Research shows that forests absorb much more mercury than imagined

Research shows that forests absorb much more mercury than imagined

Researchers studying the forests of Massachusetts say that the amount of toxic element mercury deposited in global forests may be much greater than previously known. The study shows that the mercury load carried by forests is underestimated by half. This mercury accumulates in the soil, eventually flows into streams and rivers, and finally into lakes and oceans.The research was published this week in Proceedings of the National Academy of Sciences.

Mercury threatens fish, birds, mammals and humans. Pollutants are released into the atmosphere every year through coal-fired power plants, gold mining and other industrial processes, and are distributed globally through wind and water currents. Long-term exposure or consumption of foods containing high concentrations of it can cause people’s reproductive, immune, neurological and cardiovascular problems.

Currently, the total amount of mercury deposited on land worldwide is estimated to be approximately 1,500 to 1,800 metric tons per year. If further research in other forests confirms the results of the new study, it may actually more than double.

For 16 months, the team has accurately measured how atmospheric mercury is deposited in the Harvard Forest in Petersham, Massachusetts. This is a nearly 4,000-acre site that includes deciduous trees such as red oak and red oak. Red maple tree. Instruments placed at different heights on a 100-foot-high research tower in the forest observe how mercury deposits from the canopy to the forest floor.

The results showed that three-quarters of the sediments came from gaseous mercury—five times more than rain and snow sediment sediments, and three times more than litter sediment sediments, in which mercury is transported by leaves that fall to the ground. Most previous studies have not directly involved gaseous mercury; other researchers have used litterfall as its proxy before. However, in the new study, the researchers directly measured gaseous deposition.

Lead author Daniel Obrist of the University of Massachusetts Lowell said that this study is the first comprehensive study of how atmospheric mercury is deposited in any rural forest. “Trees absorb gaseous mercury from the atmosphere through their leaves, and when plants shed their leaves or die, they basically transfer the mercury from the atmosphere to the ecosystem,” he said.

“By measuring trace gases from the top of the tree canopy to the forest floor, we can understand how these gases move in the forest and where the various gases are absorbed and emitted,” said co-author of the study and Columbia University atmospheric researcher Roísín Commane. Lamont-Dougherty Earth Observatory.

The researchers are continuing their work in the second forest in northern Maine. The Howland Forest in the state is a research site of nearly 600 acres, full of evergreen plants, keeping their leaves all year round, providing a completely different habitat. Obrist said that evaluating the two forests will allow researchers to examine differences in mercury accumulation between different forest types.

Other contributors to the study include students from the University of Massachusetts Lowell and Columbia University; collaborators with Harvard University; the Reno Desert Research Institute in Nevada; the Northwest Institute of Eco-Environment and Resources; and Lanzhou University, Chinese Academy of Sciences. The research was supported by the National Science Foundation; additional research support came from the US Department of Energy.

Adapted from a press release from the University of Massachusetts Lowell.