本文選題：河流碳　切入點(diǎn)：碳同位素　出處：《中國地質(zhì)大學(xué)(北京)》2016年博士論文

【摘要】：河流系統(tǒng)是全球生物地球化學(xué)循環(huán)的重要環(huán)節(jié),是將陸地侵蝕物質(zhì)輸入海洋的主要通道。最新研究表明,河流每年的CO_2釋放量(1.8 Pg C)是入海碳通量(0.9 Pg C)的2倍,占內(nèi)陸水體(河水,湖水和濕地)釋放總量的43%,是大氣碳平衡的重要成分。河流碳為水生生物提供能量,并影響水生環(huán)境的地球化學(xué)性質(zhì)。中國西南喀斯特流域以突出的地球化學(xué)敏感性和生態(tài)脆弱性為特征,自然風(fēng)化是其物源的主要營力,人為擾動使河水的成分更加復(fù)雜。僅僅依靠離子組成難以區(qū)分河流碳的不同來源,而穩(wěn)定碳同位素(δ~(13)C)成為示蹤河水物源的重要手段。本文利用δ~(13)C對比分析西江源區(qū)南、北盤江流域物源特征,深入討論影響這些變異的機(jī)制和控制因素,并查明西江源區(qū)在整個西江水系乃至世界河流的碳收支中所扮演角色。結(jié)果表明：1.離子組成分析和相關(guān)性分析表明,南、北盤江離子成分受控于碳酸作用下碳酸鹽巖的風(fēng)化。硫酸和農(nóng)業(yè)肥料作為媒介參與了流域內(nèi)碳酸鹽礦物的風(fēng)化,尤其是在北盤江流域。南盤江河水受城鎮(zhèn)工農(nóng)業(yè)和生活污水的影響較大,而北盤江河水成分除了農(nóng)業(yè)污染之外,還來源于煤炭產(chǎn)業(yè)廢水的排放。2.南、北盤江δ~(13)CPOc和C/N分異明顯,懸浮態(tài)的土壤有機(jī)碳是POC的主要來源。然而,北盤江POC一部分來源于陸生高等植物,而南盤江受自源浮游生物的影響較大。土壤有機(jī)碳的淋濾可能是北盤江DOC的重要來源,土壤在河道的輸移過程發(fā)生的降解作用是南盤江DOC的來源之一。此外,北盤江山區(qū)支流水土流失強(qiáng)烈,DOC/POC比值低至0.18；南盤江受沿程蓄水工程的影響,河水DOC/POC比值普遍高于1。DOC與Cl-、NO3-口SO42-三種污染物特征離子的相關(guān)性表明,人為活動不僅影響南、北盤江水化學(xué)成分,還使河水有機(jī)碳的來源更加復(fù)雜。3.南、北盤江δ~(13)CDIC變化范圍為-13.9‰～-8.1‰。碳酸鹽礦物的溶解和土壤CO_2是河水DIC的主要來源。pCO_2跟DIC和SIc分別呈正、負(fù)相關(guān)性,pCO_2顯著影響水中碳酸鹽礦物的溶解過程。南盤江上游河段城市化程度較高,pC02和DIC普遍高于其他以碳酸鹽巖地層為主的西江河段。光合作用的增強(qiáng)、基流和匯流中的土壤CO_2混入以及有機(jī)碳的氧化是影響南盤江河水pCO_2分布的因素之一。北盤江河水pCO_2跟硫酸的參與、風(fēng)景區(qū)人為活動的輸入以及地下水的混合密切相關(guān)。有機(jī)碳的氧化是維持北盤江河水pC02的主要動力。南盤江δ~(13)CP1C值和PIC含量普遍低于北盤江流域,海相碳酸鹽的風(fēng)化是北盤江河水PlC的重要來源。4.南盤江流域CO_2的逸出量高于北盤江流域,且普遍高于西江中、下游流域。與世界其他氣候類型的流域相比,南、北盤江流域CO_2的逸出量低于熱帶流域,普遍高于溫帶流域,而和世界其他亞熱帶流域相近。
[Abstract]:The river system is an important part of the global biogeochemical cycle, and is the main channel of the terrestrial erosion material into the ocean.The latest research shows that the annual CO_2 release of rivers is twice as much as that of the amount of carbon fluxes (0.9 PG C) released into the sea, accounting for 43% of the total amount released from inland waters (rivers, lakes and wetlands), which is an important component of the atmospheric carbon balance.River carbon supplies energy to aquatic organisms and affects the geochemistry of aquatic environments.Karst basin in southwestern China is characterized by prominent geochemical sensitivity and ecological vulnerability. Natural weathering is the main source of the water and the composition of the river is complicated by artificial disturbance.It is difficult to distinguish the different sources of carbon from rivers only by ion composition, and stable carbon isotope (未 ~ (13) C) is an important means to trace the source of river water.In this paper, the provenance characteristics of the southern and northern Panjiang basins in Xijiang source region are analyzed by means of 未 ~ (13) C, the mechanism and controlling factors affecting these variations are discussed in depth, and the role of Xijiang source region in carbon budget of the whole Xijiang river system and even the rivers of the world is found out.The result shows that 1: 1.The ion composition analysis and correlation analysis show that the ion composition of Pangjiang is controlled by the weathering of carbonate rock under carbonation.Sulphuric acid and agricultural fertilizers are involved in the weathering of carbonate minerals in the basin, especially in the Beipanjiang basin.Nanpanjiang River is greatly affected by urban industrial, agricultural and domestic sewage, while the composition of Beipanjiang River is derived from coal industry wastewater discharge in addition to agricultural pollution.The 未 ~ (13) C ~ (13) C ~ (3 +) and C / N in the south and north of Panjiang are distinct, and the suspended soil organic carbon is the main source of POC.However, some of the POC in Beipanjiang are derived from terrestrial higher plants, while the Nanpanjiang is greatly influenced by autoplankton.The leaching of soil organic carbon may be an important source of DOC in Beipanjiang River, and the degradation of soil in the course of channel transport is one of the sources of DOC in Nanpan River.In addition, the ratio of soil and water loss in tributaries of Beipanjiang River is as low as 0.18.The DOC/POC ratio of Nanpanjiang River is generally higher than that of 1.DOC and the characteristic ions of so _ 42- in Cl-no _ 3- mouth, which indicates that anthropogenic activities affect not only the south, but also the south.The chemical composition of the Beipanjiang River also makes the source of organic carbon in the river more complicated. 3.In the south and north of Panjiang River, the variation range of CDIC is from -13.9 鈥，

本文編號：1693326