FORM OF MERCURY IN STREAM FISH EXPOSED TO HIGH-CONCENTRATIONS OF DISSOLVED INORGANIC MERCURY

The form of mercury predominating in mercury-contaminated fish from bo th pristine and industrialized waters in North America and Europe has almost universally been methylmercury. Sunfish (Lepomis auritus) livin g in a stream contaminated with 0.5 -1 mu g/L dissolved inorganic merc ury accumulated greater concentrations of total mercury at headwater s ites, where the dissolved mercury concentrations were greatest, than t hey did at downstream sites. However, despite evidence from laboratory studies that dissolved inorganic mercury is rapidly accumulated by fi sh without transformation to methylmercury, methylmercury constituted 85% or more of the total mercury concentration in fish at all sites.