Plants absorb a large amount of toxic mercury in the atmosphere and help reduce the pollutant worldwide by depositing the element in soils, the researchers said.
The process is similar to the way plants absorb carbon dioxide emissions, said the University of Massachusetts Lowell team in the United States.
Every year hundreds of tons of mercury are released into the atmosphere as a gas through the burning of coal, mining, and other industrial and natural processes.
When the plants shed leaves or die, the mercury is transferred to soils, which also find large amounts of it in water catchment areas, threatening wildlife and people who eat contaminated fish, the researchers said in Nature Reviews – Earth & Environment published study.
According to Daniel Obrist, professor at UMass Lowell, long-term exposure to high levels of mercury can lead to neurological and cardiovascular problems in humans.
According to the World Health Organization, there is no safe level of mercury for humans. Exposure to the dangerous element can lead to irritability, speech and vision disorders, hypospermia, kidney failure, and Alzheimer’s disease, among others.
For the study, the team collected 200 published studies containing data on mercury levels in vegetation in more than 400 locations around the world.
They found that about 88 percent of the mercury found in plants comes from plant leaves, which absorb gaseous mercury from the atmosphere.
Globally, vegetation can absorb more than 1,300 tons of mercury each year, which is 60 to 90 percent of what is deposited over land, according to Jun Zhou, research associate at UMass Lowell.
The study is the world’s largest comprehensive overview of the uptake of mercury in vegetation and its effects on the mercury cycle worldwide. The work will bring scientists to a better understanding of how the mercury cycle works, Zhou said.
(With contributions from agencies)