多组分有机质作用下碳酸钙的矿化现象

Mineralization of calcium carbonate under the action of multi-component organic matter

采用SEM、XRD、FT-IR等手段对氨基酸、多糖以及有机酸混合体系中形成的碳酸钙晶体进行了表征,进而比较了多组分有机质作用下碳酸钙的矿化现象。结果表明,氨基酸-单糖体系(A-M)促进了碳酸钙的沉积,其钙化速率相较于对照组提高了36%;有机酸则抑制了碳酸钙的沉积,单糖-有机酸体系(M-O)、氨基酸-有机酸体系(A-O)和氨基酸-有机酸-单糖体系(A-O-M)的钙化速率分别下降了33%、29%、17%。其次,A-M体系合成的晶体以方解石为主,包含少量的球霰石,M-O、A-O和A-O-M体系则在柠檬酸的调控下合成了方解石。最后,A-M体系合成了块状晶体(粒径为10μm)及中空的环状晶体(粒径为5μm),而A-O和M-O体系合成了棒状晶体(长轴径5~15μm,短轴径3~5μm)。A-O-M体系存在含量最高的有机质,导致成核速率高于生长速率,因此合成的晶体呈粒状(粒径1~3μm)且发育不完整。研究揭示了多组分共存体系中的生物矿化现象,阐明了柠檬酸在多组分体系中对晶体成核及生长的主导调控作用,对研究黄龙高寒环境下的生物矿化机制具有重要意义。

In this study, the mineralization of calcium carbonate in the mixed system with amino acid, polysaccharide and organic acid was comparatively studied, and CaCO3 crystals were characterized by SEM, XRD and FT-IR.The results showed that the deposition of CaCO3 was promoted by A-M, and the calcification rate was increased by36% compared with the control group. The deposition of CaCO3 was inhibited by organic acids, and the calcification rate of M-O, A-O and A-O-M decreased by 33%, 29%, and 17%, respectively. In the A-M, the main crystal composition of CaCO3 was calcite, which also contained a small amount of vaterite. However, there was only calcite in M-O, A-O, A-O-M under the regulation of citric acid. The particle size of blocky calcite was 10 μm in A-M, and the vaterite was like a hollow circle with a particle size of 5 μm. Rod-shaped calcite with particle size of5 ~ 15 μm and 3 ~ 5 μm was synthesized in A-O and M-O. A-O-M contained the most abundant organic matter, so that the nucleation rate was higher than the growth rate;the particle size of granular crystal was only 1 ~ 3 μm, and most crystals were incompletely developed. The research revealed the phenomenon of biomineralization in multicomponent coexisting systems and emphasized the leading role of citric acid in regulating crystal nucleation and growth. The results obtained by the authors provide a reference for exploring the biomineralization mechanism in the subnival environment of Huanglong.