Strontium Uptake in Shell Aragonite from the Freshwater Gastropod Limnaea stagnalis

Shell aragonite from 96 specimens of the freshwater gastropod Limnaea stagnalis grown in laboratory tanks at different temperatures in water with variable strontium/calcium ratios have been analyzed for its strontium content in order to evaluate the mechanisms of strontium uptake in molluskan aragonite. Within the limits defined by natural freshwater environments, the strontium/calcium ratio in the aragonite was found to be linearly related to the strontium/calcium ratio in the water. A distribution coefficient k(A)(Sr) = 0.237 +/- 0.029, unaffected by variations in temperature and growth rate, has been found. This finding substantiates the existence of a strontium-discriminating effect in aragonite precipitated by mollusks as compared to the case for nonbiogenic aragonite which contains about five times as much strontium when precipitated under the same conditions.