Mercury in coastal watersheds along the Chinese Northern Bohai and Yellow Seas

► [Hg] in waters, sediments, carp and crabs from coastal watersheds were examined. ► We studied spatial distributions and bioavailabilities of Hg. ► Most carp had [Hg] and [MeHg] less than international standards. ► [Hg] and [MeHg] in some crabs were higher than the limit for human consumption. ► Industrialization and urbanization were the primary sources of Hg.