长江有机碳通量的季节变化及三峡工程对其影响

Seasonal variation of organic carbon fluxes in the Yangtze River and influence of Three-Gorges engineering

2003年6月-2005年7月在长江口每月采集表层水样,测定溶解有机碳（DOC）和颗粒有机碳（POC）.结果表明,DOC和POC平均浓度分别为1.59±0.21和0.91±0.42mg/L,其中枯季的DOC浓度较洪季高,而POC则呈相反趋势.POC浓度与水体中总悬浮颗粒物（TSM）浓度有显著性正相关关系,在TSM中的POC%随着TSM浓度的增加而减小.2003,2004年长江的DOC通量分别为1.32×10^6t和1.20×10^6t,POC通量分别为2.69×10^6t和1.63×10^6t,约76%的总有机碳在洪季输送入海,组成以颗粒态为主.2003-2004年间POC通量急剧减少,DOC通量与POC通量的比值迅速增大,可能与三峡水库对颗粒物的拦蓄、改造及富营养化有关.

The water samples of the surface layer sampled in the lower Yangtze River from June 2003 to July 2005 were used for determination of dissolved organic carbon （DOC） and particulate organic carbon （POC）. The concentrations of DOC and POC during the observation were 1.59±0.21 and 0.91±0.42mg/L, respectively, in which DOC in dry season was higher than that in flood; while POC showed the opposite tendency. POC concentration and total suspended matter （TSM） in waters had marked positive correlationship, the POC% in TSM decreased with the increasing of TSM concentration. The DOC fluxes of Yangtze River in 2003, 2004 years were 1.32×10^6t and 1.20×10^6t respectively, the POC fluxes were 2.69×10^6t and 1.63×10^6t, and about 76% of the total organic carbon was transported into sea in flood season with its composition being mainly particular phase. In 2003-2004 years POC fluxes decreased rapidly. The ratio value of DOC and POC fluxes increased rapidly, related possibly with retaining, reforming and eutrophication.