Aerosol dissolution at high ionic strength and low pH

Aerosols provide a key mechanism of nutrient delivery to the open ocean, which is an important component of global carbon and biogeochemical cycling. The bioavailability of nutrients is related to their solubility. Aerosols go through atmospheric ageing, where the interactions within clouds and as wet aerosols with deliquescent layers can influence solubility and speciation. Variations in pH, ionic strength, particle mineralogy and size are among many variables that impact this solubility. In the deliquescent layer surrounding an aerosol, electrolyte solutions are highly concentrated in the high dust/liquid ratio environment. pH may be as low as -2 due to dissolved acids of natural and anthropogenic origin.

The aim of the project is to improve constraints on the dissolution of nutrients and toxins such as iron, copper and phosphates, under different pH and ionic strength conditions, by determining total dissolution and rate constants of dissolution. The work will help us to understand better the anthropogenic impact on nutrient cycling and fertilisation through changing acidity and aerosol composition. A series of systematic experiments will be conducted to determine the total dissolution and initial rate of natural and anthropogenic dusts under relevant environmental conditions of radiation and temperature. The dissolution experiments and data analysis of concentration-time curves will be used for the development of rate equations for the process. Once the rates and rate equations have been determined, concentrations on nutrients in solution can be calculated based on different modelled conditions.