The Hydrologic Evolution of Glacial Meltwater: Insights and Implications from Alpine and Arctic Glaciers.

[摘要] Glaciers are of critical importance in the global hydrological cycle and the implications of theirrecent rapid decline are still poorly understood. Subglacial processes impact glacial hydrologythrough nutrient production, water chemistry, and aquifer recharge, but are inaccessible to directobservation. Furthermore, understanding the impact current subglacial melt processes have onsurrounding environments may provide insight to changes that likely occurred on glacial-interglacialtimescales. In my work, I combine multiple elemental and isotopic systems tounderstand glacial hydrology, including the subglacial environment. First, I have developed aBayesian Monte Carlo isotope-mixing model that incorporates stable isotope, δ18O and δD,measurements to extrapolate relative contributions of ice and snowmelt to the glacial system.This model can also be applied to other earth surface systems with distinct end member isotopiccompositions. Second, I have combined the melt fractions from my isotope-mixing model with aradioactive uranium-series (U-series) isotope age model to quantify the average residence timeand storage length of subglacial melt. By combining these two isotopic systems, I provide uniqueinsights on the size of the subglacial meltwater reservoir and its potential impacts on glacialsliding and meltwater nutrients. Third, I investigate the influence of the U chemistry of currentglacial meltwater from the Greenland Ice Sheet on adjacent seawater as a proxy to reconstructthe potential influence of glacial melt on global seawater U chemistry over glacial-interglacialtimescales using a simple seawater U budget box model. The models presented here are appliedto a broad geographic range to investigate the universality of climate-melt relationships and theimpact of glacial melt on the chemistry of both freshwater and seawater reservoirs.

[发布机构] University of Michigan

[效力级别] Isotope geochemistry

[关键词] Glacial hydrology;Isotope geochemistry;Bayesian Monte Carlo isotope mixing model;Glacial-interglacial timescales;Subglacial environment;Meltwater residence time;Geology and Earth Sciences;Science;Earth and Environmental Sciences