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GREENHOUSE GAS RELEASE FROM BURIED SOIL IN THE LENA RIVER DELTA, SIBERIA: FIELD INCUBATION STUDY

Светлана Евграфова

Abstract

A fundamental research question related to the impact of thawing permafrost on global change is, how fast organic matter in the thawing permafrost can be converted to CO2 and CH4 and released into the atmosphere. Current estimates on the degradability of thawing organic matter in permafrost are based on incubation studies which are highly artificial and probably overestimate the greenhouse gas production under in situ conditions. We aimed at identifying the microbial response and associated release of CO2 and CH4 from thawing soil that has previously been permanently frozen. For this, we performed an in situ field-based incubation experiment in a rim of an ice-wedge polygon on Samoylov island in the Lena River Delta, Russia, at 72В°22?N, 126В°28?E. We moved formerly frozen soil to the active layer. This material was either placed partly in the subsoil, to mimic the cryoturbation processes, or was exposed to the soil surface to simulate an eroded river bank. Data from the incubation experiment showed low intensity of gas emission which indicates a weak involvement of the buried soil in the present-day processes of microbial decomposition.

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