Affiliations: Institute of Atmospheric Physics, Chinese Academy of
Sciences, Beijing 100029, China | Northeast Institute of Geography and Agricultural
Ecology, Chinese Academy of Sciences, Changchun 130012, China | Graduate School of the Chinese Academy of Sciences,
Beijing 100049, China
Abstract: Wetlands at the interface of the terrestrial and aquatic ecosystems
are intensive sites for mineralization of organic matter, but the contribution
of winter season fluxes of CH_4, CO_2 and
N_2O from wetland ecosystems to annual budgets is poorly
known. By using the static opaque chamber and GC techniques, fluxes of
CH_4, CO_2 and N_2O at
two freshwater marshes in the Sanjiang Plain were measured during the winter
seasons of 2002/2003 and 2003/2004 with contrasting snow conditions and
flooding regimes. The results showed that there were significant interannual
and spatial differences in CH_4, CO_2 and
N_2O fluxes. The Carex lasiocarpa marsh emitted more
CH_4 and CO_2 while absorbed less
N_2O than the Deyeuxia angustifolia marsh during the winter
seasons. Over the winter season, emissions of CH_4,
CO_2 and N_2O ranged from 0.42 to 2.41
gC/m^2, from 24.13 to 50.16 gC/m^2, and
from −25.20 to −148.96 mgN/m^2, respectively.
The contributions of winter season CH_4 and
CO_2 emission to the annual budgets were 2.32%–4.62%
and 22.17%–27.97%, respectively. Marshes uptake N_2O
during the freezing period, while release N_2O during the
thawing period. The winter uptake equaled to 13.70%–86.69% of the
growing-season loss. We conclude that gas exchange between soil/snow and the
atmosphere in the winter season contributed greatly to the annual budgets and
cannot be ignored in a cool temperate freshwater marsh in Northeast China.
Keywords: freshwater marsh, winter flux, greenhouse gas emission, Sanjiang Plain
