Levels of mercury in the skies around Mount Fuji were found to be 10 times higher than that of the average urban area in 2007, a new survey says.
A research team led by Osamu Nagafuchi, an environmental science professor at the University of Shiga Prefecture, has measured mercury concentration levels in the air at the top of 3,776-meter-high Mount Fuji every summer since 2007, using equipment designed specifically for the measurement of mercury levels.
By also analyzing weather data, the team learned that the airborne mercury had been carried into Japan by air blowing in through northeastern China and the Korean Peninsula.
“We have confirmed the cross-border mercury pollution from the continent,” said Nagafuchi. “It is necessary to enhance monitoring to clarify the actual conditions (of the pollution).”
Nagafuchi said he thinks mercury was blown from the continent together with other airborne pollutants.
Financially supported by the Environment Ministry, the research team detected a record 25.1 nanograms of mercury per cubic meter at Mount Fuji in late August 2007.
The concentration level does not exceed the annual limit value of 40 nanograms set by the Air Pollution Control Law, but the figure is 11 times the 2.2 nanograms for the average urban area in 2007.
On the other hand, the concentration levels in 2011 and 2012, when air was flowing into Japan from the Pacific Ocean, were around 2 nanograms.
Mercury is harmful to the human body and known as the causative material of Minamata disease, a neurological disorder that struck communities around Minamata Bay, Kumamoto Prefecture, in the 1950s.
Nagafuchi also confirmed a rise in mercury concentration levels at Mount Kuromidake on Yakushima island, Kagoshima Prefecture; Ibukiyama mountain straddling Shiga and Gifu prefectures; and Mount Norikuradake in the Northern Japan Alps, when northwest winds blow in from China.
The research team measured concentration levels in the three mountains, at altitudes of 1,831 meters, 1,348 meters and 2,876 meters, respectively.
At Mount Norikuradake last October, the mercury levels surged fivefold to 2.5 nanograms from 0.5 nanograms in half a day, when a cold front blowing in from China dumped the first snow of that season.
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