Mud containing arsenic is being washed ashore in coastal communities already struggling to come to terms with the enormity of the destruction wrought by the March 11 mega-earthquake, tsunami and Fukushima nuclear disaster.
Mud containing arsenic is being washed ashore in coastal communities already struggling to come to terms with the enormity of the destruction wrought by the March 11 mega-earthquake, tsunami and Fukushima nuclear disaster.
At 36 out of 129 sampling points in Iwate, Miyagi and Fukushima prefectures, the three prefectures hardest hit by the March 11 disaster, Tohoku University researchers found arsenic concentrations exceeding environmental standards.
In several places, arsenic contamination was 4 or 5 times the government's maximum, and at one sampling point in Kesennuma, Miyagi Prefecture, the concentration was 25 times the standard.
"Arsenic that flowed into the sea and accumulated on its floor in the past was apparently stirred up by the tsunami," said Noriyoshi Tsuchiya, a professor of geomaterials and energy science at Tohoku University.
The Tohoku coastline used to be dotted with mines, where arsenic and other heavy metals were generated during smelting. Arsenic also exists in nature, and was detected in soil along the coast of Miyagi Prefecture in a 2006-08 survey by Tohoku University.
Continued intake of water contaminated with arsenic can sometimes lead to liver and kidney damage. It is also associated with darkening of the skin and hardening of palms and soles. The growth of rice plants may also be affected.
Between June and July, Tohoku University analyzed samples of mud that had apparently been disturbed on the seabed by the March 11 tsunami. The samples were taken from the seashore and beside rivers along a section of the coast from Kuji, Iwate Prefecture, to Soma, Fukushima Prefecture.
The environmental standard for the maximum safe level of arsenic in water is 0.01 milligram or less per liter. The concentration was over 5 times that standard in samples taken at Ofunato Port, Iwate Prefecture, and about 4 times the standard in Iwanuma and Natori in Miyagi Prefecture and Noda in Iwate Prefecture.
"You don't have to be too nervous about it, but if you are removing rubble in areas with concentrations 4 to 5 times the standard, wearing gloves and masks and washing your hands are essential to prevent inhalation," Tsuchiya said.
Twenty-five times the safety standard was detected near the old Oya gold mine which operated until 1976 in Kesennuma, Miyagi Prefecture. About 40,000 cubic meters of mining waste containing arsenic from a slag heap that collapsed during the March 11 disaster flowed into nearby fields, a nearby river, and the seashore. Concentrations of 12 and 10 times the government maximum were detected at other stations nearby.
Tsuchiya advised people not to drink water from nearby wells or use groundwater and river water for agricultural purposes.
The study also found lead in excess of environmental standards at 12 locations. Those concentrations slightly exceeded safety standards in most areas except Miyako, Iwate Prefecture, where the lead concentration was about 5 times the safety standard. Researchers also found an excess of the toxic metal cadmium at one location.