A study on seasonal changes of phosphorus fractions in marine sediments of the Akyaka Beach in Gökova Bay, Turkey

The purpose of this study was to determine the changes of phosphorus fractions in marine water and sediments of the Akyaka Beach in Gökova Bay, Turkey. The values of the loosely bound phosphorus fraction, iron-bound phosphorus fraction (Fe–P), bound aluminium phosphorus fraction (Al–P), calcium-bound phosphorus fraction (Ca–P), and non-sequentially extracted phosphorus fractions (inorganic and organic phosphorus) were determined for the period of April 2007 to May 2008. Among the forms of phosphorus, phosphorus distribution ranges were 77% for inorganic phosphorus fraction, 21% for organic phosphorus fraction, 10% for loosely bound phosphorus fraction, 41% for Ca-bound P, 4% for Al-bound P, and 4% for Fe-bound P. The release values of inorganic phosphorus in the sediment samples ranged from 271 ± 0.03 to 1,156 ± 2.94 ppm. Inorganic phosphorus value was the highest in January and the lowest in November. Average value for the organic phosphorus in the beach was found to be 184.33 ppm, maximum value was observed in May as 315 ± 0.44 ppm, and minimum value was observed in March as 78 ± 0.01 ppm. Mean value for the loosely bound phosphorus fraction in the beach was found to be 115.5 ppm in the sediment samples. The mean values for the sequentially extracted phosphorus fractions in Akyaka Beach were standard error of the mean (SEM), 96 ± 0.04 ppm of iron-bound phosphorus fraction, SEM, 115 ± 0.01 ppm aluminium-bound phosphorus fraction, and 267 ± 0.02 to 869 ± 1.55 ppm calcium-bound phosphorus fraction. Consequently, the beach sediments are both phosphorus traps and phosphorus sources. Here, the important point is that external loading can be limited to maintain the present nutrition level of the beach. Even if the phosphorus from external resources is limited, phosphorus based on internal sources is observed to penetrate into liquid environment.