Environ. Sci. Technol. 1982, 16, 602-606 Pa
Ta
= 1 + m(r, - a,)
(A241
It should be noted that these relationships can be easily corrected for the mass associated with the residual supernatannt if its volume is known by simply adding that mass to the left-hand side of eq A14.
Literature Cited Mayer, F. L., Hamelink, J. L., Eds. “Aquatic Toxicology and Hazard Evaluation”; Proc. First Annual Symposium on Aquatic Toxicology, ASTM STP 634; ASTM: Philadelphia, PA, 1977. Marking, L. L., Kimberle, R. A., Eds. “Aquatic Toxicology Proc. Second Annual Symposium on Aquatic Toxicology”; ASTM STP 667; ASTM: Philadelphia, PA, 1979. Hague, R., Ed. “Dynamics, Exposure, and Hazard Assessment of Toxic Chemicals”; Ann Arbor Science: Ann Arbor, MI, 1980. van Genuchten, M. Th.; Davidson, J. M.; Wierenga, P. J. Soil Sei. SOC.Am. Proc. 1974, 38, 29-35. Baughman, G. L.; Lassiter, R. R. In “Estimating the Hazard of Chemical Substances to Aquatic Life“; Cairns, J., Dickson, K. L., Maki, A. W., Eds.; ASTM STP 657; ASTM: Philadelphis, PA, 1978; pp 35-70. Thomann, R. V., Di Toro, D. M., submitted for publication. O’Connor, D. J.; Schnoor, J. L. Manhattan College Summer Institute Proceedings, 1980. Rao, P. S. C.; Davidson, J. M. In “Environmental Impact of Nonpoint Source Pollution”; Overcash, M. R., Davidson, J. M., Eds.; Ann Arbor Science: Ann Arbor, MI, 1980; pp 23-67.
(9) Horzempa, L. M.; Di Toro, D. M. Water Res., in press. (10) Huang, J.-C.; Liao, C. J. Sanit. Eng. Diu., ASCE 1970,19, 1057-1078. (11) Pierce, R. H.9 Jr.; O h Y , C. E.; Felbeck, G. T.9 Jr. Geochim. Cosmochim. Acta 1980, 24, 20-26. (12) Felsot, A.; Dahm, P. A. J. Agric. Food Chem. 1979, 27, 557-563. (13) Wildish, D. J.; Metcalfe, C. D.; Akagi, H. M.; McLeese, D. W. Bull. Environ. Toxicol. 1980, 24, 20-26. (14) Swanson, R. A.; Dutt, G. R. Soil Sei. SOC.Am. Proc. 1973, 37, 872-876. (15) Rao, P. S. C.; Davidson, J. M.; D. P. Kilcrease. “Examination of Nonsingularity of Pesticide AdsorptionDesorption Isotherms for Soil Pesticide Systems”; Agron. Abstr. 1982, 34. (16) Savage, K. E.; Wauchope, R. D. Weed. Sci. 1974, 22, 106-110. (17) van Genuchten, M. Th.; Wierenga, P. J.; O’Connor, G. A. Soil Sei. SOC.Am. J. 1977, 41, 278-285. (18) Koskinen, W. C.; O’Connor, G. A.; Cheng, H. H. Soil Sci. SOC.Am. J. 1979,43,871-874. (19) Kishk, F. M.; Abu-Sharar, T. M.; Bakry, N. M.; Abou-Donia, M. B. Arch. Environ. Contam. Toxicol. 1979,8,637-645. (20) Bowman, B. T.; Sans, W. W. Soil Sei. SOC.Am. J . 1977,41, 514-519. (21) Bowman, B. T. Can. J. Soil Sci. 1979,59, 435-427. (22) Peck, D. E.; Convin, D. L.; Farmer, W. J. J. Enuiron. Qual. 1980,9, 101-106.
Received for review November 3, 1980. Revised manuscript received October 9,1981. Accepted April 5,1982. The research described in this report was conducted under EPA research grants CR805229 and CR807853.
A 1O-pm Cutpoint Inlet for the Dichotomous Sampler James B. Wedding,* Michael A. Welgand, and Theodore C. Carney Aerosol Science Laboratory, Colorado State Unlversity, Affiliated with the Research Institute of Colorado, Fort Collins, Colorado 80523
The United States Environmental Protection Agency is considering an alternative standard requiring the collection of a specific size fraction of atmospheric aerosol termed the thoracic fraction. This new standard provides an impetus for the inlet development described herein. An ambient air inlet for the dichotomous sampler has been designed, fabricated, and performance tested. It is in compliance in all aspects with the proposed U.S. Environmental Protection Agency Federal Reference Method performance specifications. The device operates at 16.7 L/min and has an aerodynamic particle size of 10 pm associated with a 50% effectiveness value, which is commensurate with the anticipated changes in the air quality standards. The system is independent of all environmental conditions, most importantly windspeed. The inlet employs a unique, omnidirectional cyclone fractionator. Under dynamic conditions the inlet was tested with solid particles and exhibited no evidence of particle bounce. H
Introduction The U.S.Environmental Protection Agency (EPA) under the auspice of the Clean Air Act Amendment of 1977 is mandated to review the total suspended particulates (TSP) standard for its applicability to the protection of health and welfare. The present standards for particulate matter are 75 pg/m3 average annual limit (geometric mean) and 260 pg/(m3 24-h) limit (geometric mean) for particles
