黄河口潮滩湿地系统CO2和CH4通量特征与影响机制研究 | |
姜欢欢 | |
学位类型 | 硕士 |
导师 | 孙志高 |
2012-05-22 | |
学位授予单位 | 中国科学院研究生院 |
学位授予地点 | 北京 |
学位专业 | 环境科学 |
关键词 | Co2 Ch4 通量特征 影响机制 潮滩湿地 黄河口 |
其他摘要 | 黄河口潮滩湿地作为黄河入海河段与渤海相互作用形成的重要生态类型,是陆源碳、氮的重要“汇”区,其CO2和CH4排放不仅会对大气环境产生重要影响,而且还深刻影响着湿地生态系统的稳定与健康。为了深入理解潮滩湿地系统CO2和CH4的通量特征及影响机制,论文以今黄河入海口北部的滨岸潮滩湿地为研究对象,基于野外原位观测与室内控制实验,探讨了潮滩湿地CO2和CH4的通量特征及年内变化规律,揭示了潮滩湿地CO2和CH4排放的影响机制,评估了潮滩湿地CO2和CH4的“源/汇”功能及其对大气环境的影响。主要结论如下:(1)潮滩湿地CO2和CH4排放通量具有明显的时空变化特征。就CO2而言:时间上,夏季CO2通量最大(141.74 mg·m-2·h-1),春季(81.80 mg·m-2·h-1)和秋季(80.01 mg·m-2·h-1)次之,冬季(31.80 mg·m-2·h-1)最小;空间上,高潮滩CO2的排放通量最大(229.99mg·m-2·h-1),低潮滩(42.41 mg·m-2·h-1)和中潮滩(36.77 mg·m-2·h-1)次之,光滩(26.18 mg·m-2·h-1)最小。就CH4而言:时间上,秋季的CH4排放通量(0.09 mg·m-2·h-1)最大,春季(0.01mg·m-2·h-1)次之,夏季(-0.11 mg·m-2·h-1)和冬季(-0.01mg·m-2·h-1)较小;空间上,光滩的CH4通量(0.03 mg·m-2·h-1)最大,低潮滩(0.01mg·m-2·h-1)次之,高潮滩(-0.02 mg·m-2·h-1)和中潮滩(-0.03 mg·m-2·h-1)最小。(2)潮滩湿地CO2和CH4通量的日变化特征明显。低潮滩和光滩的CO2日通量范围与均值分别为66.61~130.11 mg·m-2·h-1(98.18mg·m-2·h-1)和-16.10~47.28 mg·m-2·h-1(16.13 mg·m-2·h-1),均表现为CO2的排放源;低潮滩和光滩的CH4日通量范围与均值分别为-0.21~0.04 mg·m-2·h-1(-0.02 mg·m-2·h-1)和-0.04~0.22 mg·m-2·h-1mg·m-2·h-1(0.08 mg·m-2·h-1),前者表现为CH4的弱汇,后者表现为CH4的较弱排放源。(3)黄河口潮滩湿地的CO2排放通量范围及均值与国内外湿地相关研究结果相差不大,而CH4通量同大多数研究相比偏低;潮滩湿地全年CO2和CH4排放量均值为366335.11 mg·m-2和9.07 mg·m-2,年排放总量分别为674385.20 t 和16.70 t,为CO2和CH4的重要释放源。在100a时间尺度上,黄河口潮滩湿地系统全年CO2和CH4的综合GWP为366561.90 mg·m-2,且夏季GWP最高,秋季和春季次之,冬季最低;在全年CO2和CH4的综合GWP中,CO2的贡献达到99.94%,而CH4仅为0.06%。(4)潮滩湿地不同样点环境因子的时空变化特征明显。温度与潮滩湿地CO2年内通量特征变化较为一致,温度与CH4通量变化特征缺乏一致性;水分对潮滩湿地CH4通量的影响程度较CO2通量大,潮汐对 CO2和CH4排放通量特征亦具有重要影响;盐分可能并不是影响潮滩湿地CO2和CH4排放通量的重要因素;各点CO2和CH4通量与各环境基质因素之间大部分并未表现出显著相关关系;植被可能是潮滩湿地CO2排放的主要因素,未割除植被样点CO2排放通量显著高于割除植被样点,但植被对潮滩湿地CH4通量的影响并不显著。(5)有机碳矿化受到温度、水分及碳、氮等多因素的重要影响。各潮滩表层土壤的有机碳矿化速率均表现为35℃>25℃>15℃,有机碳矿化对温度的响应在15℃~25℃范围内较25℃~35℃更为敏感,本文Q10结果较其它研究结果稍微偏高;水分差异对有机碳矿化的影响并不显著,可能与黄河口潮滩湿地土壤经常处于饱和或过饱和状态,土壤微生物对70%WHC的水分状况和淹水状况均能很容易适应有关;除高潮滩有机碳矿化速率在高氮处理下表现为抑制外,其它潮滩两种氮输入处理对有机碳矿化速率均表现出一定促进作用,低氮输入对有机碳矿化速率具有较强的促进作用;中潮滩翅碱蓬枯体和低潮滩翅碱蓬枯体输入对有机碳矿化产生显著影响,且后者对有机碳矿化的促进作用要高于前者。(6)潮滩湿地土壤CH4产生潜力和氧化潜力受到温度、碳和氮等因素的重要影响。就CH4产生而言:温度升高在一定程度上促进了CH4的产生,温度系数Q10随着温度的增加而提高, CH4产生率对温度的响应在20℃-30℃之间较15℃-25℃之间敏感;氮输入对高潮滩和中潮滩土壤的CH4产生表现为促进或抑制作用,低潮滩和光滩对各种氮输入形态的响应均表现为促进;有效碳和耐性碳整体促进了CH4的产生潜力,翅碱蓬枯体对各潮滩土壤CH4产生的促进程度表现为中潮滩>低潮滩>光滩>高潮滩,两种翅碱蓬枯体的效应表现为低潮滩翅碱蓬>中潮滩翅碱蓬。就CH4氧化而言:整个潮滩湿地CH4氧化率在25℃下最大,30℃和20℃次之,15℃最小,潮滩湿地土壤CH4氧化的最适温度在25℃左右。CH4氧化率对温度的响应在15℃~25℃之间较20℃~30℃之间敏感,CH4氧化的Q10较CH4产生小,可能与CH4氧化菌对温度的依赖性低于产CH4菌有关;NH4Cl浓度越大,对CH4氧化的抑制作用越强;葡萄糖、甲酸钠和乙酸钠等3种碳源物质的输入对CH4氧化均起到了一定的抑制作用,且抑制程度表现为葡萄糖>乙酸钠>甲酸钠。 ; The tidal wetland, located in the interaction zone between the Yellow River estuary and the Bohai sea, is a very important ecosystem. As important terrestrial carbon (C) and nitrogen (N) "sink", the emission of carbon dioxide (CO2) and methane (CH4) of tidal wetland will not only have important effects on atmospheric environment, but also deeply influence the stability and health of wetland ecosystem. In this thesis, the tidal wetland ecosystem in the northern coastal zone of the Yellow River estuary was selected as study object to understand the characteristics and influence mechanisms of CO2 and CH4 emission. Based on in situ observation and laboratory control experiment, the thesis discussed the CO2 and CH4 flux characteristics and annual variation rules, revealed the influence mechanisms of CO2 and CH4 emission, and assessed the "source/sink" function and the effects on the atmospheric environment of CO2 and CH4 in different tidal wetlands. The main results were drawn as follows:(1)The spatial and temporal variations of CO2 and CH4 flux were significant in different tidal wetlands. For CO2, from the aspect of time, the CO2 fluxes differed among the four seasons, in the order of summer (141.74 mg·m-2·h-1) > spring (81.80 mg·m-2·h-1) > autumn (80.01mg·m-2·h-1) > winter (31.80 mg·m-2·h-1); From the aspect of space, the CO2 fluxes also differed among the four study sites, in the order of high tidal wetland (229.99 mg·m-2·h-1) > low tidal wetland (42.41 mg·m-2·h-1)> middle tidal wetland (36.77 mg·m-2·h-1) > bare flat (26.18 mg·m-2·h-1). For CH4, from the aspect of time, the CH4 fluxes differed among the four seasons, in the order of autumn (0.09 mg·m-2·h-1) > spring (0.01 mg·m-2·h-1) > summer (-0.11 mg·m-2·h-1) > winter (-0.01mg·m-2·h-1); From the aspect of space, the CH4 fluxes also differed among the four study sites, in the order of bare flat (0.03mg·m-2·h-1) > low tidal wetland (0.01mg·m-2·h-1)> high tidal wetland (-0.02mg·m-2·h-1)> middle tidal wetland (-0.03mg·m-2·h-1).(2)The diurnal variation characteristics of CO2 and CH4 flux also were significant in tidal wetlands. The CO2 flux ranges in low tidal wetland and bare flat were 66.61~130.11 mg·m-2·h-1 and -16.10~47.28 mg·m-2·h-1, and the day average fluxes were 98.18 mg·m-2·h-1 and 16.13 mg·m-2·h-1, respectively, indicating that both low tidal wetland and bare flat were the sources of CO2. The CH4 flux ranges in low tidal wetland and bare flat were -0.21~0.04 mg·m-2·h-1 and -0.04~0.22 mg·m-2·h-1, and the day average fluxes were -0.02 mg·m-2·h-1 and 0.08 mg·m-2·h-1, respectively, indicating that the former was the weak sink of CH4, while the latter was the weak source of CH4.(3)The ranges and averages of CO2 flux in this thesis approximated to most domestic and foreign relative results, while relatively lower for CH4 flux. The annual average CO2 and CH4 emissions of tidal wetland were 366335.11 mg·m-2and 9.07 mg·m-2, and the total CO2 and CH4 production in tidal wetland of the Yellow River estuary were 674385.20 t·a-1 and 16.70 t·a-1, respectively, showing that the tidal wetland was important source of CO2 and CH4. The comprehensive global warming potential (GWP) of CO2 and CH4 of tidal wetland at 100a scales were 366335.11 mg·m-2·h-1, of which the contribution of CO2 accounted for 99.94%, only 0.06% for CH4. Moreover, from the aspect of time, the GWP contribution also differed among the four seasons, in the order of summer >autumn> spring>winter.(4)The spatial and temporal variations of environmental factors were significant in different tidal wetlands. The CO2 flux characteristics in a year were nearly consistent with the variation of corresponding temperatures, while not for CH4. Water content had more significant effects on CH4 fluxes than those on CO2. The tide also had important influences on the fluxes of tidal wetland. Salinity status might be not an important factor on the emission of CO2 and CH4. Most the correlations between CO2 fluxes and soil substrates were not significant, similar results were found between CH4 fluxes and soil substrates. The vegetation also had important influences on the CO2 fluxes of tidal wetland, and the CO2 fluxes were high in the site without plants clipped. However, the effects of vegetation on CH4 fluxes were not significant. (5)Soil organic carbon (SOC) mineralization was mainly affected by different factors including temperature, water content, and C and N contents. The SOC mineralization rates of topsoil of the four sites differed in different temperatures, in the order of 35℃>25℃>15℃. SOC mineralization was more sensitive in the range of 15℃~25℃ than that of 15℃~25℃, and the temperature coefficients (Q10) were slightly higher compared to most domestic and foreign corresponding results. Water contents had no significant effects on SOC mineralization, one possible reason was that the tidal wetland soil of the Yellow River estuary was usually in the saturation or supersaturation status, and the soil micro-organisms could easily adapt to both the 70% WHC (Water Holding Capacity) and submerged conditions. Both high and low N imports, to some extent, promoted the SOC mineralization rates, except the SOC mineralization rates of high tidal wetland soil were suppressed as affected by high N import. Low N import had more significant effects on SOC mineralization compared to high N import. The additions of Suaeda salsa litter promoted SOC mineralization, and the effects of Suaeda salsa from low tidal wetland were greater than those from middle tidal wetland. (6)The CH4 production potential and CH4 oxidation potential were affected by temperature, C, and N etc.. For CH4 production, the increasing of temperatures, to some extent, promoted CH4 production, and the Q10 values increased with the temperatures. The CH4 production was more sensitive to temperature in the range of 20℃~30℃ than that of 15℃~25℃. N import promoted or inhibited the CH4 production of high tidal wetland soil and middle tidal wetland soil, while it promoted the CH4 production of low tidal wetland soil and bare flat soil. Both High quality C and low quality C, on the whole, promoted CH4 production potential. The additions of Suaeda salsa litter promoted the CH4 production of different tidal wetland soils, in the order of middle tidal wetland > low tidal wetland > bare flat > high tidal wetland, and the effects of Suaeda salsa litter from low tidal wetland was greater than that from middle tidal wetland. For CH4 production, the CH4 oxidation rates of tidal wetland differed among different temperatures, in the order of 25℃ > 30℃ > 20℃>15℃, and the optimal temperature was 25℃. Moreover, CH4 oxidation was more sensitive to temperature in the range of 15℃~25℃ than that of 20℃~30℃. The Q10 values of CH4 oxidation were lower than those of CH4 oxidation, which might result from the stronger dependence of methanogens on temperature compared to methanotrophs. The greater the concentrations of NH4Cl were , the stronger inhibitory effects of NH4Cl on CH4 oxidation were. Three different carbonaceous materials, to a certain degree, inhibited CH4 oxidation, in the order of glucose > sodium acetate > sodium formate. |
语种 | 中文 |
文献类型 | 学位论文 |
条目标识符 | http://ir.yic.ac.cn/handle/133337/5638 |
专题 | 中国科学院烟台海岸带研究所知识产出_学位论文 |
推荐引用方式 GB/T 7714 | 姜欢欢. 黄河口潮滩湿地系统CO2和CH4通量特征与影响机制研究[D]. 北京. 中国科学院研究生院,2012. |
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