人工湿地甲烷排放规律及其影响因素研究

发布时间：2018-03-29 23:41

本文选题：人工湿地　切入点：日变化　出处：《山东大学》2015年硕士论文

【摘要】：为了减缓全球变暖的趋势,温室气体的减排已经引起国际社会的广泛关注。CH4是一种重要的温室气体,其对温室效应的贡献仅次于C02,而且其单分子温室效应是C02的30倍。人工湿地是CH4的重要排放源。因此研究人工湿地CH4排放的规律及其影响因素对于理解人工湿地对温室气体的贡献和全面评估人工湿地的生态效应具有重要意义。本论文以新薛河人工湿地为研究对象,采用静态箱气象色谱法,通过定期野外采样监测和实验室分析,研究了人工湿地CH4排放状况和变化规律。首先研究新薛河人工湿地CH4浓度的日变化,发现了CH4浓度24小时变化规律,为了在更大时间尺度上验证这个规律,所以研究CH4浓度的四季变化,结合日变化和四季变化以及空间变化分析影响CH4排放的因素。因为野外实验有很多不确定因素,为了深入研究水位的影响专门设计了水位控制实验,结合野外实验和控制实验进行分析甲烷排放的影响因素。在研究中发现“中国湿地CH4排放规律及其影响因素研究”存在大量研究案例但缺乏深入数据挖掘,为了在更大尺度上分析影响湿地甲烷排放的因素,也做了这方面的数据挖掘和文献综述。主要研究内容及结果如下：(1)新薛河人工湿地夏季上游和下游的水——气界面的24小时CH4浓度变化规律具有一致性,呈双峰型即有两个浓度峰值,一个在上午6：00～8：00,另一个在23：00～1：00。其变化趋势大致可以分为三个阶段,从0：00～7：00,CH4浓度逐渐升高；7：00～14：00,CH4浓度又逐渐减小；14：00～24：00,CH4浓度又开始小幅度升高,并在夜间21：00～22：00之间有一个小幅降低的趋势。夏季人工湿地上、下游的水——气界面的CH4浓度与温度的变化是不同步的,CH4浓度变化相对于水温变化的滞后时间是6-11小时,而相对于气温变化的滞后时间是7-14小时,两者都在10 h时相关性最好,且CH4浓度相对于气温变化的滞后时间比相对于水温变化的之后时间要长。在10h时水温与CH4浓度的相关性大于气温与CH4的相关性。夏季湿地水——气界面CH4浓度与水体pH值无明显相关关系。但湿地水—一气界面CH4浓度与空气湿度呈正相关,无滞后时间差,说明空气湿度对水——气界面CH4浓度的影响比水温和气温更迅速。(2)人工湿地CH4在春、夏、秋、冬四季的浓度值大小为：夏季春季秋季冬季。夏季的CH4浓度比春、秋和冬季的显著的高,主要是因为夏季的高温在产CH4菌的最适温度范围内；春季CH4浓度比冬季显著的高,主要是由于冬季积累的CH4在春天温度升高后放出。从季节变化来看,CH4浓度与水温和气温都呈正相关,且水温与CH4浓度的相关性比气温更大。新薛河人工湿地水——气界面CH4浓度日变化在不同的季节具有较大差异,CH4浓度在春季呈逐渐增长趋势；夏季呈现先降低后增加趋势；秋季呈逐渐降低趋势；冬季较平缓,基本无变化。且CH4浓度变化相对于温度变化具有滞后性的规律只有在夏季平均温度在30℃以上时才成立。秋季的CH4浓度与水温和气温呈负相关,而冬季的CH4浓度与水温和气温呈正相关。(3)新薛河人工湿地上游水质比下游差,因为污水由上游流向下游并逐步净化,污水中的有机污染物在上游(一级湿地)沉淀比下游(五级湿地)较多,上游有机物含量高于下游。除冬季外下游CH4浓度均低于上游,而冬季上下游CH4浓度无明显差异。因为冬季无进水,上下游有机质含量差异不大。由此推测,水质越差,水中有机污染物越多,CH4浓度越高；水质越好,水体中有机污染物越少,产生CH4越少。从理论上来讲,大气C02浓度增加,有可能直接促进湿地土壤中由C02还原为CH4的过程,促进CH4的排放。本研究发现,新薛河人工湿地春、秋和冬季水——气表面CH4和C02浓度呈正显著相关。夏季CH4与C02浓度相关性不显著,CH4和CO2浓度的变化趋势也基本一致。(4)不同水深的控制实验显示,在计算CH4通量时,文献中常用的将1h内在0min、15min、30min和45min的四个CH4浓度强行做线性分析可能不可靠。此种线性分析的方法是在默认一定时间内CH4的浓度是呈线性分布的情况下进行的。在10cm水深时,在9点、10点和11点的一个小时内,CH4浓度都是呈先增大后减小趋势；在20cm水深时,在3个小时内是呈先减小后增大趋势；而在40cm水深时,则无明显规律。且每个小时的初始CH4浓度规律为：水深20cm水深40cm水深10cm。CH4浓度与水温和气温呈正相关,与湿度呈负相关,且CH4浓度与水温的相关性大于CH4浓度与气温的相关性。(5)通过数据挖掘,发现不同类型的湿地其CH4排放具有显著差异。按照CH4通量均值大小排列为：稻田沼泽湿地水库河滨湿地湖泊湿地海滨湿地。湖泊湿地、沼泽湿地、河滨湿地和水库的CH4排放通量之间无显著差异,但稻田和沼泽湿地的CH4通量比海滨湿地的CH4通量显著的高,且海滨湿地CH4通量部分呈负值。气候带类型对中国湿地CH4排放有显著影响。采用单因素方差分析,本节将中国气候分成5个气候带,不同气候带的湿地其CH4排放具有显著差异。暖温带和中温带湿地CH4通量无显著差异,但高原寒带的湿地CH4通量显著高于热带、亚热带湿地。本节将中国湿地CH4通量的影响因素气候带和湿地类型作双因素方差分析,发现湿地类型和气候带对湿地CH4排放具有交叉作用(α=0.05)。在热带地区,湖泊湿地和沼泽湿地的CH4通量比海滨湿地要显著的高。湖泊湿地和沼泽湿地大部分释放CH4而海滨湿地部分存在“吸收”CH4的现象。在亚热带地区,稻田的CH4排放通量显著高于湖泊湿地和海滨湿地。中温带不同湿地类型的CH4通量无显著差异。在高原寒带,青藏高原的沼泽湿地其CH4平均通量为50.25gm-2yr-1。总之,新薛河人工湿地CH4在时间变化和空间变化上都呈现各自的规律。水温、气温、pH、湿度以及水位等都是影响CH4排放的重要因素,且各自对CH4排放的影响各不相同。在对中国湿地CH4排放的数据挖掘研究中也发现,湿地类型和气候带对CH4排放影响具有交互作用,在进行湿地甲烷排放模型估算时必须考虑湿地类型和气候带的影响。
[Abstract]:In order to slow global warming, greenhouse gas emission reduction has caused widespread concern in the international community of.CH4 is an important greenhouse gas, its contribution to the greenhouse effect after C02, and the single molecule greenhouse effect is 30 times that of C02. The artificial wetland is an important source of CH4 emission. So the research on CH4 emission of artificial factors the wetland and its influence has important significance for understanding the contribution of artificial wetland on greenhouse gas and comprehensive assessment of wetland ecological effect. In this paper, Xinxue River constructed wetland as the research object, using the static chamber gas chromatography, through regular sampling analysis and laboratory monitoring, research on artificial wetland CH4 emission situation and changes in the law. The diurnal variation of first study of Xinxue River constructed wetland CH4 concentration, CH4 concentration was found 24 hours changes, in order to verify this rule in the larger time scale, the To the seasonal changes of CH4 concentration, with the diurnal variation and the seasons change and spatial change analysis of the factors affecting CH4 emission. Because the field experiment has many uncertain factors, in order to study the effect of water level specially designed water level control experiment, combining field experiment and control experiment was carried out to analyze the influencing factors of methane emission in the study. "Emission of wetland CH4 China and its influencing factors of" the existence of a large number of case studies but lack of in-depth data mining, in order to analyze the influencing factors of wetland methane emissions on a large scale, but also do this aspect of data mining and literature review. The main research contents and results are as follows: (1) consistent with the Xinxue River artificial wetland in summer upstream and downstream of the water gas interface 24 hour CH4 concentration variation, a Shuangfeng type that has two concentration peak, one at 6:00 in the morning to 8 00, another at 23:00 to 1:00. the trend can be divided into three stages, from 0:00 to 7:00, the concentration of CH4 increased gradually; ~ 7:00 14:00, the concentration of CH4 decreases; 14:00 to 24:00, the concentration of CH4 began to increase and small, at 21:00 to 22:00 between a small decreased. The summer of artificial wetland, the concentration changes of CH4 downstream of the water gas interface and the temperature is not synchronous, CH4 concentration changes with respect to the lag time temperature is 6-11 hours, compared to the lag time of the temperature change is 7-14 hours, both in the best correlation of 10 h, and the relative concentration of CH4 the lag time of the temperature change after a long time with respect to the temperature change. The correlation between temperature and concentration of CH4 in 10h and CH4 higher than the air temperature. In summer wetland water gas interface CH4 concentration and water pH No significant correlation. But the wetland water interface over the concentration of CH4 was positively correlated with air humidity, no time lag, shows the influence of air humidity on water gas interface CH4 concentration than the water temperature and air temperature more quickly. (2) artificial wetland CH4 in spring, summer, autumn and winter seasons, the concentration value of the size of for summer autumn winter spring summer. The ratio of CH4 concentration in spring, autumn and winter was significantly higher, mainly because of the summer high temperature in CH4 producing strain optimum temperature range; the concentration of CH4 in winter than in spring was high, mainly due to the accumulation of CH4 in the winter spring temperature increase after release from. The seasonal variation, the CH4 concentration and water temperature and air temperature were positively correlated, and the correlation between the temperature and the concentration of CH4 is greater than temperature. Xinxue River constructed wetland water gas interface CH4 concentration change has great difference in different seasons, the concentration of CH4 showed a gradual increase in the spring Trend; summer first decreased and then increased; autumn decreased gradually; winter is gentle, almost no change. And the change of CH4 concentration with respect to temperature change with a lag of only in the summer average temperature in 30 degrees Celsius above was set up. The fall of the CH4 concentration and water temperature was negatively correlated, while in winter the concentration of CH4 was positively correlated with water temperature and air temperature. (3) Xinxue River constructed wetland water quality upstream than downstream, upstream and downstream because of the sewage from the sewage purification gradually, the organic pollutants in the upstream (a wetland) precipitation than downstream (five level wetland) more upstream of the organic matter content is higher than the downstream in winter. The concentration of CH4 was lower than that of upstream downstream outside, but there was no significant difference in winter on the downstream of the CH4 concentration. Because no water in winter, lower organic matter content had little difference. Therefore, the water quality is poor, the organic pollutants in the sewage more, CH4 The higher the concentration; the better water quality, less organic pollutants in water, the less CH4. Theoretically, the increase in atmospheric C02 concentration, may directly promote by the reduction of C02 to CH4 in the process of wetland soil, promote the emission of CH4. The study found that the Xinxue River constructed wetland in spring, autumn and winter water gas surface CH4 and C02 concentration in summer. There was a significant positive correlation between CH4 and C02 was not significant, the change trend of CH4 and CO2 concentration are basically the same. (4) show the control experiment of different water depths, in the calculation of CH4 flux, commonly used in the literature will be 1H 15min, four in 0min, 30min and CH4 concentration 45min to do linear analysis may not be reliable. This method is linear analysis in the default CH4 concentration within a certain period of time is linear distribution. In the depth of 10cm, at 9, one hour 10 points and 11 points, the concentration of CH4 is increased After the decreasing trend; in the 20cm depth, in 3 hours is increased firstly and then decreased; and in the depth of 40cm, there was no obvious rule. The initial concentration of CH4 and the characteristics of each hour: the depth of 20cm 40cm depth depth of 10cm.CH4 concentration and water temperature and air temperature were positively correlated, negatively correlated with humidity, and the correlation between CH4 concentration and water temperature is greater than the correlation between CH4 concentration and temperature. (5) through data mining, different types of wetland CH4 emission was significant. According to the mean size of CH4 flux: paddy wetland reservoir riparian wetland Lake wetland. The coastal wetland wetland, wetland, there was no significant difference between CH4 the emission flux of riverside wetland and reservoir, but significant CH4 flux from paddy fields and marshes than the high CH4 flux of coastal wetlands, and coastal wetland CH4 flux was negative. Part of climate types on Chinese wetland CH4 Have a significant impact emissions. With single factor variance analysis, this section will be divided into 5 Chinese climate climatic zones, wetlands in different climate zones of the CH4 emissions have significant difference. There was no significant difference between the warm temperate zone and temperate zone wetland CH4 flux, but the cold plateau wetland CH4 flux was significantly higher than that of tropical, subtropical wetland. This section will influence Chinese wetland CH4 flux factors of climate zones and wetland type double factor variance analysis, found that wetland types and climate emissions in wetland CH4 with crossover (alpha =0.05). In the tropics, CH4 flux of lake and marsh wetland are significantly higher than that of the coastal wetlands of lake and marsh wetland. Most of the release of CH4 and there are some coastal wetland "absorption" CH4 phenomenon. In the subtropical region, the CH4 emission flux from paddy fields were significantly higher than that of lake wetlands and coastal wetland. CH4 flux of different types of wetland in the temperate zone. The difference in cold plateau, Qinghai Tibet Plateau Wetland and its average CH4 flux is 50.25gm-2yr-1. in Xinxue River constructed wetland CH4 are showing their rules in time and spatial change. Water temperature, air temperature, pH, humidity and water level are the important factors influencing the emission of CH4, and their influence on CH4 emission different. On CH4 emission in wetland China data mining research has also found that the interaction effect on CH4 emission with wetland types and climate, in estimating methane emissions from wetland model must consider the impact of wetland types and climatic zones.

【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X171;X511

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