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A simple sampler to monitor sulphur oxide emissions from a cement works
766
Discussions
It is our suspicion that even today most SO2 is emitted in rural areas and (since man occupies only a small percentage of the U.S. area) most of our air spends most of its time in rural settings. If this suspicion is true, then Dr. Altshuller’s mechanism for urban conversion of rural SO2 might not be operative. 3. With italics added and a change of phrase, Dr. Altshuller has stated our intention precisely: “consistent control of sulfur oxides on a regional basis is needed. That is, control of sulfur oxides (only in cities) may not be satisfactory.” We agree that the data only suggests this and that support of this statement awaits further evidence. 4. The final discussion precisely states the challenge for future experimentation. “The important point is the lack of an adequate experimental basis to differentiate among important sources as to their impact on a regional scale.” With regard to the regional scale, the relevance of the RAPS project may be limited by two factors. (a) The area covered is hardly regional, or large enough for study of SO2 kinetics over times larger than the transit time across the city, i.e., a few hours. Many current guesses suggest a reaction time constant of It&l00 h for SO, oxidation. (b) The sulfate concentrations within an air mass upon arrival at St. Louis may interfere with making any clear-cut conclusions about mechanisms within specific plumes. We suggest that the mechanisms should also be investigated over large spatial areas where and when the plumes are dispersed into “clean” air masses unaffected by a history of anthropogenic.sources, e.g. the west coast which often experiences maritime air masses. Finally, we have recently found two relationships which relate to these comments. Each of them emphasizes that air mass history is the proper framework for discussion. (a) In reference to comment (1) we have found that sulfate concentration is highly correlated (I = 0.73) to light scattering (b,,) in Sweden when the air mass came from the European industrial areas. With reasonable assumptions regarding SOi- size distribution, sulfate alone could be the major and even in some cases the sole cause of turbidity. (b) In reference to comment (4) the occurrence of ammonium sulfate is correlated with a polar continental air mass and the occurrence of the acids is correlated with a tropical marine air mass. This suggests that an effective sampling network would be positioned along the average trajectory for these air masses and would spatially extend for thousands of kilometers. This would enable monitoring the evolution of changing concentrations as sources add sulfur dioxide and sink mechanisms remove it. Department of Civil Engineering, Water and Air Resources Division, University of Washington, Seattle, Washington 98195, U.S.A.
A. H. VANDERPOL R. J. CHARLS~N A. P. WAGGONER D. S. COVERT N. C. AHLQUIST
A SIMPLE
SAMPLER
TO MONITOR SULPHUR A CEMENT WORKS*
OXIDE
EMISSIONS
FROM
The cooling water inlet to the Graham condenser is shown connected to the upper tubulation, with the drain at the bottom, This arrangement is not common, and deserves verification. In the arrangement shown in Fig. 1, it would appear that one loses the advantage of counter-current thermal gradients in the condenser, may be subjecting the top ring-seal of the condenser to excessive thermal shocks, and may have difficulties from air-lock expelling most of the coolant from the condenser. Since the cooling water entrains large volumes of air from the ejector pump, this last difficulty would seem to be serious. L. TODD REYNOLDS
Colorado Department of Health, 4210 E. 11th Avenue,
Denver, Colorado 80220, U.S.A.
AUTHOR’S
REPLY
The water flow arrangements through the condenser are verified and explained in the text. Although Dr. Reynolds comments appear theoretically sound, trial and error has shown the apparatus illustrated in Fig. 1 to offer the most satisfactory combination of gas sampling rate and cooling. The only modification that has been found necessary in over 300 h of use is the installation of a silica-gel drying tower between the Drechsel bottle and gas meter. “GRENDON”, Brackendak, Potters Bar, Hertfordshire
ON THE INFLUENCE ATMOSPHERIC
R. A.
OF SURFACE ALBEDO RADIATION BALANCE
BARNES
ON THE CHANGE IN THE DUE TO AEROSOLS7
In the last paragraph of her recent paper, Reck (1974) considers some measurements I made of the effects of a tropospheric dust suspension on the thermal radiation received at the earths surface (Idso, 1973). She speculates *BARNES R. A. (1975) Atmospheric Environment 9, 131-133. 7 RECK RUTH A. (1974) Atmospheric Environment 8, 823-833.
Discussions
It is our suspicion that even today most SO2 is emitted in rural areas and (since man occupies only a small percentage of the U.S. area) most of our air spends most of its time in rural settings. If this suspicion is true, then Dr. Altshuller’s mechanism for urban conversion of rural SO2 might not be operative. 3. With italics added and a change of phrase, Dr. Altshuller has stated our intention precisely: “consistent control of sulfur oxides on a regional basis is needed. That is, control of sulfur oxides (only in cities) may not be satisfactory.” We agree that the data only suggests this and that support of this statement awaits further evidence. 4. The final discussion precisely states the challenge for future experimentation. “The important point is the lack of an adequate experimental basis to differentiate among important sources as to their impact on a regional scale.” With regard to the regional scale, the relevance of the RAPS project may be limited by two factors. (a) The area covered is hardly regional, or large enough for study of SO2 kinetics over times larger than the transit time across the city, i.e., a few hours. Many current guesses suggest a reaction time constant of It&l00 h for SO, oxidation. (b) The sulfate concentrations within an air mass upon arrival at St. Louis may interfere with making any clear-cut conclusions about mechanisms within specific plumes. We suggest that the mechanisms should also be investigated over large spatial areas where and when the plumes are dispersed into “clean” air masses unaffected by a history of anthropogenic.sources, e.g. the west coast which often experiences maritime air masses. Finally, we have recently found two relationships which relate to these comments. Each of them emphasizes that air mass history is the proper framework for discussion. (a) In reference to comment (1) we have found that sulfate concentration is highly correlated (I = 0.73) to light scattering (b,,) in Sweden when the air mass came from the European industrial areas. With reasonable assumptions regarding SOi- size distribution, sulfate alone could be the major and even in some cases the sole cause of turbidity. (b) In reference to comment (4) the occurrence of ammonium sulfate is correlated with a polar continental air mass and the occurrence of the acids is correlated with a tropical marine air mass. This suggests that an effective sampling network would be positioned along the average trajectory for these air masses and would spatially extend for thousands of kilometers. This would enable monitoring the evolution of changing concentrations as sources add sulfur dioxide and sink mechanisms remove it. Department of Civil Engineering, Water and Air Resources Division, University of Washington, Seattle, Washington 98195, U.S.A.
A. H. VANDERPOL R. J. CHARLS~N A. P. WAGGONER D. S. COVERT N. C. AHLQUIST
A SIMPLE
SAMPLER
TO MONITOR SULPHUR A CEMENT WORKS*
OXIDE
EMISSIONS
FROM
The cooling water inlet to the Graham condenser is shown connected to the upper tubulation, with the drain at the bottom, This arrangement is not common, and deserves verification. In the arrangement shown in Fig. 1, it would appear that one loses the advantage of counter-current thermal gradients in the condenser, may be subjecting the top ring-seal of the condenser to excessive thermal shocks, and may have difficulties from air-lock expelling most of the coolant from the condenser. Since the cooling water entrains large volumes of air from the ejector pump, this last difficulty would seem to be serious. L. TODD REYNOLDS
Colorado Department of Health, 4210 E. 11th Avenue,
Denver, Colorado 80220, U.S.A.
AUTHOR’S
REPLY
The water flow arrangements through the condenser are verified and explained in the text. Although Dr. Reynolds comments appear theoretically sound, trial and error has shown the apparatus illustrated in Fig. 1 to offer the most satisfactory combination of gas sampling rate and cooling. The only modification that has been found necessary in over 300 h of use is the installation of a silica-gel drying tower between the Drechsel bottle and gas meter. “GRENDON”, Brackendak, Potters Bar, Hertfordshire
ON THE INFLUENCE ATMOSPHERIC
R. A.
OF SURFACE ALBEDO RADIATION BALANCE
BARNES
ON THE CHANGE IN THE DUE TO AEROSOLS7
In the last paragraph of her recent paper, Reck (1974) considers some measurements I made of the effects of a tropospheric dust suspension on the thermal radiation received at the earths surface (Idso, 1973). She speculates *BARNES R. A. (1975) Atmospheric Environment 9, 131-133. 7 RECK RUTH A. (1974) Atmospheric Environment 8, 823-833.