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A Preliminary Study on Methane Emission from a Seasonal-Freezing Alpine Peat Wetland during a Non-growing Period
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    Abstract:

    Alpine peat wetlands are important sources of atmospheric methane. Most of available in situ measurements were exclusively conducted in growing seasons because weather conditions are usually extremely harsh in non-growing seasons. Due to this situation, the CH4 emission from seasonal-freezing alpine peat wetlands in non-growing seasons so far has not been well known. This study aimed at the investigation of the CH4 emission characteristics in the non-growing season and its importance by carrying out 9-month field measurements (from the beginning of the winter to early summer) in a Zoigê alpine wetland with seasonal-freezing peat. The field site was located at the northeastern edge of the Qinghai-Tibetan Plateau. Methane fluxes were manually measured weekly or half-weekly at 0900 LST to 1100 LST in the morning at six random locations that were situated at typical bulge (BA), hollow (HA), and transition (TA) areas respectively. Static opaque chambers were used to collect gas samples and a gas chromatograph was used for immediate sample analysis. During the entire observational period, mean methane emission rate among the six spatial redundancies ranged from 0.1 to 1.0 mgC m-2 h-1, and significant emission was observed in the non-growing season. The temperature sensitivity (Q10, which is the fold change of CH4 flux in response to a temperature change of 10℃) during the non-growing period (18.1-29.8) was much higher than that during the growing season (1.4-2.2), implying that the methane emission in non-growing seasons could be much more sensitive to climate warming. By extrapolating our measured fluxes and taking into account results of some other studies for the growing season, the annual CH4 emission from the investigated alpine wetland was estimated to be about 29 kgC ha-1 a-1, of which at least 50% was released in the non-growing season. The CH4 flux during the observational period showed a significant seasonal variation, which may be attributed jointly to temperature variation, freezing-thawing alternation, water table (or soil moisture) dynamics and seasonality of plant growth. The CH4 fluxes were also significantly different among the micro-landforms, with the statistically lowest, highest and moderate values at the BA, HA, and TA, respectively (p<0.05). Such differences may be attributed to the spatial variations in environmental factors like as the water table (or soil moisture) and the plant distribution. Considering the area coverage proportions of individual micro-landforms, the emissions at the BA, HA, and TA areas accounted for about 16%, 11%, and 73% of the bulk annual CH4 emission from the entire wetland, respectively. It is notable that the above results and conclusions were derived from our field measurements during a relatively short period. Long-term field observations lasting for a full year or even longer are necessary to further confirm the results of the present study.

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王晓龙,张寒,姚志生,郑循华,张社奇.2016.季节性冻结高寒泥炭湿地非生长季甲烷排放特征初探[J].气候与环境研究,21(3):282-292. WANG Xiaolong, ZHANG Han, YAO Zhisheng, ZHENG Xunhua, ZHANG Sheqi.2016. A Preliminary Study on Methane Emission from a Seasonal-Freezing Alpine Peat Wetland during a Non-growing Period[J]. Climatic and Environmental Research (in Chinese],21(3):282-292.

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History
  • Received:April 13,2015
  • Revised:March 04,2016
  • Adopted:
  • Online: May 26,2016
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