Scientists in Italy have found that the surfaces of lava stones from Mount Etna, in Sicily, may be leaching manganese into the environment. Almost 1.5 million people are supplied with water from Etna's wells and these findings could help identify any health risks associated with using this water.
Antonino Gulino and colleagues, at the University of Catania, have used x-ray photoelectron spectroscopy (XPS) to characterise the surface composition of lava stones emitted from Mount Etna during activity in April 2012.
XPS involves firing x-rays at a material and measuring the electrons subsequently released from its surface layers, down to a depth of a few nanometres. XPS allowed the team to differentiate between elements in the surface and elements in the bulk, unlike bulk analysis techniques used previously.
The team found significantly lower amounts of silicon, iron, calcium and potassium, and higher amounts of aluminium, sodium and phosphorus on the surface than in the bulk. The surface manganese content was more than twice that in the bulk.
Incidence of Parkinson's disease around the volcano is well above average and doctors have been unable to rationalise these numbers. Groundwater from Etna's wells has been found to contain very high levels of some potentially toxic elements. Water samples collected in 2010 had manganese concentrations up to 2600μg/l - Italian legislation states it should be no higher than 50μg/l.
This suggests that manganese in groundwater could come from eroding lava rocks, and that the Parkinson's cases could in fact be caused by manganism - effectively manganese poisoning - which gives similar symptoms. More studies would be needed to confirm the links between manganese on the lava rocks' surfaces and in the water, and between the manganese in groundwater and Parkinson's symptoms, but the work highlights a possible source of the pollution.