A three-year time-series of dust deposition flux measurements in Gran Canaria, Spain: a comparison of wet and dry surface deposition samplers

Abstract

A three-year dataset of particle deposition flux measurements in Gran Canaria, Canary Islands, is presented. As part of this work, a comparison between wet and dry surrogate surfaces to estimate dry deposition fluxes was carried out over a period of more than two years in order to compare the particle collection efficiency of both devices. The selected recipients were buckets placed in two commercial samplers (ARS 1000, MTX Italy) equipped with a rain sensor; one of which was modified to maintain a constant volume of water during the collection time. No relationship was found between dry deposition fluxes and meteorological conditions (such as wind speed), the volume of the deposition container, or the number of days sampled. Dry deposition measurements made using a wet plate were 94% (±7%) of the corresponding measurements made by dry plate, and therefore are no better for the collection of particles. While both systems showed consistent results, with no significant differences in the estimation of total flux, the use of wet plates increased the uncertainty in the measurements and the complexity of the sampling method. During 2009-2012, wet and dry deposition fluxes showed a marked seasonality with a maximum in spring. Dry deposition dominated the particle fluxes (more than 93% of the total flux) and a value of 25.0 ± 0.3 mg m-2 d-1 was measured. Estimated dry deposition velocity was 0.85 ± 0.38 cm s-1, in good agreement with previously reported values.