Showing papers by "Paul J. Crutzen published in 1978"
TL;DR: In this paper, the authors derived from extensive field measurements on foliar emissions in the U.S. approximate global inputs of isoprene and terpenes of 3.5 times 10 to 14th power and 4.8 times 10-14th power g(C)/yr, respectively.
Abstract: Extrapolating from extensive field measurements on foliar emissions in the U.S. approximate global inputs of isoprene and terpenes of 3.5 times 10 to the 14th power and 4.8 times 10 to the 14th power g(C)/yr, respectively, are obtained. The oxidation of these hydrocarbons could contribute in an important way to the atmospheric sources of CO (4.2-13.3 times 10 to the 14th power g/yr) and H2 (10-35 times 10 to the 12th power g/yr), and to organic species soluble in rainwater
361 citations
TL;DR: In this article, the authors examined the distribution of tropospheric ozone and found that surface destruction in the Northern Hemisphere (NH) should be about three times larger than in the Southern Hemisphere (SH).
Abstract: Examination of the distribution of tropospheric ozone indicates that surface destruction in the Northern Hemisphere (NH) should be about three times larger than in the Southern Hemisphere (SH). If, according to the traditional understanding of ozone, this species were a passive tracer in the troposphere, a threefold larger flux out of the stratosphere should exist in the NH than in the SH. However, meteorological analyses fail to support such pronounced hemispheric differences in stratosphere-troposphere exchange. Alternatively, therefore, it is hypothesized that photochemical synthesis of ozone in the troposphere may be particularly important in the NH because of asymmetries in the sources and distribution of carbon monoxide, hydrocarbons and nitric oxide.
301 citations
TL;DR: In this article, a theoretical estimate of the present and the possible future impact of large sections of the chlorocarbon industry on the ozone layer was given by means of calculations with a one-dimensional photochemical-diffusive model of the atmosphere.
Abstract: By means of calculations with a one-dimensional photochemical-diffusive model of the atmosphere a theoretical estimate is given of the present and the possible future impact of large sections of the chlorocarbon industry on the ozone layer. Our estimates for 1976 are that past chlorocarbon emissions may be responsible for a 1.5% reduction in the global total ozone content (0.8% by CFCl3 and CF2Cl2, 0.5% by CCl4, and 0.2% by CH3CCl3). This estimate was obtained by comparison with the ozone content of a model atmosphere without industrial chlorocarbon emissions. The effect of the nonindustrial gas CH3Cl can best be described by stating that without CH3Cl, there would be almost 1% more ozone in the atmosphere. Considerable attention should also be given to the atmospheric effects of expanding uses of CH3CCl3. The potential impact on the ozone layer of CHFCl2 and CHF2Cl emissions is also discussed. However, there are too many uncertainties regarding the tropospheric concentrations of OH and its role as a scavenger to assess the effect of a number of chlorocarbon compounds reliably. The effect of other chlorocarbon compounds (C2Cl4, C2HCl3, C2H5Cl, C2H4Cl2, CHCl3) on the ozone layer is estimated as being comparatively negligible. Model-calculated vertical distributions of a large number of constituents are compared with observations. Substantial deviations between some theoretical and reported concentrations exist, especially for NOx, CO, and ClO. Uncertainties in our knowledge of stratospheric chemistry are discussed. It is concluded that these uncertainties are sufficiently numerous to take the given predictions of ozone reductions with some reservations.
181 citations
TL;DR: In this article, the passage of the Solar System through a supernova remnant shell was studied quantitatively, using the passage as an example of the potential environmental changes that might have been the cause of mass extinctions in the distant past.
Abstract: High levels of ionising radiation in the Earth's stratosphere will lead to increased concentrations of nitrogen oxides and decreased concentrations of ozone. Changes in the surface environment will include an increased level of biologically harmful UV radiation, caused by the ozone depletion, and a decreased level of visible solar radiation, due to the presence of major enhancements in the stratospheric concentration of nitrogen dioxide. These changes are studied quantitatively, using the passage of the Solar System through a supernova remnant shell as an example. Some of the potential environmental changes are a substantial global cooling, abnormally dry conditions, a reduction in global photosynthesis and a large increase in the flux of atmospheric fixed nitrogen to the surface of the Earth. Such events might have been the cause of mass extinctions in the distant past.
64 citations
TL;DR: In this article, a one-dimensional steady-state, stratospheric model was used to calculate ozone changes coused by atmosphric injections of NOx, N2O and chlorofluoromethanes.
Abstract: With the aid of a one-dimensional steady-state, stratospheric model we have calculated ozone changes coused by atmosphric injections of NOx, N2O and chlorofluoromethanes. Adopting the fast rate constant, for the reaction HO2+NO»OH+NO2 measured by Howard and Evenson, we calculate much smaller perturbations of the ozone layer by NOx and N2O additions than previously estimated, but about two times larger ozone reductions as a result of continued emissions of chlorofluoromethanes, CF2Cl2 and CFCl3. The model results are sensitive to adopted values for the rate coefficients for the reactions HO2+O3»OH+2O2 and OH+HO2»H2O+O2 and the eddy diffusion profile near the tropopause. More accurate assessments of ozone perturbations require the development of photochemical models that incorporate meteorological processes in more than one dimension.
49 citations
TL;DR: The ground level N2O mixing ratio from these measurements was 326 ppbv (parts per billion by volume), referenced to "dry air", and was found to be remarkably constant.
Abstract: Seventy-five ground level and six parachute descent grab samples of tropospheric air have been made at a variety of locations throughout the world over a 6-month period. The N2O mixing ratios in the samples have been determined by electron capture gas chromatography to an absolute accuracy of about 5%, an estimate that is based on the results of several interlaboratory comparisons of calibration standards. The mean ground level N2O mixing ratio from these measurements was 326 ppbv (parts per billion by volume), referenced to ‘dry air,’ and was found to be remarkably constant. The residual standard deviation was 5.3 ppbv. This worldwide mean is consistent with other recent measurements but is considerably larger than many of the earlier measurements. The present data indicate that the N2O residence time in the troposphere is very likely to be greater than 11 years. Furthermore, the data separately show that the possibility of a current annual increase in the N2O mixing ratio by more than 4% seems to be excluded. The parachute descent data, taken just below the tropopause, have a slightly smaller mean, 318 ppbv, but support the contention that the present tropospheric N2O mixing ratio is well above 300 ppbv.
30 citations