中文摘要：

于2009年至2011年在黄河下游采集溶解及颗粒态营养盐样品，分析了黄河下游各形态营养盐的浓度变化及营养盐入海通量，结果表明各形态氮的浓度多呈丰水期低、枯水期高，溶解无机氮是溶解态氮的主要存在形式；受黄河高悬浮颗粒物含量的影响，磷以颗粒态占绝对优势，而溶解态磷以溶解无机磷为主要存在形态；生物硅的含量平均约占硅酸盐与生物硅之和的20％，硅的浓度丰水期高于枯水期。颗粒态磷与生物硅的含量与悬浮颗粒物含量呈正相关。营养盐的组成具有高氮磷比、高硅磷比、低硅氮比的特点。近年来黄河下游溶解无机氮浓度显著升高而溶解无机磷变化不大，硅酸盐的浓度有所下降。黄河下游水沙通量、营养盐入海通量有明显的季节变化，丰水期占全年总入海通量的42％～84％。调水调沙期闻，各营养盐的浓度和组成均有明显变化，氮的浓度、DIN／PO4-P下降，磷与硅的浓度、SiO3-Si／DIN、SiO3-Si／PO4-P升高，颗粒态营养盐的比例明显增加。短期内大量水沙及营养盐入海通量对黄河口及渤海生态系统产生重要影响。

英文摘要：

Observations were carried out at the lower reaches late nutrient elements from 2009 to 2011. The results show of the Huanghe River to analyze dissolved and particughat the concentrations of various N forms were lower in the flood season than those in the dry season. Dissolved inorganic nitrogen （DIN） was the predominant species of TDN. Particulate phosphorus was the major form of phosphorus affected by high content of suspended particulate matter. Phosphate represented 68% of TDP. Both silicate and biogenic silicon were higher in the flood season than those in the dry season. The BSi was 20% of the sum of BSi and SiO3-Si. Particulate phosphorus and biogenic silica had a positive correlation with SPM. Nutrient composition was characterized by high N/P and Si/P ratios and low Si/N ratio. In the past decades, dissolved inorganic nitrogen concentrations increased, dissolved phosphorus concentrations remained at a stable level, and silicate concentrations slightly decreased. Nutrient transport fluxes from the river into the Bohai show significantly seasonal changes. Water discharge, sediment load and nutrient fluxes in the flood season accounted for 42 %- 84 % of the annual loads. The concentrations and composition of nutrients had an obvious change during the water-sediment regulation event. Abundant water, sediment and nutrient were transported to the Huanghe estuary and the adjacent Bohai during the water-sediment regulation event. The concentrations of N and ratios of DIN/PO4-P decreased, while the concentrations of P and Si and the ratios of SiO3-Si/PO4-P and SiO3-Si/DIN increased, the proportion of particulate phosphorus and BSi showed a distinct rise. It is expected that high terrestrial inputs transported by the Yellow River during the water-sediment regulation will lead to an extensive impact on the ecological system of the Bohai.