\documentclass[10pt]{article}

\usepackage{fullpage}
\usepackage{setspace}
\usepackage{parskip}
\usepackage{titlesec}
\usepackage[section]{placeins}
\usepackage{xcolor}
\usepackage{breakcites}
\usepackage{lineno}
\usepackage{hyphenat}





\PassOptionsToPackage{hyphens}{url}
\usepackage[colorlinks = true,
            linkcolor = blue,
            urlcolor  = blue,
            citecolor = blue,
            anchorcolor = blue]{hyperref}
\usepackage{etoolbox}
\makeatletter
\patchcmd\@combinedblfloats{\box\@outputbox}{\unvbox\@outputbox}{}{%
  \errmessage{\noexpand\@combinedblfloats could not be patched}%
}%
\makeatother


\usepackage{natbib}




\renewenvironment{abstract}
  {{\bfseries\noindent{\abstractname}\par\nobreak}\footnotesize}
  {\bigskip}

\titlespacing{\section}{0pt}{*3}{*1}
\titlespacing{\subsection}{0pt}{*2}{*0.5}
\titlespacing{\subsubsection}{0pt}{*1.5}{0pt}


\usepackage{authblk}


\usepackage{graphicx}
\usepackage[space]{grffile}
\usepackage{latexsym}
\usepackage{textcomp}
\usepackage{longtable}
\usepackage{tabulary}
\usepackage{booktabs,array,multirow}
\usepackage{amsfonts,amsmath,amssymb}
\providecommand\citet{\cite}
\providecommand\citep{\cite}
\providecommand\citealt{\cite}
% You can conditionalize code for latexml or normal latex using this.
\newif\iflatexml\latexmlfalse
\providecommand{\tightlist}{\setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}%

\AtBeginDocument{\DeclareGraphicsExtensions{.pdf,.PDF,.eps,.EPS,.png,.PNG,.tif,.TIF,.jpg,.JPG,.jpeg,.JPEG}}

\usepackage[utf8]{inputenc}
\usepackage[ngerman,english]{babel}



\usepackage{float}








\begin{document}

\title{Calcium Carbonate Tubular Structures from Soda Lake Water: Growth
Process, Characterization, and Implications to Prebiotic Chemistry and
Origin of Life}



\author[1]{Melese Getenet}%
\author[1]{Juan Manuel García-Ruiz}%
\affil[1]{Laboratorio de Estudios Cristalográficos, Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR)}%


\vspace{-1em}



  
  \date{May 24, 2024}


\begingroup
\let\center\flushleft
\let\endcenter\endflushleft
\maketitle
\endgroup





\selectlanguage{english}
\begin{abstract}
Chemical gardens are self-assembled tubular structures formed via
abiotic precipitation upon the interaction of metal-ion salts with
aqueous solutions of anionic species such as silicate, carbonate, or
phosphate. These tubular structures have been suggested to be relevant
for the early Earth and Earth-like planets and moons where alkaline
silica and carbonate rich soda oceans are thought to be widespread.
Carbonate and silica gardens are believed to be forming under the
geochemical conditions of these soda oceans. Silica gardens are
self-compartmentalized compositionally distinct bilayered mineral
membranes. These membranes are small batteries that selectively catalyze
the synthesis of prebiotically relevant organic compounds such as
carboxylic acids, amino acids, and nucleobases by condensation of
formamide. Recently, we have grown chemical gardens and mineral vesicles
by immersing different metal salts in soda lake water and inferred that
mineral self-organization could be a plausible scenario on soda oceans
of early Earth and extraterrestrial planets and moons such as Enceladus.
In this work, we have performed in-situ monitoring of the chemical
gradient, pH and electrochemical potential differences across
macroscopic calcium carbonate tubular structures grown by immersing
calcium chloride salt pellets in carbonate-rich soda lake water (Lake
Magadi, Southern Kenyan Rift Valley). To understand the temporal
evolution of the growth process, we have performed ex-situ X-ray
diffraction, Raman and infrared spectroscopy, and scanning electron
microscopy of the tubular structures isolated after different periods of
growth. We have also compared our results with calcium carbonate and
silica gardens grown in model laboratory solutions. The walls of calcium
carbonate tubular structures are composed of bilayers of texturally
different but mineralogically similar crystalline calcite. We have
observed that pH gradients across these ``natural'' calcium carbonate
tubes are comparable to that of silica gardens and higher than that of
synthetic carbonate gardens. We have discussed the implications of the
texture, ionic gradient, pH and electrochemical potential differences
across the tubes to material sciences, prebiotic chemistry, and origin
of life.%
\end{abstract}%



\sloppy




\selectlanguage{english}
\FloatBarrier
\end{document}

