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Izrael (left) and Train
gical Service of the U.S.S.R., re viewed the progress made by the joint committee so far this year. Among other things, they say that a team is measuring stratospheric aerosols at Rylsk, U.S.S.R., using both U.S. and Soviet equipment. Another team spent two months on a cruise along the Gulf Stream and the Gulf of Mexico to calibrate equipment, methodology, and tech niques of determining marine pol lutants and their effect on primary production of phytoplankton. A third team spent time along the San Andreas fault in California and in Central Asia to experiment with equipment that would im prove the ability to predict earth quakes and reduce earthquake haz ards. Earthquake prediction experi ments will continue in 1976. Further, there will be more balloon trials in the stratosphere next year, with emphasis on understanding the role of aerosols in climate. Train stresses that neither side is benefiting more from the joint co operation than the other. In any broad agreement such as this one, there are. inevitably areas where one side may be more advanced than the other, he points out. The cooperation should be viewed on the basis of equality, reciprocity, and mutual benefit, Train says. D
More evidence adds to ozone controversy More evidence has come in to indi cate that the rate of ozone deple tion by chlorofluorocarbons in the stratosphere may be only half as rapid as previously supposed. The current work was carried out by scientists at the National Bureau of Standards. Earlier, researchers at the University of Maryland, the University of Pittsburgh, and Queen Mary College, London, had come up with similar findings. Working at NBS laboratories in Gaithersburg, Md., outside Wash ington, D.C., chemists Michael J. Kurylo and Walter Braun find, for example, that at 25° C the rate of 8
C&EN Nov. 3, 1975
reaction between chlorine and ozone is only 60% of the value origi nally used by University of Califor nia scientists to predict ozone de pletion in the stratosphere. At -50° C, the NBS researchers say, the re action rate is only 44% that of the old value. Stratospheric tempera tures range from 0 to -70° C. Kurylo and Braun calculated the reaction rate constant for chlorine with ozone at several temperatures and pressures found in the strato sphere. They made measurements by a flash photolysis resonance flu orescence technique developed by Braun at NBS in 1967. Central to the chlorofluorocarbon controversy is a theory put forth in 1974 by chemists F. Sherwood Rowland and Mario J. Molina of the University of California, Irvine, that chlorofluorocarbons are broken down in the earth's stratosphere by high-energy ultraviolet light. Chlo rine atoms thus produced, accord ing to the theory, enter into a chain reaction that destroys the strato spheric ozone that shields the earth from harmful ultraviolet radiation. Chlorofluorocarbons are used wide ly as propellants in aerosol spray cans, and as refrigerants. Rowland, one of the original pro ponents of the depletion theory, discounts the latest findings. For one thing, he points out that the new data from NBS are not much different from data produced by the Maryland, Pittsburgh, and Queen Mary College researchers. "I be lieve that this does not change any thing at all," Rowland declares. "If one were to change only the reaction rate," he notes, "then it would reduce the estimated ozone depletion." But recent calculations of ozone depletion in the strato sphere have taken into account lower reaction rates, and the calcu lations "have hardly changed." Measurements of ancillary chemi cal species produced by chlorofluo rocarbon degradation in the strato sphere, Rowland believes, easily offset any decrease in the ozone de pletion brought about by factoring in lower chlorine-ozone reaction rates. •
Giant kelp farms could yield methane Macrocystis pyrifera is alive and well and growing in the ocean off the coast of California. That means that a type of giant kelp is now being grown successfully, and, if current projections are realized, it could provide large amounts of
biomass that, in turn, could be converted to methane. At the Seventh Synthetic Pipe line Gas Symposium in Chicago last week, Dr. Howard A. Wilcox of the Naval Undersea Center in San Diego described progress in the first phase of the ocean farm project. The project is funded jointly by the American Gas Association, the Navy, the National Science Foun dation, and the Energy Research & Development Administration. The first phase, costing $3.79 million, will run through 1978. The object is to demonstrate technical feasibility of growing and converting kelp to methane via anaerobic fermenta tion. In addition to biomass, har vested kelp has value as livestock feed and as a source of fertilizer. So far, the project has determined that the desired variety of kelp can be germinated in the laboratory and transplanted suc cessfully in the ocean on polypro pylene grids in deep water. Two test farms are now in operation, one near Catalina Island and the other near Corona del Mar. It also has been demonstrated that harvested kelp can be inexpensively dewatered by acid washing and mechanical compression. The energy cost of this crucial step is about 6% of the total energy in the kelp. Anaerobic fermentation of the kelp is now under study. And a contract is being negotiated with the Institute of Gas Technology to develop the industrial technique for the process, which already has been used successfully elsewhere. Most of the photochemical ener gy required for marine plants is trapped in the ocean within 500 feet of the surface. However, the nutrients, primarily phosphates and nitrates, are in deeper water. The idea behind the ocean farm project is to provide controlled mix ing of the energy and nutrient layers for optimum growth of the kelp. Projections indicate that a theo retical maximum of about 7000 tril lion scf of methane per year could be produced through ocean farm ing. Present U.S. demand is about 23 trillion scf. If, as expected, this first phase is completed successfully in 1978, it will be followed by a second phase, which will prove the concept with two 1000-acre farms, one in the At lantic and another in the Pacific. This phase would last three to five years and cost about $50 million. The final phase, commercial dem onstration, would take another three to five years and cost about $2 billion. D
