Characteristics of Phosphorus Sorption and Release on Sediments of the River Crossed Region of Suzhou City

Phosphorus(P) sorption and release on sediments collected from the river crossed region of Suzhou city were studied.The effects of chemical-physical properties of the sediments on the characteristics of P sorption and release were discussed.Moreover,the relationship between P behavior on the sediments and river water quality was elucidated.The results showed that P saturated sorption capacities ranged from 191.1 mg/kg to 771.6 mg/kg,suggesting a strong P sorption potential on river sediments,however,there was a great variation among the sediment samples.The zero equilibrium P concentration(EPC0) of the sediments ranged from 0.013 mg/L to 0.1829 mg/L,indicating a potential sink of P of the sediments.The native absorbed P(NAP) was 12.43～215.3 mg/kg,indicating that there was a high potential risk of P released from the sediments.The process of P sorption and release contained a fast and a slow reaction phase.The fast reaction phase occurred within 2 hours,and the slow reaction phase followed.The analysis of co-relation showed that CEC,TOC,the grain size,Fe and Al had no significant influence on the parameters of P adsorption and release,however,the contents of various inorganic P and Al forms were responsible for them.Such a result might be controlled by the river sediment environment.P sorption and release characteristics on river sediments is a result from many different factors.