Fluoride content in three seagrasses of the Antikyra Gulf (Greece) in the vicinity of an aluminum factory

The local and seasonal variation of the fluoride content in the seagrasses Halophila stipulacea, Cymodocea nodosa and Posidonia oceanica, in seawater and sediment of the Antikyra Gulf (Greece) near an aluminum factory are determined. Fluoride concentrations decreased in the order: sediment >C. nodosa > above parts of H. stipulacea (leaves) > below parts of H. stipulacea (stem, root, rhizoids) >P. oceanica > seawater. The above and below parts of H. stipulacea accumulated a similar (P > 0.05) concentration of fluoride. Only fluoride in C. nodosa presented a positive (P < 0.01) correlation with seawater. Significant seasonal variation was exhibited only in F− concentrations of C. nodosa (P < 0.01) and in the seawater (P < 0.001) which were similar and increased from winter to summer and autumn. Variation on C. nodosa was influenced by that in the seawater. Moreover, it seems that the new individuals, which appeared in autumn-winter accumulated higher F− concentrations than the older ones. Only the F− content in the sediment was significantly (P < 0.05) different between the six stations. The FCl ratio in the seawater of the study area varied between 0.90 × 10−6 and 6.14 × 10−6.