DEstiNi · Investigation of the Dynamic Estuarine and Marine cycling of Nickel

Investigation of the Dynamic Estuarine and Marine cycling of Nickel

This project addresses a long-standing problem with the marine mass- and isotopic budgets of the trace metal nickel (Ni). At present, there is an enormous imbalance between the known sources and sinks of Ni to and from the ocean. The biological, chemical and physical processes that exert a fundamental control on seawater Ni supply, cycling and removal, must be constrained before Ni isotopes in geological archives can be studied in any meaningful way in terms of tracing past shifts in Earth surface or deep processes. This project focusses on a potential ‘missing source’ of Ni to the ocean – the release of Ni from the surface of riverine sediments as it desorbs during estuarine cycling, and the potential sinks of Ni during formation of Fe-oxides in marine sediments. The principle aim of this project is to amend the global mass- and isotopic budgets of Ni in the ocean. This will be achieved by answering the following key questions: I. Does solute-particle interaction and desorption of Ni from particle surfaces in estuarine environments account for the missing flux of Ni to the ocean? II. What is the isotopic composition of the desorbed Ni pool and what are the effects on the oceanic Ni isotopic budget? III. How do sediment redox conditions affect the Ni isotopic composition of the dissolved marine pool? The results of the project greatly modifies trace metal concentrations from the Hooghly estuary, and subsequent flux to the ocean. The results of the project show that continental riverine fluxes are in fact amended by desorption of metals from suspended sediment particles as they reach the salinity gradient within the estuary. However, the new robust analytical techniques developed during the project reveal that the fluxes from this desorption process may be considerably smaller than previous publications suggest, as previously published data often report grossly inflated metal concentrations due to measurement of isobaric interferences in the salinity gradient. The results of the project are important in order to understand biogeochemical cycling of Ni and other trace metals. Ni isotopes are increasingly used as a biogeochemical tracer, but before they can be used to trace past shifts in environmental conditions, or the existence of ancient or extraterrestrial life, the fundamental knowledge of Ni cycling in the present day needs to be better understood.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз