Submicron Aerosol Spatial Variation in the Kathmandu Valley, Nepal 2018
BENJAMIN WERDEN, Michael R. Giordano, Khadak Mahata, Douglas Goetz, Md. Robiul Islam, Siva Praveen Puppala, Arnico Panday, Robert J. Yokelson, Elizabeth Stone, Peter F. DeCarlo,
Aerodyne Research, Inc. Abstract Number: 535
Working Group: Aerosols Spanning Spatial Scales: Measurement Networks to Models and Satellites
AbstractThe rapidly developing urban Kathmandu Valley, Nepal, is subject to poor air quality from a variety of local and regional sources. The Nepal Ambient Monitoring and Source Testing Experiment [NAMaSTE] quantified emissions for a suite of common anthropogenic South Asian pollution sources and measured ambient aerosol composition and concentration.
Ambient aerosol mass spectrometer (AMS) measurements in pre-monsoon 2015 were taken in suburban Bode at the location of the previous SUSKAT experiment, and in Winter 2018 at three locations, an urban site, a suburban site, and a rural site on the valley rim. Mobile AMS measurements in pre-monsoon 2018 reinforce the spatial variation of aerosol composition and concentration due to source proximity.
PM
1 at the 2018 urban monitoring site, Ratnapark (mean 102 µg/m
3), was dominated by traffic emissions. The rural site, Dhulikhel (mean 48 µg/m
3), served as a regional background site, with minimal local sources; oxidized organic was the major aerosol fraction. The suburban sites, Bode Thimi (mean 40 µg/m
3) 2015 and Lalitpur (mean 106 µg/m
3) 2018, had seasonal differences, but significant impact from brick kiln emissions. Suburban sulfate concentrations peaked over 16 µg/m
3. Mean PM
1 exposure was above the 24-hour WHO threshold of 25 µg/m
3 and the annual limit of 10 µg/m
3 at all sites.
The average ambient PM
1 in urban Kathmandu during April 2018 was 34 µg/m
3; the rural background was 29 µg/m
3. Mobile measurements of on-road PM
1 averaged 65 µg/m
3. On-road PM
1 was at least 20% higher than ambient.
Sulfates exhibited regional scale influence with an enhancement of 20 µg/m
3 in industrial regions. Brick kiln plumes had sulfate concentrations up to 50 µg/m
3.
Ambient and mobile measurements combined quantify the contribution and spatial impact of localized sources of anthropogenic emissions and highlight the influence of source proximity.
This work was funded by NSF awards:
(AGS1461458, AGS1351616, AGS1349976)