Assessing Past and Present Changes in the Chemical Climate of Three High Mountain Regions: Himalayas, Andes, European Alps

• Main Author: Clifford, Heather
• Format: Text
• Language: unknown
• Published: DigitalCommons@UMaine 2022
• Subjects: Earth Sciences; Ice cap; ice core
• Online Access: https://digitalcommons.library.umaine.edu/etd/3596; https://digitalcommons.library.umaine.edu/cgi/viewcontent.cgi?article=4653&context=etd

The goal of this dissertation is to assess past and present changes in the chemical climate of three high mountain regions: the Himalayas, Peruvian Andes, European Alps. In the first analysis, we report a comprehensive case study of chemical composition from streams, snow samples, and an ice core collected from around Mt. Everest Basecamp in the Khumbu region of Nepal during the late pre-monsoon period. Our findings document the 2019 pre-monsoon season, detailing chemistry from Cyclone Fani, spatial variability in snow and stream chemistry, and addressing potential pollution hazards, including the presence of heightened Pb in local streams and possible chemical signature of human waste. This is the first study to characterize the chemical composition of Khumbu Glacier ice/meltwater and create a detailed framework for pre-monsoon snow/water chemistry for the region. The second study details the correspondence in chemical climate resulting from two regional Central Andean firn cores (Quelccaya ice cap, Peru (5470 m asl) and Nevado Illimani glacier, Bolivia (6350 m asl)) and investigates the environmental proxies associated with Central Andean climate. The results show that the Quelccaya core has well-preserved environmental signals despite meltwater percolation, the two regional ice core records contain comparable signals and similar regional scale climatology, and past records of anthropogenic emissions, dust sources, volcanic emissions, forest fire signatures, evaporite salts, and marine-sourced air masses are evident within the cores. Moreover, annual layer thickness established from ultra-high-resolution chemical measurements on a near-basal ice core from the Quelccaya glacier indicates that Quelccaya ice cores drilled to bedrock may be ~1000 years older or more than previously suggested by depth-age models. Lastly, the third study focuses on a 2100-year record of heavy metals (Pb, As, Cd, Bi, Cu) extracted from a European Alps ice core, which is the first known case in which these elements have been observed ...