[Vertical Distribution Characteristics and Analysis in Sediments of Xidahai Lake]

The organic matter (OM), total nitrogen (TN), total phosphorus (TP), the morphological changes of phosphorus and the particle size in columnar sediment core of Xidahai Lake were analyzed, to discuss the vertical distribution characteristics and influencing factors. The results showed that the contents of OM, TN and TP were 0. 633% -2. 756%, 0. 150% -0. 429% and 648. 00 - 1 480.67 mg . kg-1 respectively. The contents of Ca-P, IP and OM changed less, the contents of Fe/Al-P, OP, TP and TN fluctuated from 1843 to 1970; The contents of Ca-P, IP and TP tended to decrease, the contents of Fe/Al-P, OP and OM first decreased and then increased to different degree, TN fluctuated largely from 1970 to 1996; The nutrient elements contents showed relatively large fluctuation from 1996 to 2009, the average contents of Fe/Al-P, OP and OM were the highest in the three stages. The sediment core nutrients pollution sources were mainly from industrial wastewater, sewage and the loss of fertilizers of Xidahai Lake. The ratio of C/N in the sediments showed that organic matter was mainly from aquatic organisms. The sediment particle size composition was dominated by clay and fine silt. The correlation studies showed that Ca-P, IP and TP were significantly positively correlated, showing that the contribution of Ca-P to IP and TP growth was large.