In order to study the variation of phosphorus forms

sorption capacity and the potential releasing risks

the phosphorus forms and sorption index were analyzed in the barren wetland and Spartina alterniflora invasion wetland of Min River estuary. The results indicated that inorganic phosphorus (IP) was the main form of soil phosphorus

which accounted for 61.40% and 61.01% of total phosphorus (TP) in soils of the barren wetland and Spartina alterniflora invasion wetland

respectively. The concentrations of TP

IP

iron and aluminum-bound phosphorus (Fe/A1-P) and calcium-bound phosphorus (Ca-P) were all significantly higher than those of the barren wetland

and the increase percentage were 12.58%

9.49%

11.11% and 5.32% in turn

while the organic phosphorus (Org P) had no significant change. Furthermore

Spartina alterniflora invasion had different impacts on the amorphous phosphorus (Pox)

iron (Feox)

aluminum (Alox)

the phosphorus adsorption index (PSI) and the degree of phosphorus saturation (DPS)

and the Feox and DPS were not significantly changed. However

the Pox and PSI were increased significantly

while the Alox was significantly decreased. The potential releasing risk (ERI) of the barren wetland was 12.69

which was belonged to middle risk

nevertheless

the ERI of the Spartina alterniflora invasion wetland was reduced to 9.98

which was belonged to low risk

indicating that Spartina alterniflora invasion could lower the releasing risk of soil phosphorus in wetland.