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Seven Plagues of Tierra del Fuego All Galleries
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7. Ozone Depletion

12 images Created 23 Jul 2014

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  • Cpl. Adrian Silva of the Argentine Air Force peers through protective lenses to note the position of the sun. Silva aligns a Dobson Spectrometer to measure the amount of ozone above Tierra del Fuego from an Argentine meteorological agency station in Ushuaia. Fed by decades of chlorofluorocarbon emissions, the thin spot in the upper atmosphere has grown to the size of the ice cap itself. Normally showering only Antarctica with stronger ultraviolet rays, the irregularly-shaped hole nicks Tierra del Fuego a few days each year.
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  • Lt. Gabriel Karamanian notes the spikes in ultraviolet radiation on spring days when the ozone hole passes above Ushuaia, a city that proclaims itself the southernmost in the world. Ultraviolet-blocking ozone naturally migrates toward the poles as it is produced in the atmosphere, making the protective ozone layer more dense above sub-polar regions like Tierra del Fuego than it is in the tropics. This grants moderate protection for those on the ground even when the ozone hole passes above. Though more than 95 percent of ozone is destroyed over the South Pole during the three-month ozone hole season, losses of ozone at the edge of the hole where it nicks Tierra del Fuego are 40 percent.<br />
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 "In 1998 we had a clear sky on an ozone hole day. The measurement of UV-B was similar to that in Buenos Aires on spring day," says Maj. Osvaldo Barturen, commander of the Argentine ozone observatory in Ushuaia, of the capital city nearly 2,500 kilometers north. "With this ozone (loss) in the tropics you could fry," he says. "Here in Tierra del Fuego God is very generous with us."
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  • Utah State University biologist Matt Robson, right, and assistant Nico Garibaldi stretch a mylar filter for ultraviolet-B radiation across a plot of peat bog in Tierra del Fuego National Park. Robson and colleagues are studying the effects of higher ultraviolet radiation levels on the local plant life by measuring minute changes in the growth and decay rates of plants in bogs, forests and brush lands.
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  • Matt Robson assembles a filter over a plot of peat in the Laguna Negra bog. Mylar filters block the summer's higher level of ultraviolet radiation, removing the effects of the ozone hole, allowing the team to compare growth and decay rates between filtered and unfiltered plots.<br />
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Robson and colleagues are concerned the higher ultraviolet levels may be slowing the growth of sphagnum moss in regional bogs, which filter water and provide nutrients to the rest of the environment. His "teenage" bog, some 20,000 years old, has shown early signs of slowing moss growth. "Peat bogs absorb carbon from the atmosphere," he notes, "which is a good thin in terms of global warming gases."
    04aBogWalk.jpg
  • Matt Robson assembles a filter over a plot of peat in the Laguna Negra bog. Mylar filters block the summer's higher level of ultraviolet radiation, removing the effects of the ozone hole, allowing the team to compare growth and decay rates between filtered and unfiltered plots.<br />
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Robson and colleagues are concerned the higher ultraviolet levels may be slowing the growth of sphagnum moss in regional bogs, which filter water and provide nutrients to the rest of the environment. His "teenage" bog, some 20,000 years old, has shown early signs of slowing moss growth. "Peat bogs absorb carbon from the atmosphere," he notes, "which is a good thin in terms of global warming gases."
    04BogBuild.jpg
  • Veronica Pancotto, of the University of Buenos Aires, adjusts a filter over a plot of brush in Tierra del Fuego National Park where she is studying changes in plant growth and decay as a result of increased ultraviolet exposure. Buenos Aires colleagues of Pancotto are also looking at how well plant chemical systems can patch DNA damaged by ultraviolet radiation. Unlike humans, the region's plant life evolved under ozone-rich skies of the sub-polar region. Higher levels of radiation may mean that subtle chemical changes can affect the local flora and fauna through the entire food chain.
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  • Matt Robson measures the growth of a single leaf on one of three species of beech tree in the Utah State ozone study. Trees are examined over a period of years for growth rate, stem extension, number of branches, number and size of leaves produced, pigments, damage from insects and fungi, and the waxy deposits that indicate ultraviolet radiation damage. At rear, assistant Nico Garibaldi notes the statistics.<br />
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"Leaves may produce more wax as a sunscreen which may reduce availability of nutrients to fungi, which in turn reduces decomposition after the leaves fall," Robson says of the beech trees. The waxy secretion "tastes bad for some insects," he says. The insects tend to eat less of the plants in areas of high exposure, which could cause ripples through the rest of the region's short food chain. Fewer insects mean fewer fish and birds.
    06aLeafCounting.jpg
  • Utah State University biologist Matt Robson measures a branch of an evergreen beech tree in Argentina's Tierra del Fuego National Park. Evidence of health problems in the region's human population has not been found, but a research team from Utah State University is studiously watching for the effects of higher ultraviolet exposure at the food chain's bottom. Working in cooperation with the Argentine government, Robson and others scrutinize the growth and decay rates of plants in the limited environment.
    06RobsonEye.jpg
  • Ultraviolet filters made of mylar sheets and chicken wire surround branches of an evergreen beech tree Matt Robson examines. Open to allow as close to normal air flow, insect access and motion as possible, the filters reduce a branch's exposure to the higher levels of ultraviolet radiation that strike the earth when the ozone hole passes above. Branches react to UV exposure independently, allowing researchers to compare filtered and unfiltered branches on the same tree. In filtered plots that receive the same levels of ultraviolet as pre-ozone hole days, the evergreen species of beech seems to be growing healthier leaves that appear to attract hungry caterpillars more than the unfiltered branches.
    07BranchFilter.jpg
  • Matt Robson measures the growth of a single leaf on one of three species of beech tree in the Utah State ozone study. Trees are examined over a period of years for growth rate, stem extension, number of branches, number and size of leaves produced, pigments, damage from insects and fungi, and the waxy deposits that indicate ultraviolet radiation damage.<br />
<br />
"Leaves may produce more wax as a sunscreen which may reduce availability of nutrients to fungi, which in turn reduces decomposition after the leaves fall," Robson says of the beech trees. The waxy secretion "tastes bad for some insects," he says. The insects tend to eat less of the plants in areas of high exposure, which could cause ripples through the rest of the region's short food chain. Fewer insects mean fewer fish and birds.
    08LeafMeasure.jpg
  • Rain drops pool on the mylar filter over a plot of sedges near Ushuaia, Argentina. Changes in root growth and expansion caused by higher ultraviolet levels may be helping some plants to outcompete others. This could eventually change the nature of the Fuegian ecosytem, Robson says, as bogs and brush cede to forest.
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  • A kite flies below the bright spring sun near Tierra del Fuego's Sierra Alvear mountain range. In 2000, the Antarctic ozone hole reached record size at nearly 30 million square kilometers — several million more than all of North America. In 2001 the hole was nearly as large and lingered even longer into its three- to four-month cycle. Scientists are watching to see if an anticipated reduction in the ozone hole will begin in coming years, showing the start of a recovery that may take a half-century.<br />
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The size of the hole in 2000 attracted unprecedented media attention. Tourists stayed away from the region, fearing terrible sunburns. A slowing of the tourism economy made some locals red in the face. "It's not like there are ducks falling roasted from the sky around here," one travel agent in nearby Punta Arenas, Chile, said in the local paper. Though no serious problems have been seen in the human population, tiny effects in the local ecosystem may ripple through the environment for years to come.
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