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题名: 三峡水库甲烷和二氧化碳排放及其影响因子研究
作者: 杨乐
学位类别: 博士
答辩日期: 2012
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 王效科
关键词: 甲烷 ; Methane ; 二氧化碳 ; carbon dioxide ; 江面 ; water surface ; 消落带 ; drawdown area ; 三峡水库 ; Three Gorges Reservoir
其他题名: Studies on methane and carbon dioxide emissions from the Three Gorges Reservoir and their influencing factors
中文摘要:     中国是世界上水电装机容量最大的国家,水电为国内经济的快速增长做出了重要的贡献,同时也在国家节能减排计划中起着重要作用。但是随着对水库温室气体排放研究的深入,“水电是绿色能源”的传统观点受到广泛的质疑。作为现今世界上发电量最大的水电站——三峡电站,其中的温室气体排放量引起了世界上很多学者的关注。 本研究从2009年11月至2011年1月在云阳、巫山、秭归和三斗坪四个地点,采用静态箱法测定江面和消落带上二氧化碳(CO2)、甲烷(CH4)的排放通量,同时测定气象、水文、水质、土壤等可能影响CO2和CH4排放的环境因子。主要结果如下: (1)江面上CO2平均扩散通量为163.3 ± 117.4 mg CO2 m-2 h-1,高于大多数温带和北方寒带水库中的CO2通量,但低于大多数热带水库中的CO2通量。CO2通量的季节变化与CH4通量相似,从1月开始波动上升,在夏季(6~8月)达到最大值,以后逐渐下降,主要受到温度、流速和pH值的季节变化的影响。但是CO2通量的空间变化与CH4通量不同,位于三峡水库中部的巫山处CO2平均通量最大(221.9 ± 130.3 mg CO2 m-2 h-1),坝前秭归处最低(88.6 ± 52.5 mg CO2 m-2 h-1),这与不同地点处流速的差异有关。 (2)2010年,三峡水库江面上CH4平均通量为0.62 mg CH4 m-2 h-1(其中,扩散通量:0.27 ± 0.15 mg CH4 m-2 h-1;气泡通量:0.35 ± 0.57 mg CH4 m-2 h-1),接近于其他温带水库中的CH4通量,但显著低于热带水库中的CH4通量。三峡水库夏季时的CH4通量高于其他季节,这与流速、温度和溶解氧的季节变化有关。大坝上游的河道中,从上游到下游CH4通量呈现出逐渐降低的趋势,但坝后河流中CH4通量显著高于坝前秭归处CH4通量,CH4通量的空间变化与各地点流速的差异、沉淀物的分布和涡轮机对过坝水体的扰动有关。 (3)荒地、农田、采伐迹地消落带CO2平均通量为108.37 ± 98.80 mg CO2 m-2 h-1。旱地消落带出露时,土壤呼吸排放的CO2平均通量(159.25 ± 142.37 mg CO2 m-2 h-1)高于淹没时水体表面的CO2排放通量(89.08 ± 66.84 mg CH4 m-2 h-1)。出露时,CO2通量受到气温、5 cm土温、土壤含水量和表土硝态氮影响,而在淹水时,CO2通量受到TIC、TC、pH值和DO的影响。 (4)消落带CH4年平均通量为0.23 mg CH4 m-2 h-1(其中,扩散通量:0.16 ± 0.24 mg CH4 m-2 h-1;气泡通量:0.068 ± 0.061 mg CH4 m-2 h-1)。淹没期的消落带是CH4的排放源(0.22 ± 0.26 mg CH4 m-2 h-1),而出露期的消落带是CH4的吸收汇(-0.008 ± 0.035 mg CH4 m-2 h-1)。在四种不同土地利用类型的消落带中,水稻田的CH4平均通量(2.61 ± 3.76 mg CH4 m-2 h-1)远大于其他三种旱地的通量,在三种旱地中,农田中的CH4通量(0.12 ± 0.22 mg CH4 m-2 h-1)显著低于荒地(0.19 ± 0.28 mg CH4 m-2 h-1)与采伐迹地(0.18 ± 0.24 mg CH4 m-2 h-1),与不同类型样地的淹水持续时间呈正相关。 (5)2010年三峡水库温室气体碳排放总量为0.5794~1.168 Tg C-CO2 eq. y-1,仅为由火电产生847亿度电(2010年三峡发电总量)而排放温室气体总量的2.4~4.9%。三峡水库主要碳收支途径的估算结果表明:碳年收入为10.78~13.66 Tg C yr-1,年支出10.65~11.24 Tg C yr-1,碳收入大于碳支出。
英文摘要:
    China is the largest country in hydroelectric capacity to generate electricity in the world, and hydropower contributed greatly to the booming economy in the past years, which would play a crucial role in the energy-saving and emission-reducing plan. However, the traditional standpoint that hydropower was 'green energy' was caused doubts with the development of the research on greenhouse gases (GHGs) emissions from man-made hydropower reservoirs. The Three Gorges Reservoir (TGR), currently the largest hydroelectric reservoir in the world, has drawn much attention by researchers on its GHGs emissions. In this study, methane (CH4) and carbon dioxide (CO2) samples were taken in the water surface and the drawdown area using the static chambers at Yunyang, Wushan, Zigui, and Sandouping for 15 months (November 2009 to January 2011). Environmental factors, including climatic parameters, hydrological factors, water quality, and soil physical-chemical characters, were examined simultaneously with CH4 and CO2 flux observation. The results were as follows. (1) The average annual CO2 flux was 163.3 ± 117.4 mg CO2 m-2 h-1 at the reservoir surface, which was larger than the CO2 flux in most boreal and temperate reservoirs but lower than those in tropical reservoirs. Similar to the seasonal variation in CH4 flux, the CO2 flux started to increase in January and went on rising until peaking in the summer (June–August); CO2 flux gradually decreased thereafter. The seasonal variation in CO2 flux was influenced by temperature, water velocity, and pH. However, the spatial variation in CO2 flux was different from that of CH4 flux, with the largest flux measured at Wushan (221.9 ± 130.3 mg CO2 m-2 h-1), in the middle of the TGR, and the smallest flux measured at Zigui (88.6 ± 52.5 mg CO2 m-2 h-1), near to the TGD; these differences were related to the average water velocities at these different sites. (2) The average annual CH4 flux was 0.62 mg CH4 m-2 h-1, including 0.27 ± 0.15 mg CH4 m-2 h-1 of diffusion and 0.35 ± 0.57 mg CH4 m-2 h-1 of ebullition, which was similar to CH4 emission from temperate and boreal reservoirs but significantly lower than those from tropical reservoirs. Seasonal variation in CH4 flux showed that CH4 flux reached the maximum in summer and turned to the low levels in the other seasons, which was attributed to the seasonal variations in water velocity, temperature, and dissolved oxygen. Moreover, the yearly average CH4 flux decreased from the upstream to the downstream before the Three Gorges Dam (TGD), but CH4 emission from the surface of downstream river was higher than that from the surface at Zigui, the upstream water before the TGD, which might be related to the water velocity, deposited sediment, and disturbance by turbines. (3) The drawdown areas of fallow lands, croplands, and deforested lands were CO2 emission sources (108.37 ± 98.80 mg CO2 m-2 h-1). When the drylands were exposed in the drained season, the average CO2 emission from soil respiration (159.25 ± 142.37 mg CO2 m-2 h-1) was higher than that at the water-air interface in the inundated season (89.08 ± 66.84 mg CO2 m-2 h-1). CO2 flux was influenced by air temperature, soil temperature at 5 cm depth, soil moisture, and the concentration of NO3--N at the surface soil during the drained season, while was related to TIC, TC, pH, and DO during the inundated season. (4) The annual average CH4 flux was 0.23 mg CH4 m-2 h-1 (0.16 mg CH4 m-2 h-1 of diffusive flux plus 0.068 mg CH4 m-2 h-1 of bubble flux) in the drawdown area of TGR in 2010. Except rice paddies, the drawdown areas studied here were sources in the inundated season (0.22 ± 0.26 mg CH4 m-2 h-1) and a sink in the drained season (-0.008 ± 0.035 mg CH4 m-2 h-1). The average CH4 flux across the entire sampled season was 2.61 ± 3.76 mg CH4 m-2 h-1 in the rice paddy, which was the highest among the four types of land that were examined. For the three types of drylands in the drawdown area, the annual average CH4 emission from the croplands (0.12 ± 0.22 mg CH4 m-2 h-1) was significantly lower than that of the fallows lands (0.19 ± 0.28 mg CH4 m-2 h-1) and the deforested lands (0.18 ± 0.24 mg CH4 m-2 h-1), which were positively related with the duration of the inundated season. (5) The total GHGs emission ranged from 0.5794–1.168 Tg C-CO2 eq. yr-1 in 2010, which was only 2.4–4.9% of GHG would release by thermo-power plants if the same amount of electricity (84.7 billion kWh) was generated. Carbon budget at TGR showed that the carbon input to the TGR was estimated to be 10.78–13.66 Tg C yr-1, which was larger than the carbon outflow (10.65–11.24 Tg C yr-1).
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/35132
Appears in Collections:城市与区域生态国家重点实验室_学位论文

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Recommended Citation:
杨乐. 三峡水库甲烷和二氧化碳排放及其影响因子研究[D]. 北京. 中国科学院研究生院. 2012.
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