MERCURY SPECIATION IN SURFACE FRESH-WATER SYSTEMS IN CALIFORNIA AND OTHER AREAS

Mercury concentrations and speciation were determined in surface water samples from lakes and rivers in California and other areas. The freshwater systems studied ranged from a pristine alpine lake to a system with Hg-contaminated sediments. Total Hg levels spanned between 2.4 to 500 pM, while dissolved Hg levels ranged from 2 to 60 pM. Dissolved organo-Hg compounds accounted for a majority (up to 89%) of the dissolved Hg in some lakes. Interestingly, those lakes in which high dissolved organo-Hg levels were observed also had high levels of Hg in fish tissues. A significant portion of the total Hg was usually in the particulate fraction, indicating that suspended particles can be important in influencing Hg cycling in lakes. Mercury concentration and speciation patterns in rivers were similar to that for lakes. The total Hg levels obtained in this present work, using clean sampling and analytical technologies, were considerably lower than most historical reports. © 1990, American Chemical Society. All rights reserved.