© The Author(s), 2016. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Earth-Science Reviews 163 (2016): 323-348, doi:10.1016/j.earscirev.2016.10.013.
Life requires a wide variety of bioessential trace elements to act as structural components
and reactive centers in metalloenzymes. These requirements differ between organisms
and have evolved over geological time, likely guided in some part by environmental
conditions. Until recently, most of what was understood regarding trace element
concentrations in the Precambrian oceans was inferred by extrapolation, geochemical
modeling, and/or genomic studies. However, in the past decade, the increasing
availability of trace element and isotopic data for sedimentary rocks of all ages have
yielded new, and potentially more direct, insights into secular changes in seawater
composition – and ultimately the evolution of the marine biosphere. Compiled records of
many bioessential trace elements (including Ni, Mo, P, Zn, Co, Cr, Se, and I) provide
new insight into how trace element abundance in Earth’s ancient oceans may have been
linked to biological evolution. Several of these trace elements display redox-sensitive
behavior, while others are redox-sensitive but not bioessential (e.g., Cr, U). Their
temporal trends in sedimentary archives provide useful constraints on changes in
atmosphere-ocean redox conditions that are linked to biological evolution, for example,
the activity of oxygen-producing, photosynthetic cyanobacteria. In this review, we
summarize available Precambrian trace element proxy data, and discuss how temporal
trends in the seawater concentrations of specific trace elements may be linked to the
evolution of both simple and complex life. We also examine several biologically relevant
and/or redox-sensitive trace elements that have yet to be fully examined in the
sedimentary rock record (e.g., Cu, Cd, W) and suggest several directions for future
LJR gratefully acknowledges the support of a Vanier Canada Graduate Scholarship.
Discovery Grants from the Natural Sciences and Engineering Research Council of
Canada (NSERC) to CAP, BK, DSA, SAC, and KOK supported this work. This material
is based upon work supported by the National Aeronautics and Space Administration
through the NASA Astrobiology Institute under Cooperative Agreement No.
NNA15BB03A issued through the Science Mission Directorate. NJP receives support
from the Alternative Earths NASA Astrobiology Institute. Funding from the NASA
Astrobiology Institute, and the NSF FESD and ELT programs to TWL, and the Region of
Brittany and LabexMER funding to SVL are also gratefully acknowledged. AB thanks
the Society of Independent Thinkers.
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