Trace amounts of manganese is essential to human health. Now, a team of scientists from the University of Delaware, Scripps Institution of Oceanography, the University of Hawaii, and Oregon Health and Science University has found that a dissolved form of manganese, Mn(III), is important in waterways such as the Black Sea and Chesapeake Bay. It can keep toxic hydrogen sulfide (sulphide) zones in check.

The research is based on research conducted in 2003 that explored the chemistry of the Black Sea. Nearly 90% of the mile-deep system is a no-oxygen "dead zone," containing large amounts of naturally produced hydrogen sulfide (sulphide), which is lethal to most marine life. Only specialized microbes can survive in this underwater region.