【作者】 杨洪；

【导师】 易朝路； 谢平； 倪乐意；

【作者基本信息】 中国科学院研究生院（测量与地球物理研究所） ， 自然地理学， 2004， 硕士

【摘要】 本文对长江中下游典型的富营养型湖泊东湖的碳循环过程和碳收支进行了研究，内容包括水-气界面CO₂和CH₄通量的过程、水柱中DOC、TOC和DIC的过程和2003年4月至2004年3月碳收支等方面，主要研究结果如下： 1．东湖水-气界面CH₄在一年中始终是释放的，Ⅰ、Ⅱ、Ⅲ站CH₄释放速率分别是0.97、1.071和1.136 mg m^-2 h^-1。夏季是CH₄的主要释放释放时段。水—气界面的CH₄通量与水体营养水平的相关关系不显著，但最大释放通量受到各站营养水平的控制；温度对于CH₄的释放速率有着显著的促进作用。水—气界面的CO₂在一年中变化十分剧烈，但从年平均值看，CO₂呈释放状态，Ⅰ、Ⅱ、Ⅲ站平均值分别为9.87、13.33和26.06 mg m^-2 h^-1。水—气界面的CO₂通量与水体的营养水平成负相关；温度对水—气界面的CO₂释放的影响不显著。 2．东湖水柱中DOC的平均含量是7.31mg／L，含量秋季达到最高；水柱中TOC的平均含量是8.78 mg／L，含量秋季达到最高；水柱中DIC的平均含量是11.89mg／L，春夏季的含量高于秋冬季。运用聚类分析和主成分分析，将东湖水柱中碳含量分为三类：第一类由于温度较高、营养盐较高，DOC、TOC平均含量最高；第二类DOC、TOC平均含量中等；第三类由于短时间内降雨突增，DOG、TOC平均含量最低。 3．采用清单法，主要考虑东湖生态系统的水—气界面，水—陆界面和水—泥界面三个界面的碳收支，2003年4月至2004年3月，东湖的净收支是8018.9t。其中，由水-气界面界面释放到大气的碳达到880.2 t，占支出的22.6％。与Ontario湖相比，这一比例偏低。与三江平原湿地相比，东湖水-气界面是一个较小的碳源。更多还原

【Abstract】 Carbon cycling and budget in the shallow, eutrophic Lake Donghu were studied from April 2003 to March 2004. This thesis mainly included:1) the fluxes of carbon dioxide and methane across water-air interface, 2) seasonal changes in DOC ( dissolved organic carbon ), TOC( total organic carbon ) and DIC( dissolved inorganic carbon ) in the water column, and 3) carbon budget of the whole lake. The main results and conclusions are as follows:Methane concentration in the lake water was always supersaturated and the methane emission rate at Stations I , II and III was 0.97, 1.071 and 1.136 mg m-2 h"1, respectively. Most of the methane emission took place in the summer. There was no significant relationship between methane flux across water-air interface and trophic level, but the maximum emission was associated with high trophic level. Temperature significantly promoted methane emission. There was great variation in carbon dioxide flux across water-air interface, and the average emission rates of carbon dioxide at Stations I , II and HI were 9.87, 13.33, 26.06 mg m-2 h-1, respectively. There was a negative relationship between carbon dioxide fluxes across water-air interface and trophic levels, but there was no significant relationship between carbon dioxide fluxes across water-air interface and temperature.The average concentrations of DOC, TOC and DIG in the water column were 7.31, 8.78 and 11.89 mg/L, respectively. The concentrations of both DOC and TOC were the highest in autumn, whereas the DIG concentration was higher in spring andsummer than in autumn and winter. Based on cluster and principal composition analyses, the carbon concentrations in the water column were divided into three groups: 1) highest concentrations of DOC and TOC due to higher temperature and trophic level, 2) medium concentrations of DOC and TOC, and 3) lowest DOC and POC values due to strong rainfall.Using inventory method, the carbon budget of Lake Donghu during April 2003 and March 2004 were estimated from water-air, water-land and water-sediment interfaces. Lake Donghu was a sink of carbon (8018.9t in total). The gaseous carbon released from the water-air interface was 880.2t, accounting for 22.6% of the total outflow. Compared with other lakes (e.g., Lake Ontario), this proportion was small. Compared with wetlands in San Jiang Plain, the water-air interface of Lake Donghu is a smaller source of carbon.更多还原