gives an indication of the “heaviness” of the nonhaloform halogen compounds.
Acknou:ledgment Special thanks go to Jim Burleson, Alkis Dermanci, Garmon Smith, and Fred Spies for their assistance, and to L. Hollis of Dow Chemical Co., Freeport, Tex., for his help in the dynamic sizing of the XAD resin.
Literature Cited (1) Rook, J. J., Water Treat. Exam., 23,234 (1974). ( 2 ) Bellar, T. A., Lichtenberg, J. J., Kroner, R. C., J . Am. Water Works Assoc., 66, 739 (1974). ( 3 ) Henderson, J. E., IV. Peyton, G. R., Glaze, W.H., in “Identification and Analysis of Organic Pollutants in Water”, L. H. Keith, Ed., pp 105-11, Ann Arbor Science, Ann Arbor, Mich., 1976. (4) Glaze, W. H., Peyton, G. R., Sparkman, 0 . D., Stern, R. L., American Chemical Society, Southeast Southwest Regional Meeting, Paper # 128, Memphis, Tenn., October 29-31, 1975. ( 5 ) Glaze, W. H., Henderson, J. E., IV, Bell, J. E., Wheeler, V. A , , J . Chromatogr. Sci., 11, 580 (1973).
(6) J u n k , G. A,, Richard, J. J., Grieser, M. D., Witiak, D., Witiak, J. L., Arguello, M. D., Vick, R., Svec, H. J., Fritz, J. S., Calder, G. V., J . C‘hromatogr., 99, 745 (1974). (7) Kennedy, D. G., Enuiron. Sci. Technol., 7, 138 (1973). (8) Musty, P. R., Nickless, G., J . Chromatogr., 89, 185 (1974). (9) Riley, J. P., Taylor, D., Anal. Chini. Acta, 46, 307 (1969). (10) Mantoura, R.F.C.,Riley, J. P., ibid., 76,97 (1975). (11) Harvey, G. H., Stuermer, D. H., Nature, 250,480 (1974). (12) Richard, J. J.. Fritz, J. S.. Junk, G. A . , Svec, H. J., Chang, R. C., Kissinger, L. D., Criswell, C. B., 2. Anal. Chem., 282,331 (1976). (13) Kopfler, F. C., Melton, R. G., Lingg, R. D., Coleman, W. E., in “Identification and Analysis of Organic Pollutants in Water”, L. H. Keith, Ed., pp 87--104,Ann Arbor Science, Ann Arbor, Mich., 1976. (14) Rook, J . ,J., J . Ani. Water Works A S ~ C J 68, C . . 168 (1976). (15) Kuhn, h’., Sontheimer, H., Vom Wasser, 41, 65 (1973); Park, Y.K., Sontheimer, H.. ibid., 43,291 (1974);Kuhn, b‘.,Sontheimer, H., ibid., p 327. Receiced for recieu’ August 18, 1976. Accepted February 18, 1977. Work supported by Grant Numbers R-803007-02 and K-803007-03 from L’S. Enrironmental Protection Agency and a grant from the North Texas State L‘nicersity Faculty Research Fund.
Photochemistry of the “Sunday Effect” Thomas E. Graedel”, Leonilda A. Farrow, and Thomas A. Weber Bell Laboratories, Murray Hill, N.J. 07974
T h e “Sunday Effect”, in which measured Sunday ozone concentrations in certain urban areas are similar to those occurring on workdays despite markedly decreased emissions, is reproduced by photochemical calculations representing the northern New Jersey troposphere. T h e near equality of odd oxygen [O:j,O(,’P),O(lD)] source and sink rates on workdays and Sundays is responsible for t h e Sunday Effect; this similarity results from the tight balance between ozone production through NO? photodissociation and oxygen scavenging by NO, the advection of ozone from less urban areas, and the entrainment of similar quantities of ozone from layers aloft. The higher levels of oxides of nitrogen on workdays increase morning ozone scavenging, produce enhanced NO:, advection, and result in higher concentrations of organic and inorganic nitrates and a n increased rate of reaction of NO2 with ozone. Recent statistical investigations of air quality data have clearly disclosed a tendency for similar average ozone levels on summer Sundays and workdays, despite markedly different traffic patterns ( 1 , 2). This circumstance has become known as the “Sunday Effect” and has defied straightforward chemical analyses based on precursor-product concepts. This paper presents the results of detailed chemical kinetic computations representing workdays and Sundays in Hudson County, N.J. T h e computational formulation is described, particularly the differences between workday and Sunday parametric inputs. We compare the computational results with air quality data and show t h a t good agreement is obtained for both workday and Sunday calculations. Finally, the concept of “functional oxygen groups” is defined. This concept serves as a unifying analytical technique for smog photochemistry, thus making t h e Sunday Effect a quantitatively explainable result of the chemistry and meteorology of the urban troposphere. 690
Environmental Science & Technology
C o m p u t a t i o n a l Formulation Calculation of the diurnal chemical concentrations in t h e urban troposphere is based on a chemistry of 143 reactions in 76 species. Extensive descriptions of t h e chemistry of oxides of nitrogen, hydrocarbons, and sulfur compounds are included in the reaction set, as is a representation of the heterogeneous interactions between gas-phase radicals and the atmospheric aerosol. This chemical formulation is described in detail by Graedel et al. ( 3 ) .As discussed previously ( 3 ) ,no chemical set can be considered a complete representation of tropospheric photochemistry. The excellent agreement with data t h a t results, however, indicates t h a t our formulation, a t t h e very least, captures the essential processes which control that chemistry. Sequential computations are performed for adjacent New Jersey counties; we present here the results from Hudson County, the most urban. Details of the emissions inventories and their computational treatment and of the meteorological facets of the computation have been given ( 3 ) . Several differences exist between the workday and Sunday computations. ?‘he most important is the marked difference in motor vehicle emission and power generation functions for Hudson County (Figure 1). Atmospheric aerosol concentrations are lower on Sundays, and, perhaps as a result, the solar radiation a t ground level is somewhat higher (2).In addition to its meteorological effects, the change in aerosol concentration reduces the heterogeneous interactions which have important effects on tropospheric chemistry ( , I , ci 1. T h e increased solar radiation increases the rate of the photosensitive reactions included in the chemical set. IZes11 I t s
(hmI)iitations o!’ the kinetic chemistry of the u r t m i troposphere have been performed for Morris, Essex, and Hudson Counties. N.J., for both workdays and Sundays. The workday computations have been described in detail ( 3 ) :and the
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tential insight into a wide variety of other atmospheric chemical regimes. The initial step is to divide the oxygencontaining species into groups on the basis of the function of the incorporated oxygen in photochemical reactions. Four groups are distinguished: fixed oxygen ($O),accessible oxygen ( u O ) ,dissociative oxygen (60),and odd oxygen (00). The chemical species assigned to each group depend on the chemical detail of the analysis. In this study, odd oxygen includes O(:June 22, 1976. Accepted February 22, 1977.
Correction of S-Type Pitot-static Tube Coefficients When Used for lsokinetic Sampling from Stationary Sources Bernnie J. Leland', Jerry L. Hall", Alfred W. Joensen, and John M. Carroll Engineering Research Institute, Department of Mechanical Engineering, Iowa State University, Ames, Iowa 500 11 Factors that affect t h e pitot tube coefficient, including blockage, misalignment, proximity, turbulence, Reynolds number, and calibration system characteristics, are considered. Two different calibration facilities are used t o demonstrate these effects with six different sampling probes. Results from the two facilities are in agreement only after application of correction factors for the effects mentioned above. Experimental data are given as well as relations for accomplishing these important corrections. Probe coefficients determined in this study range from 0.74 to 0.78 after the corrections are accomplished. A technique is also presented for determining the uncertainty in t h e pitot tube coefficient. T h e resulting uncertainty in probe coefficients of this study is between 2 and 3%. Finally, revised calibration techniques are suggested for determination of coefficients for those S-type Pitot-static tubes attached to sampling probes. T h e results of this study indicate that probe coefficients can be obtained to an accuracy typically within f2% if the appropriate precautions and corrections are applied.
for a n uncalibrated S-type Pitot-static tube can result in erroneous emission values which are higher than the true values (9). The stack gas time-average velocity a t a point in the flow is calculated according to the relationship
where ( VST)AVGis stack gas time-average velocity, C,, is Stype pitot tube coefficient, (U')AVG is time-average stack gas velocity head, ( T S T ) A VisGtime-average absolute stack gas temperature, PST is absolute stack gas pressure, and MST is molecular weight of t h e stack gas. The constant K includes the universal gas constant and appropriate conversion factors depending on the units used in the various measurements. Thus, any error in the calibrated probe coefficient causes a n error in the calculated average stack gas velocity and, consequently, whether or not t h e sampling is performed isokinetically.
Objectives In pollutant sampling from stationary sources, t h e Stausscheibe (or S-type) Pitot-static tube is the instrument most commonly used to determine stack gas velocity (1-3). Because the S-type Pitot-static tube is normally attached t o t h e particulate sampling probe ( 4 , 5 )in stationary source sampling, one must calibrate the S-type Pitot-static tube to ascertain the correct value of the probe coefficient (C,). The probe coefficient (C,) for t h e S-type Pitot-static tube is considerably different from that of the conventional Pitot-static tube. Typical values for the probe coefficient are 0.85 f 0.05 ( 3 )for the S-type Pitot-static tube and 0.99 f 0.01 ( 4 ) for the standard Pitot-static tube. T h e value of Cp is normally determined ( I ) by. measuring t h e velocity in a flow stream with the S-type Pitot-static tube and comparing t h e result with the same velocity measurement via a standard Pitot-static tube. In many instances when t h e value of C, is unknown, a value of 0.85 has been recommended (6-8) for the S-type Pitot-static tube without calibration. Use of this value
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Present address, Procter & Gamble Co., Cincinnati, Ohio. Environmental Science & Technology
Our own experiences as well as those of investigators in a number of very recent sudies (9-15) have demonstrated the need for a more detailed and systematic calibration procedure than is now available under the current Environmental Protection Agency guidelines ( I , 2 ) . Correspondingly, the first ohjective of this study was t o examine and measure a variety of factors believed t o be important in affecting the flow field and pressure distribution around the S-type Pitot-static tube. These factors would then govern the value of the probe coefficient (C,) for a given Stype Pitot-static tube and calibration facility. Specifically, the factors to be studied were aerodynamic interference (proximity effect) of the nozzle, misalignment (yaw and pitch angle effects), blockage (area effect), turbulence intensity (turbulence effect), Reynolds number effect, and calibration facility effect (flow tube effect). T h e second objective of this study was t o develop and perform an uncertainty analysis on the probe coefficient as corrected for by the variety of effects mentioned in the previous paragraph. The third objective was to recommend improvements in the current guidelines for the calibration of sampling probes used for particulate sampling from stationary sources.
