Distribution Characteristics of Fractionated Phosphorus in the Sediment Mud of the Tidal River

Abstract

Distribution characteristics of fractionated phosphorus content in the sediment mud of tidal river are researched and relationship between fractionated phosphorus content and current velocity, Fe content, Al content in sediment mud, pH of sediment mud is discussed in this paper.
Samples were obtained using Ekman dredge from 9 different points. Fractionated phosphorus consisting of inorganic phosphorus (I-P; CDB-P, NaOH-P and HCl-P) and organic phosphorus (Org-P) were analyzed according to previous reports. I-P was analyzed by the method of Williams, T. Mayer, J. O. Nriagu. Total phosphorus (T-P) was analyzed by the method of sulfuric acid-nitric acid decomposition. Org-P is estimated as T-P-I-P.
The pH, iron, aluminum and current velocity at each point were measured.
Correlation of the data of current velocity with CDB-P, NaOH-P, HCl-P content in sediment mud shows that phosphorus contents of three species increased when the current velocity at the sampling point was slower than that of the upper sampling point. Therefore, relationship between fluctuations of current velocity and CDB-P, NaOH-P, HCl-P content in sediment mud was inspected by field experiment.
CDB-P content increases as aluminum content and pH of sediment mud increase.
In tidal river it is suggested that CDB-P content in the sediment mud is controlled by phosphorus which is adsorbed in the process of hydrolysis of aluminum(III). Relationship between aluminum content and CDB-P content has very high correlation. Batch experiment using sediment mud and river water at Isobe bridge proved the suggestion to be reasonable.