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1.
Regulations to limit the use of trichloroethylene as a degreasing solvent have led to an increased use of the more photochemically inert solvent methyl chloroform as a substitute. Model calculations show that about 15 percent of the methyl chloroform released into the atmosphere will reach the stratosphere. Time scenarios based on past production figures and reasonable projections for future release rates lead to a steady-state ozone depletion due to this solvent about 20 percent as large as those resulting from the continuous release of chlorofluoromethanes at 1973 rates. 相似文献
2.
The concentrations of two industrially produced chlorofluoromethanes, CCl(3)F(F-11) and CCl(2)F(2)(F-12), have been measured in the water column and in the marine atmosphere of the Greenland and Norwegian seas. Measurable concentrations of these two chlorofluoromethanes have penetrated to the deep basins of both of these regions, and the general characteristics of their vertical distributions are similar to those of the bomb-produced radioisotopes injected into the atmosphere on a similar time scale. The data have been fitted to a time-dependent box model based on deep convective mixing in the Greenland Sea and lateral exchange between the deep basins. The model calculations for the two chlorofluoromethanes in the Greenland Sea give similar results, with a time scale for deep convection of about 40 years. The time scale for lateral mixing between the deep Greenland Sea and the deep Norwegian Sea is estimated to be 20 to 30 years, although the agreement between the calculations for the two chlorofluoromethanes is limited by analytical uncertainties at the low concentrations found in the deep Norwegian Sea and by uncertainties in the model assumptions. 相似文献
3.
利用Brewer分光光谱仪观测资料分析青藏高原拉萨站近几年大气臭氧的变化特征,结果表明,拉萨上空臭氧主要分布在15~35 km,反演结果的峰值出现在21~25 km。对比拉萨四季臭氧垂直分布发现,它们在平流层中上层的差异不大,且在36 km以上的分布大致相同,差异主要表现在从地面到21 km,冬春季的臭氧数密度大于夏秋季,近4年来拉萨的年平均臭氧总量的变化不大,臭氧总量的极值出现在冬春季节,臭氧总量的月平均值在8和9月较低,2008年6~9月臭氧低值的持续时间是近几年中最长的,达23 d。 相似文献
4.
为探索臭氧处理对冷库贮藏白菜的品质影响,在固定臭氧处理频率为1次·d-1的条件下,分别研究不同臭氧处理浓度、处理时间对冷库贮藏白菜主要品质指标变化的影响。结果表明,臭氧处理能够有效抑制白菜的呼吸强度,减缓白菜的Vc含量、叶绿素含量在贮藏期间的下降,降低贮藏失重率,最佳臭氧浓度为12.84mg·m-3,处理时间为30min。 相似文献
5.
为了揭示臭氧(O3)浓度升高对城市森林光合作用的影响机理,利用开顶式气室研究了高浓度O3对沈阳城内油松光合生理特性的影响。结果表明:与对照(自然O3浓度,约45 nmol/mol)相比,在O3浓度升高(80±8)nmol/mol条件下,油松针叶的叶绿素含量降低,而类胡萝卜素含量则呈现出先升高后降低的变化趋势;净光合速率和Hill反应活力明显下降,降幅分别为18.36%~45.95%和11.35%~20.84%;羧化效率降低,降幅为7.50%~26.59%;叶绿体ATP酶活性受到抑制,但Ca2+-ATP酶活性与Mg2+-ATP酶活性的变化趋势略有差异。同时O3浓度升高抑制了油松针叶可溶性糖和淀粉含量的积累,说明O3浓度升高对油松光合作用具有较强的抑制作用。 相似文献
6.
为了揭示臭氧（O3）浓度升高对城市森林光合作用的影响机理,利用开顶式气室研究了高浓度O3对沈阳城内油松光合生理特性的影响。结果表明:与对照（自然O3浓度,约45 nmol/mol）相比,在O3浓度升高（80±8 ）nmol/mol条件下,油松针叶的叶绿素含量降低,而类胡萝卜素含量则呈现出先升高后降低的变化趋势;净光合速率和Hill反应活力明显下降,降幅分别为18.36%～45.95%和11.35%～20.84%;羧化效率降低,降幅为7.50%～26.59%;叶绿体ATP酶活性受到抑制,但Ca2+ ATP酶活性与Mg2+ ATP酶活性的变化趋势略有差异。同时O3浓度升高抑制了油松针叶可溶性糖和淀粉含量的积累,说明O3浓度升高对油松光合作用具有较强的抑制作用。 相似文献
7.
Brune WH Anderson JG Toohey DW Fahey DW Kawa SR Jones RL McKenna DS Poole LR 《Science (New York, N.Y.)》1991,252(5010):1260-1266
The nature of the Arctic polar stratosphere is observed to be similar in many respects to that of the Antarctic polar stratosphere, where an ozone hole has been identified. Most of the available chlorine (HCl and ClONO(2)) was converted by reactions on polar stratospheric clouds to reactive ClO and Cl(2)O(2) throughout the Arctic polar vortex before midwinter. Reactive nitrogen was converted to HNO(3), and some, with spatial inhomogeneity, fell out of the stratosphere. These chemical changes ensured characteristic ozone losses of 10 to 15% at altitudes inside the polar vortex where polar stratospheric clouds had occurred. These local losses can translate into 5 to 8% losses in the vertical column abundance of ozone. As the amount of stratospheric chlorine inevitably increases by 50% over the next two decades, ozone losses recognizable as an ozone hole may well appear. 相似文献
8.
The role of biogenic hydrocarbons in urban photochemical smog: Atlanta as a case study 总被引：35，自引：0，他引：35
The effects of natural hydrocarbons must be considered in order to develop a reliable plan for reducing ozone in the urban atmosphere. Trees can emit significant quantities of hydrocarbons to metropolitan areas such as Atlanta, and model calculations indicate that these natural emissions can significantly affect urban ozone levels. By neglecting these compounds, previous investigators may have overestimated the effectiveness of an ozone abatement strategy based on reducing anthropogenic hydrocarbons. 相似文献
9.
The chlorofluoromethanes (CFMs: CCl(2)F(2) and CCl(3)F), methyl chloroform (CH(3)CCl(3)), and carbon tetrachloride (CCl(4)) have been measured in deep waters of the Arctic Ocean. Oceanic and atmospheric inventories of these compounds result from known anthropogenic releases; because the CFMs and CCl(4) are also chemically nonreactive, they can be used as transient tracers of ocean circulation. The input history of CCl(4) is longer than that of any other transient tracer identified to date( approximately 70 years). This long input history, together with an e-folding time scale of increase(tau) of approximately 28 years, makes CCl(4) potentially the most useful tracer for calibrating models of the oceanic uptake of the fossil-fuel CO(2) transient(tau approximately 25 years). The bottom water of the Nansen Basin, Arctic Ocean, has detectable CCl(4) but undetectable CFM(s) and CH(3)CCl(3), which suggests either that the bottom water is approximately 50 years old, or that there is a small, nonanthropogenic component of atmospheric CCl(4)(<6 parts per trillion by volume). 相似文献
10.
基于 ZigBee 的无线传感器网络自动控制臭氧气体浓度的技术,实现食品的保鲜贮藏.该控制系统主要由传感器、无线传感器网络、臭氧发生器等环境调节设备、计算机组成.实验显示无线传感器网络能够实现自动控制臭氧保鲜,臭氧气体浓度值及环境的温度、湿度值等信息,经过无线传感器节点、无线协调节点,传递到计算机;计算机决策的控制信息传递回相应的无线传感器节点,控制环境调节设备.在循环休眠模式下,通过选取合适的休眠及工作时间,实现了具有输出控制作用的无线传感器节点的节能. 相似文献
11.
采用臭氧工艺,对氨法脱硫的主要副产物亚硫酸铵进行了氧化试验研究,结果表明：在试验范围内,臭氧对高浓度亚硫酸铵具有较好氧化效果,氧化速率随着臭氧质量浓度的升高而增加,随着亚硫酸铵浓度的升高而降低,而循环流量对氧化效果影响不大,温度对氧化效果也有一定影响。在亚硫酸铵初始浓度不超过2 mol/L时,120 min内转化率基本可达到100%,亚硫酸铵完全氧化能耗约为0.5kW.h/kg,显示出良好工业应用前景。 相似文献
12.
Evidence obtained by means of rubber strip tests and an ozone recorder indicates the presence of abnormal concentrations of ozone in the atmosphere at times. Excellent correlation was obtained between appearance of "weather fleck" in tobacco and high values for ozone. The great similarity between lesions occurring naturally and those produced by ozone in chambers also indicates that ozone is the probable inciting agent of weather fleck. Varietal differences exist. Study of stomatal action helped to explain variation in leaf injury. 相似文献
13.
A curious and unambiguous event of excess ozone formation downwind of a power plant has been analyzed. A kinetic model used to simulate the event indicates that the excess ozone can be reconciled entirely on the basis of excess nitrogen oxides in the polluted air. 相似文献
14.
Harrison H 《Science (New York, N.Y.)》1970,170(3959):734-736
Simple, steady-state models for ozone photochemistry, radiative heat balance, and eddy-diffusive mass transport can be combined to estimate water-induced changes in the stratospheric ozone concentrations and temperatures, the integrated ozone column, the solar power transmitted to the earth's surface, and the surface temperature. These changes have been computed parametrically for mixing fractions of water vapor between 3 x 10(-6) and 6.5 x 10(-6). With added water from the exhausts of projected fleets of stratospheric aircraft, the ozone column may diminish by 3.8 percent, the transmitted solar power increase by 0.07 percent, and the surface temperature rise by 0.04 degrees K in the Northern Hemisphere. Due to a cancellation of terms, temperatures in the lower stratosphere remain essentially unchanged. These results are sensitive to the form of the water profile and emphasize the potential role of convective transients near 30 kilometers. 相似文献
15.
为解决鱼糜漂洗工艺中用水量过大的问题,以及研究臭氧漂洗工艺对鱼糜品质的影响,以鲢鱼肉为原料,采用传统漂洗、一次臭氧漂洗、自来水-臭氧水混合漂洗制备鱼糜,研究臭氧漂洗方式对鲢鱼糜凝胶强度、色度及不良气味的影响。结果显示,羰基含量随臭氧浓度的增加而增加,一次臭氧漂洗的鱼糜中的羰基含量高于传统漂洗和混合漂洗的鱼糜,〖JP+2〗表明一次臭氧漂洗的鱼糜蛋白的氧化程度较高,鱼糜蛋白形成较多的聚集,鱼糜凝胶性能较差;混合漂洗可以减少脂肪氧化、降低臭氧对鱼糜蛋白的氧化程度、提高鱼糜白度以及凝胶强度、且臭氧质量浓度为8 mg/L的混合漂洗能有效改善鱼糜品质。同时,用水量减少了1/3,达到了节水漂洗的目的。 相似文献
16.
臭氧抑制木材表面光化降解的机理 总被引：1，自引：0，他引：1
本文用臭氧溅射椴木单板表面,结果表明:实施这种处理后的木材表面形成一层高氧层(氧含量高于素材),在紫外光的辐射下,集聚在该层中的臭氧也将参与木材表面的自由基反应,这大大减少了原来素材表面的氧参与自由基反应的机会,进而达到抑制木材表面光化降解之目的。 相似文献
17.
The amount of ozone formed in air exposed to a 4000-curie cobalt-60 radiation source was determined. In closed glass containers exposed to about I Mrad of gamma radiation, ozone concentrations up to 18 parts per million (by volume) were recorded. In air flowing through a glass structure placed near the source, ozone contents up to 0.1 parts per million were observed. It is suggested that ozone formation might be a factor in the reported germicidal effects of ionizing radiations and that damage to plant tissues, ascribed to radiation, might have resulted from exposure to ozone. The possible health hazards from the ozone produced during irradiation should not be overlooked. 相似文献
18.
Severe reduction of stratospheric ozone over Antarctica has focused increasing concern on the biological effects of ultraviolet-B (UVB) radiation (280 to 320 nanometers). Measurements of photosynthesis from an experimental system, in which phytoplankton are exposed to a broad range of irradiance treatments, are fit to an analytical model to provide the spectral biological weighting function that can be used to predict the short-term effects of ozone depletion on aquatic photosynthesis. Results show that UVA (320 to 400 nanometers) significantly inhibits the photosynthesis of a marine diatom and a dinoflagellate, and that the effects of UVB are even more severe. Application of the model suggests that the Antarctic ozone hole might reduce near-surface photosynthesis by 12 to 15 percent, but less so at depth. The experimental system makes possible routine estimation of spectral weightings for natural phytoplankton. 相似文献
19.
冬枣湿冷保鲜技术的试验研究 总被引：19，自引：0，他引：19
研究了湿冷条件下，不同采收期、不同成熟度冬枣的耐贮性，比较了鲜枣保鲜剂和臭氧的杀菌、抑菌作用。试验结果表明，湿冷保鲜和臭氧杀菌技术能有效地延长冬枣的贮藏寿命，提高冬枣产业的经济效益。 相似文献
20.
Turco RP Toon OB Park C Whitten RC Pollack JB Noerdlinger P 《Science (New York, N.Y.)》1981,214(4516):19-23
In 1908, when the giant Tunguska meteor disintegrated in the earth's atmosphere over Siberia, it may have generated as much as 30 million metric tons of nitric oxide (NO) in the stratosphere and mesosphere. The photochemical aftereffects of the event have been simulated using a comprehensive model of atmospheric trace composition. Calculations indicate that up to 45 percent of the ozone in the Northern Hemisphere may have been depleted by Tunguska's nitric oxide cloud early in 1909 and large ozone reductions may have persisted until 1912. Measurements of atmospheric transparentiy by the Smithsonian Astrophysical Observatory for the years 1909 to 1911 show evidence of a steady ozone recovery from unusually low levels in early 1909, implying a total ozone deficit of 30 +/- 15 percent. The coincidence in time between the observed ozone recovery and the Tunguska meteor fall indicates that the event may provide a test of current ozone depletion theories. 相似文献