三峡水库蓄水期支流水体营养盐来源估算

通过对蓄水前后三峡水库库首支流香溪河沉积物-上覆水中的氢氧同位素和氮磷营养盐的测定，分析了蓄水前后沉积物-上覆水氢氧同位素和氮磷营养盐的分布特征，并利用二元线性混合模型计算了长江干流（CJ River）和古夫源头（GFYT）的贡献率.结果表明，整个蓄水期沉积物以源的形式向上覆水体释放NH₄⁺-N、DTP、PO₄^3--P，以汇的形式吸收上覆水体中的NO₃^--N.利用营养盐贡献率公式进一步分析得到，蓄水前沉积物-上覆水中氮营养盐主要来源于CJ干流，其中以DTN和NO₃^--N最为显著，蓄水后GFYT的贡献率明显上升，其中3号和4号采样点最为明显，其中DTP在蓄水前后几乎均以GFYT为主要来源，PO₄^3--P在蓄水前则以CJ干流为主要来源，蓄水后以GFYT为主要来源.说明尽管蓄水期库湾水体在较大程度上受干流倒灌影响的支配，但对于沉积物-上覆水而言受GFYT的影响更为显著.

Analysis of the nutrient supply of tributaries in the Three Gorges Reservoir during impounding period

Hydrogen-oxygen isotope and nutrients including nitrogen and phosphorus in the sediments and overlying water were monitored in the bay of the XiangXi River (XXB), the first tributary of the Three Gorges Reservoir(TGR), during the impoundment period. The measured data were used to analyze the distribution characteristics of hydrogen-oxygen isotopes and the nutrients during the impoundment period. A binary mixed linear model was utilized to determine the contribution ratio of the main stream of the Yangtze River (CJ River) to GuFuYuanTou (GFYT), the upstream of the river. The study results showed that the sediments simutaneously functioned as source releasing NH₄⁺-N (ammonia nitrogen), DTP (total dissolved phosphorus), and PO₄^3--P (phosphates), and as absorbent collecting NO₃^--N (nitrate nitrogen) during the entire impoundment period. The computed results of the contribution ratios indicated that most nitrogen in the sediment (especially for DTN (total dissolved nitrogen) and NO₃^--N) came from the main stream before the impoundment. After the impoundment, the contribution rate of GFYT increased significantly, with sampling points No. 3 and 4 as the most obvious. Among all the nutrients, most DTP were from GFYT before and after the impoundment and the main stream was the main source of PO₄^3--P before the impoundment. Therefore, while the water in the bay of the reservoir was largely dominated by the influx of the main stream during the impoundment period, the impact of GFYT is more significant than that of the main stream on the sediment-overlying water system.