Concentration of Po and Pb in macroalgae from the northern Gulf.

This baseline study highlights the Po and Pb concentration in seven macroalgae species from the northern Gulf that are frequently washed ashore during the bloom season from February to April. The highest concentrations of Po and Pb were 2.947 ± 0.032 and 1.057 ± 0.145 Bq kg wwt, respectively, in brown algae Sargassum boveanum, and the lowest in green algae Ulva prolifera with 1.533 ± 0.058 and 0.170 ± 0.069 Bq kg wwt, respectively. A Po enrichment was observed in both brown and green algae species, with the Po/Pb ratio being >1 for all the samples. The mean concentration of Po in all species was an order of magnitude higher than Pb, and the difference in mean concentration is statistically significant (p < 0.001). At the same time, the mean concentration of dissolved Po and Pb in seawater was 0.28 ± 0.01 and 0.52 ± 0.01Bq m with a Po/Pb ratio of 0.54 ± 0.02 indicating that Po was absorbed from water and more concentrated by macroalgae. The measured concentration factor (CF) for Po in these macroalgae for the northern Gulf varied between 5 × 10-1 × 10, higher than the IAEA recommended value of 1 × 10 which suggests that a revision of that value may be needed. The field derived CFs for Pb vary between 3 × 10-1.8 × 10, comparable to the ICRP recommended value of 2 × 10.