Phosphorus Geochemical Fractioning in Water and Sediment from Corrente River, Catchment, Parnaíba/PI [Fracionamento Geoquímico do Fósforo em água e Sedimentos do Rio Corrente, Bacia hidrográfica do Parnaíba/PI]

Phosphorus (P) is an essential element for all forms of life, among the various naturally occurring P species, orthophosphate (PO43-) corresponds to the more available species to autotrophs. Excess P concentrations from anthopogenic sources may trigger eutrophication in lakes, ponds, streams and headwaters of estuarine systems. In this study, different P fractions in water and in surface sediments were determined in samples collected in the Current River watershed Parnaíba/PI, in order to access the potential of sediments to contribute to P concentrations in the water column and its export downstream. In water, we measured total P (TPW), total dissolved P (TDP), particulate P (PP), dissolved inorganic P (DIP) and dissolved organic P (DOP), whereas in sediments we determined total P (TP), total inorganic P (TIP) and organic P (TOP). Particulate P is the dominant fraction in river transport, corresponding to an average of 78% of TPw, whereas in sediment the organic P fraction predominates, accounting for 53% of the total P contentin this compartment.