基于遙感與實測資料的河流有機碳通量估算研究
發(fā)布時間：2018-08-23 14:19
【摘要】：河流連通著地球最大的兩個碳庫—陸地和海洋生態(tài)系統(tǒng)碳庫。全球河流每年可以輸運約 219.50±54.36 Tg C/yr 的溶解有機碳(DOC),204.00±21.73 Tg C/yr 的顆粒有機碳(POC)進入邊緣海。河流有機碳輸運不僅影響著全球碳循環(huán),而且會影響河口和邊緣海的生態(tài)環(huán)境,輸運量也反映了流域的自然過程和人為活動的變化。在自然變化和人為活動等多種因素的影響下,河流有機碳通量具有顯著的時空變異特征,這些時空變異增加了通量監(jiān)測和估算的難度。目前,國際上關(guān)于河流有機碳輸運的研究大多關(guān)注歐美大陸河流,這些河流積累了長時間序列的有機碳(DOC、POC)觀測資料。而東亞季風影響下的亞洲河流有機碳輸運報道較少,且缺乏不同河流有機碳輸運的空間變異和同一河流的時間變異研究�；诖�,本文基于不同入海河流有機碳實測數(shù)據(jù)與流域特征數(shù)據(jù),分析了中國大陸入海河流有機碳通量的空間變異;并進一步以長江為重點研究區(qū),在長江河流(大通水文站斷面)和河口分別開展了月尺度和季節(jié)尺度的光學-化學同步現(xiàn)場觀測,利用多源遙感和實測資料估算了長江長時間序列的有機碳通量,并討論了流域特征對長江有機碳輸運時空變異的影響,為進一步估算全球河流有機碳輸運通量打下基礎(chǔ)。本文的主要研究內(nèi)容和取得的結(jié)論如下:(1)中國大陸入海河流有機碳輸運通量及空間變異。通過分析中國大陸不同入海河流有機碳(DOC、POC)數(shù)據(jù)與流域特征數(shù)據(jù),構(gòu)建了中國大陸入海河流年平均DOC濃度和POC濃度的估算模型,并以2010年為代表,估算了中國大陸不同入海河流的DOC年通量和POC年通量。2010年,中國大陸入海河流有機碳輸運通量約為5.05 Tg C的DOC和7.00TgC的POC;其中,34.65%的DOC和42.43%的POC由長江輸運。空間分布上,雖然降雨會稀釋河流DOC濃度和總懸浮物(TSM)中的POC重量百分比(POC(%TSM)),但單位面積的流域DOC與POC輸出量都與降雨量的空間分布一致。中國大陸東南部降雨多的流域,單位面積的流域DOC和POC輸出量都較高。(2)長江河流(大通水文站斷面)DOC通量估算。以流量、流域耕地面積比和總初級生產(chǎn)力為自變量,構(gòu)建了長江大通DOC濃度的多層回饋神經(jīng)網(wǎng)絡估算模型,并結(jié)合大通實測流量估算了 2000-2013年長江大通水文站的DOC月通量。2000-2013年,長江大通DOC月通量變化范圍為3.88-42.78×104tC,平均值為13.49±6.73×104tC/month。大通DOC月通量主要是由流量決定的,兩者存在顯著的正相關(guān)線性關(guān)系(R=0.8914,P0.0001)。(3)長江河流(大通水文站斷面)POC通量估算。根據(jù)大通的光學-化學同步觀測數(shù)據(jù)和生物光學模型模擬數(shù)據(jù),構(gòu)建了適用于Landsat數(shù)據(jù)(空間分辨率30 m)的POC濃度遙感算法。大通斷面上,POC濃度與TSM濃度之間存在正相關(guān)線性關(guān)系,且空間變異不顯著。結(jié)合大通流量,利用2000-2016年的TM/Landsat-5和ETM+/Landsat-7數(shù)據(jù),估算了大通長時間序列的POC月通量。2000-2016年,長江大通的POC月通量變化范圍為1.4-52.04×104tC,平均值為13.04±7.17×104tC/month。大通POC月通量與流量之間存在顯著的正相關(guān)線性關(guān)系(R=0.7143,P0.05)。過去十幾年,大通POC與DOC的平均月通量基本相等,并未呈"高POC輸運"的特征。(4)長江河口(徐六涇水文站斷面)POC通量估算。根據(jù)長江河口的光學-化學同步測量數(shù)據(jù),構(gòu)建了適用于GOCI數(shù)據(jù)(空間分辨率500 m)的POC濃度遙感算法。長江河口,POC濃度與TSM濃度存在顯著的正相關(guān)線性關(guān)系;徐六涇斷面的流量剖面分布呈線性函數(shù)變化,POC濃度剖面分布呈指數(shù)函數(shù)變化。結(jié)合大通水文站的流量,利用GOCI數(shù)據(jù)估算了徐六涇斷面的POC月通量。2015年5月至2016年4月,長江徐六涇POC月通量平均為7.14×104tC,比大通POC月通量實測值平均高44.58%。長江河口復雜的水動力環(huán)境(潮汐、風)及顆粒再懸浮等會增加該區(qū)域的POC通量,且在冬季的增加效應更明顯。(5)長江河流(大通水文站斷面)有機碳輸運時間變異和流域特征的影響。綜合分析長時間序列的長江大通有機碳(DOC、POC)月通量和流域特征遙感數(shù)據(jù),發(fā)現(xiàn):因降雨的稀釋作用,大通DOC濃度表現(xiàn)為"濕季低、干季高"的季節(jié)特征(濕季為5月至10月),干季DOC濃度平均是濕季的1.14倍;因降雨的沖刷作用,大通POC濃度表現(xiàn)為"濕季高、干季低"的季節(jié)特征。長江三峽大壩正常運行之后,大通POC濃度的季節(jié)差異正逐漸減弱;由于流量的調(diào)控作用,DOC與POC通量都表現(xiàn)為"濕季高、干季低"的季節(jié)特征。2000-2013年濕季DOC通量平均占全年通量的65.89%,2000-2016年濕季POC通量平均占全年通量的75.01%。2000-2013年,長江大通DOC濃度和DOC通量都沒有發(fā)生顯著變化;但2000-2016年,長江大通POC濃度和POC通量都呈指數(shù)顯著降低�？偟膩碚f,本文利用遙感和實測數(shù)據(jù)估算了中國大陸入海河流有機碳輸運通量及長江長時間序列的有機碳輸運通量,并分析了中國大陸入海河流有機碳輸運的時空變異。下一步將考慮河流輸運的有機碳在經(jīng)過河口過程(如轉(zhuǎn)化、分解、沉降等)后的通量,進一步研究河流輸運有機碳的有效入海通量。
[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.
【學位授予單位】：浙江大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：X143
本文編號：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.
【學位授予單位】：浙江大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：X143
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