Saeed, HHartland, ALehto, NiklasBaalousha, MSikder, MSandwell, DMucalo, MHamilton, DP2020-05-062018-12-102018-12-102018-11-14Saeed et al. (2018). Regulation of phosphorus bioavailability by iron nanoparticles in a monomictic lake. Scientific Reports, 8, 17736. doi:10.1038/s41598-018-36103-x2045-232230531915 (pubmed)https://hdl.handle.net/10182/11834Dissolved reactive phosphorous (DRP) in lake systems is conventionally considered to predominate over other dissolved P species, however, this view neglects an important set of interactions that occurs between P and reactive iron hydroxide surfaces. This study addresses the coupling of P with dispersed iron nanoparticles in lakes, an interaction that may fundamentally alter the bioavailability of P to phytoplankton. We used diffusive gradients in thin films (DGT) and ultrafiltration to study Fe-P coupling in the water column of a monomictic lake over a hydrological year. Fe and P were predominantly colloidal (particle diameters > ~5 nm < ~20 nm) in both oxic epilimnetic and anaerobic hypolimnetic waters, but they were both DGT-labile under sub-oxic conditions, consistent with diffusion and dissolution of Fe-and-P-bearing colloids within the DGT diffusive gel. During peak stratification, increases in Fe and P bioavailability were spatially and temporally coincident with Fe nanoparticle dissolution and the formation of a deep chlorophyll maximum at 5–8 m depth. These results provide a window into the coupling and decoupling of P with mobile iron colloids, with implications for our understanding of the behaviour of nutrients and their influence on phytoplankton community dynamics.14 pagesElectronicen© The Author(s) 2018.phosphorusnitrogendissolved reactive phosphorusJournal Article10.1038/s41598-018-36103-xANZSRC::03 Chemical SciencesANZSRC::0402 GeochemistryANZSRC::0502 Environmental Science and ManagementANZSRC::060204 Freshwater EcologyANZSRC::079902 Fertilisers and Agrochemicals (incl. Application)ANZSRC::0503 Soil Sciences2045-2322https://creativecommons.org/licenses/by/4.0/Attribution