These are mainly attributed to the mining's geological background, the distribution of mercury belt and the mercurymining scale, and the mine closure time.
Seafloor mining might therefore be less destructive than mining on land, which brings such not-exactly-benign consequences as mountaintop removal, mercury pollution, and destruction of watersheds.
"Our forefathers had been mining for mercury since the Ming Dynasty [1368-1644] and in olden days there was no pollution from such small mines," said a 72-year-old farmer, named Shen.