Characteristics of phosphorus transformation from vivianite mediated by sulphide

Abstract

The release of phosphorus (P) from anaerobic sediments becomes the dominant source of P loading with effective control of external P pollution. As a crucial component responsible for binding P, vivianite (Fe₃(PO₄)₂·8H₂O) in sediment inevitably impacts the P level and transformation. The release of P from vivianite mediated by sulphide was investigated using simulated overlying water-sediment and chemical reaction systems. The percentage of redox-stable P in the sediments increased with vivianite input in the overlying water-sediment system. Increasing P concentrations in both the overlying water and interstitial water occurred before day 10, accompanied by a decreasing percentage of redox-sensitive P in the sediments driven by sulphide. The continuous release of P from vivianite clarifies the influence of sulphide on promoting vivianite dissolution in a chemical reaction system with vivianite and sulphide solution. Additionally, Mössbauer spectrum and nanoscale secondary ion mass spectrometry (NanoSIMS) images based on the chemical reaction with ⁵⁷Fe isotope labelling demonstrated the presence of initial vivianite, newly produced vivianite, and FeS₂.