title: Colloidal stability of nanoparticles derived from simulated cloud-processed mineral dusts.
abstract: Laboratory simulation of cloud processing of three model dust types with distinct Fe-content (Moroccan dust, Libyan dust and Etna ash) and reference goethite and ferrihydrite were conducted in order to gain a better understanding of natural nanomaterial inputs and their environmental fate and bioavailability. The resulting nanoparticles (NPs) were characterised for Fe dissolution kinetics, aggregation/size distribution, micromorphology and colloidal stability of particle suspensions using a multi-method approach. We demonstrated that the: (i) acid-leachable Fe concentration was highest in volcanic ash (1 m Mg(-1) dust) and was followed by Libyan and Moroccan dust with an order of magnitude lower levels; (ii) acid leached Fe concentration in the<20 nm fraction was similar in samples processed in the dark with those under artificial sunlight, but average hydrodynamic diameter of NPs after cloud-processing (pH~6) was larger in the former; iii) NPs formed at pH~6 were smaller and less poly-disperse than those at low pH, whilst unaltered zeta potentials indicated colloidal instability; iv) relative Fe percentage in the finer particles derived from cloud processing does not reflect Fe content of unprocessed dusts (e.g. volcanic ash>Libyan dust). The common occurrence of Fe-rich "natural nanoparticles" in atmospheric dust derived materials may indicate their more ubiquitous presence in the marine environment than previously thought.
authors: Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth PL1 3DH, UK. Electronic address: enik@pml.ac.uk.
authors: Enikö
authors: E
authors: Kadar
authors: Andrew
authors: A
authors: Fisher
authors: Björn
authors: B
authors: Stolpe
authors: Sergio
authors: S
authors: Calabrese
authors: Jamie
authors: J
authors: Lead
authors: Eugenia
authors: E
authors: Valsami-Jones
authors: Zongbo
authors: Z
authors: Shi
keywords: Atmospheric deposition; Dissolution; Ferrihydrite; Nanoparticle