Gas Geochemistry and 222Rn Migration Process (invited paper)

Deep seated fluids generate remarkable geochemical processes when forced toward the earth's surface. Intense water-gas-rock interaction reactions characterise fluid motion in the earth's crust due to changes in pressure-volume-temperature conditions. Due to their chemical characteristics noble gases have been indicated as tracers of fluid dynamic changes. Among them 222Rn plays an important role due to wide distribution of U, and to low cost monitoring equipment. A correct understanding of transport phenomena is crucially important in data interpretation. The general features of 222Rn migration processes are discussed. (author)