DEVELOPING A NOVEL TECHNIQUE FOR RECONSTRUCTING HISTORIC LAKE TROPHIC STATES USING CALCIUM CARBONATE CO-PRECIPITATION WITH PHOSPHORUS
Anthropogenic phosphorus pollution is the leading cause of the eutrophication and degradation of water bodies. Managing these systems requires an accurate understanding of historical conditions. However, the vertical mobility of phosphorus (P) in lake sediments has prevented accurate determinations of historical loading. Because P has a high affinity for Ca, and will co-precipitate with CaCO3 in lake systems, we hypothesize the CaCO3-P fraction of sediments can accurately reconstruct historical ambient water column concentrations. We precipitated CaCO3 in a range of P solutions (0, 5, 25, 50, 100, 250 ?g/L) and found the precipitates had P concentrations that closely match the solution from which they formed (R^2=0.9959, P=<0.001). Our research now focuses on P inclusions in individual grains, employing SEM microscopy and microprobe analyses to develop a way to quantify CaCO3-P concentrations.We anticipate developing a calibration relating P concentrations in CaCO3 to P concentrations in the solution from which the grains precipitate. Our results will inform a new approach to measuring trophic history of alkaline, calcareous lakes. Specifically, this method may inform debates regarding whether Utah Lake was eutrophic prior to large-scale development within the watershed.
Janice Brahney (Co-Presenter/Co-Author), Utah State University, email@example.com;
Mark Devey (Primary Presenter/Author), Utah State University, firstname.lastname@example.org;