基于遥感与实测资料的河流有机碳通量估算研究
发布时间：2018-08-23 14:19
【摘要】：河流连通着地球最大的两个碳库—陆地和海洋生态系统碳库。全球河流每年可以输运约 219.50±54.36 Tg C/yr 的溶解有机碳(DOC),204.00±21.73 Tg C/yr 的颗粒有机碳(POC)进入边缘海。河流有机碳输运不仅影响着全球碳循环,而且会影响河口和边缘海的生态环境,输运量也反映了流域的自然过程和人为活动的变化。在自然变化和人为活动等多种因素的影响下,河流有机碳通量具有显著的时空变异特征,这些时空变异增加了通量监测和估算的难度。目前,国际上关于河流有机碳输运的研究大多关注欧美大陆河流,这些河流积累了长时间序列的有机碳(DOC、POC)观测资料。而东亚季风影响下的亚洲河流有机碳输运报道较少,且缺乏不同河流有机碳输运的空间变异和同一河流的时间变异研究。基于此,本文基于不同入海河流有机碳实测数据与流域特征数据,分析了中国大陆入海河流有机碳通量的空间变异;并进一步以长江为重点研究区,在长江河流(大通水文站断面)和河口分别开展了月尺度和季节尺度的光学-化学同步现场观测,利用多源遥感和实测资料估算了长江长时间序列的有机碳通量,并讨论了流域特征对长江有机碳输运时空变异的影响,为进一步估算全球河流有机碳输运通量打下基础。本文的主要研究内容和取得的结论如下:(1)中国大陆入海河流有机碳输运通量及空间变异。通过分析中国大陆不同入海河流有机碳(DOC、POC)数据与流域特征数据,构建了中国大陆入海河流年平均DOC浓度和POC浓度的估算模型,并以2010年为代表,估算了中国大陆不同入海河流的DOC年通量和POC年通量。2010年,中国大陆入海河流有机碳输运通量约为5.05 Tg C的DOC和7.00TgC的POC;其中,34.65%的DOC和42.43%的POC由长江输运。空间分布上,虽然降雨会稀释河流DOC浓度和总悬浮物(TSM)中的POC重量百分比(POC(%TSM)),但单位面积的流域DOC与POC输出量都与降雨量的空间分布一致。中国大陆东南部降雨多的流域,单位面积的流域DOC和POC输出量都较高。(2)长江河流(大通水文站断面)DOC通量估算。以流量、流域耕地面积比和总初级生产力为自变量,构建了长江大通DOC浓度的多层回馈神经网络估算模型,并结合大通实测流量估算了 2000-2013年长江大通水文站的DOC月通量。2000-2013年,长江大通DOC月通量变化范围为3.88-42.78×104tC,平均值为13.49±6.73×104tC/month。大通DOC月通量主要是由流量决定的,两者存在显著的正相关线性关系(R=0.8914,P0.0001)。(3)长江河流(大通水文站断面)POC通量估算。根据大通的光学-化学同步观测数据和生物光学模型模拟数据,构建了适用于Landsat数据(空间分辨率30 m)的POC浓度遥感算法。大通断面上,POC浓度与TSM浓度之间存在正相关线性关系,且空间变异不显著。结合大通流量,利用2000-2016年的TM/Landsat-5和ETM+/Landsat-7数据,估算了大通长时间序列的POC月通量。2000-2016年,长江大通的POC月通量变化范围为1.4-52.04×104tC,平均值为13.04±7.17×104tC/month。大通POC月通量与流量之间存在显著的正相关线性关系(R=0.7143,P0.05)。过去十几年,大通POC与DOC的平均月通量基本相等,并未呈"高POC输运"的特征。(4)长江河口(徐六泾水文站断面)POC通量估算。根据长江河口的光学-化学同步测量数据,构建了适用于GOCI数据(空间分辨率500 m)的POC浓度遥感算法。长江河口,POC浓度与TSM浓度存在显著的正相关线性关系;徐六泾断面的流量剖面分布呈线性函数变化,POC浓度剖面分布呈指数函数变化。结合大通水文站的流量,利用GOCI数据估算了徐六泾断面的POC月通量。2015年5月至2016年4月,长江徐六泾POC月通量平均为7.14×104tC,比大通POC月通量实测值平均高44.58%。长江河口复杂的水动力环境(潮汐、风)及颗粒再悬浮等会增加该区域的POC通量,且在冬季的增加效应更明显。(5)长江河流(大通水文站断面)有机碳输运时间变异和流域特征的影响。综合分析长时间序列的长江大通有机碳(DOC、POC)月通量和流域特征遥感数据,发现:因降雨的稀释作用,大通DOC浓度表现为"湿季低、干季高"的季节特征(湿季为5月至10月),干季DOC浓度平均是湿季的1.14倍;因降雨的冲刷作用,大通POC浓度表现为"湿季高、干季低"的季节特征。长江三峡大坝正常运行之后,大通POC浓度的季节差异正逐渐减弱;由于流量的调控作用,DOC与POC通量都表现为"湿季高、干季低"的季节特征。2000-2013年湿季DOC通量平均占全年通量的65.89%,2000-2016年湿季POC通量平均占全年通量的75.01%。2000-2013年,长江大通DOC浓度和DOC通量都没有发生显著变化;但2000-2016年,长江大通POC浓度和POC通量都呈指数显著降低。总的来说,本文利用遥感和实测数据估算了中国大陆入海河流有机碳输运通量及长江长时间序列的有机碳输运通量,并分析了中国大陆入海河流有机碳输运的时空变异。下一步将考虑河流输运的有机碳在经过河口过程(如转化、分解、沉降等)后的通量,进一步研究河流输运有机碳的有效入海通量。
[Abstract]:Rivers connect the Earth's two largest carbon pools, terrestrial and marine ecosystem carbon pools. Global rivers can transport about 219.50 Under the influence of many factors such as natural changes and human activities, the fluxes of organic carbon in rivers have remarkable spatial-temporal variations, which increase the difficulty of fluxes monitoring and estimation. Most of the studies on transport focus on the Continental Rivers in Europe and America. These rivers accumulate long time series of organic carbon (DOC, POC) observations. However, there are few reports on the transport of organic carbon in Asian rivers under the influence of East Asian monsoon, and there is no study on the spatial variability of the transport of organic carbon in different rivers and the temporal variability of the same river. The spatial variability of the organic carbon fluxes in the inbound rivers of the mainland of China was analyzed based on the measured data and the basin characteristics of the inbound rivers. The long time series of organic carbon fluxes over the Yangtze River are estimated and the effects of river basin characteristics on the temporal and spatial variability of organic carbon transport in the Yangtze River are discussed, which lays a foundation for further estimating the global fluxes of organic carbon transport in rivers. Based on the analysis of DOC data and basin characteristic data of different inbound rivers in mainland China, an estimation model of annual average DOC concentration and POC concentration of inbound rivers in mainland China was established. The annual DOC flux and POC flux of different inbound rivers in mainland China were estimated in 2010. The DOC and POC of 5.05 TgC and 7.00 TgC were transported by the Yangtze River, of which 34.65% and 42.43% were transported by the Yangtze River. (2) Estimation of DOC flux in the Yangtze River (section of Datong Hydrological Station). Taking discharge, area ratio of cultivated land and total primary productivity as independent variables, a multi-layer feedback neural network model for estimating DOC concentration in the Yangtze River Datong Hydrological Station was constructed. The monthly DOC flux of Datong Hydrological Station in the Yangtze River from 2000 to 2013 was estimated. From 2000 to 2013, the monthly DOC flux of Datong Hydrological Station in the Yangtze River ranged from 3.88 to 42.78 Estimation of POC flux in river (section of Datong Hydrological Station). Based on optical-chemical synchronous observation data and bio-optical model simulation data of Datong Hydrological Station, a remote sensing algorithm of POC concentration suitable for Landsat data (spatial resolution 30 m) is constructed. Based on the data of TM/Landsat-5 and ETM+/Landsat-7 from 2000 to 2016, the monthly POC flux of Datong was estimated. From 2000 to 2016, the monthly POC flux of Changjiang Datong ranged from 1.4 to 52.04 *104tC, with an average value of 13.04 +7.17 *104tC/month. There was a significant positive correlation between the monthly POC flux and the flow. (4) Estimation of POC flux in the Yangtze Estuary (section of Xuliujing Hydrological Station). Based on synchronous optical-chemical measurements in the Yangtze Estuary, a remote sensing algorithm of POC concentration suitable for GOCI data (spatial resolution 500 m) was constructed. In the estuary of the Yangtze River, there is a significant positive correlation between the concentration of POC and the concentration of TSM; the distribution of the flow profile in Xuliujing section is a linear function, and the distribution of the POC concentration profile is an exponential function. The average monthly POC flux is 7.14 *104 tC, which is 44.58% higher than that of Datong POC. The complex hydrodynamic environment (tide, wind) and particle resuspension in the Yangtze Estuary will increase the POC flux in this area, and the increasing effect is more obvious in winter. (5) Time variation and regional characteristics of organic carbon transport in the Yangtze River (section of Datong Hydrological Station) Based on the long time series of remote sensing data of DOC (POC) monthly flux and watershed characteristics, it is found that the concentration of DOC in Datong is characterized by "low wet season, high dry season" (wet season from May to October), and the average concentration of DOC in dry season is 1.14 times of that in wet season. The seasonal variation of POC concentration in Datong is gradually weakening after the normal operation of the Three Gorges Dam. Due to the regulation of discharge, DOC and POC fluxes are both characterized by high wet season and low dry season. In the wet season, POC flux averaged 75.01% of the total annual flux. During 2000-2013, the DOC concentration and DOC flux of Datong in the Yangtze River did not change significantly, but in 2000-2016, the POC concentration and POC flux of Datong in the Yangtze River decreased exponentially. The long time series of organic carbon flux in the Yangtze River and the temporal and spatial variability of organic carbon transport in the mainland of China are analyzed.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：X143
本文编号：2199327
[Abstract]:Rivers connect the Earth's two largest carbon pools, terrestrial and marine ecosystem carbon pools. Global rivers can transport about 219.50 Under the influence of many factors such as natural changes and human activities, the fluxes of organic carbon in rivers have remarkable spatial-temporal variations, which increase the difficulty of fluxes monitoring and estimation. Most of the studies on transport focus on the Continental Rivers in Europe and America. These rivers accumulate long time series of organic carbon (DOC, POC) observations. However, there are few reports on the transport of organic carbon in Asian rivers under the influence of East Asian monsoon, and there is no study on the spatial variability of the transport of organic carbon in different rivers and the temporal variability of the same river. The spatial variability of the organic carbon fluxes in the inbound rivers of the mainland of China was analyzed based on the measured data and the basin characteristics of the inbound rivers. The long time series of organic carbon fluxes over the Yangtze River are estimated and the effects of river basin characteristics on the temporal and spatial variability of organic carbon transport in the Yangtze River are discussed, which lays a foundation for further estimating the global fluxes of organic carbon transport in rivers. Based on the analysis of DOC data and basin characteristic data of different inbound rivers in mainland China, an estimation model of annual average DOC concentration and POC concentration of inbound rivers in mainland China was established. The annual DOC flux and POC flux of different inbound rivers in mainland China were estimated in 2010. The DOC and POC of 5.05 TgC and 7.00 TgC were transported by the Yangtze River, of which 34.65% and 42.43% were transported by the Yangtze River. (2) Estimation of DOC flux in the Yangtze River (section of Datong Hydrological Station). Taking discharge, area ratio of cultivated land and total primary productivity as independent variables, a multi-layer feedback neural network model for estimating DOC concentration in the Yangtze River Datong Hydrological Station was constructed. The monthly DOC flux of Datong Hydrological Station in the Yangtze River from 2000 to 2013 was estimated. From 2000 to 2013, the monthly DOC flux of Datong Hydrological Station in the Yangtze River ranged from 3.88 to 42.78 Estimation of POC flux in river (section of Datong Hydrological Station). Based on optical-chemical synchronous observation data and bio-optical model simulation data of Datong Hydrological Station, a remote sensing algorithm of POC concentration suitable for Landsat data (spatial resolution 30 m) is constructed. Based on the data of TM/Landsat-5 and ETM+/Landsat-7 from 2000 to 2016, the monthly POC flux of Datong was estimated. From 2000 to 2016, the monthly POC flux of Changjiang Datong ranged from 1.4 to 52.04 *104tC, with an average value of 13.04 +7.17 *104tC/month. There was a significant positive correlation between the monthly POC flux and the flow. (4) Estimation of POC flux in the Yangtze Estuary (section of Xuliujing Hydrological Station). Based on synchronous optical-chemical measurements in the Yangtze Estuary, a remote sensing algorithm of POC concentration suitable for GOCI data (spatial resolution 500 m) was constructed. In the estuary of the Yangtze River, there is a significant positive correlation between the concentration of POC and the concentration of TSM; the distribution of the flow profile in Xuliujing section is a linear function, and the distribution of the POC concentration profile is an exponential function. The average monthly POC flux is 7.14 *104 tC, which is 44.58% higher than that of Datong POC. The complex hydrodynamic environment (tide, wind) and particle resuspension in the Yangtze Estuary will increase the POC flux in this area, and the increasing effect is more obvious in winter. (5) Time variation and regional characteristics of organic carbon transport in the Yangtze River (section of Datong Hydrological Station) Based on the long time series of remote sensing data of DOC (POC) monthly flux and watershed characteristics, it is found that the concentration of DOC in Datong is characterized by "low wet season, high dry season" (wet season from May to October), and the average concentration of DOC in dry season is 1.14 times of that in wet season. The seasonal variation of POC concentration in Datong is gradually weakening after the normal operation of the Three Gorges Dam. Due to the regulation of discharge, DOC and POC fluxes are both characterized by high wet season and low dry season. In the wet season, POC flux averaged 75.01% of the total annual flux. During 2000-2013, the DOC concentration and DOC flux of Datong in the Yangtze River did not change significantly, but in 2000-2016, the POC concentration and POC flux of Datong in the Yangtze River decreased exponentially. The long time series of organic carbon flux in the Yangtze River and the temporal and spatial variability of organic carbon transport in the mainland of China are analyzed.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：X143
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