Perceived as romantic by many, the fallen leaves of autumn transfer mercury from the atmosphere to the earth’s environment, posing a health risk to humans and wildlife, a recent study has revealed.
According to U.S. Geological Survey research, the litterfall, the leaves and needles that drop to the forest floor each year, delivers as much mercury as precipitation does every year to eastern U.S. ecosystems.
"Our research found that annual amounts of mercury deposited in autumn litterfall from deciduous forests were equal to or exceeded the annual amounts deposited in precipitation," USGS research hydrologist Martin Risch said in a statement.
"Before these studies, we didn't know the extent of litterfall as a mercury pathway in different types of forests across the eastern U.S.," he said, adding that precipitation, a major avenue by which mercury is transferred from the atmosphere into the environment, has been increasing in the Great Lakes region.
Mercury contaminates the environment as it accumulates in fish and food webs, directly affecting the health of man and animals.
“Most of the mercury that eventually ends up in fish and food webs come from the air, and much of the mercury in the air comes from human sources such as coal-fired power plants, industrial boilers, cement manufacturing, and incinerators. Forest canopies naturally remove mercury from the air and incorporate the mercury into and onto the leaves and needles of trees,” USGS scientists said.