Voyageurs National Park Air Quality Information
Overview
The air quality related values (AQRVs) of Voyageurs NP are those resources that are potentially sensitive to air pollution, and include vegetation, wildlife, water quality, soils, and visibility.
Although Voyageurs NP is relatively distant from large urban and industrial areas, long-range transport of pollution generated in the Midwest and Ohio River Valley, as well as pollutants emitted by local sources, can affect air quality in the park.
A National Atmospheric Deposition Program/National Trends Network (NADP/NTN) wet deposition monitor was installed at Voyageurs NP (site #MN32 (Sullivan Bay)) in 2000. Trend data are not yet available from the site. Data have been collected at the NADP/NTN site at Fernberg, Minnesota (site #MN18 (Snowbank Lake)), approximately 50 miles southeast of Voyageurs NP, since 1980. Wet sulfate concentration and deposition have decreased at Fernberg since 1982, with elevated values in 1998 and 1999. Wet nitrate concentration showed no overall trend, while wet nitrate deposition has decreased, with elevated values in 1998 and 1999. Wet ammonium concentration and deposition showed no overall trend, with elevated values in 1998 and 1999.
A Clean Air Status and Trends Network (CASTNet) dry deposition site was installed at Voyageurs NP (site #VOY413) in 1996. A trend analysis is not available for the park CASTNet site, and there are no other sites nearby.
Surface water chemistry data collected in and near Voyageurs NP were summarized in a 1995 Baseline Water Quality Data Inventory and Analysis report. The summarized data, as well as data collected subsequent to the report, indicate surface waters in the park are not sensitive to acidification from atmospheric deposition.
Ozone has been continuously monitored at Voyageurs NP since 1986—at Black Bay from 1987 to 1996 (site #27-071-0101) and at Sullivan Bay from 1996 to present (site #27-137-0034). 1990-1999 trend data for the two sites combined showed an annual 4th highest 8-hour average ozone concentration of 63 parts per billion, with a significant increasing trend. Concentrations at the Sullivan Bay monitor have been dropping slightly since it began operating in 1996.
Several plant species that occur in Voyageurs NP are known to be sensitive to ozone, e.g., common milkweed (Asclepias syriaca) and quaking aspen (Populus tremuloides), although the specific genotypes found in the park have not been tested under controlled conditions for sensitivity. Ozone concentrations measured at the park are low enough that ozone-induced foliar injury and/or growth effects are unlikely.
As part of the Interagency Monitoring of Protected Visual Environments (IMPROVE) network, visual air quality in Voyageurs NP has been monitored using an aerosol sampler (1988 through 1996 and 1999 through the present) and 35mm camera (1986 through 1994 at Kabetogama and 1990 through 1994 at Black Bay). The U.S. Environmental Protection Agency’s new Regional Haze regulations require improving visibility in Class I air quality areas on the days with best visibility and no deterioration on the days with worst visibility. Visibility trend data are not yet available for Voyageurs NP or other IMPROVE sites in the Great Lakes area. 1996 through 1998 IMPROVE data from the Boundary Waters Canoe Area site, 50 miles southeast of the park, show the major contributors to visibility impairment at the site from November through March were sulfates, followed by nitrates, then organics, then soil, and then light absorbing carbon. In April through October, organics contributed more than nitrates to impairment.
The NPS is particularly concerned about ambient concentrations, deposition, and effects of airborne toxics, such as persistent organic pollutants, and particularly, mercury, at Voyageurs NP. Research and monitoring in and near the park have evaluated contaminant levels and effects in ambient air, soil, surface waters, fish, crayfish, loons, eagles, and other birds.
The Minnesota Pollution Control Agency monitors air toxics at a number of locations throughout the state including International Falls, near Voyageurs NP. Concentrations of formaldehyde, carbon tetrachloride, chloroform, and ethylene dibromide have exceeded the inhalation health benchmarks at International Falls.
Voyageurs NP does not have a Mercury Deposition Network (MDN) wet mercury monitoring site, but one has been operating in Fernberg (site #MN18) since 1995. The MDN program has not yet performed trend analyses for their sites. National wet mercury concentration and deposition maps show that values from monitors in the Great Lakes region are generally higher than those in the Northeast and Western U.S. and comparable to values in Florida and the Gulf Coast.