Mojave Desert Network
The Mojave Desert Vital Signs Network (MOJN) includes six national park units in California, Arizona, and Nevada: Death Valley National Park (NP), Great Basin NP, Joshua Tree NP, Lake Mead National Recreation Area (NRA), Manzanar National Historic Site (NHS), and Mojave National Preserve (NPres). MODN encompasses a wide variety of ecosystems, from below-sea-level deserts to high alpine forests. Joshua Tree NP is a Class I air quality area, receiving the highest protection under the Clean Air Act. The other park units are Class II air quality areas and receive protection under the Act, but to a lesser degree.
Death Valley NP, Great Basin NP, and Joshua Tree NP have on-site monitoring for wet and dry atmospheric deposition, ozone, and visibility. Lake Mead NRA has passive and portable samplers for ozone. The other parks have no nearby monitoring. The air pollutants of greatest concern for the MODN are nitrogen (wet and dry deposition) and ozone. Nitrogen may increase the dominance of invasive alien plants and decrease the diversity of plant communities in desert regions, as it has in other ecosystems. Ozone, in addition to harming human health, harms vegetation. Joshua Tree NP is in an area designated non-attainment for the 8-hour ozone standard. An ozone injury risk assessment indicates the risk of injury to vegetation is high in Joshua Tree NP, Mojave NPres, and Manzanar NHS.
The Network map below provides information on air quality monitoring. Ozone, sulfur dioxide, dry deposition, and meteorology are collected by the Clean Air Status and Trends (CASTNet) and Gaseous Pollutant Monitoring (GPMN) networks. Ozone is also monitored with passive samplers and portable continuous analyzers. Wet Deposition is monitored through cooperation with National Atmospheric Deposition Program/National Trends Network (NADP/NTN). Visibility is monitored as part of the Interagency Monitoring of Protected Visual Environments (IMPROVE). Additional details on these parameters are described in Air Quality Monitoring.
Air quality monitoring in or near the network is indicated on the map by symbols, with the blue line showing the approximate borders of the network. The legend shows the symbols for the type of monitoring present, with NPS park units in green. The Class I area has linkable access to ARIS information.