Phosphate oxygen isotopes within aquatic ecosystems: global data synthesis and future research priorities

The oxygen isotope ratio of dissolved inorganic phosphate (δ18Op) represents a novel and potentially powerful
stable isotope tracer for biogeochemical research. Analysis of δ18Op may offer new insights into the relative importance
of different sources of phosphorus within natural ecosystems. Due to the isotope fractionations that
occur alongside the metabolism of phosphorus, δ18Op could also be used to better understand the intracellular
and extracellular reaction mechanisms that control phosphorus cycling. In this review focussed on aquatic ecosystems,
we examine the theoretical basis to using stable oxygen isotopes within phosphorus research.We consider
the methodological challenges involved in accurately determining δ18Op, given aquatic matrices in which
potential sources of contaminant oxygen are ubiquitous. Finally,we synthesise the existing global data regarding
δ18Op in aquatic ecosystems, concluding by identifying four key areas for future development of δ18Op research.
Through this synthesis, we seek to stimulate broader interest in the use of δ18Op to address the significant research
and management challenges that continue to surround the stewardship of phosphorus.