Environmental effects and potential impact on human health caused by the recent Nyiragongo eruption (Democratic Republic of Congo)

Volcanic activity emits large amounts of gases and particles to the atmosphere subsequently spreading contaminants to rain, surface waters and soils, negatively impacting on the environment and the human health. The recent eruption of Nyiragongo occurred on 22nd of May, injected large quantities of ash affecting the environment of the Virunga area, and more than 2 million people living between 18-25 km far from the main crater of Nyiragongo. Several studies demonstrated that drinking waters and plants may contain high contents of natural pollutants, and when ingested they become harmful to human health causing acute or chronic diseases. In this study, we investigated the impact of the recent eruption on Virunga area through a multidisciplinary approach, analysing the chemical composition of drinking waters, soils, volcanic ash and edible plants. Samples were collected in several sites few days after the last eruption of Nyiragongo. All samples were analysed by ionic chromatography and inductively coupled mass and atomic emission spectrometry for a large suite of major and trace elements. In general, the collected samples show significant enrichments of fluoride, sulfate and chloride, along with many trace elements such as Al, As, Cd, Cr, Cu, Fe, Mo, Pb, Sb, Se, Pb, Te, Tl and V. These elements are mostly linked to the volcanic activity, carried by the atmospheric depositions which were directly affected by volcanic emissions (gases, particulates and ashes). Especially, fluorine and some toxic metals may be harmful to the end users/local people. Some elements exceed concentration limits in drinking water (World Health Organisation), including fluoride, aluminium, copper and thallium, making the already scarce water resources (water traditional drainage or tanks collecting runoff from roofs) unsuitable for human consumption.