Mercury levels in the atmosphere have decreased by almost 70% in the last 20 years, mainly due to the reduction of emissions from human activity. But there is another problem: The soil is releasing more mercury.
Mercury concentrations in the air have significantly decreased in the last two decades, especially due to the reduction of emissions caused by human activity. Still, soils – the largest natural reservoir of this toxic metal – continue to release it, and with greater intensity, warns a new study.
Mercury atmospheric concentrations have decreased almost 70% since 2000, concludes an investigation published in the magazine This descent is mainly associated with the reduction of emissions caused by the human being, especially through the qEima fossil fuels, waste incineration and mining.
“By monitoring Mercury pollution over four decades at the top of the world, we have shown that global efforts to reduce pollution are results: Mercury levels in the air around Mount Evereste have decreased in the last two decades,” explained Yindong Tong, the study’s author.
Toxic mercury for the human being and the environment
Mercury is released through environmental and anthropogenic processes. Some forms, particularly methylmercury, are, It can affect the nervous system, especially in children and fetuses under development.
Therefore, policies and regulations have been implemented to limit mercury emissions around the world.
Toxic metal not only
The fall in mercury levels can be seen as a positive sign for environmental policies such as in force since 2017. This international convention aims to Limit the main sources of mercury pollutionand its effectiveness is partly measured by the levels of this element in the atmosphere.
But there is another problem: The soil is releasing more mercury.
Despite the descent in emissions of human origin, the investigators noted that The emissions from the ground are gaining weight.
Soil is the largest natural reservoir in Mercury and can release it again to the atmosphere – a phenomenon known as reissue – especially under the effect of Increased temperatures and changes in vegetation cover.
Evereste plants keep the record of the past
To distinguish between new emissions from human sources and terrestrial mercury re -sessions stored in the soil, researchers can observe mercury isotope standards in the atmosphere.
However, regular measurements of atmospheric mercury isotopes were only performed about a decade ago. Thus, Tong, Rooyu Sun and his colleagues wanted to rebuild information about previous levels of atmospheric mercury to understand how they had changed.
To retreat in time, the investigators resorted to Leaves of a small perennial plant (Androsace carpet) that grows at the top of Mount Evereste. Like the trunk rings of a tree, this plant develops a new layer of external leaves each year, reflecting what its environment was like.
When collecting samples of older leaves in the center of two Evereste factories, the team obtained An idea of atmospheric mercury levels since 1982.
They found that between 2000 and 2020, total atmospheric concentrations of elementary mercury decreased 70%, and terrestrial mercury emissions represent a larger fraction of the total annual emissions. At the moment, The soil emits significantly more mercury (62%) than artificial sources (28%).
The authors of the study warn that, although anthropogenic emissions control policies are working, next efforts should focus on Limitation of soil re -sessions, especially in a context of climate change.
These conclusions are aligned with data from other studies conducted in the northern hemisphere, which also indicate a general decline in mercury levels in the atmosphere in recent decades.
