Fogo Volcano (Cape Verde) 2014-2015 Eruption: Dust Characterization and Impacts on Environment and Human Health

Abstract

Fogo (Fogo island, Cape Verde Republic) is the youngest and most active volcano of the archipelago. The last eruption occurred in 2014–2015. Aiming at studying dust emissions and transport during the eruption period and assessing their impact on air quality and human health, a mineralogical and chemical characterization was undertaken in outdoor dust from all over the island, as well as in the lava resulting from this event. Air quality monitors were used to obtain concentrations of atmospheric particulate matter (PM) and gaseous pollutants. The mineralogical constitution of the samples was analysed by X-ray diffraction and Electron Microprobe, while the chemical characterization was performed through X-ray Fluorescence Spectrometry and ICP-MS. The volcanic rock was found to be tephritic to basanitic, with high potassium content. Several minerals were identified, such as titanian augite with ilmenite, basaltic hornblendes, pyrrhotites, apatites, pyroxenes, basaltic hornblendes and hematites. Concentrations of the particulate matter inhalable fraction (PM10) exceeded the 24-hour mean of 50 µg/m3 recommended by the World Health Organization. Nevertheless, total volatile organic compounds (TVOCs) showed levels lower than the worrying range. The highest levels of CO2 were recorded in more populated villages and farthest from the volcano. The Pollution Load Index (PLI) for outdoor dust collected on rooftops was always above 1, suggesting enrichment, with higher values in the dust size fraction < 63 µm. In the same way, the Contamination Factor pointed to high enrichment of As, Ni and Pb, and very high enrichment of Cd in the same size fraction. The Non-carcinogenic Hazard Quotient and Hazard Index estimated for Children suggest that health problems may arise. The Carcinogenic Risk, for all size fractions, was above the target risk. The element that most contributed to the global risk was As, followed by Pb and Co. Ingestion was the main exposure route for all size fractions. The dust size fraction that represented the highest risk was < 63 µm, mostly due to the As concentration.