chemocline

noun

che·​mo·​cline ˈkē-mə-ˌklīn also ˈke- 

plural chemoclines

: the boundary in a body of water that separates a fresh upper layer from a deeper layer containing higher concentrations of dissolved solids and gases

The boundary, called the chemocline, between the deep water, rich with gas and minerals, and the fresh upper water stays intact. Gas saturates the bottom water and stays trapped there, like the carbon dioxide in a sealed bottle of seltzer.

—Marguerite Holloway, New York Times, 27 Feb. 2001

This sulfide usually changes into a benign sulfate salt when the dissolved gas encounters oxygen to flourish at an underwater boundary called a chemocline.

—N. Moreira, Science News, 28 May 2005

Word History

Etymology

chemo- + -cline

Note: Term introduced by the British-born ecologist George Evelyn Hutchinson (1903-91; U.S. resident from the 1930's) in "A Contribution to the Limnology of Arid Regions," Transactions of the Connecticut Academy of Arts and Sciences, vol. 33 (1937), p. 74: "The zone of transition, where the rate of change of concentration with respect to depth is maximal, may be termed the chemocline."

First Known Use

1937, in the meaning defined above

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

• More than 250,000 words that aren't in our free dictionary
• Expanded definitions, etymologies, and usage notes
• Advanced search features
• Ad free!