Measurement system for particulate nitrate based on the scrubber difference NO-O3 chemiluminescence method in remote...

Area of Science:

• Atmospheric Chemistry
• Environmental Monitoring
• Analytical Chemistry

Background:

• Accurate measurement of particulate nitrate (NO3(-)(p)) is crucial for understanding atmospheric processes in remote regions.
• Existing methods may face challenges in detecting low concentrations or specific particle sizes.

Purpose of the Study:

• To develop and validate a novel analyzer for measuring particulate nitrate concentrations in remote areas.
• To assess the performance and applicability of the scrubber difference/NO-O3 chemiluminescence (SD-CL) method for NO3(-)(p) analysis.

Main Methods:

• Utilized a scrubber difference/NO-O3 chemiluminescence (SD-CL) method for NO3(-)(p) quantification.
• Employed annular denuders coated with NaCl for gaseous nitric acid (HNO3) and PTFE filters for NO3(-)(p) as scrubbers.
• Conducted measurements at Cape Hedo, Okinawa, Japan, analyzing NOy, HNO3, and NO3(-)(p).

Main Results:

• The SD-CL method demonstrated high sensitivity, with over 99.5% of observed NO3(-)(p) concentrations exceeding the detection limit.
• The analyzer showed good transmission efficiency for coarse particles (93.4 ± 5.8%), with losses within the method's uncertainty (±20%).
• Comparison with a standard nitrate monitor showed a strong correlation (R = 0.73), indicating reliable measurement of coarse NO3(-)(p).

Conclusions:

• The developed SD-CL method is a viable and effective tool for measuring particulate nitrate in remote environments.
• The technique is particularly useful for detecting coarse particulate nitrate, which often dominates in remote areas.
• The SD-CL method offers a reliable approach for atmospheric nitrate monitoring where coarse particles are prevalent.