Distribution of geochemical fractions of phosphorus and its ecological risk in sediment cores of a largest brackish water lake, South Asia

Abstract The current study focuses on the vertical profile of different geochemical fractions of phosphorus - loosely bound (Lo–P), aluminium bound (Al–P), iron bound (Fe–P), calcium bound (Ca–P), and organic bound phosphorus (O–P) along with ecological risk assessment of sediment cores from Chilika Lake, east-coast of India. The percentage contribution of the different fractions to the sedimentary phosphorus in the sediment column of the whole lake are on the order: O–P (33.2%) > Ca–P (20.3%) > Fe–P (18%) > Al–P (6.7%) > Lo–P (0.35%). The Phosphorus Pollution Index (PPI) revealed the contamination of lake sediment with phosphorus. The principal component and cluster analyses highlighted the anthropogenic contribution of phosphorus. The negative loading of Ca–P with Ca points towards its origin from marine shells. The discriminate analysis showed that the variables like Ca–P, bio-available phosphorus (BAP), and pH were able to effectively discriminate the sectors in a significant manner.