(NaturalNews) A recent study has found that, while mercury is released into the atmosphere every year from industrial sources, about 30 percent as much makes its way there via forest fires.
According to researchers at the National Center for Atmospheric Research (NCAR) in Boulder, Colo., who authored the 2007 study, fires in several states, including Alaska, California, Oregon, Louisiana and Florida, were responsible for emitting large quantities of the toxic metal substance. Additionally, more mercury is sent into the atmosphere from sources in the southeast than in any other part of the country, they said.
In all, scientists said fires in the continental U.S. and Alaska release about 44 metric tons of mercury annually.
"It's important to understand the movement of mercury through the environment," said Cliff Jacobs of the National Science Foundation (NSF), NCAR's principal sponsor. "This study offers new insights, and points to the need for additional research to reduce uncertainty and improve our understanding of the chemical and physical processes at work."
'Mercury from other sources is being deposited in the soil'
The six-year-old study builds on earlier particulate matter research but was the first to estimate the amount of mercury emitted in each state. The calculations were based on a computer model developed at NCAR. The study's authors cautioned that their estimates for the nation were preliminary and were subject at the time to a 50-percent margin of error.
The study, "Mercury Emission Estimates from Fires: An Initial Inventory for the United States," was published online in the journal Environmental Science and Technology.
The researchers note that mercury does not originate in the fires, but rather, it comes from industrial and natural sources and then often settles into soil and plant matter. Intense fires can then release mercury back into the atmosphere, where it then poses new dangers to sensitive waterways and other areas.
"What we are seeing is that mercury from other sources is being deposited into the soil and then being released back into the atmosphere, where it can travel far downwind and contaminate watersheds and fragile ecosystems," said NCAR scientist Christine Wiedinmyer, one of the study's coauthors. "It's important for federal and state officials to have this type of information and to know where mercury is coming from so they can better protect public health and the environment."
Mercury is a toxin that can threaten human health and ecosystems, said the scientists. Also, they say, depending on what form it takes, it can travel quite a way into the atmosphere before finally returning to Earth via precipitation or dust particle settling.
It is particularly dangerous if it ends up in water, because there it can transform into methylmercury and move up the aquatic food chain as it becomes increasingly concentrated.
The Environmental Protection Agency has warned that pregnant women and young children should avoid eating some types of fish and shellfish, because they can contain unsafe levels of mercury.
Alaska, California emit the most
To get an estimate of the mercury emissions, Wiedinmyer and NCAR scientist Hans Friedli, who coauthored the article, "used satellite observations of fires, aircraft and ground-based measurements of mercury, and a new computer model of fire emissions that Wiedinmyer created," said a press release by the group. "They focused on a five-year period from 2002 to 2006 and examined every state except Hawaii, where they lacked detailed data."
"These are initial estimates, but they clearly point to fires in certain states emitting particularly high amounts of mercury," Wiedinmyer said.
According to the researchers, Alaska and California - both states that experienced large wildfires from 2002 to 2006 - released more mercury than other states. They said that, over the five-year period, Alaska's annual emissions were estimated at about 12.5 metric tons, while California averaged 3.5 metric tons. These states were followed by Oregon (2.5 tons), Louisiana (1.95 tons) and Florida (1.89 tons).
"We would like to determine the risk of mercury exposure for residents who live downwind of large-scale fires," Friedli says.
Dr. Marsha Honn, PhD, writing for the Environmental Health Policy Institute, says increasing fire activity, whether due to out-of-control wildfires or controlled burns, is increasingly putting particulate matter into the atmosphere, and that matter is having negative health effects.
Writing in 2012, Honn said that new modeling efforts by the National Oceanic and Atmospheric Administration (NOAA) indicate that, each year, wildfires emit about 1.5 to 2.5 million tons of particulate matter.
"This is more than is emitted by better-known sources of PM such as fuel combustion, industrial processes and transportation," she said. "This smoke poses a danger for everyone, but is particularly hazardous to children and the elderly."
She said that about 80-90 percent of wood smoke particles are 2.5 microns or smaller, and that EPA studies show that the miniscule, dagger-shaped particles can be really harmful to children, since they are able to penetrate more deeply into a child's lungs. Other particles, she said, pass through the lungs and find their way into the blood stream, where they then attack vital organs.
"An article by the American Thoracic Society found that with an increase of 10 micrograms per cubic meter of particles over two years, the risk of dying was increased by 32 percent for people with diabetes, 28 percent for people with COPD, asthma and pneumonia, 27 percent for people with congestive heart failure and 22 percent for people with inflammatory diseases," she wrote.
Of all that is being emitted, mercury is the worst
There are several harmful substances released through burning, but, she says, mercury is the worst.
"Scientists estimate that fires in the continental U.S. and Alaska release 44 metric tons of mercury into the atmosphere every year," she said, citing the 2007 study.
In an earlier study, in 2001, "researchers collected foliage and ground litter samples from seven forests across the continental United States," she wrote. "These samples were set alight at a U.S. Forest Service fires laboratory, where sensors detected large amounts of mercury. The samples released 94 to 99 percent of all the mercury stored in the foliage, and 'All the coniferous and deciduous samples contained mercury at levels ranging from 14 to 71 nanograms per gram of fuel.'"