PM Speciation Monitors in USEPA Study

The USEPA is evaluating the feasibility of operating continuous particulate matter (PM) speciation monitors in a pilot program. The initial phase of the monitoring study involves five test sites across the US, and is projected to last one year. One of the aims of the study will be to compare conventional filter-based sampling and analysis methods with results generated by the continuous monitors.

The scenes below were taken at a Texas Natural Resource Conservation Commission (TNRCC) facility in Austin, Texas, where the agency's new speciation monitoring station was readied. The first Texas field campaign involving the station will be in Houston.

Each of the test sites contains three continuous PM speciation monitors manufactured by Rupprecht & Patashnick:

• Series 5400 Ambient Carbon Particulate Monitor
• Series 8400N Ambient Particulate Nitrate Monitor
• Series 8400S Ambient Particulate Sulfate Monitor

Many of the USEPA-sponsored PM supersites also operate these monitors. All three instruments have proven their performance at many locations in the US and overseas.

The Series 5400 monitor provides an indication of the organic and elemental carbon content of ambient particulate matter. These carbon species can be an indicator of the man-made impact upon air quality, and may also point to particular sources.

The Series 8400N and 8400S monitors measure the mass concentration of particulate nitrate and particulate sulfate contained in ambient air. These constituents are often the result of secondary aerosol formation in which reactions among gases, sunlight and humidity lead to the formation of these particles. Particulate nitrate can represent an important proportion of fine particulate mass concentrations in certain western US locations, while the eastern part of the US tends to be dominated by particulate sulfate.

- Feb 02 -

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