三峡截流后长江口秋季TSM、POC和PN的分布特征

基于2004年11—12月长江口56个站位的悬浮体调查资料,分析了长江口区悬浮体总量(TSM)、颗粒有机碳(POC)和颗粒氮(PN)质量浓度的平面分布特征,探讨该区TSM及颗粒有机质的物质来源和三峡截流对长江三角洲的影响。结果表明,表、底层TSM与POC、PN质量浓度之间存在显著的正线性相关关系并都呈现出南高北低的格局,说明了长江悬浮颗粒物入海后主要沿东南方向输运。POC、PN质量分数与POC、PN的质量浓度不同,它们与TSM质量浓度对数有负相关关系。由于河口区底质再悬浮作用显著,TSM和POC、PN质量浓度呈现表层低、底层高的特点。长江口悬浮体主要来自长江径流和底质沉积物的再悬浮。与三峡截流前数据的对比表明,截流对目前长江口区的TSM和POC尚未造成明显的影响。

Distributions of TSM, POC and PN in the Changjiang Estuary Area in Autumn After the River Closure at Three Gorges

Based on the suspended matter data collected at 56 stations in the Changjiang estuary area in November and December 2004,the horizontal distribution characteristics of total suspended matter(TSM),particulate organic carbon(POC) and particulate nitrogen(PN) concentrations in the Changjiang estuary area are analyzed,and the sources of TSM and particulate organic matter in the area and the effect of river closure at three gorges on the Changjiang River delta are discussed.It is shown from the analysis results that the surface and bottom TSM concentrations are linearly correlated with the surface and bottom POC and PN concentrations,respectively,and their concentration distributions all show a pattern of high concentration in the south and low concentration in the north,which indicates that the particulate suspended matter discharged from the Changjiang River are transported mainly to the southeast.The percent contents of POC and PN have negatively logarithmic relations with the TSM concentration.The TSM,POC and PN concentrations all show a feature of high concentration in the bottom layer and low concentration in the surface layer due to the significant bottom material resuspension in the estuary area.The suspended matter in the Changjiang estuary area originates mainly from the Changjiang River runoff and the resuspension of bottom sediments.It is shown from the comparison between the TSM,POC and PN concentrations in the Changjiang estuary area observed before and after the river closure that the river closure at three gorges has not yet caused significant effects on the TSM and POC concentrations in the Chagjing estuary area.