Distribution characteristics and causes of pollution of phosphorus in sediments of Changtan Reservoir

The total phosphorus( TP) and various forms of phosphorus in surface sediments were measured by the sediment phosphorus form analysis method of the standard measurement and test( SMT) during the period from October 2011 to July 2012 at five sampling sites in the Changtan Reservoir,in order to explore the distribution characteristics of phosphorus in the sediments of deep lakes and reservoirs. The results show that the sediments of the Changtan Reservoir were in restoration conditions,especially in the middle and lower reaches and in the summer. The water contents in the sediments and the TOC content were low in the upper reaches and high in the middle and lower reaches. The TOC content was high in the spring and summer. The average value of the TP content in the Changtan Reservoir ranged from 0. 56 to 0. 79 mg / g,with a spatial distribution of relatively higher levels in the middle reaches and lower levels in the upper and lower reaches. The content of Fe / Al-bound phosphorus( Fe / Al-P) ranged from 27% to 48% of TP,with an average value of 41%. The content of Ca-bound phosphorus( Ca-P) ranged from 16% to 25% of TP,with an average value of 19%. The content of organic phosphorus( OP) ranged from 35% to 52% of TP,with an average value of 40%. Fe / Al-P accounted for the highest content of all phosphorus forms,and it was available for algae in the water. The main source of phosphorus pollutants of the Changtan Reservoir was the settlement of overlying water.