problems; and, third, it is important to coordinate federal-state actions to avoid o r alleviate groundwater prob- lems. This is particularly true a s EPA and the states a re about to launch the Resources Conservation and Recovery Act ( R C R A ) and Underground In- jection Control ( U I C ) programs, and a re looking hopefully to the passage of the Superfund legislation.

With the new initiative and con- centrated effort in attempting to pre- vent a problem with enormous health implications from becoming a reality. the EPA will be living up to its man- date.

ES&T is to be congratulated for running the groundwater article and keeping this issue before the public. blarion-bllay U S . EPA, Office of Water and Waste Management Washington,b.C. 20460

Atmospheric mixing Dear Sir: The article “Atmospheric

mixing” (ES& T, January 1980, p 15) gives a somewhat incomplete descrip- tion of research efforts tha t have con- tributed to current understanding of the transport processes by w h ic h ozone-rich air from the stratosphere

can rapidly intrude into the tropo- sphere. This correspondence is in- tended to provide an expanded over- view of tha t research.

The concept of tropopause folding appears in the literature as early as 1937. However, it was not until 1955 that Reed ( I ) presented rather con- vincing evidence tha t tropopause folding involved transport of strato- spheric air into the troposphere. Dur- ing the 1960s. tropopause folding was extensively researched by Danielsen (2) and Reiter (3) in connection with airborne measurements of the trans- port of radioactive debris from the stratosphere into the troposphere. I n 1970, Danielsen ( 4 ) published aircraft da ta that showed the transport of high concentrations of stratospheric ozone through the tropopause fold.

These researchers found tropopause folding to be associated with low- pressure systems and jet streams in the upper troposphere. Over the conti- nental United States, such weather systems occur frequently during winter and spring, and generally move from west t o east under the influence of the prevailing westerly winds. In 1973, Mahlman ( 5 ) computed the a i r cir- culation associated with a jet stream. It showed strong downward motion

from the stratosphere to the lower troposphere on the north side of the jet core. This downward branch trans- ports the natural ozone as observed by Danielsen.

I n addition to Shapiro’s spring 1978 flight program, another experimental program was carried out in the spring and fall of 1978 by S R I International and results published (6, 7 ) . This pro- gram, sponsored bq the Air Pollution Research Advisory Committee of the Coordinating Research Council, Inc., investigated by instrumented aircraft several cases of tropopause folding and stratospheric/tropospheric ozone transport in areas east of the Rocky Mountains, \I here the occurrence and organization of such events had never been documented. In one case observed during October 1978, the stratospheric ozone intrusion penetrated down to 2 km above ground level. A t this time, the fa te of intrusions below 2 km re- mains unexplored. S R I , however, is continuing its research on the impact of stratospheric ozone on ground level measurements, as a re several other researchers. (1) Reed, R. J., “A Study of a Characteristic Type of Upper Level Frontogenesis,” J Meteorol 1955,12, 226-37.

continued on page 631

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Volume 14, Number 6, June 1980 629

( 2 ) Danielsen, E. F., “Stratospheric-Tro- pospheric Exchange Based on Radioactivity, Ozone, and Potential Vorticity,” J . Atmos. Sci. 1968,25, 502-18. (3) Reiter, E. R., “A Case Study of Radio- active Fallout,” J . Appi . Meteorol. 1963, 2 (6), 691-705. (4) Danielsen, E. F.; Bleck, R.; Shedlovsky, J.; Wartburg, A,; Haagenson, P.; Pollock, W., “Observed Distribution of Radioactivity, Ozone, and Potential Vorticity Associated with Tro-Dooause Foldine.” J . Geoahvs. Res. ‘ . 1970, 75 I l i ) , 2353-61. ( 5 ) Mahlman, J. D.. “On the Maintenance of the Polar Front Jet S t ream,”J . Atmos Sti 1973,30, 544-56. (6) Johnson. W. B.: Viezee. W.: Cavanaeh. L.: Ludwig, F. L.; Singh, H. n.; Danielsen,-E. F., “Measurements of Stratospheric Ozone Penetrations Into the Lower Troposphere,” Proceedings of the 4th Symposium on Tur- bulence and Diffusion, p. 355-62, Boston, Mass. January 1979; American Meteorolog- ical Societv. ( 7 ) Viezee, W.; Johnson, W. B.; Singh, H. B.. “Airborne Measurements of Stratospheric Ozone Intrusions Into the Troposphere Over the United States,” Final Report, Volume I. Contract CRC-APRAC Project No. CAPA- 15-76 (1-77), 219 Perimeter Center Parkway, Atlanta, Ga., September 1979; Coordinating Research Council, Inc. William Viezee Warren B. Johnson Hanwant B. Singh SRI International Menlo Park. Calif. 94025

Alcohol fuel Dear Sir: Your discussion of gasohol

(ES& T, February 1980, p 140) omits three items which promise to be im- portant to the energy input required to produce fuel and which I would like to see discussed.

( I ) W h a t is the comparison with octane boosters? Alcohols increase octane without lead and without en- ergy-intensive refining. Hut what are the numbers?

(2) Alcohols can be separated from the mash catalytically; again, what are the numbers and who is developing the technology?

(3) Solar energy can very conve- niently be used on a small scale by farmers both for distillation and for drying. Paul Butkerert Freeport, N.Y. 11520

Marine pollution Dear Sir: This is an expression of

our appreciation for the fine job you and your colleagues did on our article on marine pollution ( E S & T, January 1980, p 32). The organization you in- troduced in the representation of fig- ures and tables was particularly grat- ifying. Donald C. Malins Director Northwest and Alaska Fisheries Center Seattle, Wash. 98 1 12

Volume 14, Number 6, June 1980 631