The 2011 earthquake in Japan released more than 7,000 tons of environment-damaging chemicals into the air, a new report estimates.
Those chemicals typically damage Earth’s protective ozone layer and contribute to global warming, according to the study, prepared for Geophysical Research Letters, a journal of the American Geophysical Union.
The thousands of buildings destroyed and damaged during the magnitude-9.0 earthquake and tsunami that struck Japan four years ago released 7,275 tons of gases stored in insulation, appliances and other equipment into the atmosphere, the study concludes.
Emissions of these chemicals, called halocarbons, increased by 21 percent to 91 percent, depending on the particular chemical, over typical levels, according to the study.
"What we found is a new mechanism of halocarbon emissions coming from the earthquake," said Takuya Saito, a senior researcher at the National Institute for Environmental Studies in Tsukuba, Japan, and lead author of the study, in a statement Thursday.
The study is the first to look at how the Tohoku earthquake affected the release of halocarbons into the atmosphere and likely one of the first to examine emissions of these gases following a natural disaster, according to the researchers.
Halocarbons released as a result of the earthquake include chemicals that deplete the ozone layer and contribute to global warming, including some gases that are no longer used because of those harmful effects on the environment. These include chlorofluorocarbons such as CFC-11, a powerful ozone-depleting chemical used in foam insulation until it was phased out in 1996, and hydrochlorofluorocarbons such as HCFC-22, an ozone-depleting refrigerant that is also a powerful greenhouse gas and is being phased out of use.
Among other halocarbons released by the quake were hydrofluorocarbons, or HFCs, and sulfur hexafluoride, both potent greenhouse gases.
The emissions of the six halocarbons released from Japan in 2011 are equivalent to the discharge of 1,433 tons of CFC-11 alone — equal to the amount of CFC-11s in 2.9 million refrigerators manufactured before the chemical was banned. The total emissions of the six chemicals are also equivalent to the release of 21.2 million tons of carbon dioxide into the atmosphere — an amount equal to about 10 percent of Japanese vehicle emissions in 2011, according to the report.
Saito and his colleagues decided to investigate halocarbon emissions and their relationship to the earthquake after ground-based air monitoring stations in Japan recorded surprisingly high levels. The stations are on Hateruma Island, east of Taiwan; Cape Ochiishi, on the east side of Hokkaido; and Ryori, north of Tokyo.
The study’s authors combined these measurements with an atmospheric model and other mathematical methods to figure out that increased emissions from the earthquake were involved, how much of the emissions could be attributed to the disaster and how they compared with previous years.
About 50 percent of the halocarbon emissions after the earthquake were of HCFC-22, likely due to damage to refrigerators and air conditioners. Emissions of the gas were 38 percent higher than the years before the earthquake.
Emissions of CFC-11 were 72 percent higher than emissions before the earthquake, likely due to damage to insulation foam used in appliances and buildings, according to the study.
