Dr. Andrzej Bytnerowicz
US Forest Service, Pacific Southwest Research Station
4955 Canyon Crest Drive, Riverside, CA 92507, USA

Passive samplers have offered new opportunities for monitoring gaseous air pollutants in mountains and other remote areas. Since the early 1990s, ozone (O3) concentrations have been monitored in the Carpathian Mountains and other smaller ranges of Central and Eastern Europe. Since the late 1990s and early 2000s, concentrations of nitrogen oxide (NO2), ammonia (NH3) and sulfur dioxide (SO2) have been also were also monitored in selected areas of the Carpathian range, specifically in the Tatra National Park in Poland and Slovakia, and Retezat and Bucegi National Parks in Romania. In California, O3, NO2, NH3 and nitric acid (HNO3) concentrations have been monitored in the San Bernardino and Sierra Nevada Mountains for the 1999  summer seasons in the entire Sierra Nevada and for the 2002 - 2006 summer seasons in the San Bernardino Mountains.

Additionally, air pollutants have also been measured in the San Francisco Bay Area, Joshua Tree National Park, Sequoia National Park, Kings River watershed and Lake Tahoe Basin in California; Columbia River Basin and Hells Canyon in Oregon and Idaho; coastal areas of Alaska; and the Athabasca Oil Sands Region of northern Alberta, Canada. With the aid of geostatistics (ESRI Geostatistical Analyst), maps of spatial and temporal distribution of various air pollutants at the scales of watershed, landscape or region have been generated. Results of passive sampler monitoring help in understanding where potential problems related to air pollution exposure may be taking place. Portable, battery-operated UV absorption instruments have been used for real-time monitoring of O3 concentrations in selected remote locations. Information from those monitors has been used for calibration of passive samplers and also for evaluation of pollution transport across mountain ranges, as well as to evaluate a potential for phytotoxic O3 effects. Information on concentrations of HNO3, NH3 and NO2 can be used for determinations of N dry deposition to forest and other ecosystems, provided that deposition velocities of these pollutants and information on vegetation cover and leaf area index are known.