Black carbon deposition in the European Arctic from the preindustrial to the present

• Main Author: Ruppel, Meri M.
• Other Authors: Bindler, Richard, University of Helsinki, Faculty of Biological and Environmental Sciences, Department of Environmental Sciences, Environmental Change Research Unit, Helsingin yliopisto, bio- ja ympäristötieteellinen tiedekunta, ympäristötieteiden laitos, Helsingfors universitet, bio- och miljövetenskapliga fakulteten, miljövetenskapliga institutionen, Korhola, Atte, Weckström, Jan
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Helsingin yliopisto 2015
• Subjects: ympäristötieteet; Arctic; Svalbard; Arktis*; black carbon; Global warming; ice core
• Online Access: http://hdl.handle.net/10138/154674

The Arctic has been warming twice as fast as the rest of the world during the last decades of global warming. Reasons for the amplified Arctic warming are thought to partly relate to positive feedbacks affecting the radiative budget of the area. Black carbon (BC) is a light-absorbing particulate produced by incomplete combustion of biomass and fossil fuels. BC strongly warms the atmosphere, and its climate effects are amplified in the Arctic where its deposition on light surfaces decreases their reflectivity, resulting in elevated heat absorption and further hastening melt of snow and ice. Globally, BC is estimated to be the second most important climate-warming agent after carbon dioxide. Historical information on BC deposition plays a significant role in the assessment of long-term climate effects of BC, but scarce data on this past variability has been available from the Arctic. Historical BC records can be attained from environmental archives, such as ice cores, peat deposits and marine and lake sediments, which store direct evidence of past BC deposition in chronological order. The objective of this thesis is to collect new spatial and temporal data on BC deposition in the European Arctic from the preindustrial to the present (i.e., the last ca. 300 years), and assess BC sources and climatic implications, by analysing five lake sediment cores from Arctic Finland and an ice core from Svalbard. No standard method exists to determine BC, and the precise definition of BC depends on the methodology used for its quantification. Here, three different analytical methods were used to quantify different components of BC. Spheroidal Carbonaceous Particles (SCP) and soot-BC (SBC) were analysed from the Arctic Finland lake sediments by SCP analysis and chemothermal oxidation at 375 °C, respectively, and elemental carbon (EC) from the Svalbard ice core with a thermal optical method. The results suggest temporal variation in past BC trends, both between study sites and between methods. While SCPs show a marked trend with ...