Diverse arsenic-containing lipids in the surface ocean

Arsenic is present at nanomolar levels throughout the ocean, and microbes
assimilate this potentially toxic element due to its similarity to
inorganic phosphorus. Although dissolved arsenic has been a focus of
several oceanographic studies, the size and chemical character of the
particulate arsenic pool is poorly understood. We measured particulate
arsenic in five samples from the open ocean and determined the
contribution of arsenic-containing lipids to this pool. Here we show that
the accumulation of arsenic into lipids is a widespread phenomenon in the
surface ocean. Particulate arsenic concentrations were 15 to 42 pmol L−1
with 7–20% of the particulate arsenic pool within arsenolipids. We found
that arsenosugar phospholipids dominated the arsenolipid pools in our
samples with a minor component of arsenohydrocarbons and other
unidentified lipids. A significant portion of the arsenosugar
phospholipids (up to 35%) were present as previously undescribed mixed
acyl ether lipids, suggesting a bacterial source.