African Dust Over Northeastern Spain: Mineralogy and Source Regions

The dust contained in red rains (rainwater with a reddish silty content) has been collected at La Castanya Biological Station in the Montseny mountains (NE Spain) over 11-years. Dust deposition was highly variable from year to year. In fact, two events accounted together for 63% of the total deposition of dust in the 11-yr record. The mean dust deposition was 5.1 g m−2 yr−1. Red rain events were associated with two main meteorological synoptic situations determining the air-mass trajectories to come from Morocco-Algeria and Tunisia-Libya. Dust of Libya-Tunisian provenance was richer in smectite and kaolinite, and poorer in quartz than dust from Morocco-Algeria. Palygorskite, an African tracer, was present in all dust samples, while chlorite, indication of local peninsular sources, was absent in all samples.