三峡水库沉积物不同赋存形态磷的时空分布

为了认识三峡水库沉积物磷的赋存状况,利用磷形态标准测试程序SMT法对干流和三条代表性支流(香溪河、大宁河、小江)的柱状沉积物进行了总磷(TP)、无机磷(IP)、有机磷(OP)、铁/铝磷(Fe/Al-P)、钙磷(Ca-P)的测定,结果表明干流沉积物TP含量为781~1026 mg·kg-1,支流沉积物TP含量为382~1085 mg·kg-1.TP主要由IP组成,OP所占比例较低;IP主要由Ca-P组成,Fe/Al-P所占比例较低.干流TP含量空间差异不显著,但各赋存形态磷的含量普遍高于支流,支流中香溪河磷含量高于大宁河和小江.垂直方向上各赋存形态磷含量在不同沉积深度没有明显规律;TP、IP、Ca-P三者变化趋势较一致,主要受Ca-P含量的影响.鉴于支流的独特水文条件,相比于干流,更应警惕支流沉积物磷的释放风险及其对水体的环境化学效应.

Spatio-temporal distribution characteristics of different phosphorus forms in sediments from the Three Gorges Reservoir

In order to investigate the distribution characteristics of phosphorus in the sediment from the Three Gorges Reservoir (TGR), samples were collected from the main channel and tributaries (Xiangxi River, Daning River and Xiaojiang River) of the TGR, concentrations of total phosphorus (TP), inorganic phosphorus (IP), organic phosphorus (OP), iron/aluminium bound phosphorus (Fe/Al-P) and calcium bound phosphorus (Ca-P) were measured by using the standard measurement procedure of phosphorus forms. The results indicate that TP concentration was in a range from 781 mg·kg^-1 to 1026 mg·kg^-1 in the main channel, and was from 382 mg·kg^-1 to 1085 mg·kg^-1 in the tributary. IP accounted for the large proportion of all the phosphorus forms; IP consisted of Ca-P and Fe/Al-P, Ca-P was the dominate composition. The difference of TP concentration in the samples from the main channel was not significant. Concentrations of five phosphorus forms in the main channel were higher than that in tributaries. As to the tributaries, the concentrations of different phosphorus forms in the Xiangxi River were higher than the other two tributaries. No significant changes were observed in the vertical distribution of different phosphorus forms. In the sediment cores, variation of various phosphorus forms concentration showed no relationship with the increasing depth. TP showed a positive relationship with IP and Ca-P, and mainly affected by Ca-P. Compared with the main channel, tributaries should be paid more attention on the risk of phosphorous releasing because of the special hydrogeological conditions.