Environ. Sci. Technol. 1982, 16, 473-479
(6) Zitko, V.; Cunningham, T. D. “Fenitrothion, Derivatives and Isomers: Hydrolysis, Absorption and Biodegradation”; Fish Res. Board Can. Tech. Rept. 458, Environment Canada, St. Andrews, N. B., 1974. (7) Greenhalgh, R.; Dhawan, L.; Weinberger,P. J. Agric. Food Chem. 1980,28, 102. (8) Brewer, D. G.; Wood, G.; Unger, I. Chemosphere 1974,3, 91. (9) Okhawa, H.; Mikami, N.; Miyamoto, J. J. Agric. Biol. Chem. 1974, 38, 2247. LO) Greenhalgh, R.; Marshall, W. D. J. Agric. Food Chem. 1976, 24, 708. 11) Miyamoto, J. “Fenitrothion: the long-term effects of its use in forest ecosystem”; Roberts, J. R., Greenhalgh, R., Marshall, K., Eds.; NRCC No. 16073,1977,Envirqnmentd Secretariat, National Research Council Ottawa, Canada. 12) Marshall, W. D.; Greenhalgh, R.; Batora, V. Pestic. Sci. 1974, 5, 781. (13) Forbes, M. A.; Wilson, B. P.; Greenhalgh, R.; Cochrane, W. Bull. Environ. Contam. Toxicol. 1975, 13, 141. (14) Wetzel, R. G. “Limnology”;Saunders: Philadelphia, PA, 1975. (15) Takimoto, Y.; Hirota, M.; Inui, H.; Miyamoto, J. J . Pestic. Sci. 1976, 1 , 831. (16) Dickman, M.; Johnson, M. Can. Field Naturalist, 1975,89, 361. (17) Moody, R. P.; Weinberger, P.; Greenhalgh, R.; Massalski, A. Can. J . Bot. 1981,59, 1003. (18) Nichols, B. W. Biochirn. Biophys. Acta 1965, 106, 274. (19) Greenhalgh, R. “A screen for the relative persistence of lipophilic organic chemicals is aquatic ecosystems”;Roberta, J. R., M. F. Mitchell, M. F., Bollington, M. J., Ridgeway, J. M., Eds.; NRCC No. 18570, 1981, Environmental Secretariat, National Research Council, Ottawa, Canada.
aminofenitrothion [O,O-dimethylO-(4-amino-3-carboxyphenyl) phosphorothioate] from the polar fraction of the water compartment in the field study. It was characterized by the mass spectrum of its methyl ester, with base peak m/z 125 and other prominent ions at 134,150,79,93,109, 106,182,and 291 (parent) and had a relative retention time of 1.63 to fenitrothion on GC. In the dark systems, only 3-methyl-4-nitrophenoland dimethylphosphorothioic acid were isolated. These results indicate that degradation of fenitrothion in water is photocatalyzed and is oxidative in nature. Summarizing, in both field and laboratory systems, the uptake of fenitrothion from water by micro- and macrophytes was rapid. Although polar derivatives were found in plants, they could have resulted from phytodegradation or have been sequestered from the ambient water, thus uptake may be active or passive. In d cases, light had the effect of increasing the uptake of fenitrothion from water by both macro- and microphytes. Given the plant loads found at a 1-m depth in a representative lake, aquatic biota represent only a small proportion of the total environmental sink. However, the ability of aquatic biota to absorb xenobiotics, particularly those with high KOw, could constitute a potential environmental hazard.
Literature Cited (1) Symons, P. E. K. C SIR Res. Rev. 1977,68, 1. (2) Kodama, T.; Kuwatsuka, S. J . Pestic. Sci. 1980, 5, 351. (3) Moody, R. P.; Greenhalgh, R.; Lockhart, L.; Weinberger, P. Bull. Environ. Contam. Toxicol. 1978, 19, 8. (4) Eidt, D. C.; Sundaram, K. M. S. Can. Entomol. 1975,107, 735. ( 5 ) Kovacicova, J.; Batora, V.; Truchlik, S. Pestic. Sci. 1973, 4, 759.
Received for review April 29,1981. Revised manuscript received January 27, 1982. Accepted April 19, 1982.
Influence of Bromide and Ammonia upon the Formation of Trihalomethanes under Water-Treatment Conditions Tieu V. Luong, Chrlstophgr J. Peters, and Roger Perry’ Public Health and Resource Engineering Section, Imperial College of Science & Technology, London SW7 2BU, United Kingdom
A detailed quantitative study of the effects of bromide and ammonia upon the trihalomethane balance obtained when water is chlorinated under varying conditions is described. Experiments at a chlorine dose of 2 and 8 mg L-’ utilizing waters having total organic carbon (TOC) contents of 2.5 and 12.7 mg L-’ demonstrated the significance of these parameters and bromide (0-2000 pg L-l) on the overall reaction process. Trihalomethane distribution is principally dependent on the bromide concentration. An outline kinetic interpretation of the data is presented, and factors influencing the consumption of bromide and free chlorine are evaluated. The effect of ammonia (0.5 mg L-l, NH,-N) upon trihalqmethane formation under breakpoint Chlorination conditions was investigated.
Introduction Previous work in this laboratory (1,2)established, with the development of specific analytical procedures, the presence of organochlorine intermediates of the haloform reaction. These were found to be relatively stable a t ambient temperature although they rapidly broke down to produce dissolved chloroform upon increasing pH, thus 0013-936X/82/0916-0473$01.25/0
indicating the presence of an active trichloroacetyl group (CC1,CO). Subsequent hydrolytic attack on such a group made up the final stage of the haloform reaction. The implications in water-treatment practice are important in terms of both the unknown health effects of such intermediates, which at low pH make a substantial contribution to total chloroform, and the potential even in the absence of chlorine for additional chloroform production during water distribution. Emphasis has recently centered on establishing the source of bromine present in the trihalomethanes, where contrary to initial expectation, there is little evidence to support the view that bromine impurity in the chlorine used for disinfection is a prime source involved. Indeed, indications are that organic bromine originates principally from the inorganic bromide in the raw water that, following rapid oxidation by chlorine, is made available for bromination reactions (3). Few data are presently available regarding bromide levels in source waters, although a recent limited survey (4) revealed that all sources relating to London’s water supply contained bromide ranging in concentration between 50 and 120 pg L-l, with ground waters generally containing lower levels than surface waters.
0 1982 American Chemical Society
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Table I. Experimental Conditions
PH 7 8 9 7 8 9 8
chlorine dose,mg L-I
8 8 8 8 8 8 2
TOC, mg L-I 12.7 12.7 12.7 2.5 2.5 2.5 2.5
temp,
Br- added, p g L“
“C
10 10 10 10
10 10 10
0 0 0 0 0 0 0
Upland surface waters like ground waters are normally of good bacteriological quality and contain low concentrations of bromide and ammonia. One such water studied contained between 10 and 20 pg L-l of bromide, and consequently less than 5% of the total trihalomethane produced was brominated. By contrast, in London’s water supply, over 80% of which derived from surface waters with a mean bromide concentration of 90 pg L-l, over 54% of the trihalomethane produced contained bromide ( 4 ) . The work presented includes a detailed quantitative study of the effect of bromide and ammonia upon the trihalomethane balance with particular reference to the “residual” and “dissolved” components of the individual species ( I ) . This involved straight chlorination and breakpoint chlorination experiments utilizing an upland water with a high humic content as a source of humic material but with very low levels of “natural” bromide and ammonia. Bromide dosing ranges were chosen to typify concentrations found in ground and lowland surface waters.
Experimental Section Trihalomethane Analysis. Residual and dissolved components of the trihalomethanes chloroform, bromodichloromethane, chlorodibromomethane, and bromoform were measured by direct aqueous injection (DAI) as described previously (1). Chromatographic separation of the trihalomethanes was improved by using Tenax as the column packing material in place of Chromosorb 101. This permitted the analysis of all four trihalomethanes at a single column temperature of 145 “C and thus considerably reduced the time requirements for complete analysis. Total, Dissolved, and Residual Trihalomethane. Total trihalomethane (TTHM) analysis of the individual trihalomethane species was evaluated by injection of a 5-pL sample into the chromatograph under the same conditions. Residual trihalomethane (Res THM) analysis was carried out by a 5-pL injection of a previously purged water sample (5 mL) under the same conditions. Purging was carried out with nitrogen a t a flow rate of 150 mL min-’ for 10 min. Dissolved trihalomethane (Dis THM) was calculated by difference as TTHM = Res THM + Dis THM. Bromide Analysis. Bromide concentrations were determined by using a modified version of the ASTM catalytic method as previously described (4). Free-and Combined-HalogenAnalysis. The standard DPD method (5) measures, in addition to the mono and dichloramine, the total free halogen expressed in terms of C1. This includes free chlorine, free bromine, and bromamines, which are indistinguishable with this analytical method (6). The initial halogen concentration is equivalent to the free-chlorine dose. Straight Chlorination. Experiments were conducted at two TOC levels by utilizing undiluted slow sand-filtered (SSF) upland water (TOC 12.7 mg L-l) and SSF water diluted &fold with haloform-free deionized distilled water 474
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50 50 50
50 50 50 50
500 500 500 50 0 500 500 500
2000 1000
2000
(TOC 2.5 mg L-l). The “natural” background level of bromide and ammonia for the undiluted SSF water was
