| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1991: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1990: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
Mercury contents of samples of sea water and shellfish from Kagoshima Bay, volcanic ashes, rain water, sediments in rivers, and the surface soil from the area surrounding a waste incinerator in the city of Kagoshima were measured to search for the source of mercury in Magoshima Bay. The results obtained were as follows :
I Mercury contents of sea water samples at 26 stations in Kagoshima Bay ranged from 6.3 to 19.7 ng/l. When the 26 stations were classified into four areas, the entrance, the middle and the interior of the Bay, and the water around the Sakurajima area, mercury contents of the samples from the last area were significantly higher than either at the entrance or in the interior of the Bay. Methylmercury contents of sea water samples at the coast around Sakurajima were lower than those at the Minamata-Hyakken port, but higher than those at the coast of Minamata-Yunoko.
2 Mercury contents of fish from the shine coast station, the innermost part of the Bay, were significantly hi
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gher than those from the other collecting stations. Moreover, significant interactions between the species of fish and the sampling stations were detected.
3 River sediments obtained 1 km from the mouth of each river contained from 4 to 96mug/kg of mercury. Mercury contents of the river sediments from the Wide river were higher than those from the other five rivers examined. Mercury contents obtained from the surface soils every 0.5 km in eight directions, with the waste incinerator as the central point, ranged from 6 to 128 mug/kg ; however, neither distance nor direction showed significant differences.
Possible sources of mercury in Kagoshima Bay were mainly eruptive products of Mt. Sakurajima and partly man-made products such as mercury-containing pesticides. Mercury levels in the bay remain unchanged with a state of mercury balance between the eruptive products from the increasing activity of Mt. Sakurajima and the reduction of man-made ones by administrative control. Mercury in the environment of Kagoshima Bay should be monitored for the prevention of human disease caused by consuming mercury contaminated fish. Less
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