Soybean chloroplast responses to enhanced ultraviolet irradiation

1993 ◽  
Vol 51 ◽  
pp. 348-349
Author(s):  
Richard F.E. Crang ◽  
Audrey E. Vassilyev ◽  
Yevgeney A. Miroslavov
Keyword(s):  
Ultraviolet Irradiation ◽  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
Ozone Layer ◽  
Ultraviolet B ◽  
Ambient Conditions ◽  
Greenhouse Soil ◽  
The Past ◽  
Computer Calculations ◽  
Clay Pots

Environmental concerns over the degradation of the earth’s stratospheric ozone layer have been expressed for the past decade in recognition that with ozone depletion, enhanced ultraviolet irradiation will be received at the earth's surface. Such increase in ultraviolet irradiation can be hypothetically determined by making appropriate computer calculations based on proposed cloud cover, season, latitude, elevation, and percent of stratospheric ozone depletion. We have proposed a 40% reduction in the ozone layer corresponding to a daily increase of 19.1 kJ in the limits of ultraviolet-B (UV-B) spectral irradiation (280-320 nm). This is within the range of realistic possibilities based on current estimated ozone depletion rates for the next 40-50 years. We wish to determine the extent to which chloroplasts are ultrastructurally altered compared with those from plants raised under ambient conditions lacking an UV-B irradiation component.Uninoculated seeds of soybean (Glycine max), cv. “Forrest” were sown in standardized greenhouse soil in 4" clay pots, watered daily, and fertilized once per week.

scholarly journals Stratospheric ozone depletion

2006 ◽  
Vol 361 (1469) ◽  
pp. 769-790 ◽  
Author(s):  
F. Sherwood Rowland
Keyword(s):  
Ultraviolet Radiation ◽  
Ozone Depletion ◽  
Biological Activities ◽  
Stratospheric Ozone ◽  
Ozone Layer ◽  
Ultraviolet B ◽  
Montreal Protocol ◽  
Atmospheric Measurements ◽  
Solar Ultraviolet Radiation ◽  
Solar Ultraviolet

Solar ultraviolet radiation creates an ozone layer in the atmosphere which in turn completely absorbs the most energetic fraction of this radiation. This process both warms the air, creating the stratosphere between 15 and 50 km altitude, and protects the biological activities at the Earth's surface from this damaging radiation. In the last half-century, the chemical mechanisms operating within the ozone layer have been shown to include very efficient catalytic chain reactions involving the chemical species HO, HO 2 , NO, NO 2 , Cl and ClO. The NO X and ClO X chains involve the emission at Earth's surface of stable molecules in very low concentration (N 2 O, CCl 2 F 2 , CCl 3 F, etc.) which wander in the atmosphere for as long as a century before absorbing ultraviolet radiation and decomposing to create NO and Cl in the middle of the stratospheric ozone layer. The growing emissions of synthetic chlorofluorocarbon molecules cause a significant diminution in the ozone content of the stratosphere, with the result that more solar ultraviolet-B radiation (290–320 nm wavelength) reaches the surface. This ozone loss occurs in the temperate zone latitudes in all seasons, and especially drastically since the early 1980s in the south polar springtime—the ‘Antarctic ozone hole’. The chemical reactions causing this ozone depletion are primarily based on atomic Cl and ClO, the product of its reaction with ozone. The further manufacture of chlorofluorocarbons has been banned by the 1992 revisions of the 1987 Montreal Protocol of the United Nations. Atmospheric measurements have confirmed that the Protocol has been very successful in reducing further emissions of these molecules. Recovery of the stratosphere to the ozone conditions of the 1950s will occur slowly over the rest of the twenty-first century because of the long lifetime of the precursor molecules.

Stratospheric ozone depletion - an overview of the scientific debate

1995 ◽  
Vol 19 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Frances Drake
Keyword(s):  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
Ozone Layer ◽  
Scientific Uncertainty ◽  
Perceived Threat ◽  
Stratospheric Ozone Depletion ◽  
Scientific Debate ◽  
Supersonic Transport ◽  
Model Predictions ◽  
Predicted Values

For almost half a century it was widely believed that the photochemistry of the stratosphere and hence ozone distribution were well understoood. As observations revealed a gap between observed and predicted values it was recognized that a number of substances acted as catalysts thereby increasing the destruction of ozone and that humanity could augment those catalysts and affect the ozone layer. Initial concern focused on nitrogen oxides from the exhausts of supersonic transport, but attention switched in the mid-1970s to chlorofluorocarbons (CFCs). Although the theory of anthropogenic ozone depletion by CFCs found widespread scientific support the perceived threat was minimized in particular by successive model predictions downgrading the amount of depletion. The appearance of the ozone hole over Antarctica in the mid-1980s reopened the debate as to whether such depletion was anthropogenic or natural in origin. It also highlighted the model's inadequate treatment of the processes occurring in the stratosphere and the importance of dynamics and radiative transfer in stratospheric ozone destruction. Scientific consensus again favours the anthropogenic depletion of the ozone layer. In conclusion it is considered that the degree of consensus outweighs the image of scientific uncertainty that is often portrayed in relation to the issue of stratospheric ozone depletion.

The effects of ultraviolet-B radiation on freshwater ecosystems of the Arctic: Influence from stratospheric ozone depletion and climate change

2004 ◽  
Vol 12 (1) ◽  
pp. 1-70 ◽  
Author(s):  
S Perin ◽  
D RS Lean
Keyword(s):  
Climate Change ◽  
Uv Radiation ◽  
Climate Warming ◽  
Ozone Depletion ◽  
Aquatic Ecosystems ◽  
Stratospheric Ozone ◽  
Aquatic Organisms ◽  
Ultraviolet B ◽  
The Arctic ◽  
Uvb Radiation

Depletion of stratospheric ozone, the principal atmospheric attenuator of ultraviolet-B (UVB) radiation, by man-made chemicals has raised scientific and public concern regarding the biological effects of increased UVB radiation on Earth. There is an increased awareness that existing levels of solar UV radiation have an important influence on biological and chemical processes in aquatic ecosystems. For aquatic organisms, numerous studies have shown direct detrimental effects of UVB radiation at each trophic level. Fortunately, many aquatic organisms also possess a range of photoprotective mechanisms against UV radiation toxicity. In addition to its direct impact, harmful effects of UVB radiation at a single-trophic level can cascade through the food web and indirectly affect organisms from other trophic levels. Because UV radiation photochemically reacts with humic substances and other photosensitive agents in the water, increases in solar UVB can also indirectly affect aquatic organisms through the production and (or) release of different photoproducts like biologically available nutrients and harmful reactive oxygen species. Polar aquatic ecosystems have been of particular concern, since stratospheric ozone-related UVB increases have been the greatest in these regions. With the influences of climate warming and the possibility of future volcanic eruptions, ozone losses are expected to get worse in the Arctic stratosphere, and the ozone layer recovery may not follow the slow decline of industrial ozone-depleting compounds in the atmosphere. Climate warming is also expected to bring important changes in underwater ultraviolet radiation (UVR) penetration in Arctic freshwaters that would be more significant to the aquatic biota than stratospheric ozone depletion.Key words: Arctic, UV radiation, UVB, ozone depletion, climate change, aquatic ecosystems.

Attempts to Probe the Ozone Layer and the Ultraviolet-B Levels of the Past

AMBIO ◽  
2007 ◽  
Vol 36 (5) ◽  
pp. 366-371 ◽  
Author(s):  
Lars Olof Björn ◽  
Richard L. McKenzie
Keyword(s):  
Ozone Layer ◽  
Ultraviolet B ◽  
The Past

scholarly journals The Importance of the Montreal Protocol in Protecting Earth’s Hydroclimate

2013 ◽  
Vol 26 (12) ◽  
pp. 4049-4068 ◽  
Author(s):  
Yutian Wu ◽  
Lorenzo M. Polvani ◽  
Richard Seager
Keyword(s):  
Ozone Depletion ◽  
Radiative Forcing ◽  
Hydrological Cycle ◽  
Stratospheric Ozone ◽  
Atmospheric Model ◽  
Ultraviolet B ◽  
Montreal Protocol ◽  
Mixed Layer Ocean ◽  
The World ◽  
Ozone Depleting Substances

Abstract The 1987 Montreal Protocol regulating emissions of chlorofluorocarbons (CFCs) and other ozone-depleting substances (ODSs) was motivated primarily by the harm to human health and ecosystems arising from increased exposure to ultraviolet-B (UV-B) radiation associated with depletion of the ozone layer. It is now known that the Montreal Protocol has helped reduce radiative forcing of the climate system since CFCs are greenhouse gases (GHGs), and that ozone depletion (which is now on the verge of reversing) has been the dominant driver of atmospheric circulation changes in the Southern Hemisphere in the last half century. This paper demonstrates that the Montreal Protocol also significantly protects Earth’s hydroclimate. Using the Community Atmospheric Model, version 3 (CAM3), coupled to a simple mixed layer ocean, it is shown that in the “world avoided” (i.e., with CFC emissions not regulated), the subtropical dry zones would be substantially drier, and the middle- and high-latitude regions considerably wetter in the coming decade (2020–29) than in a world without ozone depletion. Surprisingly, these changes are very similar, in both pattern and magnitude, to those caused by projected increases in GHG concentrations over the same period. It is further shown that, by dynamical and thermodynamical mechanisms, both the stratospheric ozone depletion and increased CFCs contribute to these changes. The results herein imply that, as a consequence of the Montreal Protocol, changes in the hydrological cycle in the coming decade will be only half as strong as what they otherwise would be.

scholarly journals Potential environmental impact of bromoform from Asparagopsis farming in Australia

2021 ◽  
Author(s):  
Yue Jia ◽  
Birgit Quack ◽  
Robert D. Kinley ◽  
Ignacio Pisso ◽  
Susann Tegtmeier
Keyword(s):  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
Dry Weight ◽  
Ozone Layer ◽  
Stratospheric Ozone Layer ◽  
Asparagopsis Taxiformis ◽  
Enteric Methane ◽  
The Impact ◽  
Ozone Depletion Potential ◽  
Ruminant Feed

Abstract. To mitigate the rumen enteric methane (CH4) produced by ruminant livestock, Asparagopsis taxiformis is proposed as an additive to ruminant feed. During the cultivation of Asparagopsis taxiformis in the sea or in terrestrial based systems, this macroalgae, like most seaweeds and phytoplankton, produces a large amount of bromoform (CHBr3), which may contribute to ozone depletion once released into the atmosphere. In this study, the impact of CHBr3 on the stratospheric ozone layer resulting from potential emissions from proposed Asparagopsis cultivation in Australia is assessed by weighting the emissions of CHBr3 with the ozone depletion potential (ODP), which is traditionally defined for long-lived halogens but has been also applied to very short lived substances (VSLSs). An annual yield of ~3.5 × 104 Mg dry weight (DW) is required to meet the needs of 50 % of the beef feedlot and dairy cattle in Australia. Our study shows that the intensity and impact of CHBr3 emissions varies dependent on location and cultivation scenarios. Of the proposed locations, tropical farms near the Darwin region are associated with largest CHBr3 ODP values. However, farming of Asparagopsis using either ocean or terrestrial cultivation systems at any of the proposed locations does not have potential to impact the ozone layer. Even if all Asparagopsis farming was performed in Darwin, the emitted CHBr3 would amount to less than 0.016 % of the global ODP-weighted emissions. The remains are relatively small even if the intended annual yield in Darwin is scaled by a factor 30 to meet the global requirements, which will increase the global ODP-weighted emissions by 0.48 %

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