Provenance fingerprints of atmospheric dust collected at Granada city (Southern Iberian Peninsula). Evidence from quartz grains

Abstract

Dust in the Earth́s atmosphere is increasing, particularly in southern Spain. The study of dust properties allows for a hypothesis on the origin and provenance of dust. This study characterised atmospheric dust deposited in the city of Granada (south of Spain) during three spring periods (samples 4PA, 16PA, and 28PA, collected in 2012, 2013, and 2014, respectively). The aim was to ascertain dust characteristics and genesis using a set of methodological techniques. The backward trajectories study separated the samples into two groups: scarce Saharan influence (sample 16PA, 6% of backward trajectories are from, or have passed through, Africa) and greater influence (samples 4PA and 28PA, 26% and 33%, respectively). This grouping was verified by the rest of the properties analysed, namely, PM10 concentration, deposition rates, grain size, mineralogy, and elemental composition (minor, including rare earth elements). In addition, mineral quartz showed differences in particle morphology and surface microtextures. The mineralogical and geochemical studies of our samples have proved similarities with other dust collected in Granada and soils from the Iberian Peninsula. The principal component analysis of the quartz shape parameters insists on the differentiation of these groups. We propose the morphoscopy of quartz grains (a significant component of atmospheric dust) as a fingerprint of provenance.