Dynamics of PM2.5 concentrations in Kathmandu Valley, Nepal

Aryal, Rupak Kumar, Lee, Byeong-Kyu, Karki, Rahul, Gurung, Anup, Baral, Bivek and Byeon, Seung-Hyeok (2009) Dynamics of PM2.5 concentrations in Kathmandu Valley, Nepal. Journal of Hazardous Materials, 168 2-3: 732-738. doi:10.1016/j.jhazmat.2009.02.086

Author Aryal, Rupak Kumar
Lee, Byeong-Kyu
Karki, Rahul
Gurung, Anup
Baral, Bivek
Byeon, Seung-Hyeok
Title Dynamics of PM2.5 concentrations in Kathmandu Valley, Nepal
Formatted title
Dynamics of PM2.5 concentrations in Kathmandu Valley, Nepal
Journal name Journal of Hazardous Materials   Check publisher's open access policy
ISSN 0304-3894
Publication date 2009-09-15
Sub-type Article (original research)
DOI 10.1016/j.jhazmat.2009.02.086
Volume 168
Issue 2-3
Start page 732
End page 738
Total pages 7
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Language eng
Formatted abstract
This study analyzed daily patterns and dynamics of PM2.5 concentrations in the Kathmandu Valley during three winters. The PM2.5 data showed a daily repetitive cycle which represents influence of local air flow and dispersion and accumulation of air pollutants in the valley. Two concentration peaks were observed in the morning and in the evening periods, and they fell down during the daytime and the nighttime periods. This indicates local emission sources as major contributors in the valley. The more pronounced morning peak compared to the evening peak showed that the upslope wind in the morning helped to move the polluted inversion layer downward, subsequently adding to freshly emitted pollutants and causing a sharp pollutant concentration rise in the morning. Katabatic wind and rise of temperature in the basin during the day helped the pollutant upflow and dilution, resulting in a sharp PM2.5 concentration decline. Through the afternoon, the decrease in air temperature followed by decrease in wind speed caused to lower PM2.5 peaks in the evening. Also, higher morning peaks of PM2.5 concentrations compared to the evening indicated pollution from the previous day is added to the fresh emission. The valley had increased PM2.5 from the beginning of October which continued till the first week of February. The increase in PM2.5 peak fit the logistic equation y = [k/(1 + exp (pqx)] + a sin(bx) where k, p, q, a, and b are constants.
Keyword Diurnal cycle
Kathmandu Valley
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
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Created: Fri, 10 Feb 2012, 12:05:59 EST by Dr Rupak Aryal on behalf of Advanced Water Management Centre