The crisis is commonly attributed to the formation of the Siberian Traps Large Igneous Province although The crisis is commonly attributed to the formation of the Siberian Traps Large Igneous Province although the causal mechanisms remain disputed. We have recently suggested that heating of Tunguska Basin sediments by the ascending magma played a key role in triggering the crisis. Our conclusions are based on extensive field work in Siberia in and Here we present new data on contact metamorphism and gas release.
Heating of organic-rich shale and petroleum bearing evaporites led to greenhouse gas and halocarbon generation in sufficient volumes to cause global warming and atmospheric ozone depletion. This is supported by experiments on heated rock samples from Siberia. The gases were released to the end-Permian atmosphere partly through spectacular phreatomagmatic pipe structures with kilometre-sized craters, formed during sill emplacement We demonstrate that the composition of the heated sedimentary rocks below the flood basalts is the most important factor in controlling whether a Large Igneous Provinces causes an environmental crisis or not.
Measuring environmental degradation: developing pressure indicators for Europe. Mr Sivertsen has been responsible for several air quality investigations worldwide. Midpoints are considered to be links in the cause-effect chain environmental mechanism of an.
Biomedical consequences of ozone depletion. The major effect of this ozone loss will be an increase in the amount of ultraviolet radiation UV reaching the biosphere. This increase will be completely contained within the UVB nm - nm. It is imperative that assessments be made of the effects of this additional UVB on living organisms. This requires a detailed knowledge of the UVB photobiology of these life forms.
One analytical technique to aid in the approximations is the construction of UV action spectra for such important biological end-points as human skin cancer, cataracts, immune suppression; plant photosynthesis and crop yields; and aquatic organism responses to UVB, especially the phytoplankton. Combining these action spectra with the known solar spectrum and estimates for various ozone depletion scenarios can give rise to a series of effectiveness spectra for these parameters.
This manuscript gives a Evaluation of biologically harmful ultraviolet radiation in Antarctica with a biological dosimeter designed for aquatic environments. Cytogenetic, cellular, and developmental responses in antarctic sea urchins Sterechinus neumayeri following laboratory ultraviolet-B and ambient solar radiation exposures. Page 1. LEN V. Algae and cytokinins. Plant Physiol. Tentative identification of cytokinins in Sargassum heterophyllum Tentative identification of cytokinins in Sargassum heterophyllum Phaeophyceae.
Transmission of solar ultraviolet radiation through invertebrate exteriors. The occurrence of springtime ozone depletion over the Antarctic has created concern about the effects of increases ultraviolet-B on marine organisms, particularly in intertidal and subtidal populations. The first line of defense that an The first line of defense that an animal has to solar radiation exposure is its outer covering.
This paper examines four species of antarctic invertebrates to determine the amount of UV protection provided. Ozone depletion: ultraviolet radiation and phytoplankton biology in antarctic waters. Temporal and spatial occurrence of UV-absorbing mycosporine-like amino acids in tissues of the antarctic sea urchin Sterechinusneumayeri during springtime ozone-depletion. Feeding larvae of Antarctic bottom invertebrates have proven to be scarce in the plankton and consequently our knowledge of their ecology is limited.
We collected bipinnaria larvae assignable to the genus Odontaster and several types of The average number of pilidium and bipinnaria larvae in the upper 40 m of the water column was 0. A study was undertaken by McMurdo in that showed that the concentrations of nitrogen oxides were remarkably low, hence disapproved the solar cycle model.
He also observed that the levels of long-lived tracers were due to complex reactions and was unlikely to occur, and that the high levels of chlorine in the stratosphere was the most probable cause of ozone depletion Storlaski et al, pp. The Montreal Protocol was signed in , although the origin of the ozone hole was not well understood, the protocol recognized that the stratosphere had been disturbed.
The Montreal Protocol was signed by 31 countries and was aimed at cutting CFC emissions as shown below:. The pact has been ratified by nations to date and aims at reducing CFC emissions gradually so that no emissions will be made by Unfortunately, only a few countries have implemented the emission control mechanisms.
This enabled scientists to re-assess present and early trends in the stratospheric ozone. Studies undertaken in Punta Arenas, Chile, in that involved making flights above the Antarctica gave a good understanding of the role of CFCs in ozone depletion Farman et al, pp. Chlorine and low concentrations of bromine were detected in this area, the study also found out that the level ClO was considerably high. The most common form of skin cancer in man, basal and squamous cell carcinomas, have been attributed to exposure to ultraviolet-B UVB Kelfkens et al, pp.
Another form of skin cancer, malignant melanoma, is caused by exposure to ultraviolet-A radiation, however, some studies have shown this cancer is caused by exposure to UVB radiation. A relationship also exists between cortical cataracts and exposure to UV-B radiation. Scientists have also said that a rise in ozone depletion may increase the occurrence of malaria and other infectious diseases while the EPA forecasts that close to 60 million Americans born by will have skin cancer Zehr, pp.
A November research at the Institute of Zoology in London revealed that whales off the coast of California coast exhibited a drastic rise in sun damage, they attributed this observation to the depletion of the ozone.
Increase of exposure to radiation affects crops and other plants. Economically important crops such as rice and beans depend on cyanobacteria living on their roots to help in nitrogen fixation, however, cyanobacteria are responsive to UV light and would be easily affected by increase of exposure to radiation. Oceans will also be affected: microscopic organisms such as planktons may not survive in the future, this would imply that animals above planktons in the food chain would not survive.
Fish numbers will dwindle and this will in turn. Due to the grave effects of ozone depletion, we must strive to work towards abating and reversing the damages that have been done to the ozone layer. Some of these solutions are outlined below:.
The challenge with this method is that ethane or propane would decompose after one year and the expensive would have to be repeated annually Norman et al, pp. Depletion of stratospheric ozone layer by chlorofluorocarbons is a universal problem. While the issue was a matter of scientific guesswork in the mid 20 th century, it is now an urgent policy question for governments around the world.
The weight of scientific evidence strongly points to CFCs as the main source of the reduction in stratospheric ozone over the Antarctica. Satellite images supported by ground-based surveillance show that ozone has been declining since the late s in both hemispheres, and this decline cannot be explained by any known natural processes.
In weight of this evidence, we can conclude that halogenated compounds are largely responsible for the depletion of the ozone. Scientists have mentioned that the ozone hole will be around for the next 50 years, and its repair can only start in However, this does not bar us from carrying out activities aimed at reducing and reversing depletion of the ozone layer. More than two decades after the Montreal Protocol was signed, the world is yet to get tangible results from these efforts.
This stems partly from the lack of stringent legislation to aid in implementation of the agreement and can be compared to the Kyoto Protocol. A working solution to lessen the depletion of the ozone would be to limit the quantity of CFCs released in the atmosphere. All countries would sign a deal that binds them to the pact. To ensure that all countries adhere to the pact, meetings would be held after every three years to check on the progress of its implementation. This would also be a time to evaluate the challenges that each country faces, and find possible solutions.
This solution stems from the failure of the Montreal Protocol to reduce the emission of CFCs into the atmosphere. Adequate protection of the ozone layer will require the full co-operation between all countries, both developed and developing. Farman, Joseph C. Kelfkens, Gert, de Gruijl, Frank R.
McFarland, Mack. Chlorofluorocarbons and ozone, Environ. Newman, Paul. On the size of the Antarctic ozone hole? Geophysical Research Letters L When will the Antarctic ozone hole recover? Geophysical Research Letters L, The Montreal Protocol at Ongoing opportunities for integration with climate protection. Global Environmental Change 18 2 : High concentrations of chlorine monoxide at low altitudes in the Antarctic spring stratosphere: secular variation.
Nature : Weatherhead, Elizabeth, and Andersen, Signe Bech. The search for signs of recovery of the ozone layer. Zehr, Stephen C. The Sociological Quarterly 35 4 : Need a custom Term Paper sample written from scratch by professional specifically for you? Ozone Depletion.
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But the trend toward more frequent and more extreme low temperatures in the polar vortex concerns the researchers, because those conditions promote the formation of clouds, and that promotes ozone loss in the polar stratosphere. Most of the chlorine and a significant amount of the bromine in the stratosphere comes from the breakdown of CFCs, halons and other ozone-depleting substances. Normally within the Arctic polar vortex the chlorine is non-reactive, but clouds provide the right conditions for the chlorine to change form and react with bromine and sunlight to destroy ozone.
Despite drastic reduction of the industrial production of CFCs and halons since the Montreal Protocol in and the global ban that followed in , these long-lasting compounds are still abundant in the atmosphere. To determine what this situation means for the future, the researchers projected ozone loss out to the year based on the long-term temperature trend in the polar vortex and the expected decline in chlorine and bromine compounds.
They based their predictions on the output from 53 top climate models used by the Intergovernmental Panel on Climate Change. Combining these projections with analyses of meteorological data from the past 56 years, the researchers confirmed that the Arctic is already experiencing a significant trend toward lower stratospheric temperatures and associated increases in ozone losses.
Salawitch and his colleagues do not yet fully understand how increasing greenhouse gas emissions and the associated changes to global climate are causing the extreme cold winters in the stratospheric layer of the polar vortex. But some of the underlying mechanisms are understood. Warming at the surface causes changes to prevailing wind patterns, and the researchers suggest that these changes also produce lower temperatures in the polar vortex.
The researchers also note that recent years have seen a rapid increase in methane, a more powerful greenhouse gas than carbon dioxide, in the lower atmosphere. As this gas travels to the stratosphere, it increases humidity, which also leads to conditions that promote ozone-destroying chemical reactions in the Arctic.
But there is hope for avoiding future ozone depletion, according to the researchers. Their study shows that substantial reductions in greenhouse gas emissions over the coming decades could lead to a steady decline in conditions that favor large ozone loss in the Arctic stratosphere. DOI: The content of this article does not necessarily reflect the views of these organizations. The sun is not directly overhead the high latitudes during the wanderings of the polar vortex.