中文摘要：

2005年7月沿黄河干流及4条主要支流系统采集了28个水样,对水及悬浮物的化学组成、矿物组成、水化学成分和硅同位素组成进行了综合分析。黄河水中悬浮物在不同站点的浓度差异悬殊,由8.8～302120mg/L不等,与黄河两岸人类活动（水库、牧场、农田）和自然环境变化（流域岩性、植被覆盖程度）关系密切。悬浮物中SiO2含量介于41.39%～67.85%之间,平均值54.67%,与中国黄土（59.81%）接近。黄河悬浮物中硅同位素δ30Si变化范围为-0.5‰～0.0‰,反映了粘土矿物（-1.9‰～0.0‰）和碎屑矿物（-0.3‰～0.3‰）以不同比例混合的结果。黄河水的溶解硅浓度范围0.68～6.90mg/L,相应的硅同位素δ30Si变化范围为-0.2‰～2.1‰。从上游到下游整体呈上升趋势,但波动较为明显,该趋势可能与流域植物和作物的生长情况有关,此外,还可能与水中HCO-3浓度有关。在此次研究中,黄河入海口（渤海）样品溶解硅的δ30Si值为1.1‰,低于长江入海口（东海）水中溶解硅的δ30Si值（3.0‰）,这不但为评估世界河流对海洋硅同位素组成的影响提供了新的资料,同时也说明对地表不同地理位置、具有不同水文地貌特征的不同河流开展系统、深入的硅同位素研究对探索全球硅同位素循环有十分重要的意义。

英文摘要：

Twenty-eight water samples were collected along the main channel and four major tributaries of the Yellow River during July 2005, and which silicon isotope compositions and chemical compositions of dissolved silicon and suspended matter in water were systematically researched. The concentration of suspended matter of the different sites in the Yellow River differ obviously from 8.8 mg/L to 302120 mg/L, and which correlate with human activities （dams, pasture and farmland） and natural environment （regional rocks and vegetations） closely. The silica contents of suspended matter between 41.39% and 67.85%, very close to Loess in China. The δ30Si values of suspended matter in the Yellow River vary from -0.5‰ to 0.0‰, reflecting the mixture values of clay minerals （-1.9‰~0.0‰） and clastic minerals （-0.3‰~0.3‰） with different proportion. The concentrations of dissolved silicon vary from 0.68~6.90 mg/L from the upper reaches to the lower reaches and their δ30Si values vary from -0.2‰ to 2.1‰, tends to increase from the upper reaches to the lower reaches, whilst fluctuate obviously. The trend is main correlation with the contents of carbonates and clay minerals in rocks and soils, in addition, likely to involve in the concentrations of CO2 in atmosphere and its dissolution in water. In this study, the δ30Si value of dissolved silicon output from the Yellow River to the Bohai Sea is 1.1‰, lower than the δ30Si of dissolved silicon （3.0‰） output from the Yangtze River to the East Sea, which not only provides new data for ocean silicon isotope compositions of the world rivers, and also indicates that more further and detailed investigations to other rivers with different geographic and hydrological background are very important to study global silicon cycle.