Comparison of fractions and sorption behaviors of sediment phosphorus between typical zones with different trophic states in Lake Taihu, China
Typical zones with different trophic states were selected to study fractions and sorption behaviors of phosphorus in sediment of Lake Taihu,China.Results showed that the surface sediment sampled at Site T1 in the Meiliang Bay as a typical area dominated by algae had a higher content of total phosphorus (TP) relative to that at Site T2 in the Xukou Bay as a typical area dominated by macrophyte.Additionally,there existed a significantly negative relationship between phosphorus sorption energy (K) and TP content (p < 0.05).Hence high phosphorus loading would increase risk of its release from sediment into water column.Furthermore,organic matter (OM) content was found to be positively related to the degree of phosphorus sorption saturation (DPS) (p <0.05),coupled with a significantly negative relationship between DPS and K value (p < 0.05) in the sediment.In short,OM can indirectly affect phosphorus sorption behaviors by adjusting DPS in sediment.In sediment of Site T2,equilibrium phosphorus concentration (EPC0) increased with depth,it meant that macrophyte existed there kept surface sediment to still function as phosphorus sink.While,in the sediment of Site T1,the EPC0 showed the lowest value at subsurface layer (10-15 cm),which may serve as a suitable depth for sediment dredging.The results provided a theoretical basis and technical parameters for restoration of eutrophic lakes.