Isotope tracing of ammonium in the Coorong Lagoons: From where is that nitrogen coming from?
New ways to trace nutrient sources and cycling in the Coorong lagoons.
The ongoing hydrological and geochemical changes occurring in the Coorong Lagoon represent a major environmental problem that needs attention and long-term solutions. Specifically, a progressive salinization and eutrophication of the South Lagoon waters is of concern, where an excess of nutrients, including ammonium (NH4+), is likely driven by inputs of nutrient-rich agricultural waters supplied via the southeast drainage system and/or local groundwater sources.
The aim of this project is to identify the internal bio-geochemical cycling and sources of dissolved ammonium (NH4+) species in hypersaline and eutrophic South Lagoon. To address these questions, the project will use stable N isotopes (δ15N) to test if ammonium is released into the lagoon waters from the pore waters of anoxic and nutrient-rich lagoonal sediments; or alternatively if ammonium is rather derived from atmospheric N2, which might be converted to bioavailable NH4+ via cyanobacteria and algal communities that are dominant in the South Lagoon.
This project will involve fieldwork, sampling of lagoon waters, sediment pore waters, as well as ammonia gas flux, and follow up N isotope analyses and modelling of data.
Research area: Mineral and energy systems, Tectonics and solid earth processes, Palaeoclimatology, Palaeontology and palaeoenvironments, Environmental geochemistry
Recommended honours enrolment: Honours in Geology