Origin of the carbon dissolved in the groundwater and derivation of Earth diffuse emission of CO_2: the case of the Italian Peninsula

摘要

Diffuse Earth degassing is the main source for the carbon dissolved in the groundwaters of Apennines, which host the main aquifers of the Italian Peninsula. We used data from about 200 springs to derive a regional map of CO_2 Earth degassing from central and south Italy. A globally significant amount of deeply derived CO_2 (～10% of global CO_2 emitted from subaerial volcanoes) is released by two large areas located in western Italy. The map shows that the anomalous flux of CO_2 suddenly disappears in correspondence of a narrow band where most of the Italian seismicity concentrates. Here, at depth, the gas accumulates in crustal traps generating CO_2 overpressured reservoirs which favor seismogenesis.