Date of Award
Three sites were chosen along Blacktail creek to compare sediment pore water chemistry. The sites were chosen to reflect a valley superfund site, a Beaver Mimicry Structure (BMS) restoration site, and a wetland with a natural/historical beaver dam. Sediment pore water diffusion samplers (peepers) were deployed in each of the three sites to sample metals, dissolved inorganic carbon, δ13C isotopes, alkalinity, and major anions. Data sets from the peepers were used to determine microbial process that influence the geochemistry of the creek with regard to trace metals and DIC. A wetland (historical) site displayed δ13C ratios and DIC concentrations consistent with acetoclastic methanogenesis which converts acetate to isotopically enriched CO2 and isotopically depleted CH4. The beaver mimicry restoration site (BMS) site sees aerobic respiration producing DIC in Blacktail creek. The BMS site also sees a 5 cm layer where Fe and Mn oxide reduction is taking place, this is indicated by a large increase in dissolved Fe, Mn, As, and P. The downstream peeper displayed methanogenesis, Fe/Mn oxide reduction, and bacterial sulfate reduction. Dissolved Fe and Mn increase more than tenfold in the sediment and there is also a corresponding spike in As and P. These processes can be identified by comparing the concentration of DIC in the sediment to the δ13C isotopic value, as well as Fe, Mn, As, and P.
Nacey, Kyle, "Comparison of Pore Water Chemistry Between an Upland Restoration Site and a Valley Superfund Site Using Inorganic Carbon Isotopes Along Blacktail Creek, Butte, MT" (2021). Graduate Theses & Non-Theses. 265.