Showing papers by "Paul J. Crutzen published in 1986"

Nitric acid cloud formation in the cold Antarctic stratosphere: a major cause for the springtime ‘ozone hole’

Abstract: Large depletions in stratospheric ozone were first reported by Farman et al [1] at Halley Bay (76 °S), and confirmed by satellite observations [2] Chubachi [3] gives a detailed account of ozone decreases and temperatures in the lower stratosphere during the spring of 1982 at 69 °S There is now evidence [2] for annual declines in total ozone by ~6 and 3 % in regions of total ozone minima and maxima, respectively, from September to mid-October since the late 1970s We propose here a chemical mechanism for the formation of the ozone hole It involves removal of gaseous odd nitrogen by ion- and/or aerosol-catalysed conversion of N2O5 and ClONO2 to HNO3 vapour, followed by heteromolecular HNO3–H2O condensation, leading to HNO3–H2O aerosols At an altitude of 17 km, these processes start at temperatures below 205 ± 5 K, well above the condensation temperature of pure water vapour We propose that the absence of gaseous odd nitrogen and catalytic methane oxidation reactions driven by sunlight in early spring lead to large OH concentrations which rapidly convert HCl to ClOX Catalytic reactions of ClOX and BrOX cause drastic ozone destructions and can account for the springtime ‘ozone hole’ first observed by Farman et al [1] By our model the depletion would be mainly due to emissions of industrial organic chlorine compounds Arctic regions may also become affected The depletion lasts while HNO3, but not HCl, is incorporated in the particles in the temperature range 205 ± 5 to 192 K

Methane production by domestic animals, wild ruminants, other herbivorous fauna, and humans

Abstract: A detailed assessment of global methane production through enteric fermentation by domestic animals and humans is presented. Measured relations between feed intake and methane yields for animal species are combined with population statistics to deduce a current yearly input of methane to the atmosphere of 74 Tg (1 Tg = 10 12 g). with an uncertainty of about 15%. Of this, cattle contribute about 74%. Buffalos and sheep each account for 8-9%, and the remainder stems from camels, mules and asses, pigs, and horses. Human CH 4 production is probably less than 1 Tg per year. The mean annual increase in CH 4 emission from domestic animals and humans over the past 20 years has been 0.6 Tg, or 0.75% per year. Population figures on wild ruminants are so uncertain that calculated CH, emissions from this source may range between 2 Tg and 6 Tg per year. Current CH 4 emission by domestic and wild animals is estimated to be about 78 Tg, representing 15-25% of the total CH 4 released to the atmosphere from all sources. The likely CH 4 production from domestic animals in 1890 was about 17 Tg, so that this source has increased by a factor of 4.4. A brief tentative discussion is also given on the potential CH 4 production by other herbivorous fauna, especially insects. Their total CH 4 production probably does not exceed 30 Tg annually. DOI: 10.1111/j.1600-0889.1986.tb00193.x

Atmospheric Conditions After a Nuclear War

Abstract: During a full scale nuclear war, the atmosphere would be loaded with huge quantities of pollutants, which are produced by fires in urban and industrial centers, cultivated lands, forests and grasslands. Especially detrimental are the meteorological effects of light absorbing airborne particles. Estimates are presented of the amounts of various types of fuels which would burn in the event of a maor war and of the resulting particulate matter production. The fires could produce several hundred million tons of airborne particulate matter, by which the penetration of sunlight to the earth's surface would be reduced greatly over extended areas of the northern hemisphere, maybe even globally. This could temporarily reduce crop growth and bisopheric producitivity in important ways. This situation would last for several weeks and cause very anomalous meteorological conditions. Much solar radiation would be absorbed in the atmosphere instead of at the earth's surface. The land areas and lower atmosphere would, therefore, cool and the overlying atmosphere warm, creating strong vertical thermal stability in a highly polluted atmosphere. For extended periods, worldwide weather patterns would be abnormal. The resulting could, probably freezing, temperatures a the ground could also interfere severely with crop production during the growing season and cause extreme conditions for large sections of the biosphere. The combination of lack of sunlight, cold temperatures and other abnormal meteorological conditions would add enormously to the already huge problems of the survivors.

Inconsistencies in Current Photochemical Models Deduced from Considerations of the Ozone Budget

Abstract: During the last decade there have been varying predictions for an expected decrease of total atmospheric ozone through catalytic photochemical processes caused by human activities such as release of various chlorinated hydrocarbons, operation of high-altitude aircraft or use of mineral fertilizers. In the last years the picture has been broadened by consideration of photochemical ozone production in the troposphere, which can compensate for some of the stratospheric ozone depletion. This process is sensitive to injection of methane and nitrogen oxides into the troposphere. Recently, it has also been pointed out that an increase of CO2 can increase stratospheric ozone by decreasing the temperature in the stratosphere. While model scenarios predict changes for total ozone between +0.5% and -1.5% until the year 1980, a statistical analysis of total ozone measurements gives a slightly positive trend with most probable values below 0.5%.

Globale Aspekte der atmosphärischen Chemie: Natürliche und anthropogene Einflüsse

Abstract: Die Zusammensetzung der Atmosphare wird zu einem betrachtlichen Teil durch biologische Prozesse bestimmt. Dies gilt auch fur die am haufigsten vorkommenden atmospharischen Gase, N2 und O2, deren Volumenmischungsverhaltnisse etwa 78% und 21% betragen. Da die jahrliche Netto-Aufnahme und Abgabe dieser Gase an der Erdoberflache viel kleiner ist als deren atmospharisches Reservoir, betragen die Lebenszeiten beider Gase einige 10000 Jahre. Demzufolge sind innerhalb der Zeitspanne von Jahrzehnten oder Jahrhunderten keine nennenswerten Anderungen der Mischungsverhaltnisse dieser Gase zu erwarten. Da photochemische Prozesse, die N2 und O2 angreifen, in den untersten 100 km der Atmosphare vergleichsweise langsam ablaufen, sind diese Gase in der gesamten Atmosphare bis zu einer Hohe von etwa 100 km gleichmasig durchmischt. In diesem Artikel werden wir uns hauptsachlich auf Gase mit viel kurzeren Lebenszeiten konzentrieren, und N2 und O2 als konstante „Background“-Gase ansehen. Zwei in geringen Mengen auftretende Reaktionsprodukte von N2 und O2, namlich das NO und das O3, sind fur die atmospharische Chemie von groser Bedeutung.