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

Abstract

In this paper, the characterization of CaCO 3 -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 CaCO 3 -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 CaCO 3 -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 CaCO 3 -P on the leaf surface of P. crispus was proposed based on the morphology and structure analysis of CaCO 3 -P coprecipitation.

Interspecific Differences in the Effects of Calcium and Phosphorus Coprecipitation Induced by Submerged Plants on the Water-to-Phosphorus Cycle

“…The same results have been proven by Chen and Wang [14]. According to Liu et al [23], the precipitates on the surface of P. crispus were carbonate-containing hydroxylapatite. The difference in the SEM images of the precipitates on the surface of the two species (Figure 5) confirmed the specific differences in calcium and phosphorus coprecipitation.…”

“…In hard-water environments, most aquatic plants can precipitate carbonates (CaCO 3 ) [10,22] and exhibit calcification. Liu et al [23] found that the precipitates on the surface of P. crispus leaves were carbonate-containing hydroxylapatite by scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDX). Furthermore, the photosynthesis-induced calcium and phosphorus coprecipitation of submerged macrophytes, showed as calcium phosphorus (HCl-P) in total ash phosphorus [10], can effectively reduce the phosphorus content in water [14,21], and there are significant interspecific differences in the HCl-P between Ceratophyllum demersum L. and P. crispus [14].…”

Avoiding and allowing apatite precipitation in oxygenic photolithotrophs

“…This has been shown for the freshwater benthic rhizophyte Chara spp. (Murphy et al ., 1983; Kiyosawa, 2001; Siong & Asada, 2006; Kufel et al ., 2013, 2015; Sand‐Jensen et al ., 2018, 2021), and also in CaCO 3 incrustation on the upper leaf surface of the submerged flowering plant Potamogeton crispus (Liu et al ., 2016). The investigation by Sand‐Jensen et al .…”