Assessing permafrost erosion in the Canadian Beaufort Sea, Herschel Island - a biomarker approach

Herschel Island is the remnant of an ice-push moraine, formed during the farthest advance of the Laurentide Ice Sheet in the late Wisconsin. The island is located in the Canadian Beaufort Sea, in the northwestern part of the Yukon Territory. A marine depression (Herschel Basin), southeastern adjacent to Herschel Island, acts as a sink of organic matter (OM) derived from various sources. The main objective of this master thesis was to determine the amount of OM, derived from Herschel Island, in the deposits of Herschel Basin. Rapidly increasing mean annual air temperatures (MAAT) in high latitude areas raise awareness of a changing Arctic climate and consequences for the Arctic carbon cycle. Biomarker analyses of soil and sediment samples from various study sites on and around Herschel Island show that sediments in Herschel Basin are of prevailing terrigenous origin. Approximately 60 % of the OM in the surface sediments of Herschel Basin and the adjacent nearshore area can be assigned to eroded material from Herschel Island. Investigations on a sediment core from the centre of the basin suggest enhanced erosion rates and increased supply by OM from Herschel Island in the upper section of the core. Results of biomarker analyses of this thesis corroborate a progressing change of the Arctic climate, amplified by positive carbon feedback mechanisms