| OCR Text |
Show Silver iodide is not a hazard to humans. The design of modern ground- based generators is such that the plume is released fairly high above the ground, and humans would only be exposed to the plume briefly. The Merck Index '" states that silver iodide is the most water- insoluble salt known. As a result of the insolubility of silver iodide and its complexes in water and the brevity of exposure to the plume as it fumigates the surface, there is practically no hazard to people from operation of a silver- iodide generator. Other artificial nucleating agents are ( l) ammonium nitrate- urea mixture, ( 2) sodium chloride, ( 3) solid carbon dioxide ( dry ice), and ( h) acetone. All of these substances except acetone are generally released from aircraft. The concentration of each of these agents would be small, and no measurable adverse environmental impact is expected from the use of these materials. Effects of Increased Precipitation The environmental impacts of increased snowfall are difficult to assess. At the present time scientists are unable to specify the ecological effects cf small year- to- year variations in precipitation. Determination of the effect of a precipitation- management program is even more difficult, since the additional precipitation is an incremental change imposed on a naturally variable condition. The effect of long- term secular climatic trends further complicates assessment of the environmental impact of enhanced precipitation because natural ecosystems respond slowly to changes in environmental parameters. Even though an increase in precipitation could be demonstrated statistically with a high degree of certainty, it might be difficult to detect an environmental change which would be rightfully attributed to the additional precipitation. The difficulty is accentuated by the normal fluctuations in populations of many plant and animal species reported from a wide variety of sites. In any locality snow regularly accumulates more heavily in some areas than in others. It is common for half of the snow in a region to accumulate on 20 percent of the area. Artificially enhanced snowfall 512 |
