Search

Mercury (Hg) levels are alarmingly high in fish from lakes across Fennoscandia and northern North America. The few published studies on the ways in which silviculture practices influence this problem indicate that forest operations increase Hg in downstream aquatic ecosystems. From these studies, we estimate that between onetenth and one-quarter of the Hg in the fish of high-latitude, managed forest landscapes can be attributed to harvesting. Forestry, however, did not create the elevated Hg levels in the soils, and waterborne Hg/MeHg concentrations downstream from harvested areas are similar to those from wetlands. Given the current understanding of the way in which silviculture impacts Hg cycling, most of the recommendations for good forest practice in Sweden appear to be appropriate for high-latitude regions, e.g., leaving riparian buffer zones, as well as reducing disturbance at stream crossings and in moist areas. The recommendation to restore wetlands and reduce drainage, however, will likely increase Hg/MeHg loadings to aquatic ecosystems. [ABSTRACT FROM AUTHOR]

The atmosphere remains the major source of mercury in Swedish ecosystems. Since the late eighties, atmospheric emissions of mercury have drastically decreased in Europe. Wet deposition of mercury has decreased over the last decade but still exhibits a clear south-to-north gradient, greatly influenced by source areas in northern and central Europe. The decreases in emissions can be attributed to both direct measures to close known point sources and a declining economy and energy consumption in many East European countries. Further reductions of mercury emissions will require that other source categories such as indirect emissions from mercury-containing products and crematories are be considered. [ABSTRACT FROM AUTHOR]