Fine particulate chemical composition and light extinction at Meadview, AZ

Area of Science:

• Atmospheric Chemistry
• Environmental Science
• Air Quality Research

Background:

• Particulate matter significantly affects air quality and visibility, especially in protected areas like Grand Canyon National Park.
• Understanding the chemical composition and sources of fine particulate matter is crucial for effective air pollution management.

Purpose of the Study:

• To measure fine particulate matter composition (nitrate, sulfate, carbonaceous material) during the Project MOHAVE study.
• To determine the contribution of various particulate species to light extinction and visibility reduction.
• To identify the anthropogenic sources responsible for air pollution impacting the Grand Canyon region.

Main Methods:

• Utilized diffusion denuder samplers for 12-hr day-night sampling of fine particulate matter.
• Employed multiple techniques to measure organic material, including semivolatile organic compounds.
• Integrated data on particulate mass, relative humidity, light absorption, scattering, and extinction.

Main Results:

• Fine particulate organic material was the primary contributor to light extinction, followed by fine particulate sulfate.
• Periods of highest light extinction were dominated by organic material, sulfate, and light-absorbing carbon.
• Anthropogenic emissions from Los Angeles and Las Vegas were identified as major contributors to regional light extinction.

Conclusions:

• Fine particulate organic material and sulfate are key drivers of visibility impairment in the Grand Canyon region.
• Urban emissions from major Californian and Nevadan cities significantly influence regional air quality.
• Secondary sulfate from the Mohave Power Project had a negligible impact on light extinction.