天津于桥水库上游河流表层沉积物不同形态磷的空间分布

Spatial distribution of different forms of phosphorus in sediments of the upstream of Tianjin Yuqiao Reservoir

为了解天津于桥水库上游河流表层沉积物中磷形态的空间分布规律,采用SMT法对于桥水库上游流域33个样点的河流表层沉积物中不同形态的磷进行连续分级提取和空间统计分析,探讨沉积物中各形态磷的空间聚集特征及其与土地利用的关系.结果表明:(1)于桥水库上游流域河流表层沉积物中,总磷(TP)含量为425.94~3412.96 mg/kg,TP中各形态磷含量的顺序为:钙磷(Ca-P)>有机磷(OP)>铁铝磷(Fe/Al-P).OP和Fe/Al-P在各样点间的含量差异较大,其变异系数分别为71.92%和100.48%.(2)全局自相关分析发现,5种形态的磷中,只有OP和Fe/Al-P在空间分布上存在聚集模式,其对应的Moran′I指数分别为0.27和0.19;自相关分析结果表明,OP和Fe/Al-P热点区域均位于流域中下游村镇,冷点区域在流域上游山区.(3)相关性分析结果表明,TP、无机磷和Ca-P主要存在于粗颗粒沉积物中,含量与砂的质量分数均呈显著正相关;Fe/Al-P和OP含量均与村镇分布和不透水面指数呈显著正相关,与林地和高程呈显著负相关.

To learn the distribution rule of the phosphorus forms in the river sediments of the upstream of Tianjin Yuqiao Reservoir, the different forms of phosphorus in superficial sediments of the 33 sampling sites in the upstream of reservoir were extracted sequentially, and their spatial statistical analysis were conducted by the method of SMT. The spatial distribu-tion of different forms of phosphorus in sediments and its relationships with land utilization were explored. The results showed that：（1）The total phosphorus（TP） content ranged from 425.94 to 3 412.96 mg/kg, and the order of different forms of phosphorus was calcium-phosphorus（Ca-P） organic phosphorus（OP） iron and aluminum combination state of phosphorus（Fe/Al-P）. The differences of OP and Fe/Al-P contents among the 33 sampling sites were big, and the coefficients of variation were 71.92% and 100.48% respectively.（2） The results of global autocorrelation analysis showed that among five forms of phosphorus, only OP and Fe/Al-P had aggregation mode in the aspect of spatial distribution, the corresponding Moran ′ I index were 0.27 and 0.19 respectively; the results of autocorrelation analysis showed that the hot areas of OP and Fe/Al-P were in the towns and villages which were located in the middle and lower reaches, and the cold spots were in the mountains lo-cated in the upper reaches.（3）The correlation analysis showed that TP, inorganic phosphorus and Ca-P were mainly in coarse sediments and positively correlated with the mass fraction of sand; Fe/Al-P and OP were positively correlated with the distribution of villages, towns and expansion of impervious surface, and negatively correlated with woodland and elevation.