Permafrost is soil that is frozen for two or more consecutive years at 2C or lower. The city of Fairbanks, Alaska is underlain by rapidly thawing discontinuous permafrost. This discontinuous permafrost leads to pockets of land not underlain by permafrost and the formation of taliks. A talik is a pond formed from degrading permafrost causing the surface soil to sink into the ground and fill with water. During the summers, the active layer of permafrost thaws annually creating a cushion of soil that becomes saturated with water. Permafrost acts as a barrier that causes rain water to pool at the surface, creating wetland like conditions in the summer. The permafrost that is thawing is classified as yedoma permafrost, which contain a high carbon content, upwards of 45% carbon with the majority of that carbon being organic in nature. Inorganic carbon content was not detected in permafrost soil samples analyzed. These conditions provide taliks with extremely high carbon content and through field measurements extremely high iron concentrations, ranging from 18 ppb to 18 ppm. A seasonality study was conducted in a discontinuous permafrost region in Fairbanks, Alaska to observe seasonality trends with frozen and water saturated conditions for a period of 3 years. This study captured two winters and three summers and observed a variety of metals, anions, and photochemical parameters to determine seasonality trends. It was determined that iron concentrations increase during winter complicating photochemical parameters. Thus, photochemical parameters proved to not be an indicator of seasonality so further assessment was conducted on trace metal analysis for seasonality determination. Preliminary results show that some metals, iron and manganese, increase in winter while other trace metals decrease in winter; barium, aluminum, and nickel.

Seasonality geochemistry cycles in a seasonal sub-arctic wetland underlain by permafrost

2019 Fall National Meeting

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