A large sample set of subglacial sediments and waters was initially generated through extensive fieldwork and archived samples (Figure 1), which came from glaciers of different sizes (ice sheet and icefield), bedrock types (e.g. carbonate, silicate and ancient silicate) and climates (rainforest, high altitude and Arctic). Each sample underwent rigorous geochemical measurements and high-precision analyses to ascertain the controls on elemental distributions between sediments and waters and how these evolved downstream. The large geochemical data sets produced were incorporated into computer modeling programs to determine the elemental speciation and redox environments within each subglacial system, and in the case of the Greenland fieldwork samples, how these parameters changed over the course of a melt seasons, and how they varied downstream and into the oceans. Geochemical and isotopic method development was also at the core of this project. State-of-the-art analytical machines have been utilized throughout ICE-OTOPE to maximize the data quality and precision so that the highest quality research can be produced.
A particular emphasis was placed on the element Fe, Fe-isotopes, and the coupled sulfur-Fe biogeochemical cycle. Using the analytical-modeling techniques above I was able to broadly determine in what conditions Fe is released in different subglacial systems around the Arctic, how much of the Fe is bioavailable and its fate downstream in glacial rivers. One of the key findings is that the concentration of Fe (and other elements) from glaciers draining different regions of the Greenland Ice Sheet (and other regions of the Arctic) span orders of magnitude. Therefore a huge amount of care must be taken when calculating elemental and nutrient fluxes from regions such as the Greenland Ice Sheet into the proximal oceans.
