wAbstract
@This study aimed to understand the seasonal and spatial variations
of N2O emissions from newly created littoral
marshes in the drawdown area of the Three Gorges Reservoir (TGR),
China. We measured N2O emissions at 10-day
intervals during the growing season (early July to late September)
in 2008. N2O emissions were measured with
static chambers in four typical vegetation stands. The results
showed great spatial variations of N2O emissions
among the four stands. The greatest N2O emissions
(0.052}0.063 mg N2O m-2 h-1)
were from Scirpus triqueter stand, while the lowest N2O emissions (0.020}0.020 mg N2O
m-2 h-1) were from Tupha angustifolia
stand. To such spatial variations in N2O
emissions, standing water depths and soil water content may be
important explaining factors. Besides spatial variations, we also
found significant temporal variations of N2O
emissions in this area. The temporal variation of N2O
emissions in the growing season was not found significantly related
to any measured factor in the study. However, based on principal
component analysis, we consider it partly caused by thermal conditions
and the marked temporal variation of the standing water depth
in the growing season, which to some degree influenced the process
of denitrification and N2O emissions. These
results about TGR enable us to make a more reasonable estimate
of N2O emissions from large dam reservoirs,
particularly those with a large drawdown area in the growing season
in an agricultural landscape.
Keywords: Water regime; Temporal variations; N cycling; Three
Gorges Damx
1. Introduction
2. Materials and methods
@2.1. Study sites
@2.2. Soil physical-chemical characteristics
@2.3. Growth of vegetation
@2.4. Establishment of sampling plots and N2O
emission measurement
@2.5. Statistical analysis
3. Results
@3.1. Physical factors of littoral marshes
@3.2. The N2O emission from littoral marshes
of the TGR
@3.3. Key factors influencing N2O emissions
from littoral marshes of the TGR
4. Discussion
Acknowledgements
References