Jornal de Ecossistema e Ecografia

Abstrato

Observed Effects of Acidity and Basicity on Clam Shell Composition

Arjavon Talebzadeh

Air pollution has effectively increased the acidity of marine and freshwater ecosystems by yielding increased amounts of greenhouse gases like carbon dioxide or nitrogen oxide, which can react with water to form acids. Acidification of surrounding aqueous environment can effectively corrode the calcareous shells of bivalves by protonating dissociated carbonate ions (CO3 2-) to increase the solubility of the constituent calcium carbonate (CaCO3). In this study, Asian clam (Corbicula fluminea) aragonitic shells were subjected to aqueous solutions of different pH for eight days. Solubility of aragonite (CaCO3) from the shell of each environment was measured by titration, and hardness was measured before and after the shells were exposed to their respective environments. Results for this study conflicted with formulated hypotheses based on contemporary chemical models. It was hypothesized that only acidic conditions would change shell aragonite solubility by protonating carbonate ions to increase solubility, but the collected data suggest that the solubility only changed (decreased) in basic conditions.