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Phosphorus(P) fractions and their bioavailability in the sediments from El Mex Bay and Lake Mariut in Egypt were investigated using different chemical extraction methods. Sodium bicarbonate(NaHC03)extractable P(Olsen-P) was the largest fraction(14.42%), followed by algal available P(AAP)(3.56%),water soluble P(WSP)(0.79%), and readily desorbable P(RDP)(0.06%) for El Mex Bay. While AAP contributed 9.94% to total P in sediments from Lake Mariut, Olsen-P 8.53%, WSP 4.11%, and RDP 0.92%.Summation of the bioavailable P fractions didn’t exceed the sediment quality guidelines, and, therefore, P doesn’t represent a danger to marine organisms. Correlation coefficients showed that no apparent relations between total P(TP) and iron(Fe), aluminum(Al), and calcium(Ca) in the sediments. Furthermore, Fe:P ratio was less than 15 indicting that there was not enough Fe in surface sediments to bind to P at most of the sampling sites. The positive correlation between TP and organic matter(OM) for Lake Mariut and El Mex Bay sediments indicated that the organic matter content of the sediment was a useful predictor of the total phosphorus content. Data from this study constitute a baseline of phosphorus bioavailability in sediments from El Mex Bay and Lake Mariut and could be used as a reference for future studies on the changes of bioavailable and residual phosphorus fractions over time.
Sodium bicarbonate (NaHCO 3) extractable P (Olsen-P) was the largest fraction (14.42%), followed by while AAP contributed 9.94% to total P in sediments from (RAP) (0.06%) for El Mex Bay by algal available P (AAP) (3.56%), water soluble P Lake Mariut, Olsen-P 8.53%, WSP 4.11%, and RDP 0.92% .Summation of the bioavailable P fractions did not exceed the sediment quality guidelines, and, therefore, P does not represent a danger to marine organisms. Correlation coefficients showed that no apparent relations between between P (TP) and iron (Fe), aluminum (Al), and calcium (Ca) in the sediments. Fe: P ratio was less than 15 indicting that there was not enough Fe in surface sediments to bind to P at most of the sampling sites. The positive correlation between TP and organic matter (OM) for Lake Mar iut and El Mex Bay sediments indicated that the organic matter content of the sediment was a useful predictor of total phosphorus content. Data from this study constitute a baseline of phosphorus bioavailability in sediments from El Mex Bay and Lake Mariut and could be used as a reference for future studies on the changes of bioavailable and residual phosphorus fractions over time.