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Mercurial Breathing Of The Earth

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17.11.2006

The Baikal rift zone is characterized by high seismic, thermal and hydrothermal activity. Therefore, this area is very convenient for investigation of geochemical activity of fractures, in particular for “ mercurial breathing”. As the substances from fractures accumulate in the soil, the Irkutsk researchers measured mercury content in the soil profiles that cut the fracture zones.

The background content of mercury in the soil humus level of the Baikal region lies within the range of 16 through 29 thousandth of milligram per kilogram of soil. All active fractures of the Bailak rift zone, regardless of their type, are accompanied by mercurial anomalies in the water, soil, soil and surface air. Mercurial streams in the fracture zones are extremely changeable in time and space. Their intensity depends on seismic activity and, probably, powerful atmospheric disturbances (cyclones). In the state of seismic rest, the fractures’ background exceeds by 2 to 10 times the background of sections adjacent to the fracture. But during seismic activity, mercury content bursts may exceed the background by 20 to 30 and more times. Mercury emission from fractures reaches the maximum values on the eve of major earthquakes.

Mercury is present not only in the soil air, but accumulates in the humus layer and forms strong complexes with humus. Although in the regions of man-caused contamination, much higher amount of mercury is connected with the humus layer.

Thus, human beings confidently surpass the nature in terms of soil contamination.

The researchers have counted that in quiet conditions the mercury stream in the Baikal rift zone makes approximately 4 grams per square kilometer per year. In the seismically quiet period, the stream value varies by approximately five times, during the earthquakes, it can jump up to 1,200 grams per square kilometer per year. Drastic increase of mercury stream should be expected in case of catastrophic seismic events. The example is seismoactive 2003 in the Yellowstone Park, when annual mercury emission was equal to about 20 kilograms per square kilometer.

Being aware of active zone sites within the bounds of the Baikal rift zone, the researchers evaluated the total mercury inflow from the fracture zones. In quiet conditions, mercury emission is equal to 170 through 430 kilograms per year, but in extraordinary seismic activity conditions it can theoretically reach 65 tons, which is somewhat higher than the natural emission of the entire territory of Siberia. However, such turn of events seems unlikely to the researchers.

Nadezda Markina | Source: alphagalileo
Further information: www.informnauka.ru

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