在三门峡水库影响下黄河有机碳的输送特征

Impacts of the Sanmenxia Reservoir on Organic Carbon Transport Characteristics of the Huanghe River

通在黄河三门峡水文站进行1 a的连续采样分析和调水调沙期间的密集采样分析,揭示了三门峡水库水沙调控对黄河有机碳输送过程的影响。结果表明,在水库调水调沙期间,三门峡站POC含量与TSS含量同步增加,而DOC含量变化趋势不明显;在1 a内,DOC和POC含量均有明显的季节变化。三门峡站POC年通量为124.8万t,其中调水调沙期间POC输送量约占POC年通量的38%,水库敞泄期间（8~9月）的POC输送量约占POC年通量的60%;三门峡站DOC年通量为7.6万t,其中7~9月DOC输送量约占DOC年通量的52%。

The Sanmenxia Reservoir, controlling 89% of the water and nearly 100% of the sediment, is an important hydro-junction in the middle reaches of the Huanghe River. By sampling within a complete hydrologic year at the Sanmenxia Station and intensive investigation during water-sediment regulation period, combining with the hydrological data over the same period, impacts of the Sanmenxia Reservoir on organic carbon transport processes was revealed by the operation mode. Water storage, sediment interception（water and sediment regulation）, and open discharge were well studied. Results indicated that the particulate organic carbon（POC）rise simultaneously with the sharp increasing of total suspended particle（TSS） contents, whereas the dissolved organic carbon（DOC） content showed no significant change during the water-sediment regulation of the Sanmenxia Reservoir. Over the whole year, DOC content implied significant seasonal change, which was higher in January-February and July-September, lower in other months; POC content showed higher from July-September but lower in the other months. At the Sanmenxia Station, annual POC flux was 1.248 million t, of which POC transport in July accounted for about 38% of the total, and POC during August-September occupied 60%of the total. Annual DOC flux was 76,000 t, the part during July-September was 52% of the annual total. Under the influence of the reservoir, organic carbon transport was dominated by POC during the flood season,while mainly controlled by DOC during the dry season. On the whole year, the organic carbon transport was firstly affected by POC, which was about 16.5 times of DOC. Influence of Sanmenxia Reservoir on organic carbon transport in the Huanghe River was significantly different from other reservoirs, by not only intercepting POC in the dry season, but also discharging a large number of intercepted POC during the flood season.Moreover, organic carbon could transports directly from the upstream to the downstream during discharge period from August to September