Glaciochemical Investigations in Three Southern Hemisphere Mountain Sites

The research presented in this dissertation focuses on glaciochemical records of trace elements, major ions, and stable water isotopes from three mountain regions: the Antarctic Peninsula, the Central Chilean Andes, and South Georgia Island. The first section reports a significant increase in U concentration over 27 years on Detroit Plateau, Antarctic Peninsula. U concentrations in the ice core increase by as much as 102 between the 1980s and 2000s, accompanied by increased variability in recent years. The U concentration increase coincides with expanded open pit mining in the Southern Hemisphere, most notably Australia. Since other land-source dust elements do not show similar large concentration increases, and since the increased U concentrations are enriched above average levels in the Earth\u27s crust, the source of U is attributed to human activities rather than atmospheric circulation changes. The second section of this dissertation presents a 100-year, continuous, sub-annually dated ice core record from Tupungatito glacier, Central Chilean Andes. This section documents change over time of atmospheric pollution in Central Chile and a significant change in atmospheric pollutant concentrations coincident with anthropogenic activities in this region. Moreover, Cd, As, Pb, Cu, and Ag concentrations exhibit enriched values far in excess of natural levels over the last century, with the increases beginning around the 1930’s. Lastly, the third section of thesis dissertation focuses on a short glaciochemical record from a snow/firn core collected on South Georgia Island. This reconnaissance study provides information about snow chemistry and preservation of environmental records at an elevation of 850 m a.s.l. The results presented in this section help to determine the feasibility of future deep ice coring on South Georgia Island

Physical properties of shallow ice cores from Antarctic and sub-Antarctic islands

The sub-Antarctic is one of the most data-sparse regions on earth. A number of glaciated Antarctic and sub-Antarctic islands have the potential to provide unique ice core records of past climate, atmospheric circulation, and sea ice. However, very little is known about the glaciology of these remote islands or their vulnerability to warming atmospheric temperature. Here we present melt histories and density profiles from shallow ice (firn) cores (14 to 24 m) drilled on three sub-Antarctic islands and two Antarctic coastal domes. Additionally, complementary ground-penetrating radar (GPR) data were collected to further characterize each site and assess the spatial distribution of the observed melt layers. This study includes the first ever firn cores from Bouvet Island (54∘25′19′′ S, 03∘23′27′′ E) in the South Atlantic, from Peter I Island (68∘51′05′′ S, 90∘30′35′′ W) in the Bellingshausen Sea, and from Young Island (66∘31′44′′ S, 162∘33′21′′ E) in the Ross Sea sector's Balleny island chain. Despite their sub-Antarctic location, surface melt is low at most sites (melt layers account for ∼ 10 % of total core), with undisturbed ice layers in the upper ∼ 40 m, suggesting minimal impact of meltwater percolation. The exception is Young Island, where melt layers account for 47 % of the firn core. Surface snow densities range from 0.47 to 0.52 kg m−3, with close-off depths ranging from 21 to 51 m. Based on the measured density, we estimate that the bottom ages of a 100 m ice core drilled on Peter 1 Island would reach ∼ 1856 CE and ∼ 1874 CE at Young Island

Examining links between dust deposition and phytoplankton response using ice cores

Dust is a major source of nutrients to remote ocean environments, influencing primary productivity (PP). Enhanced oceanic PP causes drawdown of atmospheric CO2 and is considered likely to be a driver of climate variability on glacial-interglacial timeframes. However, the scale of this relationship and its operation over shorter timescales remains uncertain, while it is unclear whether dust fertilisation, or other mechanisms, e.g. nutrient upwelling, are the primary driver of PP in high-nutrient low-chlorophyll (HNLC) ocean regions. In this study, we demonstrate, using dust derived Fe and Methanesulfonic acid (a measure of ocean PP) deposition in ice cores from the South Atlantic (South Georgia Island) and North Pacific (Yukon), that PP is significantly correlated with Dust-Fe on both an event and annual scale. However, measuring the relationship between (dust) Fe fertilization and PP in high resolution ice cores is subject to a number of highly complex factors, which are discussed and together used to recommend future research directions. In conclusion, our research suggests that changes in aeolian Fe flux, due to climate change and human activity in dust source regions, could have significant implications for HNLC ocean PP and, therefore potentially, carbon sequestration

A case study using 2019 pre-monsoon snow and stream chemistry in the Khumbu region, Nepal

This case study provides a framework for future monitoring and evidence for human source pollution in the Khumbu region, Nepal. We analyzed the chemical composition (major ions, major/trace elements, black carbon, and stable water isotopes) of pre-monsoon stream water (4300–5250 m) and snow (5200–6665 m) samples collected from Mt. Everest, Mt. Lobuche, and the Imja Valley during the 2019 pre-monsoon season, in addition to a shallow ice core recovered from the Khumbu Glacier (5300 m). In agreement with previous work, pre-monsoon aerosol deposition is dominated by dust originating from western sources and less frequently by transport from southerly air mass sources as demonstrated by evidence of one of the strongest recorded pre-monsoon events emanating from the Bay of Bengal, Cyclone Fani. Elevated concentrations of human-sourced metals (e.g., Pb, Bi, As) are found in surface snow and stream chemistry collected in the Khumbu region. As the most comprehensive case study of environmental chemistry in the Khumbu region, this research offers sufficient evidence for increased monitoring in this watershed and surrounding areas

Prefacing unexplored archives from Central Andean surface-to-bedrock ice cores through a multifaceted investigation of regional firn and ice core glaciochemistry.

Shallow firn cores, in addition to a near-basal ice core, were recovered in 2018 from the Quelccaya ice cap (5470 m a.s.l) in the Cordillera Vilcanota, Peru, and in 2017 from the Nevado Illimani glacier (6350 m a.s.l) in the Cordillera Real, Bolivia. The two sites are ~450 km apart. Despite meltwater percolation resulting from warming, particle-based trace element records (e.g. Fe, Mg, K) in the Quelccaya and Illimani shallow cores retain well-preserved signals. The firn core chronologies, established independently by annual layer counting, show a convincing overlap indicating the two records contain comparable signals and therefore capture similar regional scale climatology. Trace element records at a ~1?4 cm resolution provide past records of anthropogenic emissions, dust sources, volcanic emissions, evaporite salts and marine-sourced air masses. Using novel ultra-high-resolution (120 ?m) laser technology, we identify annual layer thicknesses ranging from 0.3 to 0.8 cm in a section of 2000-year-old radiocarbon-dated near-basal ice which compared to the previous annual layer estimates suggests that Quelccaya ice cores drilled to bedrock may be older than previously suggested by depth-age models. With the information collected from this study in combination with past studies, we emphasize the importance of collecting new surface-to-bedrock ice cores from at least the Quelccaya ice cap, in particular, due to its projected disappearance as soon as the 2050s

Change of grain size parameters of sediments as a result of wind activity. Barchans Jarangiyn els in Gobi, Mongolia

Research conducted on the Jarangiyn els field on the Gobi desert in Mongolia took place during the transformation of barchans resulting from the changes in wind direction. The investigation undertaken by the authors had as its goal the evaluation of the changes in the morphology of the forms, extended by the interpretation of the grain size parameters distribution in the longitudinal profiles of the dunes. The results indicate that the processes of barchan transformation are recorded in grain size parameters

Weather condition characteristics at the H. Arctowski Station (South Shetlands, Antarctica) for 2006, in comparison with multi-year research results

The maritime Antarctic is characterised by highly variable weather conditions throughout the year, as well as over multi-year periods. The annual variability of weather conditions constitutes an important basis for biological and geographical studies, allowing for the monitoring of the functioning and changes of the geographical environment of the west coast of Admiralty Bay (King George Island, South Shetlands, Antarctica). Year-round meteorological observations (1.2006-12.2006) measured: atmospheric pressure, wind speed and direction, cloud cover, air temperature, relative humidity, total precipitation, snow cover, and Admiralty Bay ice cover