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Characteristics of CH4Emission from a Typical Carex Dominated Wetland in Poyang Lake

Author: ZhuLiLi
Tutor: HuQiWu
School: Jiangxi Normal University
Course: Physical Geography
Keywords: Poyang Lake Carex dominated wetland CH4 emission characteristics
CLC: P343.3
Type: Master's thesis
Year: 2013
Downloads: 34
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Abstract


Wetlands are the largest natural sources of emissions of the global methane(CH4). With the change of global climate, especially in the context of global warming,the emission of greenhouse gases CH4in the wetland has become the focus attentionof the world’s governments and scientists. However, the study on China’s largestfreshwater lake-Poyang Lake with its unique characteristics is still empty. In fact, itcan provide the basic data for estimating the emissions of CH4in China’s lakes andwetlands, deepen the understanding of the mechanism of emission process of CH4inlakes and wetlands. The researchers selected a typical Carex wetlands in theNanjishan wetlands Nature Reserve in Poyang Lake from May2009to June2011, andset up two treatments, one is TC, which maintains the natural state of Carex soil-plant system; The other called TJ: cut off the ground from aerial parts of plants, andrepeat three times. Then, the researchers observe the flux distribution of CH4in carextypical wetlands and its impact factor with gas chromatography static box. The mainresults are as follows:(1) The emission flux of CH4of the wetland in Carex wetland during theflooding period shows the obvious diurnal variation law. The emission of CH4lasts allthe day, and its CH4flux is higher than the overall flux in the night. The maximum ofemission flux is5.625mg·m-2·h-1, which happens around13:00; While the minimumis2.637mg·m-2·h-1. Water temperature is one of the most important environmentalfactors that control the the diurnal variation of CH4emissions in Carex wetland. Thediurnal variation of CH4release rate and water temperature keep a significant positivecorrelation (r=0.76, n=10, P <0.01).(2) Changes of water level in Poyang Lake comprise an important factor ofWetland CH4release. There are two experiments treating CH4release rate before andafter the flooding of the soil. The release of CH4after the flooding is nearly a hundredtimes of that before the flooding.(3) The two methods of CH4emission treatment showed obvious seasonalvariation: CH4release during spring and summer was significantly higher than thatduring the fall and winter seasons. The negative emissions of CH4(absorption ofatmospheric CH4) appeared continuouslyduring TC treatment from November2010toFebruary2011. And the absorptive amount was up to0.18mg·m-2·h-1. The entireobservation during the TJ treatment gave priority to with CH4release. (4) The correlation between the seasonal variation of CH4emission flux duringnon-flooding period and the Influencing factors of air temperature, soil temperature,the surface temperature reached a significant level. The temperature becomes the maincontrol factor of CH4emissions during the non-flooded period.(5) The annual CH4emission flux of Nanjishan Carex wetland in Poyang Lakeis about19.51gCH4·m-2·a-1.

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CLC: > Astronomy,Earth Sciences > Geophysics > Hydrological Sciences (water sector physics) > Land hydrology, hydrology (water phenomenology ) > Lakes and reservoirs
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