【作者】 桂祖胜；

【导师】 张龙军；

【作者基本信息】 中国海洋大学 ， 环境科学， 2007， 硕士

【摘要】 碳循环研究是全球变化研究项目“国际地圈生物圈计划”(IGBP)的核心内容,化石燃料的燃烧等人类活动每年向大气排放60多亿吨碳(Houghton et al.,2001;N oble,2001),大约有一半停留在大气中,这已被观测证实。工业革命以来,化石燃料燃烧等人类活动己经显著地改变了全球碳循环。CO2等微量气体的“温室效应”己成为影响全球气候变化的一个重要而不可忽视的因素。人类活动不仅加大了CO2在大气圈、海洋和陆地生态系统之间的交换量,也加剧了河流的直接碳输运,加速了陆地的碳流失。因此,要深入系统地理解陆地生态系统的碳循环过程,总体把握陆地的碳收支状况,就有必要了解通过河流作用的陆地—海洋间碳输运量和输运规律。长江是我国第一大河,是世界长度第三、径流量第五、输沙量第四的河流(Eisma,1998);长江河水中HCO3-的平均浓度为1.66mo1/m3,其中碳酸盐本身风化溶解贡献约45.7%的HCO3-,54.3%的HCO3-是在岩石风化作用中消耗的大气CO2,由此长江流域岩石化学风化过程每年消耗的大气CO2总量为828.00×109mol,约占世界流域岩石风化消耗大气CO2总量的3.45%,为中国岩石风化消耗大气CO2最多的流域盆地(李晶莹,2003)。本论文通过2006年2月对长江口及邻近海域以及2006年4月-5月从重庆涪陵至南通的长江干流各主要站点碳参数进行的调查,同时,于2006年5月到2007年5月在长江下游安庆站做的每月两次的连续观测,结合相关水文、化学和生物等要素的同步观测资料,初步探讨了长江干流及河口各种形态碳的时空分布规律,估算了长江干流碳的水-气界面通量。本文主要内容如下:长江干流水体pCO2在867～1651μatm之间,平均值为1106μatm,在世界主要河流中应属于中等偏下水平,是大气CO2的源区;长江三峡库区奉节以上河段水体pCO2应受水体生物好氧呼吸作用控制,长江奉节以下河段总体上受碳酸盐体系控制。长江三峡库区一期蓄水后,长江干流水体DIC含量(1.36~2.8mM)普遍稍高于蓄水前(1.2~2.7mM),DIC沿程的逐步降低主要是受洞庭湖、鄱阳湖水体输入的物理稀释作用所引起的;长江干流水体PIC含量平均值仅有0.04 mg/l,且长江库区和中下游水体泥沙来源不同;长江安庆站水体pCO2主要是受pH的高低影响;冬季长江口水体pCO2自西向东逐渐降低,生物活动不是控制表层水pCO2分布的主要因素,温度和pH是影响长江河道内表层水pCO2分布的主要因素;冬季长江口混合区表层水pCO2的分布不受碳酸盐体系控制,而在外海区没有咸淡水的剧烈混合pCO2的变化受碳酸盐体系的影响,但不构成主控因素。更多还原

【Abstract】 Study on the carbon cycle is the central content in the IGBP, the fossil fuel and other human activities can release more than 6×109tC/yr(Houghton et al.,2001;Noble,2001),from our observation, we conform that about half of them still in the atmosphere. Since the Industrial Revolution, the fossil fuel and other human activities have changed the global carbon cycle. CO2 and other“green house”gases have being the important factor to influence the global climate. Human activities not only strengthen the exchange quantity of CO2 between atmosphere、sea and earth ecosystem, but also the river transport carbon directly and the run off of land carbon. So if we want to realize the carbon cycle progress in the earth ecosystem thoroughly and systemic, we must know the quantity and rules between land-sea systems from river.Yangtze river is the longest river in our country and the third long、fifths discharge、fourth sediment quantity in the world (Eisma,1998);The average concentration of HCO3- is 1.66mo1/m3, which is offered 45.7% by carbonate and 54.3% is offered by atmosphere CO2 what consume in the rock weathering. Therefore, Yangtze river drainage basin consumes atmosphere CO2 is 828.00×109mol by rock weathering, which about 3.45% of the rock weathering in the world drainage basin and it consumes the mostly atmosphere CO2 in the Yangtze river drainage basin.We investigate the Yangtze estuary in the Feb. 2006 and from Fuling to Nantong in the April to May, 2006. Meanwhile, we investigate the Yangtze River in Anqing twice a month from May, 2006 to May, 2007. The main content of the paper as flowing:pCO2 varies from 867 to 1651μatm; the average is 1106μatm in the mainstream of Yangtze river. This is lower than other important river in the world and it is the source of CO2. The upper reaches of Fengjie in the Three Gorge, the pCO2 is subjected to the biological aerobic respiration, the lower reaches of Fengjie in the Yangtze river, and the pCO2 is subjected to the carbonate system. After the first impound of Three Gorge, the DIC concentration in the mainstream of Yangtze river is 1.36 to 2.8mM, a little higher than not impound. The main reason of DIC decrease from upper to lower is dilution by Dongting lake and Poyang lake. The average of PIC in the Yangtze river mainstream is only 0.04 mg/l; this is because of the difference source of sediment. In Anqing, the pCO2 in the Yangtze river is subjected to pH; In winter Yangtze estuary, the pCO2 is subjected to pH and temperature.更多还原