Environ. Sci. Technol. 1988,22, 231-231 (4) Eisenreich, S. J. In The Sources and Fates of Aquatic Pollutants; Hites, R. A., Eisenreich, S. J., Eds.; Advances in Chemistry 316; American Chemical Society: Washington, DC, 1987; Chapter 13. (5) Swackhamer, D. L.; McVeety, B. D.; Hites, R. A., unpublished data. (6) Murphy, T. J.; Pokojowczyk, J. C.; Mullin, M. D. In Physical Behavior of PCBs in the Great Lakes; Mackay, D., Paterson, s.,Eisenreich, s. J., Simmons, M. s.,Eds.; Ann Arbor Science: Ann Arbor, MI, 1983; Chapter 3. (7) Doskey, P. D.; Andren, A. W. J. Great Lakes Res. 1981, 7, 15-20. (8) Andren, A. W., personal communication.
Deborah L. Swackhamer* Environmental and Occupational Health University of Minnesota Minneapolis, Minnesota 55455
Davld E. Armstrong Water Chemistry Program university of Wisconsin Madison, Wisconsln 53706
Comment on “Reaction Products and Rates of Disappearance of SZmple Bromoalkanes, 1,2-Dibromopropane, and 1,2-Dlbromoethane in Water” SIR A recent article in this journal by T. M. Vogel and M. Reinhard (1)concerned itself with the disappearance, rates, and reaction products of mono- and dibromoalkanes in water. One conclusion of this article was that 1,2-dibromoethane (EDB) degraded to the bromoalkane vinyl bromide as a “main product” causing them to conclude that “...dehydrobromination is the most significant degradation mechanism for alkanes with two bromines in vicinal position, although substitution cannot be ruled out from the data due to analytical limitations”. Since the authors did not specify at what EDB concentrations their studies were performed, it is impossible to put such observations in perspective with those of ours (2) and Jungclaus and Cohen (3). We have shown that, in natural groundwaters, ethylene glycol and bromide ions account for nearly all the degradation of EDB when studies are done at EDB concentrations that have been observed in groundwater (2; 10-100 pg/L). Vogel and Reinhard (1) did not look for water-soluble products but concentrated their effors on pentane-soluble ones. When your readers consider the relative mammalian toxicities of ethylene glycol and vinyl bromide, it is important for them to know that the more innocuous ethylene glycol accounts for nearly all the degradation of EDB in groundwaters. Registry No. EDB, 106-93-4; BrCH2CHBrCH3, 78-75-1.
L i t e r a t u r e Cited (1) Vogel, M. T.; Reinhard, M. Environ. Sci. Technol. 1986, 20(10),992-997. (2) Weintraub, R. A.; Jex, G. W.; Moye, H. A. Evaluation of Pesticides in Ground Water; Garner, Willa Y., Honeycutt, Richard C., Nigg, Herbert N., Eds.; ACS Symposium Series 315; American Chemical Society: Washington, DC, 1986; Chapter 15. 0013-936X/88/0922-0231$01.50/0
(3) Jungclaus, G. A.; Cohen, S. Z. Extended Abstracts, 191st National Meeting of the American Chemical Society, Division of Environmental Chemistry, New York, NY; American Chemical Society: Washington, DC, 1986: paper 6.
H. Anson Moye,” Randy Welntraub Pesticide Research Laboratory Institute of Food and Agricultural Sciences University of Florida Gainesville, Florida 3261 1
SIR: Weintraub et al. (1)and Jungclaus and Cohen (2) report that 1,2-dibromoethane (EDB) hydrolyzes in aqueous buffers to form ethylene glycol as the primary product. Recent data obtained in this laboratory are consistent with this finding (3). In addition, Vogel and Reinhard ( 4 ) ,Jungclaus and Cohen (2),and recently Haag and Mill (5) have found vinyl bromide as a product of EDB decomposition in water. Haag and Mill (5) have found degradation via elimination to be 9 times slower than hydrolysis. Although ethylene glycol is quantitatively the major product of aqueous EDB degradation, vinyl bromide may be the more significant product because of its elevated toxicity. We specified that the initial EDB concentrations in our studies were 10 mg/L ( 4 ) . However, product distribution is not expected to change with the initial concentration since the rates of both elimination and hydrolysis are first order with respect to organic reactant. Degradation of 100 pg/L EDB (the upper limit in groundwater quoted by Moye and Weintraub) in water may react to form approximately 30 pg/L ethylene glycol via hydrolysis and 6 pg/L vinyl bromide via elimination. For the purpose of comparison, the final maximum contaminant levels set by the U.S. EPA for vinyl chloride (the chlorinated analogue of vinyl bromide) is 2 hg/L. Registry No. EDB, 106-93-4; BrCH2CHBrCH3, 78-75-1,
L i t e r a t u r e Cited (1) Weintraub, R. A,; Jex, G. W.; Moye, H. A. Evaluation of Pesticides in Ground Water; Garner, Willa Y., Honeycutt, Richard C., Nigg, Herbert, N., Eds.; ACS Symposium Series 315; American Chemical Society: Washington, DC, 1986; Chapter 15. (2) Jungclaus, G. A,; Cohen, S. Z. Extended Abstracts, 191st National Meeting of the American Chemical Society, Division of Environmental Chemistry, New York, NY; American Chemical Society: Washington, DC, 1986; paper 6. (3) Barbash, J. E.; Reinhard, M. Extended Abstracts, 194th National Meeting of the American Chemical Society, Division of Environmental Chemistry, New Orleans, LA; American Chemical Society: Washington, DC, 1987. (4) Vogel, T. M.; Reinhard, M. Environ. Sci. Technol. 1986, 20,992-997. (5) Haag, W. R.; Mill, T., personal communication, 1987.
Martin Reinhard” Department of Civil Englneering Stanford University Stanford, California 94305
Timothy M. Vogel Environmental Engineering Michigan State University East Lansing, Michigan 48824-1212
0 1988 American Chemical Society
Environ. Sci. Technol., Vol. 22,No. 2, 1988 231
