Vertical Variation of Phosphorus Forms in Core Sediments from Dongping Lake, China

Abstract

The SMT sequential extraction method was applied to determine content of TP, IP, OP, NaOH-P and HCl-P in the core sediments of Dongping Lake, vertical variation of phosphorus forms and correlations of them and LOI were discussed in this study. Results indicated that TP averaged 548.36 mg/kg, in the range from 498.01 to 596.77 mg/kg and mainly composed of IP (69.26%-79.14%). The three main forms of phosphorus followed the order HCl-P>OP>·NaOH-P, and HCl-P was the dominant component of TP. All the phosphorus forms had similar vertical distribution pattern under 5 cm (corresponding to 1995), with stable content and narrower fluctuation, and started to present remarkable change above 5 cm, an upward trend in NaOH-P and OP, a downward trend in HCl-P, IP and TP, which indicating that the distribution of phosphorus forms in the sediments was obviously affected by human activities from 1995. Correlation analyses showed that HCl-P was the main factor controlling TP and IP, there were significant correlations between TP and other phosphorus forms except OP, and correlations between phosphorus species (except NaOH-P and OP) were obvious. LOI had obvious correlation with OP and TP, and no relationships with NaOH-P, HCl-P and IP.