Evaluating the Relationship between Phosphorus Bioavailability and Phosphorus Speciation in Sediments from Rural Rivers in the Taihu Lake Area, China

Abstract

The concentrations of different phosphorus (P) species and four kinds of bioavailable P (algae-available P, AAP; Olsen P, OLP; water-soluble P, WSP; and readily desorbable P, RDP) were determined to investigate the relationship between phosphorus bioavailability and phosphorus speciation in sediments from rural rivers in Taihu Lake area, China, using a European Commission “Standards Measurements and Testing Program” protocol and four chemical extraction techniques. The total P and inorganic P concentrations in the sediments were 179-2,293 mg/kg and 137-1,857 mg/kg, respectively. The concentrations of the P species in the sediments followed the order NaOH- extractable P > HCl-extractable P > organic P. The bioavailable P concentrations followed the order AAP (340 mg/kg) > OLP (38.7 mg/kg) > WSP (1.8 mg/kg) > RDP (0.3 mg/kg). Regression analyses showed that there were good correlations between the P species concentrations and the bioavailable P concentrations measured using the four different methods, except for between WSP and the HCl-extractable P concentrations. The OLP concentrations had highly significant correlations with AAP, WSP, RDP and the P species concentrations. The OLP method was found to be most suitable for determining the bioavailability of P species under the prevalent geochemical conditions in the rural river sediments that were analyzed.