Differential dissolution of biogenic carbonates: Implications of secretion at higher pH
Abstract
A selective preferential dissolution of a few initial chambers of several specimens of calcareous planktic foraminifera Globigerinoides rubber has been noted in the surface sediments collected from the eastern Arabian Sea and northern Bay of Bengal. Based on a recent finding stating the capability of foraminifera to modulate the vacuolar seawater pH for easy secretion of calcite, it is postulated that these initial two-three chambers were formed at relatively higher pH conditions, inside the cyst during asexual reproduction. The secretion of chambers at relatively higher pH results in increased incorporation of magnesium into the calcareous test. This increased Mg carbonate probably renders the initial chambers more prone to dissolution. The findings have an implication for the application of G. ruber for paleoclimatic/paleoceanographic studies
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