Africa dust tainted S Europe soil red‎

Spanish and American researchers have found that the mineral dust of African regions has created the reddish soil of the Mediterranean region.

Chemical and mineralogical analyses showed that mineral dust from Africa’s Sahara and Sahel regions, which emit between 600 and 700 tones of dust per year, led to the formation of the red soil between 12,000 and 25,000 years ago.

Terra rossa (red soil in Italian) is located on carbonate rock and is spread throughout the Iberian Peninsula, the South of France, the Mediterranean islands, Italy and along the coast of the Adriatic Sea, from Slovenia to Greece.

“The first hint of the relationship between African dust and certain soils in the region of the Mediterranean is their reddish or reddish-brown color, similar to that of African aerosol filters, caused by their clay content,” ScienceDaily quoted Anna Avila, co-author of the study and a researcher at the Center for Ecological Research and Forestry Applications (CREAF) at the Universidad Autonoma de Barcelona, as saying.

According to the study published in Quaternary Science Reviews, African mineral dust additions “play an important role” in the origin of the Mediterranean soils, namely on the island of Majorca.

“African dust explains the origin of the ‘terra rossa’ soils in the Mediterranean region located on top of mother carbonate rock,” Avila added.

Researchers considered three different theories about the source of the red soil, from which the hypothesis of non-native contribution seemed more rational and “was reinforced due to the geochemical value of the land coinciding with that of African dust.”

The study also suggests that although African dust is the main contributor to the formation of the soil, “the underlying rock also contributes, probably with residual quartz.”