Any proposed model of Earth's primitive environments requires a combination of geochemical variables. Many experiments are prepared in aqueous solutions and in the presence of minerals. However, most sorption experiments are performed in distilled water, and just a few in seawater analogues, mostly inconsistent with a representative primitive ocean model. Therefore, it is necessary to perform experiments that consider the composition and concentration of dissolved salts in the early ocean to understand how these variables could have affected the absorption of organic molecules into minerals. In this work, the adsorption of adenine, adenosine, and 5'AMP onto Na+montmorillonite was studied using a primitive ocean analog (4.0 Ga) from experimental and computational approaches. The order of sorption of the molecules was: 5'AMP > adenine > adenosine. Infrared spectra showed that the interaction between these molecules and montmorillonite occurs through the NH2 group. In addition, electrostatic interaction between negatively charged montmorillonite and positively charge N1 of these molecules could occur. Results indicate that dissolved salts affect the sorption in all cases; the size and structure of each organic molecule influence the amount sorbed. Specifically, the X-ray diffraction patterns show that dissolved salts occupy the interlayer space in Na-montmorillonite and compete with organic molecules for available sites. The adsorption capacity is clearly affected by dissolved salts in thermodynamic terms as deduced by isotherm models. Indeed, molecular dynamic models suggest that salts are absorbed in the interlamellar space and can interact with oxygen atoms exposed in the edges of clay or in its surface, reducing the sorption of the organic molecules. This research shows that the sorption process could be affected by high concentration of salts, since ions and organic molecules may compete for available sites on inorganic surfaces. Salt concentration in primitive oceans may have strongly affected the sorption, and hence the concentration processes of organic molecules on minerals.

中文翻译：

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盐度对钠化合物在蒙脱土上吸附核酸化合物的影响：益生元化学实验。

任何提议的地球原始环境模型都需要结合地球化学变量。在水溶液中和矿物质存在下进行了许多实验。但是，大多数吸附实验是在蒸馏水中进行的，只有少数实验是在海水类似物中进行的，大多数与典型的原始海洋模型不一致。因此，有必要进行考虑早期海洋中溶解盐的成分和浓度的实验，以了解这些变量如何影响有机分子向矿物中的吸收。在这项工作中，使用来自实验和计算方法的原始海洋类似物（4.0 Ga）研究了腺嘌呤，腺苷和5'AMP在Na +蒙脱土上的吸附。分子的吸附顺序为：5'AMP> 腺嘌呤>腺苷。红外光谱表明，这些分子与蒙脱石之间的相互作用是通过NH2基团发生的。此外，这些分子的带负电的蒙脱土和带正电的N1之间可能会发生静电相互作用。结果表明，在所有情况下，溶解的盐都会影响吸附。每个有机分子的大小和结构都会影响吸附量。具体地，X射线衍射图表明溶解的盐占据了钠蒙脱石的层间空间，并且与有机分子竞争可用的位点。吸附容量明显受等温线模型推导的热力学条件下溶解盐的影响。的确，分子动力学模型表明，盐被吸收在层间空间中，并且可以与暴露在黏土边缘或其表面的氧原子相互作用，从而减少有机分子的吸收。这项研究表明，高浓度的盐可能会影响吸附过程，因为离子和有机分子可能会竞争无机表面上的可用位点。原始海洋中的盐浓度可能强烈影响了吸附，因此影响了有机分子在矿物上的浓缩过程。