Mercury loss from gold rush era placer mines in the Fraser Basin

Gold-rush era mercury loss at mine sites in the Fraser Basin was investigated. 109 soil and sediment samples were collected from suspected hotspots on 15 legacy placer mine sites and tested for total mercury. 89% of sites that had clearly discernable signs of mining had at least one test sample that exceeded all control samples taken during the study, suggesting that mercury use was widespread during B.C.'s Fraser and Cariboo gold rushes. An estimated 17,768 to 247,665 kg was lost in the Fraser Basin between 1858 and 1910, calculated by relating mercury loss to different records of gold extraction. Historical records show that 26,749 kg of mercury was shipped to B.C. from California between 1860 and 1883, and mercury imports into Canada between 1882 and 1899 exceeded expected mercury needs for gold amalgamation practices.