Abstract
Eastern Siberia is a key region for understanding CH4 emissions from permafrost, as has been demonstrated in several landmark publications. Three sources of CH4 can be distinguished: ecosystem CH4 (produced from recently photosynthesised carbon in wetlands), old-carbon CH4 (generated by mobilisation of old soil carbon), and deep CH4 (liberated from shallow gas reservoirs in the permafrost, including hydrates). The data uncertainty of these sources is large due to the sparseness of the observation network and challenges in obtaining winter flux measurements. Despite low winter temperatures, ecosystem CH4 flux has proven to be active during this season.
To elucidate ecosystem and old-carbon CH4, a better understanding of the microbial ecology of soils and lake sediments in relation to hydrology and electron acceptor availability is needed. At a large scale, both sources are closely linked to geomorphological processes resulting from permafrost thaw. Deep-permafrost CH4 is likely activated in northwest Siberia; however, there is no evidence for its enhanced activation on land in eastern Siberia.
There is evidence for increasing biogenic volatile organic compound (BVOC) emissions in Siberian forests, which could reduce OH radical oxidation of CH4 in the atmosphere. However, BVOC oxidation also contributes to the formation of aerosols, and is reduced by higher atmospheric CO2 concentrations. Studies modelling future emissions have shown that the net radiative effect is uncertain, varying from negative to positive depending on assumptions about the interaction between BVOC emissions and atmospheric CO2 concentration.
To elucidate ecosystem and old-carbon CH4, a better understanding of the microbial ecology of soils and lake sediments in relation to hydrology and electron acceptor availability is needed. At a large scale, both sources are closely linked to geomorphological processes resulting from permafrost thaw. Deep-permafrost CH4 is likely activated in northwest Siberia; however, there is no evidence for its enhanced activation on land in eastern Siberia.
There is evidence for increasing biogenic volatile organic compound (BVOC) emissions in Siberian forests, which could reduce OH radical oxidation of CH4 in the atmosphere. However, BVOC oxidation also contributes to the formation of aerosols, and is reduced by higher atmospheric CO2 concentrations. Studies modelling future emissions have shown that the net radiative effect is uncertain, varying from negative to positive depending on assumptions about the interaction between BVOC emissions and atmospheric CO2 concentration.
Original language | English |
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Title of host publication | Water-Carbon Dynamics in Eastern Siberia |
Editors | Takeshi Ohta, Tetsuya Hiyama, Yoshihiro Iijima, Ayumi Kotani, Trofim C. Maximov |
Publisher | Springer Singapore |
Pages | 101-134 |
Number of pages | 34 |
ISBN (Electronic) | 9789811363177 |
ISBN (Print) | 9789811363160 |
DOIs | |
Publication status | Published - 2019 |
Keywords
- Acetoclastic pathway, Atmospheric sink, Biogenic Volatile Organic Compound (BVOC), Floodplains, Hydrates, Methanotrophy
VU Research Profile
- Science for Sustainability