摘要
This study reports for the first time a comprehensive analysis of nitrogenous and carbona-ceous aerosols in simultaneously collected PM_(2.5) and TSP during pre-monsoon(March-May 2018)from a highly polluted urban Kathmandu Valley(KV)of the Himalayan foothills.The mean mass concentration of PM_(2.5)(129.8 μg/m^(3))was only-25%of TSP mass(558.7 μg/m^(3))indicating the dominance of coarser mode aerosols.However,the mean concentration as well as fractional contributions of water-soluble total nitrogen(WSTN)and carbonaceous species reveal their predominance in find-mode aerosols.The mean mass concentration of WSTN was 17.43±4.70 μg/m^(3)(14%)in PM_(2.5) and 24.64±8.07 μg/m^(3)(5%)in TSP.Moreover,the fractional contribution of total carbonaceous aerosols(TCA)is much higher in PM_(2.5)(~34%)than that in TSP(~20%).The relatively low OC/EC ratio in PM_(2.5)(3.03±1.47)and TSP(4.64±1.73)suggests fossil fuel combustion as the major sources of carbonaceous aerosols with contributions from secondary organic aerosols.Five-day air mass back trajectories sim-ulated with the HYSPLIT model,together with MODIS fire counts indicate the influence of local emissions as well as transported pollutants from the Indo-Gangetic Plain region to the south of the Himalayan foothills.Principal component analysis(PCA)also suggests a mixed contribution from other local anthropogenic,biomass burning,and crustal sources.Our re-sults highlight that it is necessary to control local emissions as well as regional transport while designing mitigation measures to reduce the KV's air pollution.
基金
supported by the Strategic Priority Research Program of Chinese Academy of Sciences,Pan-Third Pole Environment Study for a Green Silk Road (Pan-TPE)(No.XDA20040501)
the National Natural Science Foundation of China (Nos.41705132,41675130)
the State Key Laboratory of Cryospheric Science (No.SKLCS-ZZ-2020)
the grant received from the AsiaPacific Network for Global Change Research (APN)(Project referenceCRECS2020-07MY-Tripathee)
Chinese Academy of Science for international Young staff support under the PIFI(2020FYC0001) program
part of the framework across the TPAtmospheric Pollution and Cryospheric Change(APCC)
HKSAR governmentfor providing Belt&Road scholarship
the Research Grants Council (RGC) of Hong Kong for providing Hong Kong PhD Fellowship Scheme (HKPFS),2020/21 (No.PF19-33279)
support from the Institute for Advanced Sustainability Studies (IASS),which is funded by the German Federal Ministry for Education and Research (BMBF)and the Brandenburg State Ministry for Science,Research and Culture (MWFK)
