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USDA Forest Service
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Washington, D.C.
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Above: California's Mokelumne Wilderness


The Clean Air Act directed federal land managers to determine those features of a national wilderness area which are affected in some way by air pollution. Monitoring these Air Quality Related Values (AQRVs) serves the purposes of determining ecosystem health related to air pollution impacts and gathering background data for the Prevention of Significant Deterioration (PSD) permit process.

In addition to AQRV monitoring, both air chemistry and atmospheric deposition monitoring are necessary to establish the linkages between air pollution and any changes to the physical, chemical, or biological condition of the sensitive receptors.


Lichen on a tree

Lichens are a prime example of a sensitive receptor to atmospheric deposition. They absorb most of their nutrients and water directly from the atmosphere, have a high retention capacity and accumulate chemicals during their long lives.

Monitoring of lichens includes tracking changes in community composition, individual lichen characteristics and physiology, and sampling chemical concentrations in the tissues. See www.nacse.org/lichenair for more information about the Forest Service's lichen monitoring program.

Aquatic Ecosystems

Monitoring lakes for changes in chemistry

Assessing the effects of air pollutant emissions on aquatic ecosystems requires an understanding of the processes that control the chemistry and biology of each lake or stream. Aquatic monitoring often begins with a chemical and biological survey of surface waters to identify particularly sensitive ecosystems.

Water chemistry is generally monitored directly as it will show changes more quickly than plant and animal communities. Many studies combine the monitoring of water quality with biological monitoring of plankton, aquatic insects, amphibians, and fish.


Visibility monitoring equipment

The Forest Service conducts visibility monitoring as one of the cooperators in Interagency Monitoring of Protected Visual Environments (IMPROVE) Program. At some sites, visibility is monitored directly using optical equipment. The Forest Service has monitored many sites over the years using automatic cameras and still monitors some with real-time cameras. You can view these historical and real-time images at www.fsvisimages.com. The particulates that contribute to haze are also collected on filters and measured to determine how visibility is impacted over time and by which pollutants. For more information, visit http://vista.cira.colostate.edu/improve or download the following documents: Abating regional haze briefing (.pdf 252kb); Atmospheric deposition monitoring briefing (.pdf 296kb); Visibility management briefing (.pdf 323kb); Visibility monitoring briefing (.pdf 323kb).

Image Credit (top): Peter Druschke (Wilderness.net image library)

[graphic] USDA logo, which links to the department's national site. [graphic] Forest Service logo, which links to the agency's national site. [graphic] A link to the US Forest Service home page.