[Spatial and temporal variations of phosphorus forms in surface sediments of Chaohu Lake]

Total phosphorus (TP), inorganic-phosphorus(IP), organic-phosphorus (OP), Fe/Al-bound phosphorus (NaOH-P) and Ca-bound phosphorus (HCl-P) in surface sediments of Chaohu Lake were measured, using the standard measurement and test (SMT) procedure of phosphorus forms in freshwater sediments. ArcGIS 9.2 and goestatistics software GS + 5. 3 were applied to process the spatial data and interpolation. Results showed that no significant seasonal variation of TN, TP and organic matter contents in sediments were presented, and the western lake had higher contents of TN, TP and organic matter than those in eastern lake; the C/N ratios varied from 21.35 to 28.19, with average value of 24.94, which demonstrated the dominance of non-point source pollution. The TP contents in surface sediments ranged from 528.90 to 1 385.71 mg x kg(-1), and the main form of TP in sediments was IP(accounted for 55.78% -79.86% of TP). The OP in sediments ranged from 169.05 mg x kg(-1) to 841.24 mg x kg(-1), with eastern lake and western lake were 376.02 mg x kg(-1) and 406.53 mg x kg(-1), respectively (accounted for 47.49% and 36.28% of TP); the NaOH-P contents in sediments ranged from 33.77 mg x kg(-1) to 411.37 mg x kg(-1), with eastern lake and western lake of 376.02 mg x kg(-1) and 406.53 mg x kg(-1), respectively (accounted for 21.73% and 33.12% of the IP); the HCl-P contents ranged from 194.95 mg x kg(-1) to 477.45 mg x kg(-1), with eastern lake and western lake 321.71 mg x kg(-1). and 338.08 mg x kg(-1), respectively (accounted for 64.50% and 40.53% of the IP), which was the main species of IP. The OP contents was high in spring and winter compared with summer and autumn, while the contents of HCl-P and NaOH-P in summer and autumn were higher than those in spring and winter.