Investigating the size, distribution, and associations of contaminants in the Upper Clark Fork River, Montana
Presentation Type
Poster Presentation
Abstract/Artist Statement
Mine waste and the metal contaminants it releases are common globally and can have negative effects on aquatic ecosystems, resulting in decreased abundance and diversity of invertebrates and fish. Contaminants have historically been thought to enter aquatic food webs in the “dissolved” fraction, which is operationally defined as anything passing through a filter of a given size (e.g., 700 nm). However, this definition of dissolved may be inaccurate for three reasons: 1) it lumps small particles in the 1 – 700 nm size range with truly dissolved solutes (< 1 nm); 2) for some elements, these submicron particles (colloids) may be their dominant form; and 3) work on manufactured particles in this size range has shown that organisms like algae and filter feeders can accumulate these colloids, and may thus colloids may drive exposure to the rest of the food web. For elements like iron, which may be found as colloids, the iron itself may not be toxic, but it can serve as a vector of other toxins by sorbing arsenic, copper, and lead and thereby indirectly drive their accumulation by organisms. The goal of this study was to examine the distribution of elements across the continuum of particle sizes in the mine waste contaminated Upper Clark Fork River, Montana. We collected water samples from twenty-two sites in the summer 2018 during base flow conditions, with sites distributed between the Clark Fork’s headwaters by Warm Springs to where the river enters Missoula. Samples were analyzed using single particle inductively coupled plasma time-of-flight mass spectrometry, which measures the elemental composition of individual particles, in this case in the 1-1000 nm size range. The most abundant particles that we observed were iron, followed by manganese, which had sizes in the lower end of the colloidal size range. Manganese, zinc, and copper were all commonly associated with iron particles, suggesting that iron may indeed be serving as a vector for these elements in this ecosystem. These data begin to illuminate the potential importance of submicron particles in both the transport of contaminants in mining contaminated rivers, as well as in driving exposure to organisms.
Mentor Name
Ben Colman
Investigating the size, distribution, and associations of contaminants in the Upper Clark Fork River, Montana
UC North Ballroom
Mine waste and the metal contaminants it releases are common globally and can have negative effects on aquatic ecosystems, resulting in decreased abundance and diversity of invertebrates and fish. Contaminants have historically been thought to enter aquatic food webs in the “dissolved” fraction, which is operationally defined as anything passing through a filter of a given size (e.g., 700 nm). However, this definition of dissolved may be inaccurate for three reasons: 1) it lumps small particles in the 1 – 700 nm size range with truly dissolved solutes (< 1 nm); 2) for some elements, these submicron particles (colloids) may be their dominant form; and 3) work on manufactured particles in this size range has shown that organisms like algae and filter feeders can accumulate these colloids, and may thus colloids may drive exposure to the rest of the food web. For elements like iron, which may be found as colloids, the iron itself may not be toxic, but it can serve as a vector of other toxins by sorbing arsenic, copper, and lead and thereby indirectly drive their accumulation by organisms. The goal of this study was to examine the distribution of elements across the continuum of particle sizes in the mine waste contaminated Upper Clark Fork River, Montana. We collected water samples from twenty-two sites in the summer 2018 during base flow conditions, with sites distributed between the Clark Fork’s headwaters by Warm Springs to where the river enters Missoula. Samples were analyzed using single particle inductively coupled plasma time-of-flight mass spectrometry, which measures the elemental composition of individual particles, in this case in the 1-1000 nm size range. The most abundant particles that we observed were iron, followed by manganese, which had sizes in the lower end of the colloidal size range. Manganese, zinc, and copper were all commonly associated with iron particles, suggesting that iron may indeed be serving as a vector for these elements in this ecosystem. These data begin to illuminate the potential importance of submicron particles in both the transport of contaminants in mining contaminated rivers, as well as in driving exposure to organisms.