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Leighton, D. T.; Calo, J. M. J. Chem. Eng. Data 1981,26, 382-385. Lincoff, A. H. MS. Thesis, Cornel1 University, 1983.
Zhong, W.; Lemley, A. T.; Wagenet, R. J. In Evaluation of Pesticides in Ground Water;Garner, W. Y., Honeycutt, R. C., Nigg, H. N., Eds.; ACS Symposium Series 315; American Chemical Society: Washington, DC, 1986; pp 61-77. Farmer, W. J.; Yang, M. S.; Letey, J.; Spencer,W. F. Soil Sci. SOC.Am. J. 1980,44, 676-680. Lunge's Handbook of Chemistry, 13th ed.; Dean, J. A,, Ed.; McGraw-Hill: New York, 1985; p 10-52. Parker, J. C.; van Genuchten, M. Th Virginia Agricultural Experiment Station, Bulletin 84-3, 1984. Malcolm, R. L.; MacCarthy, P. Environ. Sci. Technol. 1986, 20,904-911.
Garbarini,D. R.; Lion, L. W. Environ. Sci. Technol. 1986,
(23) Millington, R. J.; Quirk, J. M. Trans. Faraday SOC.1961, 57, 1200-1207. (24) Reid, R. C.; Sherwood, T. K. Properties of Gases and Liquids, 3rd ed.; McGraw-Hill: New York, 1977. (25) Jury, W. A.; Spencer, W. F.; Farmer, W. J. J. Environ. Qual. 1983, 12(4), 558-564. (26) Jury, W. A.; Spencer,W. F.; Farmer, W. J. J. Environ. Qual. 1984, 13(4), 567-572. (27) Jury, W. A.; Spencer,W. F.; Farmer, W. J. J. Environ. Qual. 1984, 13(4), 572-579. (28) Jury, W. A.; Spencer, W. F.; Farmer, W. J. J. Environ. Qual. 1984, 13(4), 580-586. (29) Wilke, C. R.; Chang, P. AIChE J. 1955, 1, 264-270. (30) Gustafson (Peterson),M. M.S. Thesis, Cornel1University, 1986.
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Gauthier, T. D.; Seitz, W. R.; Grant, C. L. Environ. Sci. Technol. 1987,21, 243-248. Himenz, P. C. Principles of Colloid and Surface Chemistry;
Dekker: New York, 1981.
Received for review March 16,1987. Accepted November 19,1987. This research was supported by the Jessie Noyes-Smith Foundation and the USGS through the Water Resources Institute for New York State.
Atmospheric Reactions of a Series of Dimethyl Phosphoroamidates and Dimethyl Phosphorothioamidates Mark A. Goodman,+ Sara M. Aschmann, Roger Atkinson," and Arthur M. Wlner Statewide Air Pollution Research Center, University of California, Riverside, California 9252 1
The kinetics of the atmosphericallyimportant gas-phase reactions of a series of dimethyl phosphoroamidates and dimethyl phosphorothioamidates with OH and NO, radicals and 0, were investigated at 296 f 2 K and -740 Torr total pressure of air. The rate constants obtained for the OH radical, NO, radical, and O3reactions (in units of cm3 molecule-l s-l) were respectively as follows: (CH,O),P(O)N(CH,),, (3.19 f 0.24) X CH-), and F(>CNH, and >N- groups are (in units of cm3 molecule-' s-') 2.0, 6.0, and 6.0, respectively, with factors F(-NH,) = F(>NH) = F(>N-) = 10 (11). Our previous data for trimethyl phosphate and the trimethyl phosphorothioates (6, 7) yield the factors F(-OP-) = F(-SP-) = 20 and the group rate constants k-P=O E 0 and k-+S = 5.5 x 1O-I' cm3 molecule-' s-' (7). Use of these group rate constants and substituent factors, with no assumed effect of the P atom on the -NR2 group rate constants, leads to predicted room temperature rate constants (in units of cm3 molecule-' s-') for (CH~O)ZP(O)N(CHJ~, (CH3O),P(S)N(CH,)2, (CH3O),P(S)NHCH3, and (CH30),P(S)NH2of 6.9, 12.4, 12.1, and 8.1, respectively, compared to our measured values of (in the same units) 3.2, 4.7, 23.2, and 24.4, respectively. Clearly, discrepancies of up to a factor of 3 exist, and without making the structure-activity relationship too detailed and cumbersome for easy use, these may well represent the inherent uncertainties for more complex chemicals containing multiple substituent groups. However, our calculated data show, for example, that the agriculturally used chemical Methamidophos will be reactive, with room temperature OH and NO, radical reaction rate constants of 1 x cm3molecule-' s-' and -3 X cm3molecule-' s-', respectively. The calculated atmospheric lifetimes are then -3 h for OH radical reaction and -4 h for NO3 radical reaction, for ambient OH and NO3 radical concentrations of 1 X lo6 molecule cm-3 and 2.4 X lo* molecule cm-,, respectively.
-
Acknowledgments
We thank R. Fukuto and S. Keadtisuke of the Department of Entomology, University of California, Riverside, for valuable assistance in the syntheses. Registry No. NO3, 12033-49-7;HO', 3352-57-6; Ox, 10028-15-6; (CH,O),P(O)N(CHJ,, 597-07-9; (CH3O)zP(S)N(CH,),, 28167-51-3; (CH,O)ZP(S)NHCHs, 31464-99-0; (CH,O)ZP(S)NHz, 17321-47-0.
Literature Cited Jury, W. A.; Winer, A. M.; Spencer, W. F.; Focht, D. D. Rev. Environ. Contam. Toxicol. 1987, 99, 119-164. Finlayson-Pitts, B. J.; Pitts, J. N., Jr. Atmospheric Chemistry: Fundamentals and Experimental Techniques; Wiley: New York, 1986. Atkinson, R. In Air Pollution, The Automobile and Public Health; Bates, R. R., Kennedy, D., Eds.; National Academy Press: Washington, DC, 1988; in press. Atkinson, R. Chem. Rev. 1986,86, 69-201. Atkinson, R.; Carter, W. P. L. Chem. Rev. 1984,84,437-470. Tuazon, E. C.; Atkinson, R.; Aschmann, S. M.; Arey, J.; Winer, A. M.; Pitts, J. N., Jr. Enuiron. Sci. Technol. 1986, 20, 1043-1046. Goodman, M. A.; Aschmann, S. M.; Atkinson, R.; Winer, A. M. Arch. Environ. Contam. Toxicol., in press. Worthing, C. R. The Pesticide Manual, 7th ed.; The British Crop Protection Council Publications: Croydon, UK, 1983. Quistad, G. B.; Fukuto, T. R.; Metcalf, R. L. J . Agric. Food Chem. 1970, 18, 189-194. Magee, P. S. In Insecticide Mode of Action; Academic: New York, 1982; p p 101-161. Atkinson, R. Int. J . Chem. Kinet. 1987, 19, 799-828. Atkinson, R.; Carter, W. P. L.; Winer, A. M.; Pitts, J. N., Jr. J. Air Pollut. Control Assoc. 1981, 31, 1090-1092. Atkinson, R.; Aschmann, S. M.; Winer, A. M.; Pitts, J. N., Jr. Int. J. Chem. Kinet. 1982, 14, 507-516. Atkinson, R.; Plum, C. N.; Carter, W. P. L.; Winer, A. M.; Pitts, J. N., Jr. J . Phys. Chem. 1984, 88, 1210-1215.
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(22) Platt, U. F.; Winer, A. M.; Biermann, H. W.; Atkinson, R.; Pitts, J. N., Jr. Environ. Sci. Technol. 1984, 18, 365-369. (23) Atkinson, R.; Winer, A. M.; Pitts, J. N., Jr. Atmos. Enuiron. 1986,20, 331-339. (24) Crutzen, P. J. In Atmospheric Chemistry;Goldberg, E. D., Ed.; Springer-Verlag: Berlin, West Germany, 1982; pp 313-328. (25) Singh, H. B.; Ludwig, F. L.; Johnson, W. B. Atmos. Environ. 1978, 12, 2185-2196. (26) Oltmans, S. J. J. Geophys. Res. C: Oceans Atmos. 1981, 86, 1174-1180.
Atkinson, R.; Pitts, J. N., Jr.; Aschmann, S. M. J. Phys.
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Carter, W. P. L.; Atkinson, R.; Winer, A. M.; Pitts, J. N., Jr. Experimental Protocol for Determining Photolysis Reaction Rate Constants; EPA-600/3-83-100; U.S.Government Printing Office: Washington, DC, Jan 1984. Atkinson, R.; Aschmann, S. M.; Carter, W. P. L. Int. J. Chem. Kinet. 1983,15, 1161-1177.
Taylor, W. D.; Allston, T. D.; Moscato, M. J.; Fazekas, G. B.; Kozlowski, R.; Takacs, G. A. Int. J. Chem. Kinet. 1980, 12, 231-240. Magee, P. S. U.S.Patent 3 309 266, March 14, 1967.
Ravishankara, A. R.; Mauldin, R. L., I11 J. Phys. Chem. 1985,89,3144-3147.
Atkinson, R.; Aschmann, S. M.; Winer, A. M.; Pitts, J. N., Jr. Int. J. Chem. Kinet. 1984,16, 697-706.
Received for review August 7,1987. Accepted December 14,1987. The financial support of the University of California,Riverside, Toxic Substances Research and Training Program is gratefully acknowledged.
Xenon-I33 in California, Nevada, and Utah from the Chernobyl Accident Robert W. Holloway" and Chung-King Llu Environmental Monitoring Systems Laboratory, US. Environmental Protection Agency, P.O. Box 93478, Las Vegas, Nevada 89 193-3478
The accident a t the Chernobyl nuclear reactor in the USSR introduced numerous radioactive nuclides into the atmosphere including the noble gas xenon-133. EPA's Environmental Monitoring Systems Laboratory, Las Vegas, NV, detected xenon-133 from the Chernobyl accident in air samples from a monitoring network that consists of 15 stations located in Nevada, Utah, and California. The peak concentration of xenon-133 was found in weekly air samples collected during May 6-13, 1986. The network average concentration of xenon-133 was 41 pCi/m3 during that time. A lower average was found in air samples collected in the following week. These concentrations are comparable to or less than that of natural radionuclides (such as radon) normally present in the atmosphere and are much lower than the peak xenon-133 concentration measured in New York State following the accident at the Three Mile Island reactor. Introduction The Chernobyl nuclear accident, which occurred in the Soviet Union on April 26,1986, released various radioactive nuclides into the atmosphere. An early report (I) indicated that xenon-133 was one of several isotopes detected in Sweden by April 29, 1986. Xenon-133 is a convenient tracer to detect leakage from a reactor or recent nuclear explosion since it is a noble gas and its short 5.3 day half-life prevents the accumulation of a significant inventory in the atmosphere. Since 1972, the Environmental Protection Agency's Environmental Monitoring Systems Laboratory a t Las Vegas has maintained a network of noble gas monitoring stations in Nevada, Utah, and California as a part of the radiation monitoring program for the region near the Nevada Test Site. The network was established to measure the concentrations of radioactive noble gases released into the atmosphere either from underground nuclear detonations, from posttest operations, or from seepage from previous underground tests. The locations of the 15 stations in the network are shown in Figure 1. The network is approximately 200 miles wide (east to west) and 300 miles along a line from Las Vegas to Austin. The concentration of radioactive xenon is routinely measured in air samples collected from the network, and 0013-936X/88/0922-0583$01.50/0
therefore no special sampling program was required to monitor for xenon-133 emission from the Chernobyl accident. Analytical Procedures Air samples are collected by two methods. One method employs air-compressing units as described by Andrews (2). The other method is a cryogenic technique in which whole air samplts are collected in the field at the temperature of liquid nitrogen and returned to the laboratory where they are allowed to warm to room temperature and are analyzed as compressed air. In both methods, approximately 1 m3 of air is collected during continuous operations over a 1-week period. All samples are analyzed in our laboratory by the procedure described by Johns et al. (3). The procedure involves the separation and purification of krypton and xenon by adsorption on chromatographic columns and the subsequent analysis of the radioactivity in the krypton and xenon fractions by liquid scintillation counting. The accuracy of the method is checked periodically with samples of known radioactivity. The error involved in the analysis of known samples has been 10% or less. The errors reported with each xenon-133 determination are 2-a errors derived from the statistics of counting the sample and background. Both the xenon-133 results and the error terms are decay corrected back to the midpoint of collection. The minimum detectable concentration (MDC) of xenon-133 varies with each sample but is usually 10-25 pCi/m3. The calculation of MDC of xenon-133 includes a correction for the decay of xenon-133 during the several days between the midpoint of collection and sample analysis. Thus, the MDC refers to the midpoint of collection and not to the date of analysis. The MDCs reported for these samples are roughly twice as high as would be obtained for grab samples analyzed immediately after collection. In analyzing samples that are only slightly above the normal background of the counting equipment, statistical methods must be used to ensure that results above zero are caused by real activity rather than normal background fluctuations. For the results reported in Table I, all nu-
0 1988 American Chemical Society
Environ. Sci. Technol., Vol. 22, No. 5, 1988
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