Environ. Sci. Technol. 1982, 76, 796-799
moved due to oxidation could approach 40%. Therefore, chlorine-induced carbon oxidation probably represents a significant pathway for carbon transfer within the Patuxent River system. In rivers where cooling flows are not so important, the potential impact would probably be much less. The loss of carbon should not have a significant impact upon organically associated metals as the complexation capacities of estuarine systems far exceed the quantity of carbon lost. Oxidation of reduced metals resulting from chlorination, and their subsequent precipitation, can be an important transport mechanism in an estuary as heavily impacted as the Patuxent River.
Acknowledgments
I thank C. D. Zamuda, D. A. Wright, and C. F. D’Elia for comments and suggestions and A. C. Sigleo, J. C. Means, and G. R. Helz for criticism of the manuscript. Literature Cited (1) Rook, J. J. Water Treat. Exam. 1974, 23, 234. (2) Helz, G. R.; Hsu, R. Y. Limnol. Oceanogr. 1978,23, 858. (3) Helz, G. R.; Sugam, R.; Hsu, R. Y. In “Water Chlorination: Environmental Impact and Health Effects”; Jolley, R. L., Gorchev, H., Hamilton, D. H., Eds.; Ann Arbor Science: Ann Harbor, MI, 1978; Vol. 2, p 209. (4) Eppley, R. W.; Renger, E. H.; Williams, P. M. Estuarine Coast. Mar. Sci. 1976, 4, 147. (5) Helz, G. R.; Dotson, D. A.; Sigleo, A. C. In “Water Chlorination: Environmental Impact and Health Effects”; Jolley, R. L., Cumming, R. B., Mattice, J. S., Eds.; Ann Arbor Science: Ann Arbor, MI; Vol. 4, in press. (6) Sigleo, A. C.; Helz, G. R.; Zoller, W. H. Enuiron. Sci. Technol. 1980, 14, 673. (7) Mantoura, R. F. C.; Dickson, A.; Riley, J. P. Estuarine Coast. Mar. Sci. 1978, 6, 387. (8) Zuehlke, R. W.; Kester, D. R. In ”Trace Metals in Seawater”; Wong, C. S., Ed.; Proceedings of a NATO Advanced Research Institute, in press. (9) Barber, R. T.; Ryther, J. H. J. Exp. Mar. Biol. Ecol. 1969, 3, 191. (10) Barber, R. T.; Dugdale, R. C.; MacIsaac, J. J.; Smith, R. L. Inuest. Pesq. 1971, 35, 171.
(11) Sunda, W.; Guillard, R. R. L. J. Mar. Res. 1976, 34, 511. (12) Carpenter, J. H.; Smith, C. A. In “Water ChlorinationEnvironmental Impact and Health Effects”; Jolley, R. L., Gorchev, H., Hamilton, D. H., Eds.; Ann Arbor Science: Ann Arbor, MI, 1978; Vol. 2, p 195. (13) Goldman, J. C.; Quinby, H. L.; Capuzzo, J. M. Water Res. 1979, 13, 315. (14) Menzel, D. W.; Vaccaro, R. F. Limnol. Oceanogr. 1964,9, 138. (15) Kinrade, J. D.; Van Loon, J. C. Anal. Chem. 1974,46,1894. (16) Patterson, C. C.; Settle, D. M. Proc. Mater. Res. Symp. 7th NBS Spec. Publ. 422, 1976; p 321. (17) Hobbie, J. E.; Daley, R. J.; Jasper, S. Appl. Environ. Microbiol. 1977, 33, 1225. (18) Mattson, J. S.; Smith, C. A.; Jones, T. T.; Gerchakov, S. M.; Epstein, B. D. Limnol. Oceanogr. 1974, 19, 530. (19) Smith, R. G. Anal. C h e h . 1976, 48, 75. (20) Wheeler, J. R. Limnol. Oceanogr. 1977, 22, 573. (21) Mackinnon, M. D. In ”Marine Organic Chemistry”; Duursma, E. K., Dawson, R., Eds.; Elsevier: Amsterdam, 1981; p 415. (22) Sigleo, A. C., Helz, G. R. Geochim. Cosmochim. Acta 1982, 45, 2501. (23) Sigleo, A. C.; Hoering, T. C.; Hare, P. E. Year BookCarnegie Inst. Washington 1980, 79, 394. (24) Glaze, W. H.; Peyton, G. R. In “Water Chlorination: Environmental Impact and Health Effects”; Jolley, R. L., Gorchev, H., Hamilton, D. H., Eds.; Ann Arbor Science: Ann Arbor, MI, 1978; Vol. 2, p 3. (25) Eaton, A.; Chamberlain, C. “Cu Cycling in the Patuxent Estuary”; Final Report No. P42-78-04; Dept. of Natural Resources, Power Plant Siting Program, MD, 1980. (26) Mantoura, R. F. C. In “Marine Organic Chemistry”; Duursma, E. K., Dawson, R., Eds.; Elsevier: Amsterdam, 1981; p 179. (27) Academy of Natural Sciences. In “Chalk Point 316 Demonstration of Thermal Entrainment and Impingement Impacts on the Patuxent River”; 1981, p 22.
Received for review February 16, 1982. Revised manuscript received May 28, 1982. Accepted July 21, 1982. This research was supported by the Maryland Department of Natural Resources, Power Plant Siting Program (No. P70-80-04)and the Academy of Natural Sciences.
Synthesis and Analysis of Crystalline Silica Frank H. Chung Sherwin-Williams Research Center, Chlcago, Illinois 60628
rn Inadequate interlaboratory precision of silica analysis is shown in the round robin studies sponsored by NIOSH and AIHA. The inconsistency in analytical results is caused by loose analytical procedures and lack of primary standards. Primary standards of cristobalite and tridymite were synthesized from high-purity quartz to cope with this situation. A matrix-flushing X-ray diffraction procedure is described for silica analysis. The integrated intensities, flush constants, and detection limits for the three forms of crystalline silica are presented. Introduction Chronic exposure to crystalline silica may cause silicosis or fibrosis in the pulmonary system. Hence the amount of airborne silica in work places is regulated and monitored by the Occupational Safety and Health Administration 796 Environ. Scl. Technol., Vol. 16, No. 11, 1982
(OSHA). Recent eruptions of the Mt. St. Helens volcano brought up a controversy between the environmentalists and the geologists over the amount of crystalline silica (quartz, cristobalite, and tridymite) in the volcanic ash (1). The environmentalists at the Washington State Department of Labor and Industries, the University of Washington, and the National Institute for Occupational Safety and Health (NIOSH) found typically 5-10% cristobalite, 1-2 % quartz, and
