Mercury, Ozone, Nitrogen of Concern



SILVERTON – A recent booklet released by the Silverton-based Mountain Studies Institute suggests that air quality in the eastern Four Corners region may be worse than we realize.

“While our air is better than many urban areas, the deterioration of our air quality is somewhat surprising for such a rural area,” stated the not-for-profit research and education center’s “How’s the Air Out Here?” publication.

“Ground-level ozone is close to exceeding the standard for human health, fish consumption advisories for mercury exist on many reservoirs, visibility often is impaired, and concentrations of nitrogen compounds in rain and snow are rising,” it continued.

The report, created for the lay-reader, primarily compiled existing research on mercury deposition, ground level ozone, particle pollution, visibility and haze, and nitrogen and sulfur deposition in eight counties in southwestern Colorado, including San Miguel County, and two counties in northwestern New Mexico.

“It’s an effort to take information that’s often technical to bring it together in one place and to make it accessible to people who aren’t experienced in those fields,” said MSI Executive Director and report author Koren Nydick, PhD.

Although a naturally occurring element in air, water, and soil, mercury is also a potent neurotoxin, derived largely by burning fossil fuels, predominantly coal.

The U.S. Environmental Protection estimates that humans are responsible for generating two-thirds of global mercury emissions; the remaining one-third results from natural sources like erupting volcanoes and geothermal activity.

The United Nations attributed 45 percent of global mercury emissions caused by humans to the burning of fossil fuels in a 2008 report.

It also found that power plants are the largest single source of mercury emissions in most countries with high levels of mercury.

Sixteen coal-fired power plants exist within or close to the Four Corners, and Mesa Verde National Park, at17.6 nanogram per liter contains the third highest concentration of mercury in the country, according to the National Atmospheric Deposition Program/Mercury Deposition Network that collected weekly precipitation across the country US for its 2007 assessment.

The two highest concentrations were found in central Arizona and southwest New Mexico.

“There are higher levels of mercury than expected in the environment,” said Nydick.

Mercury can combine with carbon to form “organic” compounds among which

methylmercury, which is formed by bacteria in water and soil, is the most common.

“If there aren’t the right ecosystems available to methylate [mercury], then it doesn’t get into the food system,” said Nydick.

According to the Environmental Protection Agency, methylmercury easily accumulates in fish and shellfish – the consumption of which leads to most mercury exposures in the U.S.

Although exposure can harm adults, it is particularly dangerous for fetuses, infants and children who can experience neurological damage as a result.

The booklet also incorporates original research in which the MSI collected mid- to large- size zooplankton – invertebrate animals that eat microscopic algae and, in turn, are eaten by fish – in 22 lakes and reservoirs in the San Juan Mountain region.

Blue Lake (Bridal Veil), Miramonte Reservoir, Hope Lake, Woods Lake, and Silver Lake were all sampled near Telluride and among them none exceeded the 100 nanogram per gram of mercury in zooplankton considered the threshold of concern for fish-eating mammals.

However, at just over 60 nanograms per gram the concentration at Woods Lake registered very close to the Narraguinnep Reservoir where a fish consumption advisory is in place. Simarly, Silver Lake, at more than 80 nanograms per gram, exceeded that found at the Vallecito Reservoir where an advisory also exists.

Although Silver Lake was still shy of the threshold, “The level is high enough for concern,” for fish-eating mammals like otters and raccoons, said Nydick.

Crater Lake, Molas Lake and Andrews Lake each had mercury concentrations in zooplankton that exceeded the threshold of concern containing about 120, 160, and 180 nanograms per gram, respectively.

“Mercury was thought to be an issue in lakes, wetlands…but we’re finding it’s getting into terrestrial species through songbirds,” said Nydick, who recently completed fieldwork to collect blood samples from songbirds that will be tested for mercury.

“Songbirds are another good indicator of whether there is more bioaccumulation in the area,” she said.

Although there are no ozone monitors in San Miguel County, the report indicates that the region meets the EPA standard of 75 parts per billion for ground level ozone it set in 2008 – if only closely.

A number of health and environmental groups including the American Lung Association filed suit against the EPA shortly thereafter, however, because it set the standard higher than the 60 to 70 parts per billion recommended by its own scientists.

Had the recommended standard been applied, “I think it’s unlikely that we would achieve the standard,” said Nydick.

Like mercury, nitrogen and sulfur pollution result from burning fossil fuels, but nitrogen from farm fertilizer and animal waste can also evaporate into the air.

Although nitrogen and sulfur concentrations are relatively low in this region compared to other parts of the country, the mountain and desert ecosystems found here are more vulnerable to nitrogen deposition than other types.

“The short growing season and low biological productivity at high elevations and in deserts limit the amount of nitrogen that plants and microbes can absorb during the year,” the booklet stated.

Chemical changes in surface water, soils and trees have been linked to nitrogen deposition in Rocky Mountain National Park, where changes in alpine tundra and aquatic plant species have been observed.

“It really shouldn’t be in alpine streams,” said Nydick, adding that nitrogen deposition research done at Rocky Mountain National Park could indicate its effects here.

“I can’t say whether the same levels of change in Rocky Mountain National Park will happen here, but the environments are similar so it’s more likely,” she said.

“It suggests that there could be changes going on here, but no research has been funded so we don’t know.”

The Mountain Studies Institute will host its 2009 San Juan Air Quality Forum at the Durango Public Library on Wed., August 26, from 8:30 a.m. to 4:30 p.m. Call MSI in Silverton at 970-387-5161 or Fort Lewis College 970-247-7071 to learn more.