长江干流有机碳的时空输运特征及三峡工程对其影响

Spatial and Temporal Transport of Organic Carbon in Changjiang Mainstream and Influence of Three Gorges Project

2006-04,2008-04,2008-05沿长江干流采集表层水样,并于2006-05~2007-05在下游大通站进行每月2次、为期1 a的连续观测,测定溶解有机碳（DOC）、颗粒有机碳（POC）及总悬浮物（TSM）。结果表明：长江重庆以上江段DOC浓度较低,重庆至河口由于人为污染排放DOC表现出高值;干流POC与TSM显著正先关,POC%（TSM）随TSM含量增大呈负指数关系下降。大通站有机碳浓度及通量均表现出明显的季节性,2006-06~2007-05全年经大通站进入河口的DOC、POC通量分别为1.17×106tC和1.88×106tC,其中洪季（5~10月）输运的有机碳占到总有机碳的70%,组成以颗粒态为主。三峡水库135 m及156 m蓄水后,泥沙在库区的沉降作用显著影响长江POC的输运特征及入海通量;从目前观测结果看,三峡库区DOC浓度并没有表现出明显的升高趋势,可能与水库运行时间尚短有关。

The water samples of surface layer collected along the Changjiang mainstream in April 2006,April 2008 and May 2008 and collected in Datong from May 2006 to May 2007 were used for determination of dissolved organic carbon（DOC）,particulate organic carbon（POC） and total suspended matter（TSM）.The results were as follows.The concentrations of DOC demonstrated low-value above Chongqing of Changjiang and high-value from Chongqing to the river mouth due to anthropogenic emissions.Distribution of POC and TSM in Changjiang mainstream were similar and it showed good correlation between the two parameters.POC%（TSM） declined as the negative logarithm relations with the TSM concentration increasing.Variations of organic carbon concentrations and fluxes of Datong during a year showed obvious seasonal characteristics.The DOC fluxes and POC fluxes of Datong from June 2006 to May 2007 were 1.17×106tC and 1.88 106tC.About 70% of total organic carbon was transported into the sea in flood season with its main composition being mainly particular phase.135 m and 156 m water storage of Three Gorges Reservoir had significant effects on the transportation and fluxes of POC of Changjiang mainstream and the effects on DOC is not yet clear due to the monitoring data from the year 1997 to 2008.