Development of a Gas Sampling Technique for Determining Trace Elements in Submarine Volcanic Exhalations

Panarea is a submarine volcanic caldera between the active volcanoes Stromboli and Vulcano, Aeolian Islands, Italy. Many locations within the caldera at a water depth between 10 and 30 m are characterized by emissions of hot water (partly boiling) and gases (fumaroles). The fumaroleś gas consists mainly of CO2 (96 to 99.5%) with H2S being the second most abundant component. To investigate trace gases and in particular aerosols, volatile metals, and metalloids like arsenic a technique was used which allows sampling tens and even hundreds of litres of gas. The sampling system is rather simple: a stainless steel funnel, a 100 m long PE hose with an inner diameter of 4 mm and a gas bag (10 to 80 litres). After sampling, the gas is pumped into a PTFE washing bottle containing NaOCl in supra pure water which is effectively oxidizing organic compounds like methylated metals, other reduced species, and aerosols. Determination of trace elements by ICP-MS follows. First results show a huge variety of elements present in the submarine volcanic gases and aerosols of submarine gas emissions at Panarea.