第三篇

Underground Coal Fires -- a Looming Catastrophe Coal burning deep underground in China, India and Indonesia is threatening the environment and human life, scientists have warned. These large-scale underground blazes cause the ground temperature to heat up and kill surrounding vegetation, produce greenhouse gases and can even ignite forest fires, a panel of scientists told the annual meeting of the American Association for the Advancement of Science in Denver. The resulting release of poisonous elements like arsenic and mercury can also pollute local water sources and soils, they warned. "Coal fires are a global catastrophe," said Associate Professor Glenn Stracher of East Georgia College in Swainsboro, USA. But surprisingly few people know about them. Coal can heat up on its own, and eventually catch fire and burn, if there is a continuous oxygen supply. The heat produced is not caused to disappear and under the right combinations of sunlight and oxygen, can trigger spontaneous catching fire and burning. This can occur underground, in coal stockpiles, abandoned mines or even as coal is transported. Such fires in China consume up to 200 million tones of coal per year, delegates were told. In comparison, the U.S. economy consumes about one billion tones of coal annually, said Stracher, whose analysis of the likely impact of coal fires has been accepted for publication in the International Journal of Coal Ecology. Once underway, coal fires can bum for decades, even centuries. In the process, they release large volumes of greenhouse gases, poisonous fumes and black particles into the atmosphere. The members of the panel discussed the impact these fires may be having on global and regional climate change, and agreed that the underground nature of the fires makes them difficult to detect. One of the members of the panel, Assistant Professor Paul Van Dijk of the International Institute for Geo-Information Science and Earth Observation in the Netherlands, has been working with the Chinese government to detect and monitor fires in the northern regions of the country. Ultimately, the remote sensing and other techniques should allow scientists to estimate how much carbon dioxide these fires are emitting. One suggested method of containing the fires was presented by Gary Colaizzi, of the engineering firm Goodson, which has developed a heat-resistant grout (a thin mortar used to fill cracks and crevices), which is designed to be pumped into the coal fire to cut off the oxygen supply.

According to the fifth paragraph, what is the suggested method to control underground fires