Rebecca Roider* - University of Wisconsin-La Crosse
Ryan Perroy, PhD - University of Wisconsin-La Crosse
Colin Belby, PhD - Univeristy of Wisconsin-La Crosse
The purpose of this study is to determine to what extent lead-based paint has leached into the soil and rock pools surrounding the Passage Island Lighthouse complex, located in northeastern Isle Royale National Park in Lake Superior. Since its construction in 1882, the Passage Island lighthouse complex was repeatedly painted with lead-based paint, and interior and exterior painted surfaces currently display extensive peeling and chipping. A previous pilot study of Pb soil contamination on Passage Island, commissioned by the United States Coast Guard in 2001, showed soil lead levels ranging from 417 to 41,040 parts per million (ppm), well above the United States Environmental Protection Agency's hazardous Pb standard of 400 ppm. These contamination levels are a concern for the employees and tourists that visit Passage Island and the extensive wildlife found there. Of particular concern are numerous endemic aquatic species found within the Passage Island rock pools just below the lighthouse complex that may be at risk. A total of 588 soil samples (0-5 cm) and 58 rock pools were sampled over ~2 hectares adjacent to and near the lighthouse. The samples were taken back to the University of Wisconsin-La Crosse where they were dried and ground to pass through a 2mm sieve prior to being analyzed via X-ray fluorescence to determine Pb concentrations. With some exceptions, preliminary soil and rock pool sediment results show a spatial pattern of highest Pb concentrations near the lighthouse complex, decreasing with distance away from the structures.