PROSPECTING FOR SUBMICRON METAL PARTICLES IN A MINE WASTE CONTAMINATED RIVER
Metals have historically been thought to enter aquatic food webs in the “dissolved” fraction, operationally defined as anything passing through a filter of a given size (e.g., 700 nm). This definition of dissolved may be inaccurate because it lumps small, submicron particles (colloids) with truly dissolved solutes (< 1 nm). For elements like iron, the iron itself may not be toxic, but colloidal iron may serve as a vector for toxic metals by sorbing them and indirectly driving their accumulation in organisms. The goal of this study was to examine the elemental composition of particles in a mine waste contaminated river. We collected water samples during base flow and characterized the elemental composition of individual particles under 1000 nm. Iron and manganese were most abundant and had sizes in the lower end of the colloidal size range. Lead, zinc, cadmium, and copper were commonly found as particles and were sometimes found associated with iron particles, suggesting that iron may indeed be serving as a vector. These data begin to illuminate the potential importance of colloids in both the transport of contaminants and driving exposure to organisms.
Kaitlin Perkins (Primary Presenter/Author), University of Montana, firstname.lastname@example.org;