Dissolved gaseous mercury concentration and mercury evasional flux from seawater in front of a chlor-alkali plant.

The dissolved gaseous mercury concentration and mercury degassing rate have been measured in a marine area polluted by a chlor-alkali plant (Rosignano Solvay, Italy), which uses mercury in chlorine production. During the summer the DGM concentration (130 pg l(-1)) and the evasional flux (14 ng m(-2) h(-1)) were 3-4 times higher than those measured at the control stations. A seasonal behaviour has been highlighted at all the sampling sites, with minimum levels in the winter.