The kinetics of hydroxiapatite transformation in the interaction with seawa
ter was studied. Decrease of seawater pH concentrations of dissolved fluori
de and carbonate alkalinity takes place for a certain lime interval, which
confirms transition of hydroxiapatite to fluorinehydroxiapatite. Five weeks
later after the beginning of the experiments the seawater composition appr
oached the equilibrium. It was determined that the equilibrium concentratio
n of dissolved phosphorus reduces with the increase of fluoride concentrati
on and increases with elevation of carbonate alkalinity. It was shown that
seawater containing 2-3 x 10(-6) mol P/l was not saturated with respect to
fluorincarbonateapatite which confirms that direct chemogenic formation of
calcium phosphate from seawater is impossible.