\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[greek,english]{babel}



\usepackage{float}








\begin{document}

\title{Biosynthetic isotope fractionation negligibly impacts biomarker 14C ages}



\author[1]{Jordon Hemingway}%
\affil[1]{Harvard University}%


\vspace{-1em}



  
  \date{May 16, 2024}


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





\selectlanguage{english}
\begin{abstract}
Radiocarbon (14C) ages of acetogenic lipid biomarkers such as n-alkanes
are a powerful tool to track carbon-cycle turnover times. In sediments,
biomarker ages are almost always older than the depositional age due to
reservoir effects. Recently, Lane et al. {[}2021, Anomalously low
radiocarbon content of modern n-alkanes, Organic Geochemistry 152,
104170{]} reported 14C ages up to [?]1500 yr for n-alkanes extracted from
leaf tissue of living plants; they attributed this apparent
``pre-aging'' to biosynthetic fractionation against 14C. However,
reported 14C ages are always corrected for mass-dependent fractionation
using a 14C/13C mass law, b, of 2.0. Lane et al.'s interpretation
therefore requires that lipid biosynthesis follows large, anomalous
deviations from mass-dependent fractionation, with b reaching values as
high as [?] 124. Here, I test this assumption by estimating kinetic and
equilibrium mass laws for various processes involved in acetogenic lipid
biosynthesis using simple approximations and more robust computational
chemistry methods. I find that kinetic b values range from 1.880 to
1.995 and that equilibrium b values for several chain elongation steps
range from 1.856 to 1.880, consistent with previous results for other
chemical and biological processes. In contrast, complex reaction
networks may lead to large expressed b values, but only when net ln(13\selectlanguage{greek}α\selectlanguage{english})
- 0. Combined, these results imply maximum 14C age offsets due to
biosynthetic fractionation of ~ 20 to 40 yr. Biomarker 14C ages are
therefore robust to biosynthetic isotope fractionation and can be
confidently interpreted to reflect carbon-cycle turnover times.%
\end{abstract}%



\sloppy




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

