geological Sciences and Center for Environmental Sciences, University of Colorado, Boulder, Colorado 80309
Introduction The largest known deposits of oil shale are located in the Green River Formation of Tertiary age, in Wyoming, Utah, and Colorado, where an estimated 600 billion barrels of potential oil exist in deposits at least 3 m thick and averaging 0.6 barrel/ton (105 L/tonne (1)).Of the -80 billion barrels that may be recoverable by using existing technology, 75%is contained in the Piceance Creek Basin of northwestern Colorado (2)*
Perhaps the largest problem facing the oil shale industry is the disposal of the solid wastes. After mining, crushing, and retorting by surface methods, the retorted shale occupies a volume roughly 20% greater than the raw shale in place (2). Current plans are to dispose of much of this waste by filling canyons in the area. Even if production of shale oil were accomplished from underground retorts by the “modified in Present address: U.S. Geological Survey, M.S. 413, Box 25046, Federal Center, Denver, CO 80225. 1340
Environmental Science & Technology
situ” method ( 3 ) ,-2040% of the rock would have to be mined and brought to the surface. The removed rock probably will be retorted and disposed of aboveground. In addition to waste from retorted oil shale, significant quantities of waste unretorted oil shale may be generated; these will also have to be disposed of on the surface. One important aspect of an oil shale industry concerns the potential problem of contamination of groundwater and surface water by toxic materials resulting from the natural leaching of the waste oil shale. If natural waters pick up significant quantities of potential pollutants, they could contaminate the valuable water resources of this semiarid region. This study is concerned chiefly with the release and mobility of selected elements in oil shale including boron, fluorine, molybdenum, arsenic, and selenium. These elements were chosen because of their known toxic effects on plants and animals and because they may exhibit increased solubility and mobility at the elevated values of pH that result from the in-
This article not subject to U S . Copyright. Published 1981 American Chemical Society
Leachability of selected trace elements in retorted and unretorted oil shale was studied in order to determine the potential for degradation or pollution of water. Emphasis was placed on As, Se, Mo, B, and F because these elements are relatively toxic and because they may occur as soluble anions under the pH conditions (8-12) of water associated with retorted oil shale. On the basis of the samples of shale used in this study, the initial leachate that migrates from actual disposal piles of waste oil shale (depending upon the source of
the shale) will probably contain the following approximate concentrations (all values in mg/L): (a) fresh oil shale-TDS, 18 000; Mo, 9; B, 32; F, 16; (b) Paraho retorted oil shale-TDS, 28 000; Mo, 3; B, 3; F, 10; (c) TOSCO I1 retorted oil shaleTDS, 55 000; Mo, 9; B, 18; F, 19. Solubility calculations indicate that the aqueous Mo is predicted to be present chiefly as M004~-,boron as B(OH)3Oand B(OH)4-, and fluorine as free F-. Powellite (CaMo04) may control dissolved Mo, and fluorite (CaF2) probably controls dissolved F.
teraction between oil shale and water. This anticipated behavior of anions is in contrast to that of some other trace species, such as lead, copper, zinc, and mercury, which form relatively insoluble hydroxides at elevated pH ( 4 ) .Values of pH ranging from 7.3 to 11.7 have been reported in leachates from fresh and retorted oil shale (5,6),and various published analyses show the presence of significant quantities of the five elements of interest in oil shale (7,8). During the course of our investigation, high concentrations of reduced sulfur species, principally thiosulfate (S20&), were found in leachates from retorted oil shale (9).Reduced species of sulfur can have significant effects on the environment. For example, Audus and Quastel (10) have shown that thiosulfate in concentrations ranging from 450 to 4600 mg/L inhibits seed germination in several types of plants. In addition, in Canada it has been found that reduced species of dissolved sulfur in aqueous effluent from metallurgical mills may oxidize to produce sulfuric acid in the rivers which receive the discharge (11).Changes in pH due to oxidation of reduced species of sulfur could also affect the leaching and mobility of potential contaminants from waste oil shale.
Sample POS-1, also collected by Wildeman (14),represents fresh oil shale which had been crushed too small to be fed into the Paraho retort. Current estimates indicate that up to 10% of the oil shale that is mined for the Paraho process could be lost during the crushing process. During a commercial operation, this fine material may be disposed of with the spent shale (15). Leachates were generated in the laboratory by packing -200 g of shale into borosilicate glass columns 30 cm high and of 2.8-cm inside diameter. Nylon mesh was used as a plug to contain the shale. Earlier experiments indicated that the glass tubes did not contribute to either a loss of F or a gain of B because of the limited contact between the solutions and the glass (16).Columns were initially saturated from the bottom to allow air bubbles to escape. Once saturated, the columns were sealed and allowed to stand for various periods of time before leaching in order to determine the length of time required for oil shale and water to equilibrate with respect to dissolved solids. Leaching was carried out by adding deionized water on top of the columns and collecting the leachate in increments of one-third of a pore volume, one pore volume being equal to the total porosity of the column of shale. This particular experiment is referred to as the “equilibration experiment”. Preliminary tests were conducted to determine whether the nylon mesh plugs adequately filtered the leachate. Results showed no difference in dissolved constituents between 0.45-pm filtered samples and nonfiltered replicates, and the filtering step was omitted in this experiment. A separate leaching experiment on four large columns 30 cm high and of 8.5-cm inside diameter (1500 g of shale) was carried out to obtain larger volumes of leachate. Chemical analysis of these leachates (0.45-pm filtered) were input to our computer program, WATEQFC (17), used for modeling the chemistry of natural waters. This experiment is referred to as the “chemical modeling experiment”. Both POS-1 and PSS-1were used, but there was an insufficient amount of the other two shales, OS-1 and SS-2, so another sample of TOSCO I1 retorted shale (SS-3) was obtained. This sample was virtually identical with SS-2 in grain size and chemical response. The fourth sample used in the large columns, INOS-1, was collected from Federal Oil Shale Lease Tract C-a, where the Rio Blanco Oil Shale Project is currently underway. Sample INOS-1 supplies information on shale geographically remote from the locations of the other two samples of fresh shale employed in the study. Table I lists the distribution of particle sizes of all six shales, including the surface areas measured by the BET nitrogen saturation method (18).Table I1 gives the concentrations of B, F, Mo, As, and Se in the solid shales. Specific conductance (SC), pH, total alkalinity, and reduced sulfur species were measured upon collection followed by complete evaporation and analysis of the solid residue by energy dispersive X-ray fluorescence spectrometry. Splits of the aqueous leachates were analyzed for all other dissolved components. Values of TDS were determined from SC using empirical conversion factors determined for each type of leachate from synthetic equivalents, based on complete chemical analyses of the leachates (19). This technique was
Experimental Section Materials and Methods. All of the shale samples used in this study were mined from the Mahogany Zone of the Green River Formation in Colorado. The rock is a n impure marlstone. Most leaching experimentsin our study were conducted by using four different types of oil shale. Two of the shales, OS-1 and SS-2, were characterized and supplied to us by Dr. Thomas Wildeman of the Colorado School of Mines; they were collected from TOSCO Corp. at the Colony Development site near Grand Valley, CO (12).Sample OS-1 was collected from fresh (unretorted) feedstock which was used in the TOSCO I1 aboveground retorting process, while SS-2 represents the retorted equivalent of OS-1. By comparing fresh shale to the retorted equivalent, we can estimate the effect of retorting on the solubility of the elements of interest. Sample PSS-1 is an oil shale retorted by the Paraho surface process (direct mode) at Anvil Points, CO. We collected this particular sample from two large lysimeters which were constructed in the field at Anvil Points by Drs. Trey Harbert and William Berg of Colorado State University, for the purpose of determining the best methods of revegetating and stabilizing retorted Paraho oil shale (13).This sample offers us an opportunity to determine how closely laboratory leachates simulate field conditions. Retorted shale (PSS-1)taken directly from the Paraho retort is about the same size as the initial feedstock (0.6-7.6 cm). During compaction in disposal piles, the size of fragments is significantly reduced. Based on sieve analyses in our laboratory, ca. 18 w t % are larger than 18 mm, 42% range from 2 to 18 mm, and 40% are
