Water Resources Research Act Program

Principal Investigators: Stephen Parker

Abstract: This project proposes to use both laboratory and in situ experiments to further isolate and investigate the role that benthic surfaces have in the concentration of metals in stream and river systems. The laboratory portions will utilize an aquarium system to simulate a river system with the control of both temperature and photoperiod. The tanks will be lined with benthic material (sediment and small river stone) collected in the field. The tanks will additionally be filled with water from the same source as the benthic materials. Each system will be temperature controlled, by utilizing a temperature regulator with a submersible copper coil. Additionally, full spectrum lighting will be used to simulate natural lighting and each system will be shrouded to exclude ambient lighting. An overhead stirrer will maintain homogeneity by mixing the system. The photoperiod will be cycled in a 12 hour cycle. Each system will be monitored for temperature, pH, ORP (oxidation-reduction potential), SC (specific conductivity), and PAR (photosynthetically active radiation). Additionally, Mn and Zn concentration levels will be confirmed by sampling at various points in the photoperiod. Temperature will be varied to investigate the impact on metal cycles. In situ experimentation on the Clark Fork River and the Big Hole River, both in Montana, will be conducted to examine the concentration changes of Mn and Zn at the benthic surfaces in greater detail. Commercially available flux chambers will be utilized in the river with small amounts of benthic materials from the streambeds and isolated within the river system. The diel concentration changes within the isolation chambers will be compared to the water column to better identify the sources of the metals and the cause of the cyclic phenomena.