Occurrence and characterization of CaCO3-P coprecipitation on the leaf surface of Potamogeton crispus in water.

In this paper, the characterization of CaCO3-P coprecipitation on the leaf surface of Potamogeton crispus at various temperatures in pot experiments was investigated. White precipitates occurred on the leaf surfaces during the P. crispus growth period, and the chemical analysis demonstrates that the white precipitates contain Ca and P. The primary constituent of the white precipitates on the leaf of P. crispus was octacalcium phosphate (OCP) and hydroxyapatite. XRD characterization showed that the precipitates mostly consisted of crystals formed by calcium carbonate and hydroxyapatite, and the high calcium/phosphorus ratio indicated that the white coprecipitates were CaCO3-P. The scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDX) results confirmed that the precipitates on the surface of P. crispus leaves were carbonate-containing hydroxylapatite. In addition, no significant differences was observed in the structure of CaCO3-P coprecipitation between room temperature and consistent temperature treatments, which means that a little change in the temperature cannot change the process of Ca-P coprecipitation. Finally, coprecipitation of CaCO3-P on the leaf surface of P. crispus was proposed based on the morphology and structure analysis of CaCO3-P coprecipitation.