Phosphate adsorption characteristics at the sediment-water interface and phosphorus fractions in Nansi Lake, China, and its main inflow rivers
2009
Phosphorus fractions and phosphate adsorption characteristics of 16 sediments from a shallow freshwater lake (Nansi Lake, China) and its inflow estuaries were investigated. In the present study, the sediment phosphorus is fractionated into exchangeable P (exch-P), Al-P, Fe-P, Ca-P, organic P (OP), inorganic P (IP) and total P (TP). The results show that the total phosphorus (TP) content in the sediments ranges from 571.67 to 1,113.55 mg kg⁻¹, and calcium bound phosphorus (Ca-P) is the main fraction of IP. The biologically available phosphorus (BAP) ranges from 32.02 to 229.67 mg kg⁻¹ in the Nansi Lake sediments. Phosphate adsorption on the sediments mainly occurs within 10 h and is completed within 48 h. The content of native adsorbed phosphorus (ωNAP) varies greatly from 6.05 to 194.37 mg kg⁻¹, showing a significant correlation with the total maximal amount of phosphorus adsorbed (TQmax). Adsorption efficiency (m) ranges from 574.79 to 3,220.68 l kg⁻¹ and zero equilibrium phosphorus concentration (CEPC) ranges from 0.010 to 0.157 mg l⁻¹. After the South-to-North Water Diversion Project, the inherent phosphorus present in sediments will be a major threat to the diverted water quality and be a predominant factor determining the trophic status of the lake even if the external load is reduced.
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