An automatic collector to monitor insoluble atmospheric deposition: application for mineral dust deposition

Abstract

Abstract. Deposition is one of the key terms of the mineral dust cycle. However, dust deposition remains poorly constrained in transport models simulating the atmospheric dust cycle. This is mainly due to the limited number of relevant deposition measurements. This paper aims to present an automatic collector (CARAGA), specially developed to sample the total (dry and wet) atmospheric deposition of insoluble dust in remote areas. The autonomy of the CARAGA can range from 25 days to almost 1 year depending on the programmed sampling frequency (from 1 day to 2 weeks respectively). This collector is used to sample atmospheric deposition of Saharan dust on the Frioul islands in the Gulf of Lions in the Western Mediterranean. To quantify the mineral dust mass in deposition samples, a weighing and ignition protocol is applied. Almost 2 years of continuous deposition measurements performed on a weekly sampling basis on Frioul Island are presented and discussed with air mass trajectories and satellite observations of dust. Insoluble mineral deposition measured on Frioul Island was 2.45 g m −2

Estimating chemical composition of atmospheric deposition fluxes from mineral insoluble particles deposition collected in the western Mediterranean region

“…Rinse water and rainwater pass through an AA Millipore ® cellulose ester filter with a 0.8 µm porosity in order to collect the insoluble fraction of the deposition. A complete description of the CARAGA collector and sampling network can be found in Laurent et al (2015) and Vincent et al (2016). After being brought back to the laboratory, collected filters were ashed following a progressive increase in temperature up to 550 • C in order to destroy and vaporize the filter and organic matters.…”

“…After being brought back to the laboratory, collected filters were ashed following a progressive increase in temperature up to 550 • C in order to destroy and vaporize the filter and organic matters. The mineral deposition mass, excluding volatile and organic matter, was estimated by weighing the ashed samples (Laurent et al, 2015), and the ashes were stored in acid-cleaned Eppendorf tubes.…”

“…Measured total mass fluxes of atmospheric deposition and the weighing and ignition protocols used to quantify the mineral deposition are presented in Laurent et al (2015) and Vincent et al (2016). In the present study, we investigate the possibility of using the CARAGA ashed samples to estimate the elemental mass deposition flux of nutrients and trace metals.…”

“…To do that, a long-term and large-scale deposition sampling network is required (Schulz et al, 2012). In order to obtain a long timeseries of deposition mass fluxes at several sampling sites, a CARAGA (Collecteur Automatique de Retombées Atmosphériques insolubles à Grande Autonomie) collector has been developed (Laurent et al, 2015) and implemented at five sites in the western Mediterranean region (Vincent et al, 2016). This collector has up to 6 months autonomy without human intervention.…”

Status and future of numerical atmospheric aerosol prediction with a focus on data requirements

“…Currently, there are very few stations measuring dust deposition, both in the vicinity of and far from source regions (e.g., Bergametti and Fôret, 2014). CARAGA (Laurent et al, 2015;Fu et al, 2017), which is a network of automatic deposition collectors installed throughout the western Mediterranean Basin, samples mass flux of atmospheric insoluble deposition weekly. This initial effort is focusing to constrain regional models of dust simulation but the potentiality of these low-cost and automatic instruments can also be used in remote and isolated regions such as the Sahara.…”