Mirex and Its Degradation Products in Great Lakes Herring Gulls Ross J. Norsfrom* and Douglas J. Hallett Wildlife Toxicology Division, National Wildlife Research Centre, Department of the Environment, Ottawa, Ontario K1A OE7, Canada
Frank 1. Onuska and Michael E. Comba Applied Research Division, National Water Research institute, Department Burlington, Ontario L7R 4A6, Canada
Nitrated extracts of herring gull eggs from seven Lake Ontario colonies in 1977 were analyzed by glass capillary gas chromatography/mass spectrometry. Five minor mirex-related compounds were found in addition to mirex and the previously identified 8-monohydromirex (photomirex). The levels (milligrams/kilogram wet weight f standard deviation) of all seven compounds were determined by high-resolution gas chromatography: 2,8-dihydromirex (0.016 f 0.005); CloClloH2 (111, possibly 3,8-dihydromirex (0.011 f 0.003); 8-monohydromirex (0.95 f 0.14); CloClllH (111), possibly 9-monohydromirex (0.077 f 0.019); 10-monohydromirex (0.199 f 0.025); mirex (2.58 f 0.40); and CloCll2 (11)consistent with an isomer of mirex (0.039 f 0.011). It was concluded that photodegradation was the only feasible mechanism for formation of these compounds, but that mirex and its photoproducts rapidly became sequestered in the ecosystem and protected from further degradation. The surprising discovery of mirex in Lake Ontario fish ( 1 ) sparked a considerable effort to monitor mirex concentrations in sediment (2) and various species of fish ( 3 )from the lake. In the course of investigating the levels of mirex in herring gulls, which were proposed as a monitor species for organochlorine contamination of the Great Lakes, photomirex (8monohydromirex) was discovered to be an important environmental contaminant as well as mirex ( 4 , 5). Levels of photomirex were estimated to be greater than 30% of mirex levels in eggs over the period 1972-1975. Analysis of smelt, coho salmon, and herring gull eggs sampled in 1976 confirmed that the ratio of photomirex to mirex was high and relatively constant (0.3-0.4) in Lake Ontario biota (6). The development of a nitration method which separated mirex and photomirex from polychlorinated biphenyls (PCBs) improved the ability to detect and confirm much smaller amounts of mirex and mirex degradation products than was possible by previous methods (7). Chromatograms of extracts of Lake Ontario biota treated by the nitration method had a number of unidentified minor peaks (0.3 mg/kg in Figure 7. Using this criterion, we found that 40% of the eggs collected outside Lake Ontario were indicative of prior feeding in Lake Ontario. The lower levels of mirex found in the majority of herring gull eggs outside Lake Ontario were probably accumulated from a local diet. The concentration factor from alewives and smelt to herring gull eggs is approximately 50 for mirex ( 6 ) ,requiring only 0.006 mg/kg in fish to give 0.3 mg/kg in a gull egg. Concentrations of miicex below 0.01 mg/kg in fish are likely to be undetected unless great care is taken to first remove PCB interference. The main mirex degradation product, 8-monohydromirex, was also found in isggs from all the Great Lakes. Out of a total of ten colonies, the six in Lakes Ontario, Erie, and Huron had a ratio of 8-monohydromirex to mirex of 0.36-0.41 in 1977. The colonies with the lowest levels of mirex (Silver Island, Lake Superior, and Little Sister and Hat Islands, Lake Michigan) had slightly higher ratios of 8-monohydromirex to mirex (0.50-0.57). These data suggest that a high proportion of the mirex and related compounds found in Lakes Erie and Huron herring gull eggs originates from Lake Ontario fish, whereas that found in Lake Superior and Lake Michigan eggs is from another source. These results support the hypothesis that low levels of mirex in eggs from outside Lake Ontario reflect local contamination. Degradation Pathways and Mechanisms. Mirex is essentially nonbiodegradable, as documented in a recent review on mirex (22). The only hydromirex compound which has been studied is 8-monohydromirex, which was also resistant to biodegradation ( 2 3 ) .Anaerobic bacteria in sewage sludge have been found to slowly reductively dechlorinate mirex to
10-monohydromirex ( 2 4 ) . A monohydromirex compound, probably 10-monohydromirex,was found in the feces, but not fat, of rhesus monkeys fed mirex (25).It was concluded that this compound was formed by anaerobic bacterial action in the lower gut. Carlson et al. (8) observed environmental degradation of mirex in Mississippi soils treated 12 years previously and in mirex-containing bait lying in a small, shallow pond in Florida for 5 years. In all samples 8-monohydromirex was the predominant degradation product (1040% of mirex levels), presumably resulting from photolysis (14,16).Lesser amounts (1-6% of mirex levels) of 10-monohydromirex, 2,8-dihydromirex, 5,10-dihydromirex, and kepone were found. The ratio of monohydro degradation products to mirex in the soil samples was remarkably similar to that found in Lake Ontario samples (10-monohydromirex/mirex = 0.039 and 0.046, 8monohydromirex/mirex = 0.26 and 0.31, in Mississippi soil and herring gull eggs, respectively). Unlike Carlson’s study, however, we found no 5,lO-dihydromirex and lower relative amounts of 2,8-dihydromirex in the Lake Ontario samples. CloClloHz (11)was not found in Carlson’s study, but it may not have been chromatographically resolved from 2,8-dihydromirex. We were unable to determine kepone because of the methods employed for cleanup and separation from PCB. The dynamics of mirex in a simulated marsh ecosystem have recently been reported (26). In this study, mirex bait was deposited in troughs of flowing seawater exposed to sunlight. The ratio of the 10-monohydromirex to 8-monohydromirex photoproducts formed was 0.3, which can be compared to a ratio of 0.15 from the present study and that of Carlson et al. (8).From the rate of production of 8-monohydromirex in the bait, it can be estimated that 3 years would be required to achieve the 30% 8-monohydromirex level observed in Lake Ontario biota. In trying to piece together an overall mechanism for mirex degradation in the Lake Ontario environment, it therefore can be concluded that photolytic degradation is the most important primary step. The main photoproduct is 8-monohydromirex as expected, with 10-monohydromirex and CloClllH (111)also being formed as minor products. The 10-monohydromirex may arise from photolysis of an amine-bound complex as found by Alley et al. ( 1 5 ) ,or by photosensitized decomposition. Anaerobic bacterial degradation of mirex may account for some of the 10-monohydromirex formed in the Lake Ontario environment, but is a less likely source of 10monohydromirex than photolysis. There is no information on CloClllH (111)except that this compound is a minor product of triphenylphosphine reduction as well, and therefore is probably 9-monohydromirex. The small amounts of 2,8dihydromirex and CloClloHz (11) probably arise from secondary photolysis. The source and identity of CloC112 (11) are completely unknown. Because mirex and its photoproducts are readily identifiable and stable in the environment, we are afforded a unique glimpse of the dynamics of an organochlorine compound in Lake Ontario. I t can be assumed that mirex degradation ocVolume 14,Number 7,July 1980 865
curred subsequently to discharge to the lake, since mirexcontaminated sediments did not have a significant amount of 8-monohydromirex compared to mirex (2, 6 ) . Because a large proportion (>30%) of the mirex-related compounds in biota are photodegradation products, most of the mirex which entered the food web must have been held in the water column and recycled to the surface of the lake over a period of years. Alternatively, the rate of photolysis may have been enhanced by some unknown mechanism in association with dissolved organic matter, particle surfaces, or phytoplankton. The constancy of the ratio of 8-monohydromirex to mirex levels in Lake Ontario herring gul1,eggs over the years 1972 to 1978 is shown in Table IV. The ratio h samples of five species of fish (coho salmon, alewives, smelt, carp, and eel) from Lake Ontario in 1977 was also in the range 0.3-0.4 (6, 7). These data suggest that an equilibrium between input to the lake and photodegradation existed. However, the declines in mirex levels in herring gull eggs since 1974 ( 1 9 ) ,presumably associated with cessation of direct discharge to the lake, should have resulted in an increase in the ratio if photodegradation had been occurring throughout this period. That portion of the mirex and photomirex in the lake which is available for bioaccumulation in fish and herring gulls must therefore be protected from further photodegradation by being sequestered and cycled between and within various food webs over a period of several years. The data also indicates that mirex in the sediments is not being recycled into the ecosystem at an appreciable rate.
Sampson, R., J . Agric. Food Chem., 24,1189-93 (1976). (5) Hallett, D. J., Norstrom, R. J., Onuska, F. I., Comba, M. E., “Fate of Pesticides in Large Animals”, Ivie, G. W., Dorough, H., Eds., Academic Press. New York. 1977. uu 183-92. (6) Norstrom, R. J., Hallett, D. J.,’Soktegard, R. A., J . Fish. Res. Board Can., 35,1401-9 (1978). (7) . , Norstrom. R. J.. Won. H. T.. Holdrinet. M. V. H.. Calwav. P. G.. Naftel, C. D., J . Assoc. O f f . Anal. Chem.; 63,37-42 (1980j.’ (8) Carlson, D. A., Konyha, K. D., Wheeler, W. B., Marshall, G. P., Zaylskie, R. G., Science, 194,939-41 (1976). (9) Onuska, F. I., Comba, M. E., J . Chromatogr., 26, 133-45 (1976). (10) Dilling, W. L., Dilling, M. L., Tetrahedron, 23, 1225-33 (1967). (11) Alley, E. G., Layton, R., in “Mass Spectrometry and NMR
Spectroscopy in Pesticide Chemistry”, Hague, R., Biros, F. J., Eds., Plenum Press, New York, 1974, pp 81-91. (12) Hallett, D. J., Khera, K. S., Stoltz, D. R., Chu, I., Villeneuve, D. C., Trivett, G., J . Agric. Food Chem., 26,388-91 (1978). (13) Lane, R. H., Grodner, R. M., Graves, J. L., J. Agric. Food Chem.,
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24,192-3 (1976). (14) Alley, E. G., Layton, B. R., Minyard, J. P., J. Agric. Food Chem., 22,442-5 (1974). (15) Alley, E. G., Layton, B. R., Minyard, J. P.,J. Agric. Food Chem., 22,727-9 (1974). (16) Alley, E. G., Dollar, D. A., Layton, B. R., Minyard, J. P., J. Agric. Food Chem., 21,138-9 (1973). (17) Holmstead, R. L., J . Agric. Food Chem., 24,620-4 (1976). (18) Ungefug, G. A., Scherer, K. V., Tetrahedron Lett., 33,2923-6 (1970). (19) Weseloh, D. V., Mineau, P., Hallett, D. J., Trans. North Am. Wildl. Nat. Resour. Conf., 44th 543-57 (1979). (20) Gilman, A. P., Fox, G. A., Peakall, D. B., Teeple, S. M., Carroll, T. R., Haymes, G. T., J. Wildl. Manage., 4,458-68 (1977). (21) Moore, F. R., Bird Banding, 47,141-59 (1976). (22) Waters, E. M., Huff, J . E., Gerstner, H. B., Enuiron. Res., 14, 212-22 (1977). (23) Gibson, J. R., Ivie, G. W., Dorough, H. W., J . Agric. Food Chem., 20, 1246-8 (1972). (24) Andrade, P., Jr., Wheeler, W. B., Carlson, D. A., Bull. Enuiron. Contam. Toxicol., 14,473-9 (1975). (25) Stein. V. B.. Pittman. K. A.. Bull. Enuiron. Contam. Toxicol.. 18,425-7 (1977). (26) Cripe, C. R., Livingston, R. J., Arch. Enuiron. Contam. Toxicol., 5, 295-303 (1977).
(1) Kaiser, K. L. E., Science, 185,523-5 (1974). (2) Holdrinet, M. V. H., Frank, R., Thomas, R. L., Hetling, L. J., J . Great Lakes Res., 4,69-74 (1978). (3) Kaiser, K. L. E., Enuiron. Sci. Technol., 12,520-8 (1978). (4) Hallett, D. J., Norstrom, R. J., Onuska, R. I., Comba, M. E.,
Received for review September 4, 1979. Accepted March 31, 1980. Part of the material in this study was presented at the International Symposium on the Analysis of Hydrocarbons and Halogenated Hydrocarbons, May 23-25,1978, Hamilton, Ontario, Canada.
Acknowledgments
The authors wish to thank Dr. A. P. Gilman, in particular, for the complicated task of organizing the collection of the eggs from so many different sites, and Dr. B. R. Layton for the gift of hydromirex standards. M. J. Mulvihill is thanked for the sample preparation and analysis.
Aqueous Scrubber Reactions of Pyrrhotite (FeS) with Sulfur Dioxide George D. Case’”, Derry A. Green2, and Gerald W. Stewart3 Analytical and Supporting Research Division, Morgantown Energy Technology Center, U S . Department of Energy, Morgantown, W.Va. 26505
The aerobic hydrolysis of iron sulfides has long been a subject of environmental concern. Its importance in the chemistry of acid mine drainage ( I ) and ore smelting operations ( 2 ) has been documented. Thermodynamic properties of iron sulfides (3-6) and the kinetics of their aqueous reactions (7,8) have also been reported under carefully controlled laboratory conditions. However, the roles of iron sulfides in emerging advanced environmental control technologies have only recently been examined for their applicability to coal combustion (9-13) and low-Btu gasification of coal (14-20). Recently, FeS has been cited (9-13) as a possible substitute
for limestone sorbent in flue gas SO2 removal from conventional coal-fired boilers. The present work investigates the actual chemistry of FeS reactions with SO2 under near-neutral pH conditions, and details the mechanisms by which SO2 is removed from the gas phase in aqueous scrubbers to produce soluble Fe2+ and SO4*-, as well as precipitated FeO(0H) as the only significant products (21). SO2 capture efficiency is found to depend on solution pH and buffer capacity, and is not affected by FeS.
Present address, Resource Technologies Group, Inc., Route 2, Box 93A, Morgantown, W. Va. 26505. Present address, Atlantic Research Corp., 5390 Cherokee Ave., Alexandria, Va. 22314. Present address, Aerodyne Research, Inc., Bedford Research Park, Crosby Drive, Bedford, Mass. 01730.
All chemicals were reagent grade. Physical chemical analyses of the FeS starting material (21) showed it to consist primarily of hexagonal pyrrhotite of stoichiometric composition. Aerobic hydrolysis experiments to determine reaction products and pathways were carried out in open vessels as
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Environmental Science & Technology
Experimental
This article not subject to U.S. Copyright. Published 1979 American Chemical Society
