Drivers Of Inter-Annual And Spatial Variability In The Behavior Of Iron, Manganese And Phosphorus In The Sediment And Water Column Of Frozen Lakes

Under ice metal and nutrient dynamics may impact spring water quality and biological production but are poorly understood. We present time series (January-April 2015) data from two under ice water column and sediment profiles, the hyper-eutrophic Shelburne Pond (SP) and eutrophic Missisquoi Bay (MB), Vermont USA. We demonstrate that the behavior of water column Fe, Mn and P is primarily impacted by redox conditions at the sediment-water-interface, which are closely linked to hydrodynamic and biological processes under ice. Dramatic variability in metal and P dynamics over time (compared to Schroth et al. 2015) linked to inter-annual variability in winter weather and differences between sites are linked to differences in lake/watershed/hydrodynamic and related ecological configuration. Furthermore, thaw event impacts on under ice biogeochemistry differ not only based on hydrodynamic configuration of the watershed and lake, but also by thaw event provenance (e.g. Green Mountains vs. Champlain Valley lowlands). Consequently, our data suggests that biogeochemical evolution of metal and nutrient the under ice is highly dynamic and has great potential to impact water quality and spring/summer ecosystem productivity.