On the circulation of hydrogen in the atmosphere and the Earth’s crust

Abstract

A review of data on sources and sinks of hydrogen of various origins in the atmosphere and in the near-surface part of the Earth’s crust is given (only some cases we are talking about the crust as a whole). Based on the results of the consideration of this information, it was concluded that the influence of underground non-biogenic («geological») hydrogen on the content and balance of gas in the atmosphere, up to the stratosphere, is insignificant. The complexity of the experimental determination of the flow of geological hydrogen, free of biogenic and anthropogenic interference, the influence of the testable excavation, etc. is obvious. Probable sources of deep hydrogen are considered: the remains of magmatic gases (outside the areas of volcanism), metamorphic reactions, and radiolysis of water. The potential for significant H2 flow is only apparent in areas of currently activated faults. The data on the most powerful suppliers of geological hydrogen — modern active volcanoes and thermal fields are given. The gas circulation scheme of the Avachinsky volcano is built, based on the thermal model. The latter is controlled by data from geothermometers, the results of direct temperature measurements in deep wells, and a velocity model. The possibility of fumaroles carrying unchanged hydrogen from the magma chamber has been shown. The prospects for the formation of hydrogen deposits are estimated as uncertain. Magmatic and metamorphogenic gas in some areas is formed enough to accumulate a significant deposit over several tens of thousands of years. But the possibility of its preservation during this period or longer raises doubts. Hydrocarbon deposits without material input from great depths can lose reserves in much less time. Higher rocks permeability to hydrogen contributes to much greater gas leakage.