Characterization of the sediment
Before starting any experiment all sediment samples was air-dried at room temperature and ground with pestle and mortar to put sediment through stainless steel 10 mesh sieve. The sediments physical composition including clay and silt contents were determined by hydrometer method and then sand and very find sand (Vfs) were weighed after washing over sieve and 110 C oven drying. Organic matter (OM) content was determined with the classical Walkley-Balck procedure (Rowell, 1994). The activity of H3O+, pH = [-log (H+)] and conductivity (EC) were measured in a sediment-solution ratio of 1:5. The acid-base titration method was used for determination of calcium carbonate equivalents (CCE) (Rowell, 1994). The activity of calcium carbonate (ACCE) was measured in ground uniform sediment particles with ammonium oxalate method (Loeppert and Suarez, 1996).
Sediments were extracted using several single extraction methods that are summarized in Table 1. Olsen-P and Colwell-P extraction method have been designed for calcareous soils. Mehlich III-P and Bary II-P have been designed for acidic soil, and both contain HCl acid and ammonium fluoride for dissolution of Fe/Al-P minerals such as Strengite, (FePO4·2H2O) and Variscite, (AlPO4·2H2O). AB-DTPA extraction method is chelating agent for Fe, Al, Ca, and Mg and has been shown to be a good extraction method for acidic and calcareous soils. Morgan-P was designed for soil with a high association of Ca-P pools and usually dissolve soluble calcium phosphate (Ahmad and Jones, 1967). 0.1 M NaOH is for soil and sediment with high Fe/Al-P pools. Chemical analysis of P was done colorimetrically (Murphy and Riley, 1962).