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High mercury level detected on Mt. Fuji
Publication Date : 04-10-2013
Mercury concentrations higher than the national average have been detected at the peak of Mt. Fuji, which might be caused by cross-border pollution from China, a research group has announced.
The group, which includes Prof. Osamu Nagafuchi at the University of Shiga Prefecture, measured 2.8 nanograms of mercury per cubic meter of air at the summit of Mt. Fuji in August, and a record 25.1 nanograms in 2007. The Environment Ministry will begin a fixed-point observation project in the Asia-Pacific region jointly with the United States, Vietnam and other nations next year.
Though the observed figures are not at a level harmful to humans, they exceeded the average around the mountain peak, which is almost completely free from factory pollutants.
“When analysing the situation, including weather conditions, the reason seems to be contaminated air flowing over from China,” said Nagafuchi, an expert in environmental science.
According to the Environment Ministry, the average figure at all 261 observation points in the nation was 2.1 nanograms in fiscal 2011. A guideline of the Air Pollution Control Law stipulates the yearly average should be 40 nanograms or lower to prevent health problems.
Nagafuchi and other researchers have carried out a survey at the peak of Mt. Fuji, 3,776 meters above sea level, for about two weeks every summer since 2007. The highest figures of each year, except 2007, range from 1.9 to 5.4 nanograms. The figures vary, but they mostly exceed the national average.
On Yakushima island in Kagoshima Prefecture, the research team recorded 10.0 nanograms at 410 metres above sea level in October 2007, and near the peak of Mt. Ibuki, which is at 1,340 metres above sea level, the figure reached 9.8 nanograms in April 2009. On both days when the recordings took place, wind reportedly blew strongly from the Asian continent—and China—toward Japan.
Joint observation in Asia-Pacific
According to the UN Environment Programme, 1,960 tonnes of mercury was released into the air worldwide in 2010 mainly because of industrial activity, including gold refining and coal burning. Nearly one-third of that amount comes out of China.
Mercury is hardly used in Japan after the nation experienced Minamata disease, a neurological disease caused by mercury poisoning. However, mercury is still used in developing countries, and how to reduce its presence has become a serious issue.
Next week, an international conference regarding mercury is scheduled to be held in Kumamoto and Minamata, Kumamoto Prefecture, where the Minamata Convention, which regulates mining, using, exporting and importing mercury, is expected to be adopted.
Eight nations will participate in the fixed-point observation project in the Asia-Pacific region. Starting with research on rainwater, the project will eventually expand to cover air as well.
“It is important that developing nations, mainly China, reduce the amount of mercury they use,” said a ministry official. “Although the Minamata Convention will create international regulations, we hope to collect data in the observation project that can be used to devise effective measures.”