黄柏河流域梯级水库沉积物磷形态特征及磷释放通量分析

为揭示黄柏河流域饮用水源水库的磷负荷特征，采用SMT分级方法对流域内3座梯级水库（玄庙观、天福庙、西北口水库）的沉积物磷形态特征及垂向变化特征进行了分析，并初步估算了沉积物-水界面正磷酸盐释放通量以及各形态磷含量对磷释放的影响.结果发现，沉积物总磷（TP）含量从流域上游至下游水库呈现递减趋势，平均值分别为（8070.0±2251.4）、（2681.2±1709.8）和（2656.6±1599.7）mg·kg^-1，均处于高度污染水平.3座水库中各个采样点磷形态之间的含量主要表现为：HCl-P > OP > NaOH-P.根据Fick第一定律，计算得到流域内3座梯级水库均表现为上覆水正磷酸盐的源，正磷酸盐释放通量从流域上游到下游水库呈现递减趋势，范围为0.0179~0.1825 mg·（m²·d）^-1.正磷酸盐释放通量与表层水体DO和叶绿素呈现正相关，与HCl-P，OP和TP同样表现为显著正相关.

Characteristics of Phosphorus Fractions and Phosphate Diffusion Fluxes of Sediments in Cascade Reservoirs of the Huangbai River

The Huangbai river, with a large phosphorite deposit in the basin upstream, is the drinking-water source of Yichang city, China, and water blooms often break out in it in present times. To investigate the internal contamination load, the distribution and vertical variation of sediment phosphorus and its fractions were analyzed. Phosphorus flux across the sediment-water surface was preliminarily analyzed in three reservoirs in the basin. The results showed that the concentration of total phosphorus (TP) decreased from the upstream to the downstream reservoirs of the basin, and the means of the TP were (8070.0±2251.4), (2681.2±1709.8), and (2656.6±1599.7) mg·kg^-1, in the three reservoirs, respectively. This shows that the basin is at a highly polluted level. There were similar tendencies in the concentrations of dissolved oxygen (DO) and chlorophyll a in the surface water. The order of the phosphorus fractions was HCl-P > OP > NaOH-P in most sites. According to Fick''s First Law, the flux of PO₄^3--P across the sediment-water surface was 0.0179-0.1825 mg·(m²·d)^-1, and it decreased from the upstream to the downstream reservoirs. The flux was positively related to HCl-P, OP, and TP in the high phosphorus concentration basin.