The Phosphorus Fractions Distribution of the Sediment in Water Fluctuation Zone of the Biliuhe Reservoir, China

The fluctuation of reservoir water level makes sediment in reservoir boundary area submerged and exposed alternately. Different regions are subject to different frequency of water fluctuation and different environmental conditions, which have distinct function on water quality of reservoir. To investigate the function of water level fluctuation on phosphorus (P), four sample cores on the main channel of the Biliu Reservoir were collected. The P fractions were analyzed by the Ruttenberg method, and the sum of P forms contents were calculated as total P (TP) contents. The results showed that TP contents of water fluctuation zone sediment in the Biliu Reservoir ranged from 345.95 to 929.54 mg/kg. The TP content of each sampling point showed a trend of gradual enrichment from deep to surface samples. Horizontally, the TP contents of samples samples showed a trend of D4 > D3 > D1 > D2 in 0-10 cm, and a trend of D4 > D3 > D2 > D1 in 10-16 cm. The difference of P distribution between upper and lower surface samples might be related to the periodic plant growth of D1. Inorganic P (IP) was the major component of the TP accounting for 88.75% - 97.43% and organic P content is merely 10.25-87.69 mg/kg. The contents of P fractions had no obvious trend temporally and spatially, however, the proportions of each forms remained relatively stable. The results implied that the complex environmental conditions in different regions of the WLFZ had no obvious influence on the P forms in sediment.