RESUMEN
Sediment phosphorus (P) content and component ratio from 16 sites along the North Jiulong River-reservoir system were analyzed using the Standard Measurement and Test (SMT) procedure. The spatial pattern and characteristics of sediment P and its ecological significance in the Jiulong River-reservoir system were examined in combination with water measurement and watershed information. Total P content in sediments ranged from 387 to 2092 mg x kg(-1) with an average of 1032 mg x kg(-1). Inorganic phosphorus (IP) dominated P in sediment, accounting for 48%-98% of TP, and Fe/Al-bound phosphorus (Fe/Al-P) took 43%-99% of IP. The spatial pattern of sediment showed that TP and Fe/Al-P were higher in upstream and lower in downstream, corresponding to the spatial variation of surface water P and land-based loads from animal waste, human waste and fertilizer loss. Spatial variation of TP in sediment was controlled by Fe/AI-P along the North Jiulong River. The P-rich sediment with a great release potential due to the high ratio of Fe/ Al-P, the typical spatial pattern, and the lower N/P ratio observed in upstream water (where phytoplankton growth tends to be weakly limited by phosphorus), are likely to explain the fact that algal blooms first appear in the upstream and then spread to downstream reservoirs along the North Jiulong River. Present findings concerning sediment P characteristics indicate an important regulating effect and the ecological significance on the process of algal blooms in the Jiulong River.