Project Overview:

Why Mercury?
In 2007, MSI began studying mercury in rain and snow, lakes, and forest soils. Mercury is an emerging environmental health concern in the Four Corners. It is neurotoxin to humans and wildlife and becomes more concentrated as it is passed up the food web from plants to herbivores to predators. Mercury is a naturally occurring element in rocks and soil, but it also is emitted into the air by burning mercury-containing coal and waste products. Precipitation falling in Mesa Verde National Park has some of the highest mercury concentrations measured across the United States. Many reservoirs in SW Colorado and NW New Mexico are listed for fish consumption advisories due to bioaccumulation of mercury in game fish.

Blake Meneken collects a sample of precipitation from Molas Pass. The sample was analyzed for mercury.

Mercury in precipitation
One objective was to determine the amount and concentration of mercury in precipitation falling at high altitude in SW Colorado. “We’ve found rather elevated concentrations of mercury in rain collected at Molas Pass” reported Dr. Koren Nydick, MSI’s chief scientist. As a result, the San Juan National Forest will be installing a long-term precipitation collector on Molas Pass to track mercury deposition for years to come.

Mercury in Lakes & Reservoirs
MSI also measured mercury in zooplankton from 28 lakes and reservoirs. Zooplankton are small invertebrates that fish eat. “Mercury concentrations in zooplankton varied a lot among lakes from low to quite high”, says Nydick. Six lakes had methyl mercury levels in zooplankton that were higher than the levels measured from two reservoirs with fish consumption advisories. Zooplankton from three lakes had methyl mercury concentrations above the level of concern for fish-eating mammals. Nydick noted, “The variability among lakes was not that surprising because bioaccumulation of mercury depends on a lot of factors in addition to the amount of airborne mercury deposition. However, it was surprising how high mercury concentrations were in a few of the lakes”. Additional factors regulating the amount of mercury in zooplankton can include water chemistry, watershed characteristics, and productivity of the water body. MSI plans to use water quality and watershed measurements to identify what makes lakes and reservoirs in our region more or less susceptible to bioaccumulation of mercury.

Links to More Information

Preliminary Results (2008 report, PDF)

2009 Presentation "Mercury in the Mountains" (2.5 MB PDF)

Lake sediments record a history of mercury accumulation as material is deposited on the lake bottom over time. MSI collected sediment cores from four mountain lakes and Vallecito Reservoir. The cores from the lakes show that mercury input increased since pre-industrial times, peaked between 1960 and 1990, and then decreased or remained constant in the past two decades. “The peak (in mercury input) is pretty consistent with when many coal-fired power plants came online in the western US”, says Nydick. “Recent declines are probably due to regulations that were enacted in the 1990’s on mercury emissions from waste incinerators”. Coal-fired power plants are the largest source of human-caused mercury emissions in the USA, according to the Environmental Protection Agency.

Mercury in Forest Soils
In 2008 MSI’s Nydick, along with Fort Lewis College student Anya Angst, began looking at mercury in forest soils from burned and unburned areas in Missionary Ridge. “We really want to understand how fire affects mercury bound to forest soils and the transport of this mercury into water bodies” remarked Nydick. MSI is collaborating with researchers from the University of Colorado and the US Geological Survey to study this question.
Preliminary results indicate that low intensity prescribed burning had no effect on the amount of mercury or organic matter in soil, but high intensity wildfire dramaticaly decreased both organic matter and mercury concentrations. In both cases, mercury and organic matter were highly correlated, indicating the importance of organic material to bind the mercury in these soils.

Project Updates:

In 2009 MSI will begin a pilot study of mercury in wildlife of Mesa Verde National Park and also conduct “back trajectory” meteorological modeling to better understand where the mercury comes from.

Project Partners:

Mountain Studies Institute

University of Colorado at Boulder

Mesa Verde National Park

BioDiversity Research Institute

Win Wright - Southwest HydroLogic

Thanks to the Project Supporters!

Major Funders:

US Environmental Protection Agency

US Forest Service - San Juan National Forest

National Park Service

Other Funders:

San Miguel County

US Forest Service - Grand Mesa, Uncompahgre, and Gunnison NFs

Telluride Institute.