November 2012 | Volume 120 | Issue 11
On the Cover | Focus
In 2009 a mining engineer named Marcello Veiga set out to study mercury air pollution in a part of northwest Colombia called Antioquia Department. This mountainous, conflict-ridden state, where leftist guerillas routinely battle Colombian security forces, is an important center for artisanal and small-scale gold mining (ASGM). Miners isolate gold by mixing ores dug from the ground or from stream beds with mercury to form an amalgam. When the amalgam is burned, the elemental mercury vaporizes into a toxic plume while the gold stays behind.
On the northwest edge of the continental United States, in some of the quietest and most rain-drenched lands in all of North America,1 runs the glacier-blue Elwha River. It arises from the Elwha Snowfinger, a perennial snowfield in Washington’s Olympic National Park, and flows 45 miles northward through basalt canyons and old-growth forest before spilling into the Strait of Juan de Fuca. The river traverses the reservation of the Lower Elwha Klallam Tribe, a people who have relied on the river’s salmon for physical, spiritual, and cultural sustenance for millennia.