If mercury is found among traces of our planet’s geological past, for example in sediments or ice holes, specialists would conclude that this toxic heavy metal entered our atmosphere as a result of a volcanic eruption, and then found its way into the sediments and ice. However, the origin of mercury from the recent past cannot be said to be very clear.
the Geophysical Research Letters Magazine, researchers from Harvard University report that they have evaluated the amount of mercury of volcanic origin in our current atmosphere. This type of survey has not been done before, as it is very difficult to monitor mercury.
The researchers were not able to measure mercury itself, but rather sulfur dioxide, the amount of mercury can be estimated with a fairly high degree of accuracy. The amount of sulfur dioxide of volcanic origin can be measured by satellite measurements, and due to the development of this technology and coverage, very accurate data are now available. For this reason, we now know that annual emissions of volcanic sulfur dioxide, previously thought to be 13 million tons, are now at least 20 million tons.
The researchers’ goal was to estimate the amount of volcanic mercury as accurately as possible, as well as assess the path of the atmosphere and circulation of the heavy metal, and then create a model that could be used to calculate the amount of mercury entering. Human-related environment. Modeling also made it possible to calculate where air currents carried mercury.
According to calculations, volcanoes release an average of 232 tons of mercury into the atmosphere every year (including continuous gas emissions and individual eruptions), and 580 tons of mercury can remain in the atmosphere continuously, just thanks to this emission. 75% of volcanic mercury enters the atmosphere from volcanoes in tropical regions. On the other hand, mid-latitude volcanoes are more active sources of mercury in the Northern Hemisphere, and this is responsible for the remaining amount, as the Arctic regions contribute only a practically insignificant amount to the global volcanic mercury balance. Of course, there can be large variations in mercury emissions associated with explosions. There are eruptions that release only 100 kilograms of mercury, but for example, in the 1991 eruption of Pinatubo, about 55 tons entered the atmosphere.
But between 2013 and 2015, the amount of mercury in the atmosphere was seven times higher than the 580 tons of volcanic origin: 4,000 tons! This means that compared to human-caused emissions – mining, coal power plants, cement production and other industrial sources – mercury emissions from volcanoes pale in comparison to reality. With humans, just such massive explosions competitivesuch as the Siberian Trap basalt eruption, which caused the largest extinction wave on our planet at the end of the Permian, about 250 million years ago.