Reevaluation of Minamata Bay, 25 years after the dredging of mercury-polluted sediments

•The weighted average of total-Hg in the Minamata Bay sediment was 2.3mg/kg.•The total mass of Hg in the bottom sediments in 2012 was 3.4tons.•Diss-THg and diss-MeHg released from sediments were 0.7 and 0.1kg/yr, respectively. A detailed investigation of mercury concentrations in the bottom sediment...

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Bibliographic Details
Published in:Marine pollution bulletin 2014-12, Vol.89 (1-2), p.112-120
Main Authors: Akito, Matsuyama, Shinichiro, Yano, Akihiro, Hisano, Michiaki, Kindaichi, Ikuko, Sonoda, Akihide, Tada, Hirokatsu, Akagi
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal, plant and microbial ecology
Applied ecology
Bays - chemistry
Biological and medical sciences
Ecotoxicology, biological effects of pollution
Environmental Monitoring
Environmental Pollution - analysis
Fundamental and applied biological sciences. Psychology
Geologic Sediments - chemistry
Marine
Marine and brackish environment
Mercury - analysis
Methylmercury Compounds - analysis
Minamata Bay
Outflow
Sea water ecosystems
Seawater - chemistry
Sediment
Spatial distribution
Synecology
Total-Hg
Water Pollutants, Chemical - analysis
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Summary:•The weighted average of total-Hg in the Minamata Bay sediment was 2.3mg/kg.•The total mass of Hg in the bottom sediments in 2012 was 3.4tons.•Diss-THg and diss-MeHg released from sediments were 0.7 and 0.1kg/yr, respectively. A detailed investigation of mercury concentrations in the bottom sediments of Minamata Bay was performed in May, 2012. A total of 691 sediment samples were obtained from 107 sampling points in the bay. The weighted average total mercury concentration and the total mass of mercury in the bottom sediments of Minamata Bay were estimated to be 2.3mg/kg dry weight basis and 3.4tons, respectively. The average concentration of total mercury in the surface layer of the sediments was 3.0mg/kg dry weight basis, and the distribution pattern of total mercury concentrations in the surface layer was found to have changed little in comparison to results reported 25years ago. In addition, based on the results of seawater monitoring in Minamata Bay from 2010 to 2012, the amounts of total mercury and methylmercury mobilized from sediments and dissolved in the water column were 0.7 and 0.1kg/yr, respectively.
ISSN:0025-326X
1879-3363
DOI:10.1016/j.marpolbul.2014.10.019