Human impacts in Antarctica trace-element geochemistry of freshwater lakesin the Larsemann Hills, East Antarctica

Fresh water lakes are found in basement rock basins in the Larsemann Hills, East Antarctica, during the summer months. These lakes constitute a relati vely simple natural laboratory to investigate the effects of recent and wel l-documented anthropogenic impact on a "pristine" environment. Larsemann Hi lls freshwaters have extremely low salinity (typically <1 parts per thousan d), and contain very low concentrations of trace elements of environmental significance such as Pb, U, and Zn. Typical Pb concentrations range from le ss than 5 ppt to 250 ppt. Although trace metal concentrations appear to be higher in lakes situated in the vicinity of stations, they are consistently lower (by several orders of magnitude, for some elements) than Standard In ternational Drinking Water Guidelines. The chemistry of the lake waters is dominated by sea-spray input. Consequently, it is primarily a function of g eographical factors, such as distance from the shore and exposure to winds. Shallow-level groundwater and surface water also contribute to the lake ch emistry. No evidence was found for contamination from global air circulatio n. Although contamination resulting from activities at the research station s is generally near or below detection levels, very low levels of trace met al anthropogenic contamination were found in the vicinity of some research stations.