Phosphorus Fractionation in The Sediment of Kendari Bay, Southeast Sulawesi, Indonesia

Information about the chemical structure of the phosphorus (P) fraction in sediments is very important for identifying the bioavailability of P and eutrophication in marine ecosystems. Sediment as a source of P has an important function in P adsorption in waters. To estimate the phosphorus load in water bodies, it is required to define the fraction of phosphorus compounds. This study purposed to evaluate the composition of phosphorus speciation in sediments of Kendari Bay and evaluate their possible contributions to the eutrophication of the coastal ecosystem. P fractionation was examined by chemical extraction and sequencing methods. Sediment characterization was conducted by gravimetry, hydrometry, and spectrophotometry methods. The study result found the total P concentration in the sediment ranged from 0.30 to 0.41 mg/g. Phosphorus content in exchangeable P (Exc-P), Fe-P, Al-P, Ca-P, and organic P (OP) contributed 1.8%, 12.7%, 1.5%, 63.1%, and 21.5% of total P (TP), respectively. We found significant positive correlations between Exc-P, FeP, Al-P, and OP and finer sediment and organic matter. Exc-P and OP are bioavailability (BAP) fractions that potentially release overlying water, contributing 10–35% to TP.