E Minamata disease Q&A

5. Mercury & Minamata Bay

Q3: How much mercury had accumulated at the bottom of Minamata Bay before dredging and reclamation work was done?

A3: It is said that nearly 150 tons of mercury had accumulated.

The total amount of mercury used at Chisso Corp. is estimated between 380 and 455 tons, and more than half of it is considered to have been flowed out into the bay or released into the air.
Most of the mercury in the bottom sediment that was removed from the bay by dredging was considered to be an inert form of inorganic mercury (mercury sulfide).