Phosphorus Accumulation Rate (PAR) in Lake Sediments around Eppawala Phosphate Deposit (EPD): A Case Study for Prospecting New Phosphorus Sources

Abstract

Currently, rock phosphate is predominantly used to produce phosphorus based mineral fertilizers for agricultural purposes. However, since rock phosphate is a finite and non-renewable resource, it leads the whole world vulnerable to a future phosphorus scarcity. Therefore, prospecting of new phosphorus sources is essential to address the phosphorus scarcity via a sustainable manner. In this regard, lake sediments around Eppawala phosphate deposit (EPD) in Sri Lanka is identified as a new area of interest. With respect to the location of EPD, there are two upstream lakes (Ihalahalmilla lake (L1) and Koon lake (L2)) and one downstream lake (Kiralogama lake (L3)) in the area which are fed by Jaya-Ganga. To access the potential of these lake sediments as a phosphorus source, core sediment samples were obtained and analyzed to determine average sedimentation rates (ASRs), mass accumulation rates (MARs) and phosphorus accumulation rates (PARs) based on P₂O₅%. The results reveal that L3 has the highest ASR (2.190 mm yr^-1), MAR (2935 g m^-2 yr^-1) and PAR (22.31 g m^-2 yr^-1) over the two upstream lakes. Therefore, it is evident that phosphate-bearing materials derived from the EPD have been continuously accumulated in the downstream lake sediment column with a high PAR. As a result, downstream lake sediments show the potential of being a secondary phosphorus source which can contributes to the phosphorus supply in local context. However, novel phosphorus extraction technique needs to be developed to get the maximum use of these lake sediments for a sustainable management of this secondary source.